4-Way 3-Position Directional Valve (MA)

R2026b

4-way 3-position directional valve in a moist air network

Since R2025a

• 

4-Way 3-Position Directional Valve (MA) block

To add a block to a model, double-click the canvas and start typing the block name. Then, select the block from the list.

Libraries:
Simscape / Fluids / Moist Air / Valves & Orifices / Directional Control Valves

Description

The 4-Way 3-Position Directional Valve (MA) block models a valve with four openings in a moist air network, typically between an actuator, pump, and tank. A single spool controls the valve operation according to the signal at port S. You can set the baseline configuration of your valve by specifying the orifices that are open when the spool is in the neutral position (centered at 0 m) in the Neutral spool position open connections parameter, when the spool moves in the positive direction in the Positive spool position open connections parameter, and when the spool moves in the negative direction in the Negative spool position open connections parameter. You can use the Orifice parameterization parameter to specify the valve model as a linear relationship or function of user-provided data.

This block is a composite component that comprises of multiple instances of the Orifice (MA) block. For more information about the valve parameterizations and block calculations, see the Orifice (MA) block.

In this example configuration, the Neutral spool position open connections parameter is All closed. When the spool is in the neutral position, all orifices are closed to flow:

In this configuration, Negative spool position open connections is P-A, B-T. When the signal at port S moves the spool to a negative position, the paths between ports P and A and between ports B and T are open to flow. The paths between ports P and B and ports A and T are closed to flow:

In this configuration, Positive spool position open connections is P-B, A-T. When the signal at port S moves the spool to a positive position, the paths between ports P and B and between ports A and T are open to flow and the paths between ports P and A and between ports B and T are closed:

This schematic shows this configuration:

The left side corresponds to the positive position and the right side corresponds to the negative position.

Spool Displacement and Valve Configuration

The spool stroke is the amount of spool travel an orifice takes to fully open from a closed position. You can define the spool stroke using the parameters in the Valve Configuration section. The table shows how the block calculates the stroke in accordance with the valve orifice parameterization and flow path characteristics.

The direction of spool movement specified by port S depends on the spool stroke and the orifice orientation.

Spool Position When Orifice Is Open	Spool Travel, ΔS
Always closed (orifice is not selected in any spool position configuration)	N/A
Always open (orifice is selected in positive, neutral, and negative spool position configurations)	N/A
Negative	Sorifice_max + spool stroke – S
Negative and Neutral	Sorifice_max + spool stroke – S
Positive	Sorifice_max – spool stroke + S
Positive and Neutral	Sorifice_max – spool stroke + S
Neutral	|Sorifice_max| + spool stroke – |S|
Positive and Negative	–|Sorifice_max| + spool stroke – |S|

S_{orifice_max} is the spool position at the maximum orifice area defined for each orifice. The orifice area saturates at the leakage area when ΔS is negative and saturates at the maximum orifice area when the orifice is fully open. When the orifice is fully open, ΔS is equal to the spool stroke, so a value of ΔS that is greater than the spool stroke does not further increase the orifice area.

The Consistency check for neutral spool position open connections parameter verifies that:

• Any orifice listed in Neutral spool position open connections is open when the signal at S is 0

• Any orifice that is not listed in Neutral spool position open connections is closed when the signal at S is 0

You can optionally choose to receive a warning or error when any spool positions violate this check.

This table shows the possible configurations of the 4-Way 3-Position Directional Valve (MA) block.

Configuration	Parameter Values
	All four orifices are closed in the neutral position. Positive spool position open connections: P-A, B-T Neutral spool position open connections: All closed Negative spool position open connections: P-B, A-T Spool position at maximum P-A orifice area > P-A spool stroke Spool position at maximum P-B orifice area < –P-B spool stroke Spool position at maximum A-T orifice area < –A-T spool stroke Spool position at maximum B-T orifice area > B-T spool stroke
	All four orifices are open in the neutral position. Positive spool position open connections: P-A, B-T Neutral spool position open connections: P-A, P-B, A-T, B-T Negative spool position open connections: P-B, A-T Spool position at maximum P-A orifice area < P-A spool stroke Spool position at maximum P-B orifice area > –P-B spool stroke Spool position at maximum A-T orifice area > –A-T spool stroke Spool position at maximum B-T orifice area < B-T spool stroke
	Orifices A-T and B-T are closed. Orifices P-A and P-B are overlapped. Positive spool position open connections: P-A Neutral spool position open connections: All closed Negative spool position open connections: P-B Spool position at maximum P-A orifice area > P-A spool stroke Spool position at maximum P-B orifice area < –P-B spool stroke
	Orifices A-T and B-T are open. Orifices P-A and P-B are overlapped. Positive spool position open connections: P-A, B-T Neutral spool position open connections: A-T, B-T Negative spool position open connections: P-B, A-T Spool position at maximum P-A orifice area > P-A spool stroke Spool position at maximum P-B orifice area < –P-B spool stroke Spool position at maximum A-T orifice area > –A-T spool stroke Spool position at maximum B-T orifice area < B-T spool stroke
	Orifices P-A and A-T are open in the neutral position. Orifices P-B and B-T are overlapped. Positive spool position open connections: P-B, A-T Neutral spool position open connections: P-A, A-T Negative spool position open connections: P-A, B-T Spool position at maximum P-A orifice area < P-A spool stroke Spool position at maximum P-B orifice area > P-B spool stroke Spool position at maximum A-T orifice area > A-T spool stroke Spool position at maximum B-T orifice area < –B-T spool stroke
	Orifice A-T is open in the neutral position. Orifices P-B, A-T, and B-T are overlapped. Positive spool position open connections: P-A, B-T Neutral spool position open connections: A-T Negative spool position open connections: P-B, A-T Spool position at maximum P-A orifice area > P-A spool stroke Spool position at maximum P-B orifice area < –P-B spool stroke Spool position at maximum A-T orifice area > –A-T spool stroke Spool position at maximum B-T orifice area > B-T spool stroke
	Orifice B-T is open in the neutral position. Orifices P-A, P-B, and A-T are overlapped. Positive spool position open connections: P-A, B-T Neutral spool position open connections: B-T Negative spool position open connections: P-B, A-T Spool position at maximum P-A orifice area > P-A spool stroke Spool position at maximum P-B orifice area < –P-B spool stroke Spool position at maximum A-T orifice area < –A-T spool stroke Spool position at maximum B-T orifice area < B-T spool stroke
	Orifices P-A and P-B are open. Orifices A-T and B-T are overlapped. Positive spool position open connections: P-A, B-T Neutral spool position open connections: P-A, P-B Negative spool position open connections: P-B, A-T Spool position at maximum P-A orifice area < P-A spool stroke Spool position at maximum P-B orifice area > –P-B spool stroke Spool position at maximum A-T orifice area < –A-T spool stroke Spool position at maximum B-T orifice area > B-T spool stroke
	Orifice P-A is open in the neutral position. Orifices P-B, A-T, and B-T are overlapped. Positive spool position open connections: P-A, B-T Neutral spool position open connections: P-A Negative spool position open connections: P-B, A-T Spool position at maximum P-A orifice area < P-A spool stroke Spool position at maximum P-B orifice area < –P-B spool stroke Spool position at maximum A-T orifice area < –A-T spool stroke Spool position at maximum B-T orifice area > B-T spool stroke
	Orifice P-B is open in the neutral position. Orifices P-A, A-T, and B-T are overlapped. Positive spool position open connections: P-A, B-T Neutral spool position open connections: P-B Negative spool position open connections: P-B, A-T Spool position at maximum P-A orifice area > P-A spool stroke Spool position at maximum P-B orifice area > –P-B spool stroke Spool position at maximum A-T orifice area < –A-T spool stroke Spool position at maximum B-T orifice area > B-T spool stroke
	Orifices P-B and B-T are open in the neutral position. Orifices P-A and A-T are overlapped. Positive spool position open connections: P-B, A-T Neutral spool position open connections: P-B, B-T Negative spool position open connections: P-A, B-T Spool position at maximum P-A orifice area < –P-A spool stroke Spool position at maximum P-B orifice area < P-B spool stroke Spool position at maximum A-T orifice area > A-T spool stroke Spool position at maximum B-T orifice area > –B-T spool stroke
	Orifices P-A, P-B, A-T, and B-T are closed in the neutral position. P-T is open in the neutral position and closes when the spool displaces. Positive spool position open connections: P-A, B-T Neutral spool position open connections: P-T Negative spool position open connections: P-B, A-T Spool position at maximum P-A orifice area > P-A spool stroke Spool position at maximum P-B orifice area < –P-B spool stroke Spool position at maximum A-T orifice area < –A-T spool stroke Spool position at maximum B-T orifice area > B-T spool stroke Spool position at maximum P-T orifice area = any value
	Orifice P-A is a constant orifice. Orifices P-B, A-T, and B-T are open in the neutral position. Positive spool position open connections: P-A, P-B Neutral spool position open connections: P-A, P-B, A-T, B-T Negative spool position open connections: P-A, B-T Spool position at maximum P-A orifice area < P-A spool stroke Spool position at maximum P-B orifice area < P-B spool stroke Spool position at maximum A-T orifice area = any value Spool position at maximum B-T orifice area > –B-T spool stroke
	Orifice P-B is a constant orifice. Orifices P-A, A-T, B-T are open in the neutral position. Positive spool position open connections: P-B, A-T Neutral spool position open connections: P-A, P-B, A-T, B-T Negative spool position open connections: P-A, P-B Spool position at maximum P-A orifice area > –P-A spool stroke Spool position at maximum A-T orifice area < A-T spool stroke Spool position at maximum B-T orifice area = any value
	Orifice P-A is closed in the neutral position. Ports A and T do not form a flow path. Positive spool position open connections: P-A, P-B Neutral spool position open connections: All closed Negative spool position open connections: P-A, B-T |Spool position at maximum P-A orifice area| > P-A spool stroke Spool position at maximum P-B orifice area > P-B spool stroke Spool position at maximum B-T orifice area < –B-T spool stroke
	Orifice P-B is closed in the neutral position. Ports B and T do not form a flow path. Positive spool position open connections: P-B, A-T Neutral spool position open connections: All closed Negative spool position open connections: P-A, P-B Spool position at maximum P-A orifice area < –P-A spool stroke |Spool position at maximum P-B orifice area| > P-B spool stroke Spool position at maximum A-T orifice area > A-T spool stroke
	Orifice P-A is closed in the neutral position. Orifice A-T is open in the neutral position. Positive spool position open connections: P-A, P-B Neutral spool position open connections: A-T, B-T Negative spool position open connections: P-A, B-T |Spool position at maximum P-A orifice area| > P-A spool stroke Spool position at maximum P-B orifice area > P-B spool stroke Spool position at maximum A-T orifice area = any value Spool position at maximum B-T orifice area > –B-T spool stroke
	Orifice P-B is closed in the neutral position. Orifice B-T is open in the neutral position. Positive spool position open connections: P-B, A-T Neutral spool position open connections: A-T, B-T Negative spool position open connections: P-A, P-B Spool position at maximum P-A orifice area < –P-A spool stroke |Spool position at maximum P-B orifice area| > P-B spool stroke Spool position at maximum A-T orifice area < A-T spool stroke Spool position at maximum B-T orifice area = any value
	Orifice P-B is closed in the neutral position. Orifice P-T is open in the neutral position. Ports A and T do not form a flow path. Positive spool position open connections: P-A, P-B Neutral spool position open connections: P-T Negative spool position open connections: P-B, A-T Spool position at maximum P-A orifice area > P-A spool stroke |Spool position at maximum P-B orifice area| > P-B spool stroke Spool position at maximum B-T orifice area < –B-T spool stroke Spool position at maximum P-T orifice area = any value
	Orifice P-A is closed in the neutral position. Orifice P-T is open in the neutral position. Ports A and T do not form a flow path. Positive spool position open connections: P-A, B-T Neutral spool position open connections: P-T Negative spool position open connections: P-A, P-B |Spool position at maximum P-A orifice area| > P-A spool stroke Spool position at maximum P-B orifice area < –P-B spool stroke Spool position at maximum B-T orifice area > B-T spool stroke Spool position at maximum P-T orifice area = any value

Valve Orifice Parameterizations

The Orifice parameterization parameter specifies the model for the open area or flow rate through one or all of the valve orifices. If you set Area characteristics to Identical for all flow paths, the block applies the same data for all flow paths. When you select Different for all flow paths, the block uses individual parameterizations for each flow path.

The method the block uses to control each orifice depends on the Opening characteristic parameter:

• Linear — The measure of flow capacity depends on the spool position at port S. As the spool displaces to open to orifice, the measure of flow capacity scales from the specified minimum to the specified maximum.

• Tabulated — The block calculates the measure of flow capacity as a function of the spool position at port S. This function uses a one-dimensional lookup table.

The Orifice parameterization parameter determines how the block calculates the flow rate in each orifice:

• Cv flow coefficient — The flow coefficient C_v scales the flow rate in each orifice. The flow coefficient measures the ease with which a fluid can flow when driven by a certain pressure differential.

• Kv flow coefficient — The flow coefficient K_v, where $$K_v=0.865C_v$$, scales the flow rate in each orifice. The flow coefficient measures the ease with which a fluid can flow when driven by a certain pressure differential.

• Orifice area — The size of the orifice area scales the flow rate in each orifice.

Visualize Orifice Openings

To generate a characteristic plot of the valve, click the Plot button next to Valve characteristics. The plot shows the orifices selected in the Valve Configuration settings. The plot shows the sonic conductance, K_v flow coefficient, C_v flow coefficient, or orifice area as a function of spool position.

When the positive, neutral, and negative settings in the Valve Configuration parameters feature the same orifice, the plot displays the orifice openings as a constant.

To update the data after changing the block parameters, click Reload Data on the figure window.

This image shows an example valve configuration. In the Valve Configuration settings:

• Positive spool position open connections is P-A, B-T

• Neutral spool position open connections is P-T

• Negative spool position open connections is P-B, A-T

In the P-A Orifice settings:

• Spool position at maximum P-A orifice area is 2.5e-3 m

All other spool positions are at the default values.

The visualization shows that the P-A orifice is open between the spool position at -2.53e-3 and 2.53e-3 m. Because the P-A orifice is open only when the spool is displaced in the positive direction, setting the Consistency check for neutral spool and position open connections parameter to Warning returns:

Warning: P-A orifice must be closed when the spool is in the neutral position. Adjust Spool position at maximum P-A orifice area, Neutral spool position open connections, or Consistency check for neutral spool position open connections. Right-click on the block and select Fluids > Plot Valve Characteristics to view the area or flow of each connection versus spool position.

To resolve this warning, you can change:

• Spool position at maximum P-A orifice area to a value larger than 0.005 m

• Consistency check for neutral spool position open connections to None

• The valve configuration by setting Neutral spool position open connections to P-A

Assumptions and Limitations

• The Sonic conductance setting of the Valve parameterization parameter is for pneumatic applications. If you use this setting for moist air with high levels of trace gasses or are modeling a fluid other than air, you may need to scale the sonic conductance by the square root of the mixture specific gravity.

• This block does not model supersonic flow.

• There is no heat exchange between the valve and the environment.

Ports

Conserving

A — Entry or exit port

moist air

Moist air conserving port associated with the entry or exit port to the valve.

Programmatic Use

Port: A

B — Entry or exit port

moist air

Moist air conserving port associated with the entry or exit port to the valve.

Programmatic Use

Port: B

P — Entry or exit port

moist air

Moist air conserving port associated with the entry or exit port to the valve.

Programmatic Use

Port: P

T — Entry or exit port

moist air

Moist air conserving port associated with the entry or exit port to the valve.

Programmatic Use

Port: T

Input

S — Spool displacement, m

physical signal

Physical signal associated with the spool displacement, in m.

Programmatic Use

Port: S

Parameters

Valve Configuration

Positive spool position open connections — Flow paths open when the spool is in positive position

P-A, B-T (default) | P-A, P-B | P-B, A-T | P-A | P-B | P-A, P-B, A-B

Flow paths open when the spool is in a positive position. This parameter sets the valve configuration and defines the direction of spool movement according to the signal received at port S. To check the parameter settings for consistency with other orifices, set Consistency check for neutral spool position open connections to Warning or Error.

Programmatic Use

Parameter:

open_orifices_pos

Values:

"fluids.moist_air.valves_orifices.directional_control_valves.enum.OpenOrifices4WayPosNeg.PA_BT" | "fluids.moist_air.valves_orifices.directional_control_valves.enum.OpenOrifices4WayPosNeg.PA_PB" | "fluids.moist_air.valves_orifices.directional_control_valves.enum.OpenOrifices4WayPosNeg.PB_AT" | "fluids.moist_air.valves_orifices.directional_control_valves.enum.OpenOrifices4WayPosNeg.PA" | "fluids.moist_air.valves_orifices.directional_control_valves.enum.OpenOrifices4WayPosNeg.PB" | "fluids.moist_air.valves_orifices.directional_control_valves.enum.OpenOrifices4WayPosNeg.PA_PB_AB"

Neutral spool position open connections — Flow paths open when spool is in neutral position

All closed (default) | P-A, P-B, A-T, B-T | A-T, B-T | P-A, A-T | P-A, B-T | P-A, P-B | P-B, A-T | P-B, B-T | A-T | B-T | P-A | P-B | P-T | P-A, A-T, P-T | P-A, P-B, A-B | P-B, B-T, P-T | P-A, P-B, A-T, B-T, P-T

Flow paths open when the spool is in the neutral position. This parameter sets the valve configuration and defines the direction of spool movement according to the signal received at port S. To check the parameter settings for consistency with other orifices, set Consistency check for neutral spool position open connections to Warning or Error.

Programmatic Use

Parameter:

open_orifices_neu

Values:

"fluids.moist_air.valves_orifices.directional_control_valves.enum.OpenOrifices4WayNeu.AllClosed" | "fluids.moist_air.valves_orifices.directional_control_valves.enum.OpenOrifices4WayNeu.PA_PB_AT_BT" | "fluids.moist_air.valves_orifices.directional_control_valves.enum.OpenOrifices4WayNeu.AT_BT" | "fluids.moist_air.valves_orifices.directional_control_valves.enum.OpenOrifices4WayNeu.PA_AT" | "fluids.moist_air.valves_orifices.directional_control_valves.enum.OpenOrifices4WayNeu.PA_BT" | "fluids.moist_air.valves_orifices.directional_control_valves.enum.OpenOrifices4WayNeu.PA_PB" | "fluids.moist_air.valves_orifices.directional_control_valves.enum.OpenOrifices4WayNeu.PB_AT" | "fluids.moist_air.valves_orifices.directional_control_valves.enum.OpenOrifices4WayNeu.PB_BT" | "fluids.moist_air.valves_orifices.directional_control_valves.enum.OpenOrifices4WayNeu.AT" | "fluids.moist_air.valves_orifices.directional_control_valves.enum.OpenOrifices4WayNeu.BT" | "fluids.moist_air.valves_orifices.directional_control_valves.enum.OpenOrifices4WayNeu.PA" | "fluids.moist_air.valves_orifices.directional_control_valves.enum.OpenOrifices4WayNeu.PB" | "fluids.moist_air.valves_orifices.directional_control_valves.enum.OpenOrifices4WayNeu.PT" | "fluids.moist_air.valves_orifices.directional_control_valves.enum.OpenOrifices4WayNeu.PA_AT_PT" | "fluids.moist_air.valves_orifices.directional_control_valves.enum.OpenOrifices4WayNeu.PA_PB_AB" | "fluids.moist_air.valves_orifices.directional_control_valves.enum.OpenOrifices4WayNeu.PB_BT_PT" | "fluids.moist_air.valves_orifices.directional_control_valves.enum.OpenOrifices4WayNeu.PA_PB_AT_BT_PT"

Negative spool position open connections — Flow paths open when spool moves in negative direction

P-A, B-T (default) | P-A, P-B | P-B, A-T | P-A | P-B | P-A, P-B, A-B

Flow paths open when the spool moves in the negative direction. This parameter sets the valve configuration and defines the direction of spool movement according to the signal received at port S. To check the parameter settings for consistency with other orifices, set Consistency check for neutral spool position open connections to Warning or Error.

Programmatic Use

Parameter:

open_orifices_neg

Values:

"fluids.moist_air.valves_orifices.directional_control_valves.enum.OpenOrifices4WayPosNeg.PA_BT" | "fluids.moist_air.valves_orifices.directional_control_valves.enum.OpenOrifices4WayPosNeg.PA_PB" | "fluids.moist_air.valves_orifices.directional_control_valves.enum.OpenOrifices4WayPosNeg.PB_AT" | "fluids.moist_air.valves_orifices.directional_control_valves.enum.OpenOrifices4WayPosNeg.PA" | "fluids.moist_air.valves_orifices.directional_control_valves.enum.OpenOrifices4WayPosNeg.PB" | "fluids.moist_air.valves_orifices.directional_control_valves.enum.OpenOrifices4WayPosNeg.PA_PB_AB"

Consistency check for neutral spool position open connections — Whether to check if orifice settings are consistent

Warning (default) | Error | None

Whether to check if the neutral spool position open settings in the Valve Configuration section are consistent with the specified spool position at the maximum orifice area. For each enabled orifice, the actual offset at the spool neutral position should be commensurate with the specified spool offset for each individual orifice.

Programmatic Use

Parameter:	neutral_assert_action
Values:	"simscape.enum.assert.action.warn" | "simscape.enum.assert.action.error" | "simscape.enum.assert.action.none"

Model Parameterization

Area characteristics — Flow equations for orifices

Identical for all flow paths (default) | Different for each flow path

Whether to apply uniform or individual flow equations for the valve orifice area. When you set this parameter to Identical for all flow paths, the block uses the same orifice and spool geometries, flow rates, pressure, and area vectors for all valve orifices. When you set this parameter to Different for each flow path, you can specify these parameters individually for each orifice. For both settings, orifices A, B, P, and T have the same cross-sectional areas, discharge coefficients, and Reynolds numbers when you set Orifice parameterization to Linear - Area vs. spool travel or Tabulated data - Area vs. spool travel.

Programmatic Use

Parameter:	area_spec
Values:	"fluids.moist_air.valves_orifices.directional_control_valves.enum.AreaSpec.Identical" | "fluids.moist_air.valves_orifices.directional_control_valves.enum.AreaSpec.Different"

Orifice parameterization — Variable or constant orifice parameterization

Cv flow coefficient (default) | Kv flow coefficient | Sonic conductance | Orifice area

Method the block uses to calculate the mass flow rate from the pressure difference across the orifice or the pressure difference from the mass flow rate.

Programmatic Use

Parameter:	valve_parameterization
Values:	"fluids.moist_air.valves_orifices.enum.OrificeParameterization.Cv" | "fluids.moist_air.valves_orifices.enum.OrificeParameterization.Kv" | "fluids.moist_air.valves_orifices.enum.OrificeParameterization.SonicConductance" | "fluids.moist_air.valves_orifices.enum.OrificeParameterization.Area"

Spool travel between closed and open orifice — Maximum spool stroke

0.005 m (default) | positive scalar

Maximum distance of spool travel.

Dependencies

To enable this parameter, set Area characteristics to Identical for all flow paths and Opening characteristic to Linear.

Programmatic Use

Parameter: del_S_max

Opening characteristic — Method to convert control signal to measure of flow capacity

Linear (default) | Tabulated

Method by which to convert the control signal specified at port S to the chosen measure of flow capacity.

Programmatic Use

Parameter:	opening_characteristic
Values:	"fluids.moist_air.valves_orifices.enum.OpeningCharacteristics.Linear" | "fluids.moist_air.valves_orifices.enum.OpeningCharacteristics.Tabulated"

Spool travel vector — Vector of spool opening distances relative to fully closed position

[0, .00125, .0025, .00375, .005] m (default) | 1-by-n vector

Vector of spool travel distances when parameterizing the orifice according to the tabulated valve area data. The vector elements must correspond one-to-one with the elements in the Orifice area vector parameter. List the values in ascending order. The first element must be 0. The block uses linear interpolation between table data points.

Dependencies

To enable this parameter, set Area characteristics to Identical for all flow paths and Opening characteristic to Tabulated.

Programmatic Use

Parameter: del_S_Cv_TLU

Parameter: del_S_Kv_TLU

Parameter: del_S_C_TLU

Parameter: del_S_orifice_area_TLU

Maximum Cv flow coefficient — C_v coefficient that corresponds to maximally open component

4 (default) | positive scalar

Value of the C_v flow coefficient when the orifice is fully open and the area available for flow is at a maximum. This parameter measures the ease with which the vapor traverses the resistive element when driven by a pressure differential.

Dependencies

To enable this parameter, set Area characteristics to Identical for all flow paths, Orifice parameterization to Cv flow coefficient, and Opening characteristic to Linear.

Programmatic Use

Parameter: Cv_max

Cv flow coefficient vector — C_v coefficients for values in member position vector

[1e-06, .8, 1.6, 2.4, 3.2, 4] (default) | 1-by-n vector

Vector of C_v flow coefficients. Each coefficient corresponds to a value in the Control member position vector parameter. This parameter measures the ease with which the vapor traverses the resistive element when driven by a pressure differential. The size of the vector must be the same as the Control member position vector parameter.

Dependencies

To enable this parameter, set Area characteristics to Identical for all flow paths, Orifice parameterization to Cv flow coefficient, and Opening characteristic to Tabulated.

Programmatic Use

Parameter: Cv_TLU

Maximum Kv flow coefficient — K_v coefficient that corresponds to maximally open component

3.6 (default) | positive scalar

Value of the K_v flow coefficient when the orifice is fully open and the area available for flow is at a maximum. This parameter measures the ease with which the vapor traverses the resistive element when driven by a pressure differential.

Dependencies

To enable this parameter, set Area characteristics to Identical for all flow paths, Orifice parameterization to Kv flow coefficient, and Opening characteristic to Linear.

Programmatic Use

Parameter: Kv_max

Kv flow coefficient vector — K_v coefficients for values in member position vector

[1e-06, .72, 1.44, 2.16, 2.88, 3.6] (default) | 1-by-n vector

Vector of K_v flow coefficients. Each coefficient corresponds to a value in the Control member position vector parameter. This parameter measures the ease with which the vapor traverses the resistive element when driven by a pressure differential. The size of the vector must be the same as the Control member position vector parameter.

Dependencies

To enable this parameter, set Area characteristics to Identical for all flow paths, Orifice parameterization to Kv flow coefficient, and Opening characteristic to Tabulated.

Programmatic Use

Parameter: Kv_TLU

Maximum orifice area — Maximum orifice opening area

1e-4 m^2 (default) | positive scalar

Largest open area of each orifice during the operation of the valve.

Dependencies

To enable this parameter, set Area characteristics to Identical for all flow paths, Orifice parameterization to Orifice area, and Opening characteristic to Linear.

Programmatic Use

Parameter: orifice_area_max

Orifice area vector — Vector of valve opening areas

[1e-10, 1e-05, 4e-05, 6e-05, .0001] m^2 (default) | 1-by-n vector

Vector of opening areas when parameterizing the orifice according to the tabulated valve area data. The vector elements must correspond one-to-one with the elements in the Spool travel vector parameter. List the values in ascending order. The elements must be greater than 0. The first element of this vector is the leakage area.

Dependencies

To enable this parameter, set Area characteristics to Identical for all flow paths, Orifice parameterization to Orifice area, and Opening characteristic to Tabulated.

Programmatic Use

Parameter: orifice_area_TLU

xT pressure differential ratio factor at choked flow — Ratio of pressure differentials

0.7 (default) | positive scalar

Ratio between the inlet pressure, p_in, and the outlet pressure, p_out, defined as $$(p_{in}-p_{out})/p_{in}$$ where choking first occurs.

Dependencies

To enable this parameter, set Area characteristics to Identical for all flow paths, and Orifice parameterization to Cv flow coefficient or Kv flow coefficient.

Programmatic Use

Parameter: xT_Cv

Parameter: xT_Kv

Discharge coefficient — Discharge coefficient

0.64 (default) | positive scalar

Correction factor that accounts for discharge losses in theoretical flows.

Dependencies

To enable this parameter, set Orifice parameterization to Orifice area.

Programmatic Use

Parameter: Cd

Maximum sonic conductance — Sonic conductance corresponding to maximally open component

12 l/(bar*s) (default) | positive scalar

Value of the sonic conductance when the control signal specified at port S is 1 and cross-sectional area available for flow is at a maximum.

Dependencies

To enable this parameter, set Area characteristics to Identical for all flow paths, Orifice parameterization to Sonic conductance, and Opening characteristic to Linear.

Programmatic Use

Parameter: C_max

Critical pressure ratio — Ratio of downstream and upstream pressures at which the flow first chokes

0.3 (default) | positive scalar

Pressure ratio at which flow first begins to choke and the flow velocity reaches its maximum, given by the local speed of sound. The pressure ratio is the outlet pressure divided by inlet pressure.

Dependencies

To enable this parameter, set Area characteristics to Identical for all flow paths, Orifice parameterization to Sonic conductance, and Opening characteristic to Linear.

Programmatic Use

Parameter: B_crit_linear

Subsonic index — Exponent used to characterize mass flow in subsonic flow regime

0.5 (default) | positive scalar

Empirical value used to more accurately calculate the mass flow rate in the subsonic flow regime.

Dependencies

To enable this parameter, set Area characteristics to Identical for all flow paths and Orifice parameterization to Sonic conductance.

Programmatic Use

Parameter: m

ISO reference temperature — ISO 8778 reference temperature

293.15 K (default) | scalar

Temperature at standard reference atmosphere, defined as 293.15 K in ISO 8778.

You only need to adjust the ISO reference parameter values if you are using sonic conductance values that are obtained at difference reference values.

Dependencies

To enable this parameter, set Area characteristics to Identical for all flow paths and Orifice parameterization to Sonic conductance.

Programmatic Use

Parameter: T_ref_C

ISO reference density — ISO 8778 reference density

1.185 kg/m^3 (default) | positive scalar

Density at standard reference atmosphere, defined as 1.185 kg/m3 in ISO 8778.

You only need to adjust the ISO reference parameter values if you are using sonic conductance values that are obtained at difference reference values.

Dependencies

To enable this parameter, set Area characteristics to Identical for all flow paths and Orifice parameterization to Sonic conductance.

Programmatic Use

Parameter: rho_ref_C

Sonic conductance vector — Sonic conductances corresponding to values in spool travel vector

[1e-05, 2.4, 4.8, 7.2, 9.6, 12] l/(bar*s) (default) | vector of positive values

Vector of sonic conductances inside the resistive element. Each conductance corresponds to a value in the Spool travel vector parameter. The size of the vector must be the same as the Spool travel vector parameter.

Dependencies

To enable this parameter, set Area characteristics to Identical for all flow paths, Orifice parameterization to Sonic conductance, and Opening characteristic to Tabulated.

Programmatic Use

Parameter: C_TLU

Critical pressure ratio vector — Critical pressure ratios corresponding to values in spool travel vector

0.3 * ones(1,6) (default) | vector of positive numbers

Vector of critical pressure ratios at which the flow first chokes, with each critical pressure ratio corresponding to a value in the Spool travel vector parameter. The critical pressure ratio is the fraction of downstream-to-upstream pressures at which the flow velocity reaches the local speed of sound. The size of the vector must be the same as the Spool travel vector parameter.

Dependencies

To enable this parameter, set Area characteristics to Identical for all flow paths, Orifice parameterization to Sonic conductance, and Opening characteristic to Tabulated.

Programmatic Use

Parameter: B_crit_TLU

Leakage flow fraction — Ratio of flow rates

1e-6 (default) | positive scalar

Ratio of the flow rate of the orifice when it is closed to when it is open.

Dependencies

To enable this parameter, set Opening characteristic to Linear.

Programmatic Use

Parameter: leakage_fraction

Smoothing factor — Numerical smoothing factor

0.01 (default) | positive scalar in the range of [0,1]

Continuous smoothing factor that introduces a layer of gradual change based on the flow response when the valve is in the near-open and near-closed positions. To increase the stability of your simulation in these regimes, set this parameter to a nonzero value less than one.

Dependencies

To enable this parameter, set Opening characteristic to Linear.

Programmatic Use

Parameter: smoothing_factor

Laminar flow pressure ratio — Laminar-turbulent transition pressure ratio

0.999 (default) | positive scalar

Ratio of the orifice outlet pressure to orifice inlet pressure at which the fluid transitions between the laminar and turbulent regimes. The pressure loss corresponds to the mass flow rate linearly in laminar flows and quadratically in turbulent flows.

Programmatic Use

Parameter: B_lam

Cross-sectional area at ports P, T, A, and B — Area at conserving ports

0.01 m^2 (default) | positive scalar

Maximum cross-sectional areas at the entry and exit ports P, T, A, and B, which the block uses in the pressure-flow rate equation that determines the mass flow rate through the valve.

Programmatic Use

Parameter: area

P-A Orifice

Spool position at maximum P-A orifice area — Spool offset for fully open P-A orifice

5e-3 m (default) | positive scalar

Spool offset from the neutral position for a fully open P-A orifice.

Dependencies

To enable this parameter, set one of these parameters.

Positive spool position open connections to:

• P-A, B-T

• P-A, P-B

• P-A

• P-A, P-B, A-B

Neutral spool position open connections to:

• P-A, P-B, A-T, B-T

• P-A, A-T

• P-A, B-T

• P-A, P-B

• P-A

• P-A, A-T, P-T

• P-A, P-B, A-B

• P-A, P-B, A-T, B-T, P-T

Negative spool position open connections to:

• P-A, P-B, A-T, B-T

• P-A, A-T

• P-A, B-T

• P-A, P-B

• P-A

• P-A, P-B, A-B

Note:

This parameter is enabled only when the P-A orifice settings do not appear in all three spool position parameters: Positive spool position open connections, Neutral spool position open connections, and Negative spool position open connections.

Programmatic Use

Parameter: S_max_PA

P-A spool travel between closed and open orifice — Maximum spool stroke

0.005 m (default) | positive scalar

Maximum distance of spool travel. This value provides an upper limit to calculations so that simulations do not return unphysical values.

Dependencies

To enable this parameter, set Area characteristics to Different for each flow path, Opening characteristic to Linear, and one of the following parameters:

Positive spool position open connections to:

• P-A, B-T

• P-A, P-B

• P-A

• P-A, P-B, A-B

Neutral spool position open connections to:

• P-A, P-B, A-T, B-T

• P-A, A-T

• P-A, B-T

• P-A, P-B

• P-A

• P-A, A-T, P-T

• P-A, P-B, A-B

• P-A, P-B, A-T, B-T, P-T

Negative spool position open connections to:

• P-A, P-B, A-T, B-T

• P-A, A-T

• P-A, B-T

• P-A, P-B

• P-A

• P-A, P-B, A-B

Programmatic Use

Parameter: del_S_max_PA

P-A constant orifice Cv flow coefficient — Flow coefficient

4 (default) | positive scalar

Value of the constant C_v flow coefficient for the P-A orifice. This parameter measures the ease with which the vapor traverses the resistive element when driven by a pressure differential.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Cv flow coefficient

3. One of the following settings in each parameter:

   Positive spool position open connections to:

   • P-A, B-T

   • P-A, P-B

   • P-A

   • P-A, P-B, A-B

   Neutral spool position open connections to:

   • P-A, P-B, A-T, B-T

   • P-A, A-T

   • P-A, B-T

   • P-A, P-B

   • P-A

   • P-A, A-T, P-T

   • P-A, P-B, A-B

   • P-A, P-B, A-T, B-T, P-T

   Negative spool position open connections to:

   • P-A, P-B, A-T, B-T

   • P-A, A-T

   • P-A, B-T

   • P-A, P-B

   • P-A

   • P-A, P-B, A-B

Note:

This parameter is enabled only when the P-A orifice settings appear all three spool position parameters: Positive spool position open connections, Neutral spool position open connections, and Negative spool position open connections.

Programmatic Use

Parameter: Cv_const_PA

P-A orifice maximum Cv flow coefficient — C_v coefficient that corresponds to maximally open component

4 (default) | positive scalar

Value of the C_v flow coefficient when the P-A orifice is fully open and the area available for flow is at a maximum. This parameter measures the ease with which the vapor traverses the resistive element when driven by a pressure differential.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Cv flow coefficient

3. Opening characteristic to Linear

4. One of the following parameters:

   Positive spool position open connections to:

   • P-A, B-T

   • P-A, P-B

   • P-A

   • P-A, P-B, A-B

   Neutral spool position open connections to:

   • P-A, P-B, A-T, B-T

   • P-A, A-T

   • P-A, B-T

   • P-A, P-B

   • P-A

   • P-A, A-T, P-T

   • P-A, P-B, A-B

   • P-A, P-B, A-T, B-T, P-T

   Negative spool position open connections to:

   • P-A, P-B, A-T, B-T

   • P-A, A-T

   • P-A, B-T

   • P-A, P-B

   • P-A

   • P-A, P-B, A-B

Programmatic Use

Parameter: Cv_max_PA

P-A orifice Cv flow coefficient vector — C_v coefficients for values in member position vector

[1e-06, .8, 1.6, 2.4, 3.2, 4] (default) | 1-by-n vector

Vector of C_v flow coefficients. Each coefficient corresponds to a value in the P-A orifice spool travel vector parameter. This parameter measures the ease with which the vapor traverses the resistive element when driven by a pressure differential. The size of the vector must be the same as the P-A orifice spool travel vector parameter.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Cv flow coefficient

3. Opening characteristic to Tabulated

4. One of the following parameters:

   Positive spool position open connections to:

   • P-A, B-T

   • P-A, P-B

   • P-A

   • P-A, P-B, A-B

   Neutral spool position open connections to:

   • P-A, P-B, A-T, B-T

   • P-A, A-T

   • P-A, B-T

   • P-A, P-B

   • P-A

   • P-A, A-T, P-T

   • P-A, P-B, A-B

   • P-A, P-B, A-T, B-T, P-T

   Negative spool position open connections to:

   • P-A, P-B, A-T, B-T

   • P-A, A-T

   • P-A, B-T

   • P-A, P-B

   • P-A

   • P-A, P-B, A-B

Programmatic Use

Parameter: Cv_TLU_PA

P-A constant orifice Kv flow coefficient — Flow coefficient

3.6 (default) | positive scalar

Value of the constant K_v flow coefficient for the P-A orifice. This parameter measures the ease with which the vapor traverses the resistive element when driven by a pressure differential.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Kv flow coefficient

3. One of the following settings in each parameter:

   Positive spool position open connections to:

   • P-A, B-T

   • P-A, P-B

   • P-A

   • P-A, P-B, A-B

   Neutral spool position open connections to:

   • P-A, P-B, A-T, B-T

   • P-A, A-T

   • P-A, B-T

   • P-A, P-B

   • P-A

   • P-A, A-T, P-T

   • P-A, P-B, A-B

   • P-A, P-B, A-T, B-T, P-T

   Negative spool position open connections to:

   • P-A, P-B, A-T, B-T

   • P-A, A-T

   • P-A, B-T

   • P-A, P-B

   • P-A

   • P-A, P-B, A-B

Note:

This parameter is enabled only when the P-A orifice settings appear in all three spool position parameters: Positive spool position open connections, Neutral spool position open connections, and Negative spool position open connections.

Programmatic Use

Parameter: Kv_const_PA

P-A orifice maximum Kv flow coefficient — K_v coefficient that corresponds to maximally open component

3.6 (default) | positive scalar

Value of the K_v flow coefficient when the P-A orifice is fully open and the area available for flow is at a maximum. This parameter measures the ease with which the vapor traverses the resistive element when driven by a pressure differential.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Kv flow coefficient

3. Opening characteristic to Linear

4. One of the following parameters:

   Positive spool position open connections to:

   • P-A, B-T

   • P-A, P-B

   • P-A

   • P-A, P-B, A-B

   Neutral spool position open connections to:

   • P-A, P-B, A-T, B-T

   • P-A, A-T

   • P-A, B-T

   • P-A, P-B

   • P-A

   • P-A, A-T, P-T

   • P-A, P-B, A-B

   • P-A, P-B, A-T, B-T, P-T

   Negative spool position open connections to:

   • P-A, P-B, A-T, B-T

   • P-A, A-T

   • P-A, B-T

   • P-A, P-B

   • P-A

   • P-A, P-B, A-B

Programmatic Use

Parameter: Kv_max_PA

P-A orifice Kv flow coefficient vector — K_v coefficients for values in member position vector

[1e-06, .72, 1.44, 2.16, 2.88, 3.6] (default) | 1-by-n vector

Vector of K_v flow coefficients. Each coefficient corresponds to a value in the P-A orifice spool travel vector parameter. This parameter measures the ease with which the vapor traverses the resistive element when driven by a pressure differential. The size of the vector must be the same as the P-A orifice spool travel vector parameter.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Kv flow coefficient

3. Opening characteristic to Tabulated

4. One of the following parameters:

   Positive spool position open connections to:

   • P-A, B-T

   • P-A, P-B

   • P-A

   • P-A, P-B, A-B

   Neutral spool position open connections to:

   • P-A, P-B, A-T, B-T

   • P-A, A-T

   • P-A, B-T

   • P-A, P-B

   • P-A

   • P-A, A-T, P-T

   • P-A, P-B, A-B

   • P-A, P-B, A-T, B-T, P-T

   Negative spool position open connections to:

   • P-A, P-B, A-T, B-T

   • P-A, A-T

   • P-A, B-T

   • P-A, P-B

   • P-A

   • P-A, P-B, A-B

Programmatic Use

Parameter: Kv_TLU_PA

P-A orifice spool travel vector — Vector of spool opening distances relative to fully closed position

[0, .00125, .0025, .00375, .005] m (default) | 1-by-n vector

Vector of spool travel distances for the tabular parameterization of the valve area. List the values in ascending order. The first element must be 0. The block uses linear interpolation between table data points.

Dependencies

To enable this parameter, set Area characteristics to Different for each flow path, Opening characteristic to Tabulated, and one of the following parameters:

Positive spool position open connections to:

• P-A, B-T

• P-A, P-B

• P-A

• P-A, P-B, A-B

Neutral spool position open connections to:

• P-A, P-B, A-T, B-T

• P-A, A-T

• P-A, B-T

• P-A, P-B

• P-A

• P-A, A-T, P-T

• P-A, P-B, A-B

• P-A, P-B, A-T, B-T, P-T

Negative spool position open connections to:

• P-A, P-B, A-T, B-T

• P-A, A-T

• P-A, B-T

• P-A, P-B

• P-A

• P-A, P-B, A-B

Programmatic Use

Parameter: del_S_Cv_TLU_PA

Parameter: del_S_Kv_TLU_PA

Parameter: del_S_C_TLU_PA

Parameter: del_S_orifice_area_TLU_PA

P-A maximum orifice area — Maximum orifice opening area

1e-4 m^2 (default) | positive scalar

Largest open area of the P-A orifice during the operation of the valve.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Orifice area

3. Opening characteristic to Linear

4. One of the following parameters:

   Positive spool position open connections to:

   • P-A, B-T

   • P-A, P-B

   • P-A

   • P-A, P-B, A-B

   Neutral spool position open connections to:

   • P-A, P-B, A-T, B-T

   • P-A, A-T

   • P-A, B-T

   • P-A, P-B

   • P-A

   • P-A, A-T, P-T

   • P-A, P-B, A-B

   • P-A, P-B, A-T, B-T, P-T

   Negative spool position open connections to:

   • P-A, P-B, A-T, B-T

   • P-A, A-T

   • P-A, B-T

   • P-A, P-B

   • P-A

   • P-A, P-B, A-B

Programmatic Use

Parameter: orifice_area_max_PA

P-A orifice area vector — Vector of valve opening areas

[1e-10, 1e-05, 4e-05, 6e-05, .0001] m^2 (default) | 1-by-n vector

Vector of opening areas for the tabular parameterization of the valve area. The vector elements must correspond one-to-one with the elements in the P-A orifice spool travel vector parameter. The elements must be greater than 0 and listed in ascending order. The first element of this vector is the leakage area.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Orifice area

3. Opening characteristic to Tabulated

4. One of the following parameters:

   Positive spool position open connections to:

   • P-A, B-T

   • P-A, P-B

   • P-A

   • P-A, P-B, A-B

   Neutral spool position open connections to:

   • P-A, P-B, A-T, B-T

   • P-A, A-T

   • P-A, B-T

   • P-A, P-B

   • P-A

   • P-A, A-T, P-T

   • P-A, P-B, A-B

   • P-A, P-B, A-T, B-T, P-T

   Negative spool position open connections to:

   • P-A, P-B, A-T, B-T

   • P-A, A-T

   • P-A, B-T

   • P-A, P-B

   • P-A

   • P-A, P-B, A-B

Programmatic Use

Parameter: orifice_area_TLU_PA

P-A constant orifice area — Cross-sectional area for constant orifice

1e-4 m^2 (default) | positive scalar

Orifice area when the positive and negative spool positions include the same orifice.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Orifice area

3. One of the following settings in each parameter:

   Positive spool position open connections to:

   • P-A, B-T

   • P-A, P-B

   • P-A

   • P-A, P-B, A-B

   Neutral spool position open connections to:

   • P-A, P-B, A-T, B-T

   • P-A, A-T

   • P-A, B-T

   • P-A, P-B

   • P-A

   • P-A, A-T, P-T

   • P-A, P-B, A-B

   • P-A, P-B, A-T, B-T, P-T

   Negative spool position open connections to:

   • P-A, P-B, A-T, B-T

   • P-A, A-T

   • P-A, B-T

   • P-A, P-B

   • P-A

   • P-A, P-B, A-B

Note:

This parameter is enabled only when the P-A orifice settings appear in all three spool position parameters: Positive spool position open connections, Neutral spool position open connections, and Negative spool position open connections.

Programmatic Use

Parameter: orifice_area_const_PA

P-A orifice xT pressure differential ratio factor at choked flow — Ratio of pressure differentials

0.7 (default) | positive scalar

Ratio between the inlet pressure, p_in, and the outlet pressure, p_out, defined as $$(p_{in}-p_{out})/p_{in}$$ where choking first occurs for the P-A orifice.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Kv flow coefficient or Cv flow coefficient

3. At least one of the following parameters:

   Positive spool position open connections to:

   • P-A, B-T

   • P-A, P-B

   • P-A

   • P-A, P-B, A-B

   Neutral spool position open connections to:

   • P-A, P-B, A-T, B-T

   • P-A, A-T

   • P-A, B-T

   • P-A, P-B

   • P-A

   • P-A, A-T, P-T

   • P-A, P-B, A-B

   • P-A, P-B, A-T, B-T, P-T

   Negative spool position open connections to:

   • P-A, P-B, A-T, B-T

   • P-A, A-T

   • P-A, B-T

   • P-A, P-B

   • P-A

   • P-A, P-B, A-B

Programmatic Use

Parameter: xT_Cv_PA

Parameter: xT_Kv_PA

P-A constant orifice sonic conductance — Sonic conductance for constant orifice

12 l/(bar*s) (default) | positive scalar

Sonic conductance when the positive and negative spool positions include the same orifice. This value is the ratio, measured at the onset of choking, of the mass flow rate through the resistive element to the product of the upstream pressure and mass density at standard conditions as defined in ISO 8778. This parameter determines the maximum flow rate allowed at a given upstream pressure.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Sonic conductance

3. One of the following settings in each parameter:

   Positive spool position open connections to:

   • P-A, B-T

   • P-A, P-B

   • P-A

   • P-A, P-B, A-B

   Neutral spool position open connections to:

   • P-A, P-B, A-T, B-T

   • P-A, A-T

   • P-A, B-T

   • P-A, P-B

   • P-A

   • P-A, A-T, P-T

   • P-A, P-B, A-B

   • P-A, P-B, A-T, B-T, P-T

   Negative spool position open connections to:

   • P-A, P-B, A-T, B-T

   • P-A, A-T

   • P-A, B-T

   • P-A, P-B

   • P-A

   • P-A, P-B, A-B

Note:

This parameter is enabled only when the P-A orifice settings appear in all three spool position parameters: Positive spool position open connections, Neutral spool position open connections, and Negative spool position open connections.

Programmatic Use

Parameter: C_const_PA

P-A constant orifice critical pressure ratio — Ratio of downstream and upstream pressures at which the flow first chokes for constant orifice

0.3 (default) | positive scalar

Critical pressure ratio when the positive and negative spool positions include the same orifice. This value is the pressure ratio at which flow first begins to choke and the flow velocity reaches its maximum, given by the local speed of sound. The pressure ratio is the outlet pressure divided by inlet pressure.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Sonic conductance

3. One of the following settings in each parameter:

   Positive spool position open connections to:

   • P-A, B-T

   • P-A, P-B

   • P-A

   • P-A, P-B, A-B

   Neutral spool position open connections to:

   • P-A, P-B, A-T, B-T

   • P-A, A-T

   • P-A, B-T

   • P-A, P-B

   • P-A

   • P-A, A-T, P-T

   • P-A, P-B, A-B

   • P-A, P-B, A-T, B-T, P-T

   Negative spool position open connections to:

   • P-A, P-B, A-T, B-T

   • P-A, A-T

   • P-A, B-T

   • P-A, P-B

   • P-A

   • P-A, P-B, A-B

Note:

This parameter is enabled only when the P-A orifice settings appear in all three spool position parameters: Positive spool position open connections, Neutral spool position open connections, and Negative spool position open connections.

Programmatic Use

Parameter: B_crit_const_PA

P-A orifice maximum sonic conductance — Sonic conductance corresponding to maximally open orifice

12 l/(bar*s) (default) | positive scalar

Value of the sonic conductance when the P-A orifice is fully open and the area available for flow is at a maximum.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Sonic conductance

3. Opening characteristic to Linear

4. One of the following parameters:

   Positive spool position open connections to:

   • P-A, B-T

   • P-A, P-B

   • P-A

   • P-A, P-B, A-B

   Neutral spool position open connections to:

   • P-A, P-B, A-T, B-T

   • P-A, A-T

   • P-A, B-T

   • P-A, P-B

   • P-A

   • P-A, A-T, P-T

   • P-A, P-B, A-B

   • P-A, P-B, A-T, B-T, P-T

   Negative spool position open connections to:

   • P-A, P-B, A-T, B-T

   • P-A, A-T

   • P-A, B-T

   • P-A, P-B

   • P-A

   • P-A, P-B, A-B

Programmatic Use

Parameter: C_max_PA

P-A orifice critical pressure ratio — Ratio of downstream and upstream pressures at which the flow first chokes

0.3 (default) | positive scalar

Pressure ratio at which flow first begins to choke and the flow velocity reaches its maximum, given by the local speed of sound. The pressure ratio is the outlet pressure divided by inlet pressure.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Sonic conductance

3. Opening characteristic to Linear

4. One of the following parameters:

   Positive spool position open connections to:

   • P-A, B-T

   • P-A, P-B

   • P-A

   • P-A, P-B, A-B

   Neutral spool position open connections to:

   • P-A, P-B, A-T, B-T

   • P-A, A-T

   • P-A, B-T

   • P-A, P-B

   • P-A

   • P-A, A-T, P-T

   • P-A, P-B, A-B

   • P-A, P-B, A-T, B-T, P-T

   Negative spool position open connections to:

   • P-A, P-B, A-T, B-T

   • P-A, A-T

   • P-A, B-T

   • P-A, P-B

   • P-A

   • P-A, P-B, A-B

Programmatic Use

Parameter: B_crit_linear_PA

P-A orifice sonic conductance vector — Sonic conductances corresponding to values in spool travel vector

[1e-05, 2.4, 4.8, 7.2, 9.6, 12] l/(bar*s) (default) | 1-by-n vector

Vector of sonic conductances inside the resistive element. Each conductance corresponds to a value in the P-A orifice spool travel vector parameter. The size of the vector must be the same as the P-A orifice spool travel vector parameter.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Sonic conductance

3. Opening characteristic to Tabulated

4. One of the following parameters:

   Positive spool position open connections to:

   • P-A, B-T

   • P-A, P-B

   • P-A

   • P-A, P-B, A-B

   Neutral spool position open connections to:

   • P-A, P-B, A-T, B-T

   • P-A, A-T

   • P-A, B-T

   • P-A, P-B

   • P-A

   • P-A, A-T, P-T

   • P-A, P-B, A-B

   • P-A, P-B, A-T, B-T, P-T

   Negative spool position open connections to:

   • P-A, P-B, A-T, B-T

   • P-A, A-T

   • P-A, B-T

   • P-A, P-B

   • P-A

   • P-A, P-B, A-B

Programmatic Use

Parameter: C_TLU_PA

P-A orifice critical pressure ratio vector — Critical pressure ratios corresponding to values in spool travel vector

0.3 * ones(1, 6) (default) | 1-by-n vector

Vector of critical pressure ratios at which the flow first chokes, with each critical pressure ratio corresponding to a value in the P-A orifice spool travel vector parameter. The critical pressure ratio is the fraction of downstream-to-upstream pressures at which the flow velocity reaches the local speed of sound. The size of the vector must be the same as the P-A orifice spool travel vector parameter.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Sonic conductance

3. Opening characteristic to Tabulated

4. One of the following parameters:

   Positive spool position open connections to:

   • P-A, B-T

   • P-A, P-B

   • P-A

   • P-A, P-B, A-B

   Neutral spool position open connections to:

   • P-A, P-B, A-T, B-T

   • P-A, A-T

   • P-A, B-T

   • P-A, P-B

   • P-A

   • P-A, A-T, P-T

   • P-A, P-B, A-B

   • P-A, P-B, A-T, B-T, P-T

   Negative spool position open connections to:

   • P-A, P-B, A-T, B-T

   • P-A, A-T

   • P-A, B-T

   • P-A, P-B

   • P-A

   • P-A, P-B, A-B

Programmatic Use

Parameter: B_crit_TLU_PA

P-A orifice subsonic index — Exponent used to characterize mass flow in subsonic flow regime

0.5 (default) | positive scalar

Empirical value used to more accurately calculate the mass flow rate in the subsonic flow regime.

Dependencies

To enable this parameter, set Area characteristics to Different for each flow path, Orifice parameterization to Sonic conductance, and at least one of the following parameters:

Positive spool position open connections to:

• P-A, B-T

• P-A, P-B

• P-A

• P-A, P-B, A-B

Neutral spool position open connections to:

• P-A, P-B, A-T, B-T

• P-A, A-T

• P-A, B-T

• P-A, P-B

• P-A

• P-A, A-T, P-T

• P-A, P-B, A-B

• P-A, P-B, A-T, B-T, P-T

Negative spool position open connections to:

• P-A, P-B, A-T, B-T

• P-A, A-T

• P-A, B-T

• P-A, P-B

• P-A

• P-A, P-B, A-B

Programmatic Use

Parameter: m_PA

P-A orifice ISO reference temperature — ISO 8778 reference temperature

293.15 K (default) | scalar

Temperature at standard reference atmosphere, defined as 293.15 K in ISO 8778.

You only need to adjust the ISO reference parameter values if you are using sonic conductance values that are obtained at difference reference values.

Dependencies

To enable this parameter, set Area characteristics to Different for each flow path, Orifice parameterization to Sonic conductance, and at least one of the following parameters:

Positive spool position open connections to:

• P-A, B-T

• P-A, P-B

• P-A

• P-A, P-B, A-B

Neutral spool position open connections to:

• P-A, P-B, A-T, B-T

• P-A, A-T

• P-A, B-T

• P-A, P-B

• P-A

• P-A, A-T, P-T

• P-A, P-B, A-B

• P-A, P-B, A-T, B-T, P-T

Negative spool position open connections to:

• P-A, P-B, A-T, B-T

• P-A, A-T

• P-A, B-T

• P-A, P-B

• P-A

• P-A, P-B, A-B

Programmatic Use

Parameter: T_ref_C_PA

P-A orifice ISO reference density — ISO 8778 reference density

1.185 kg/m^3 (default) | positive scalar

Density at standard reference atmosphere, defined as 1.185 kg/m3 in ISO 8778.

You only need to adjust the ISO reference parameter values if you are using sonic conductance values that are obtained at difference reference values.

Dependencies

To enable this parameter, set Area characteristics to Different for each flow path, Orifice parameterization to Sonic conductance, and at least one of the following parameters:

Positive spool position open connections to:

• P-A, B-T

• P-A, P-B

• P-A

• P-A, P-B, A-B

Neutral spool position open connections to:

• P-A, P-B, A-T, B-T

• P-A, A-T

• P-A, B-T

• P-A, P-B

• P-A

• P-A, A-T, P-T

• P-A, P-B, A-B

• P-A, P-B, A-T, B-T, P-T

Negative spool position open connections to:

• P-A, P-B, A-T, B-T

• P-A, A-T

• P-A, B-T

• P-A, P-B

• P-A

• P-A, P-B, A-B

Programmatic Use

Parameter: rho_ref_C_PA

P-B Orifice

Spool position at maximum P-B orifice area — Spool offset for fully open P-B orifice

5e-3 m (default) | positive scalar

Spool offset from the neutral position for a fully open P-B orifice.

Dependencies

To enable this parameter, set one of these parameters:

Positive spool position open connections to:

• P-B, A-T

• P-A, P-B

• P-B

• P-A, P-B, A-B

Neutral spool position open connections to:

• P-A, P-B, A-T, B-T

• P-B, A-T

• P-B, B-T

• P-A, P-B

• P-B

• P-A, P-B, A-B

• P-B, B-T, P-T

• P-A, P-B, A-T, B-T, P-T

Negative spool position open connections to:

• P-A, P-B, A-T, B-T

• P-B, A-T

• P-B, B-T

• P-A, P-B

• P-B

• P-A, P-B, A-B

Note:

This parameter is enabled only when the P-B orifice settings do not appear in all three spool position parameters: Positive spool position open connections, Neutral spool position open connections, and Negative spool position open connections.

Programmatic Use

Parameter: S_max_PB

P-B spool travel between closed and open orifice — Maximum spool stroke

0.005 m (default) | positive scalar

Maximum distance of spool travel. This value provides an upper limit to calculations so that simulations do not return unphysical values.

Dependencies

To enable this parameter, set Area characteristics to Different for each flow path, Opening characteristic to Linear, and one of the following parameters:

Positive spool position open connections to:

• P-B, A-T

• P-A, P-B

• P-B

• P-A, P-B, A-B

Neutral spool position open connections to:

• P-A, P-B, A-T, B-T

• P-B, A-T

• P-B, B-T

• P-A, P-B

• P-B

• P-A, P-B, A-B

• P-B, B-T, P-T

• P-A, P-B, A-T, B-T, P-T

Negative spool position open connections to:

• P-A, P-B, A-T, B-T

• P-B, A-T

• P-B, B-T

• P-A, P-B

• P-B

• P-A, P-B, A-B

Programmatic Use

Parameter: del_S_max_PB

P-B constant orifice Cv flow coefficient — Flow coefficient

4 (default) | positive scalar

Value of the constant C_v flow coefficient for the P-B orifice. This parameter measures the ease with which the vapor traverses the resistive element when driven by a pressure differential.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Cv flow coefficient

3. One of the following settings in each parameter:

   Positive spool position open connections to:

   • P-B, A-T

   • P-A, P-B

   • P-B

   • P-A, P-B, A-B

   Neutral spool position open connections to:

   • P-A, P-B, A-T, B-T

   • P-B, A-T

   • P-B, B-T

   • P-A, P-B

   • P-B

   • P-A, P-B, A-B

   • P-B, B-T, P-T

   • P-A, P-B, A-T, B-T, P-T

   Negative spool position open connections to:

   • P-A, P-B, A-T, B-T

   • P-B, A-T

   • P-B, B-T

   • P-A, P-B

   • P-B

   • P-A, P-B, A-B

Note:

This parameter is enabled only when the P-B orifice settings appear in all three spool position parameters: Positive spool position open connections, Neutral spool position open connections, and Negative spool position open connections.

Programmatic Use

Parameter: Cv_const_PB

P-B orifice maximum Cv flow coefficient — C_v coefficient that corresponds to maximally open component

4 (default) | positive scalar

Value of the C_v flow coefficient when the P-B orifice is fully open and the area available for flow is at a maximum. This parameter measures the ease with which the vapor traverses the resistive element when driven by a pressure differential.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Cv flow coefficient

3. Opening characteristic to Linear

4. One of the following parameters:

   Positive spool position open connections to:

   • P-B, A-T

   • P-A, P-B

   • P-B

   • P-A, P-B, A-B

   Neutral spool position open connections to:

   • P-A, P-B, A-T, B-T

   • P-B, A-T

   • P-B, B-T

   • P-A, P-B

   • P-B

   • P-A, P-B, A-B

   • P-B, B-T, P-T

   • P-A, P-B, A-T, B-T, P-T

   Negative spool position open connections to:

   • P-A, P-B, A-T, B-T

   • P-B, A-T

   • P-B, B-T

   • P-A, P-B

   • P-B

   • P-A, P-B, A-B

Programmatic Use

Parameter: Cv_max_PB

P-B orifice Cv flow coefficient vector — C_v coefficients for values in member position vector

[1e-06, .8, 1.6, 2.4, 3.2, 4] (default) | 1-by-n vector

Vector of C_v flow coefficients. Each coefficient corresponds to a value in the P-B orifice spool travel vector parameter. This parameter measures the ease with which the vapor traverses the resistive element when driven by a pressure differential. The size of the vector must be the same as the P-B orifice spool travel vector parameter.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Cv flow coefficient

3. Opening characteristic to Tabulated

4. One of the following parameters:

   Positive spool position open connections to:

   • P-B, A-T

   • P-A, P-B

   • P-B

   • P-A, P-B, A-B

   Neutral spool position open connections to:

   • P-A, P-B, A-T, B-T

   • P-B, A-T

   • P-B, B-T

   • P-A, P-B

   • P-B

   • P-A, P-B, A-B

   • P-B, B-T, P-T

   • P-A, P-B, A-T, B-T, P-T

   Negative spool position open connections to:

   • P-A, P-B, A-T, B-T

   • P-B, A-T

   • P-B, B-T

   • P-A, P-B

   • P-B

   • P-A, P-B, A-B

Programmatic Use

Parameter: Cv_TLU_PB

P-B constant orifice Kv flow coefficient — Flow coefficient

3.6 (default) | positive scalar

Value of the constant K_v flow coefficient for the P-B orifice. This parameter measures the ease with which the vapor traverses the resistive element when driven by a pressure differential.

Dependencies

To enable this parameter, set:

1. Modeling option to Vapor operating condition

2. Area characteristics to Different for each flow path

3. Orifice parameterization to Kv flow coefficient

4. One of the following settings in each parameter:

   Positive spool position open connections to:

   • P-B, A-T

   • P-A, P-B

   • P-B

   • P-A, P-B, A-B

   Neutral spool position open connections to:

   • P-A, P-B, A-T, B-T

   • P-B, A-T

   • P-B, B-T

   • P-A, P-B

   • P-B

   • P-A, P-B, A-B

   • P-B, B-T, P-T

   • P-A, P-B, A-T, B-T, P-T

   Negative spool position open connections to:

   • P-A, P-B, A-T, B-T

   • P-B, A-T

   • P-B, B-T

   • P-A, P-B

   • P-B

   • P-A, P-B, A-B

Note:

This parameter is enabled only when the P-B orifice settings appear in all three spool position parameters: Positive spool position open connections, Neutral spool position open connections, and Negative spool position open connections.

Programmatic Use

Parameter: Kv_const_PB

P-B orifice maximum Kv flow coefficient — K_v coefficient that corresponds to maximally open component

3.6 (default) | positive scalar

Value of the K_v flow coefficient when the P-B orifice is fully open and the area available for flow is at a maximum. This parameter measures the ease with which the vapor traverses the resistive element when driven by a pressure differential.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Kv flow coefficient

3. Opening characteristic to Linear

4. One of the following parameters:

   Positive spool position open connections to:

   • P-B, A-T

   • P-A, P-B

   • P-B

   • P-A, P-B, A-B

   Neutral spool position open connections to:

   • P-A, P-B, A-T, B-T

   • P-B, A-T

   • P-B, B-T

   • P-A, P-B

   • P-B

   • P-A, P-B, A-B

   • P-B, B-T, P-T

   • P-A, P-B, A-T, B-T, P-T

   Negative spool position open connections to:

   • P-A, P-B, A-T, B-T

   • P-B, A-T

   • P-B, B-T

   • P-A, P-B

   • P-B

   • P-A, P-B, A-B

Programmatic Use

Parameter: Kv_max_PB

P-B orifice Kv flow coefficient vector — K_v coefficients for values in member position vector

[1e-06, .72, 1.44, 2.16, 2.88, 3.6] (default) | 1-by-n vector

Vector of K_v flow coefficients. Each coefficient corresponds to a value in the P-B orifice spool travel vector parameter. This parameter measures the ease with which the vapor traverses the resistive element when driven by a pressure differential. The size of the vector must be the same as the P-B orifice spool travel vector parameter.

Dependencies

To enable this parameter, set:

1. Modeling option to Vapor operating condition

2. Area characteristics to Different for each flow path

3. Orifice parameterization to Kv flow coefficient

4. Opening characteristic to Tabulated

5. One of the following parameters:

   Positive spool position open connections to:

   • P-B, A-T

   • P-A, P-B

   • P-B

   • P-A, P-B, A-B

   Neutral spool position open connections to:

   • P-A, P-B, A-T, B-T

   • P-B, A-T

   • P-B, B-T

   • P-A, P-B

   • P-B

   • P-A, P-B, A-B

   • P-B, B-T, P-T

   • P-A, P-B, A-T, B-T, P-T

   Negative spool position open connections to:

   • P-A, P-B, A-T, B-T

   • P-B, A-T

   • P-B, B-T

   • P-A, P-B

   • P-B

   • P-A, P-B, A-B

Programmatic Use

Parameter: Kv_TLU_PB

P-B orifice spool travel vector — Vector of spool opening distances relative to fully closed position

[0, .00125, .0025, .00375, .005] m (default) | 1-by-n vector

Vector of spool travel distances for the tabular parameterization of the valve area. List the values in ascending order. The first element must be 0. The block uses linear interpolation between table data points.

Dependencies

To enable this parameter, set Area characteristics to Different for each flow path, Opening characteristic to Tabulated, and one of the following parameters:

Positive spool position open connections to:

• P-B, A-T

• P-A, P-B

• P-B

• P-A, P-B, A-B

Neutral spool position open connections to:

• P-A, P-B, A-T, B-T

• P-B, A-T

• P-B, B-T

• P-A, P-B

• P-B

• P-A, P-B, A-B

• P-B, B-T, P-T

• P-A, P-B, A-T, B-T, P-T

Negative spool position open connections to:

• P-A, P-B, A-T, B-T

• P-B, A-T

• P-B, B-T

• P-A, P-B

• P-B

• P-A, P-B, A-B

Programmatic Use

Parameter: del_S_Cv_TLU_PB

Parameter: del_S_Kv_TLU_PB

Parameter: del_S_C_TLU_PB

Parameter: del_S_orifice_area_TLU_PB

P-B maximum orifice area — Maximum orifice opening area

1e-4 m^2 (default) | positive scalar

Largest open area of the P-B orifice during the operation of the valve.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Orifice area

3. Opening characteristic to Tabulated

4. One of the following parameters:

   Positive spool position open connections to:

   • P-B, A-T

   • P-A, P-B

   • P-B

   • P-A, P-B, A-B

   Neutral spool position open connections to:

   • P-A, P-B, A-T, B-T

   • P-B, A-T

   • P-B, B-T

   • P-A, P-B

   • P-B

   • P-A, P-B, A-B

   • P-B, B-T, P-T

   • P-A, P-B, A-T, B-T, P-T

   Negative spool position open connections to:

   • P-A, P-B, A-T, B-T

   • P-B, A-T

   • P-B, B-T

   • P-A, P-B

   • P-B

   • P-A, P-B, A-B

Programmatic Use

Parameter: orifice_area_max_PB

P-B orifice area vector — Vector of valve opening areas

[1e-10, 1e-05, 4e-05, 6e-05, .0001] m^2 (default) | 1-by-n vector

Vector of opening areas for the tabular parameterization of the valve area. The vector elements must correspond one-to-one with the elements in the P-B orifice spool travel vector parameter. The elements must be greater than 0 and listed in ascending order. The first element of this vector is the leakage area.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Orifice area

3. Opening characteristic to Tabulated

4. One of the following parameters:

   Positive spool position open connections to:

   • P-B, A-T

   • P-A, P-B

   • P-B

   • P-A, P-B, A-B

   Neutral spool position open connections to:

   • P-A, P-B, A-T, B-T

   • P-B, A-T

   • P-B, B-T

   • P-A, P-B

   • P-B

   • P-A, P-B, A-B

   • P-B, B-T, P-T

   • P-A, P-B, A-T, B-T, P-T

   Negative spool position open connections to:

   • P-A, P-B, A-T, B-T

   • P-B, A-T

   • P-B, B-T

   • P-A, P-B

   • P-B

   • P-A, P-B, A-B

Programmatic Use

Parameter: orifice_area_TLU_PB

P-B constant orifice area — Cross-sectional area for constant orifice

1e-4 m^2 (default) | positive scalar

Orifice area when the positive and negative spool positions include the same orifice.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Orifice area

3. One of the following settings in each parameter:

   Positive spool position open connections to:

   • P-B, A-T

   • P-A, P-B

   • P-B

   • P-A, P-B, A-B

   Neutral spool position open connections to:

   • P-A, P-B, A-T, B-T

   • P-B, A-T

   • P-B, B-T

   • P-A, P-B

   • P-B

   • P-A, P-B, A-B

   • P-B, B-T, P-T

   • P-A, P-B, A-T, B-T, P-T

   Negative spool position open connections to:

   • P-A, P-B, A-T, B-T

   • P-B, A-T

   • P-B, B-T

   • P-A, P-B

   • P-B

   • P-A, P-B, A-B

Note:

This parameter is enabled only when the P-B orifice settings appear in all three spool position parameters: Positive spool position open connections, Neutral spool position open connections, and Negative spool position open connections.

Programmatic Use

Parameter: orifice_area_const_PB

P-B orifice xT pressure differential ratio factor at choked flow — Ratio of pressure differentials

0.7 (default) | positive scalar

Ratio between the inlet pressure, p_in, and the outlet pressure, p_out, defined as $$(p_{in}-p_{out})/p_{in}$$ where choking first occurs for the P-B orifice.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Kv flow coefficient or Cv flow coefficient

3. At least one of the following parameters:

   Positive spool position open connections to:

   • P-B, A-T

   • P-A, P-B

   • P-B

   • P-A, P-B, A-B

   Neutral spool position open connections to:

   • P-A, P-B, A-T, B-T

   • P-B, A-T

   • P-B, B-T

   • P-A, P-B

   • P-B

   • P-A, P-B, A-B

   • P-B, B-T, P-T

   • P-A, P-B, A-T, B-T, P-T

   Negative spool position open connections to:

   • P-A, P-B, A-T, B-T

   • P-B, A-T

   • P-B, B-T

   • P-A, P-B

   • P-B

   • P-A, P-B, A-B

Programmatic Use

Parameter: xT_Cv_PB

Parameter: xT_Kv_PB

P-B constant orifice sonic conductance — Sonic conductance for constant orifice

12 l/(bar*s) (default) | positive scalar

Sonic conductance when the positive and negative spool positions include the same orifice. This value is the ratio, measured at the onset of choking, of the mass flow rate through the resistive element to the product of the upstream pressure and mass density at standard conditions as defined in ISO 8778. This parameter determines the maximum flow rate allowed at a given upstream pressure.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Sonic conductance

3. One of the following settings in each parameter:

   Positive spool position open connections to:

   • P-B, A-T

   • P-A, P-B

   • P-B

   • P-A, P-B, A-B

   Neutral spool position open connections to:

   • P-A, P-B, A-T, B-T

   • P-B, A-T

   • P-B, B-T

   • P-A, P-B

   • P-B

   • P-A, P-B, A-B

   • P-B, B-T, P-T

   • P-A, P-B, A-T, B-T, P-T

   Negative spool position open connections to:

   • P-A, P-B, A-T, B-T

   • P-B, A-T

   • P-B, B-T

   • P-A, P-B

   • P-B

   • P-A, P-B, A-B

Note:

This parameter is enabled only when the P-B orifice settings appear in all three spool position parameters: Positive spool position open connections, Neutral spool position open connections, and Negative spool position open connections.

Programmatic Use

Parameter: C_const_PB

P-B constant orifice critical pressure ratio — Ratio of downstream and upstream pressures at which the flow first chokes for constant orifice

0.3 (default) | positive scalar

Critical pressure ratio when the positive and negative spool positions include the same orifice. This value is the pressure ratio at which flow first begins to choke and the flow velocity reaches its maximum, given by the local speed of sound. The pressure ratio is the outlet pressure divided by inlet pressure.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Sonic conductance

3. One of the following settings in each parameter:

   Positive spool position open connections to:

   • P-B, A-T

   • P-A, P-B

   • P-B

   • P-A, P-B, A-B

   Neutral spool position open connections to:

   • P-A, P-B, A-T, B-T

   • P-B, A-T

   • P-B, B-T

   • P-A, P-B

   • P-B

   • P-A, P-B, A-B

   • P-B, B-T, P-T

   • P-A, P-B, A-T, B-T, P-T

   Negative spool position open connections to:

   • P-A, P-B, A-T, B-T

   • P-B, A-T

   • P-B, B-T

   • P-A, P-B

   • P-B

   • P-A, P-B, A-B

Note:

This parameter is enabled only when the P-B orifice settings appear in all three spool position parameters: Positive spool position open connections, Neutral spool position open connections, and Negative spool position open connections.

Programmatic Use

Parameter: B_crit_const_PB

P-B orifice maximum sonic conductance — Sonic conductance corresponding to maximally open orifice

12 l/(bar*s) (default) | positive scalar

Value of the sonic conductance when the P-B orifice is fully open and the area available for flow is at a maximum.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Sonic conductance

3. Opening characteristic to Linear

4. One of the following parameters:

   Positive spool position open connections to:

   • P-B, A-T

   • P-A, P-B

   • P-B

   • P-A, P-B, A-B

   Neutral spool position open connections to:

   • P-A, P-B, A-T, B-T

   • P-B, A-T

   • P-B, B-T

   • P-A, P-B

   • P-B

   • P-A, P-B, A-B

   • P-B, B-T, P-T

   • P-A, P-B, A-T, B-T, P-T

   Negative spool position open connections to:

   • P-A, P-B, A-T, B-T

   • P-B, A-T

   • P-B, B-T

   • P-A, P-B

   • P-B

   • P-A, P-B, A-B

Programmatic Use

Parameter: C_max_PB

P-B orifice critical pressure ratio — Ratio of downstream and upstream pressures at which the flow first chokes

0.3 (default) | positive scalar

Pressure ratio at which flow first begins to choke and the flow velocity reaches its maximum, given by the local speed of sound. The pressure ratio is the outlet pressure divided by inlet pressure.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Sonic conductance

3. Opening characteristic to Linear

4. One of the following parameters:

   Positive spool position open connections to:

   • P-B, A-T

   • P-A, P-B

   • P-B

   • P-A, P-B, A-B

   Neutral spool position open connections to:

   • P-A, P-B, A-T, B-T

   • P-B, A-T

   • P-B, B-T

   • P-A, P-B

   • P-B

   • P-A, P-B, A-B

   • P-B, B-T, P-T

   • P-A, P-B, A-T, B-T, P-T

   Negative spool position open connections to:

   • P-A, P-B, A-T, B-T

   • P-B, A-T

   • P-B, B-T

   • P-A, P-B

   • P-B

   • P-A, P-B, A-B

Programmatic Use

Parameter: B_crit_linear_PB

P-B orifice sonic conductance vector — Sonic conductances corresponding to values in spool travel vector

[1e-05, 2.4, 4.8, 7.2, 9.6, 12] l/(bar*s) (default) | 1-by-n vector

Vector of sonic conductances inside the resistive element. Each conductance corresponds to a value in the P-B orifice spool travel vector parameter. The size of the vector must be the same as the P-B orifice spool travel vector parameter.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Sonic conductance

3. Opening characteristic to Tabulated

4. One of the following parameters:

   Positive spool position open connections to:

   • P-B, A-T

   • P-A, P-B

   • P-B

   • P-A, P-B, A-B

   Neutral spool position open connections to:

   • P-A, P-B, A-T, B-T

   • P-B, A-T

   • P-B, B-T

   • P-A, P-B

   • P-B

   • P-A, P-B, A-B

   • P-B, B-T, P-T

   • P-A, P-B, A-T, B-T, P-T

   Negative spool position open connections to:

   • P-A, P-B, A-T, B-T

   • P-B, A-T

   • P-B, B-T

   • P-A, P-B

   • P-B

   • P-A, P-B, A-B

Programmatic Use

Parameter: C_TLU_PB

P-B orifice critical pressure ratio vector — Critical pressure ratios corresponding to values in spool travel vector

0.3 * ones(1, 6) (default) | 1-by-n vector

Vector of critical pressure ratios at which the flow first chokes, with each critical pressure ratio corresponding to a value in the P-B orifice spool travel vector parameter. The critical pressure ratio is the fraction of downstream-to-upstream pressures at which the flow velocity reaches the local speed of sound. The size of the vector must be the same as the P-B orifice spool travel vector parameter.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Sonic conductance

3. Opening characteristic to Tabulated

4. One of the following parameters:

   Positive spool position open connections to:

   • P-B, A-T

   • P-A, P-B

   • P-B

   • P-A, P-B, A-B

   Neutral spool position open connections to:

   • P-A, P-B, A-T, B-T

   • P-B, A-T

   • P-B, B-T

   • P-A, P-B

   • P-B

   • P-A, P-B, A-B

   • P-B, B-T, P-T

   • P-A, P-B, A-T, B-T, P-T

   Negative spool position open connections to:

   • P-A, P-B, A-T, B-T

   • P-B, A-T

   • P-B, B-T

   • P-A, P-B

   • P-B

   • P-A, P-B, A-B

Programmatic Use

Parameter: B_crit_TLU_PB

P-B orifice subsonic index — Exponent used to characterize mass flow in subsonic flow regime

0.5 (default) | positive scalar

Empirical value used to more accurately calculate the mass flow rate in the subsonic flow regime.

Dependencies

To enable this parameter, set Area characteristics to Different for each flow path, Orifice parameterization to Sonic conductance, and at least one of the following parameters:

Positive spool position open connections to:

• P-B, A-T

• P-A, P-B

• P-B

• P-A, P-B, A-B

Neutral spool position open connections to:

• P-A, P-B, A-T, B-T

• P-B, A-T

• P-B, B-T

• P-A, P-B

• P-B

• P-A, P-B, A-B

• P-B, B-T, P-T

• P-A, P-B, A-T, B-T, P-T

Negative spool position open connections to:

• P-A, P-B, A-T, B-T

• P-B, A-T

• P-B, B-T

• P-A, P-B

• P-B

• P-A, P-B, A-B

Programmatic Use

Parameter: m_PB

P-B orifice ISO reference temperature — ISO 8778 reference temperature

293.15 K (default) | scalar

Temperature at standard reference atmosphere, defined as 293.15 K in ISO 8778.

You only need to adjust the ISO reference parameter values if you are using sonic conductance values that are obtained at difference reference values.

Dependencies

To enable this parameter, set Area characteristics to Different for each flow path, Orifice parameterization to Sonic conductance, and at least one of the following parameters:

Positive spool position open connections to:

• P-B, A-T

• P-A, P-B

• P-B

• P-A, P-B, A-B

Neutral spool position open connections to:

• P-A, P-B, A-T, B-T

• P-B, A-T

• P-B, B-T

• P-A, P-B

• P-B

• P-A, P-B, A-B

• P-B, B-T, P-T

• P-A, P-B, A-T, B-T, P-T

Negative spool position open connections to:

• P-A, P-B, A-T, B-T

• P-B, A-T

• P-B, B-T

• P-A, P-B

• P-B

• P-A, P-B, A-B

Programmatic Use

Parameter: T_ref_C_PB

P-B orifice ISO reference density — ISO 8778 reference density

1.185 kg/m^3 (default) | positive scalar

Density at standard reference atmosphere, defined as 1.185 kg/m3 in ISO 8778.

You only need to adjust the ISO reference parameter values if you are using sonic conductance values that are obtained at difference reference values.

Dependencies

To enable this parameter, set Area characteristics to Different for each flow path, Orifice parameterization to Sonic conductance, and at least one of the following parameters:

Positive spool position open connections to:

• P-B, A-T

• P-A, P-B

• P-B

• P-A, P-B, A-B

Neutral spool position open connections to:

• P-A, P-B, A-T, B-T

• P-B, A-T

• P-B, B-T

• P-A, P-B

• P-B

• P-A, P-B, A-B

• P-B, B-T, P-T

• P-A, P-B, A-T, B-T, P-T

Negative spool position open connections to:

• P-A, P-B, A-T, B-T

• P-B, A-T

• P-B, B-T

• P-A, P-B

• P-B

• P-A, P-B, A-B

Programmatic Use

Parameter: rho_ref_C_PB

A-B Orifice

Spool position at maximum A-B orifice area — Spool offset for fully open A-B orifice

5e-3 m (default) | positive scalar

Spool offset from the neutral position for a fully open A-B orifice.

Dependencies

To enable this parameter, set one of these parameters.

Positive spool position open connections to:

• P-A, P-B, A-B

Neutral spool position open connections to:

• P-A, P-B, A-B

Negative spool position open connections to:

• P-A, P-B, A-B

Note:

This parameter is enabled only when the A-B orifice settings do not appear in all three spool position parameters: Positive spool position open connections, Neutral spool position open connections, and Negative spool position open connections.

Programmatic Use

Parameter: S_max_AB

A-B spool travel between closed and open orifice — Maximum spool stroke

0.005 m (default) | positive scalar

Maximum distance of spool travel. This value provides an upper limit to calculations so that simulations do not return unphysical values.

Dependencies

To enable this parameter, set Area characteristics to Different for each flow path, Opening characteristic to Linear one of the following parameters:

Positive spool position open connections to:

• P-A, P-B, A-B

Neutral spool position open connections to:

• P-A, P-B, A-B

Negative spool position open connections to:

• P-A, P-B, A-B

Programmatic Use

Parameter: del_S_max_AB

A-B constant orifice Cv flow coefficient — Flow coefficient

4 (default) | positive scalar

Value of the constant C_v flow coefficient for the A-B orifice. This parameter measures the ease with which the vapor traverses the resistive element when driven by a pressure differential.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Cv flow coefficient

3. One of the following settings in each parameter:

   Positive spool position open connections to:

   • P-A, P-B, A-B

   Neutral spool position open connections to:

   • P-A, P-B, A-B

   Negative spool position open connections to:

   • P-A, P-B, A-B

Note:

This parameter is enabled only when the A-B orifice settings appear all three spool position parameters: Positive spool position open connections, Neutral spool position open connections, and Negative spool position open connections.

Programmatic Use

Parameter: Cv_const_AB

A-B orifice maximum Cv flow coefficient — C_v coefficient that corresponds to maximally open component

4 (default) | positive scalar

Value of the C_v flow coefficient when the A-B orifice is fully open and the area available for flow is at a maximum. This parameter measures the ease with which the vapor traverses the resistive element when driven by a pressure differential.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Cv flow coefficient

3. Opening characteristic to Linear

4. One of the following parameters:

   Positive spool position open connections to:

   • P-A, P-B, A-B

   Neutral spool position open connections to:

   • P-A, P-B, A-B

   Negative spool position open connections to:

   • P-A, P-B, A-B

Programmatic Use

Parameter: Cv_max_AB

A-B orifice Cv flow coefficient vector — C_v coefficients for values in member position vector

[1e-06, .8, 1.6, 2.4, 3.2, 4] (default) | 1-by-n vector

Vector of C_v flow coefficients. Each coefficient corresponds to a value in the A-B orifice spool travel vector parameter. This parameter measures the ease with which the vapor traverses the resistive element when driven by a pressure differential. The size of the vector must be the same as the A-B orifice spool travel vector parameter.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Cv flow coefficient

3. Opening characteristic to Tabulated

4. One of the following parameters:

   Positive spool position open connections to:

   • P-A, P-B, A-B

   Neutral spool position open connections to:

   • P-A, P-B, A-B

   Negative spool position open connections to:

   • P-A, P-B, A-B

Programmatic Use

Parameter: Cv_TLU_AB

A-B constant orifice Kv flow coefficient — Flow coefficient

3.6 (default) | positive scalar

Value of the constant K_v flow coefficient for the A-B orifice. This parameter measures the ease with which the vapor traverses the resistive element when driven by a pressure differential.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Kv flow coefficient

3. One of the following settings in each parameter:

   Positive spool position open connections to:

   • P-A, P-B, A-B

   Neutral spool position open connections to:

   • P-A, P-B, A-B

   Negative spool position open connections to:

   • P-A, P-B, A-B

Note:

This parameter is enabled only when the A-B orifice settings appear in all three spool position parameters: Positive spool position open connections, Neutral spool position open connections, and Negative spool position open connections.

Programmatic Use

Parameter: Kv_const_AB

A-B orifice maximum Kv flow coefficient — K_v coefficient that corresponds to maximally open component

3.6 (default) | positive scalar

Value of the K_v flow coefficient when the A-B orifice is fully open and the area available for flow is at a maximum. This parameter measures the ease with which the vapor traverses the resistive element when driven by a pressure differential.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Kv flow coefficient

3. Opening characteristic to Linear

4. One of the following parameters:

   Positive spool position open connections to:

   • P-A, P-B, A-B

   Neutral spool position open connections to:

   • P-A, P-B, A-B

   Negative spool position open connections to:

   • P-A, P-B, A-B

Programmatic Use

Parameter: Kv_max_AB

A-B orifice Kv flow coefficient vector — K_v coefficients for values in member position vector

[1e-06, .72, 1.44, 2.16, 2.88, 3.6] (default) | 1-by-n vector

Vector of K_v flow coefficients. Each coefficient corresponds to a value in the A-B orifice spool travel vector parameter. This parameter measures the ease with which the vapor traverses the resistive element when driven by a pressure differential. The size of the vector must be the same as the A-B orifice spool travel vector parameter.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Kv flow coefficient

3. Opening characteristic to Tabulated

4. One of the following parameters:

   Positive spool position open connections to:

   • P-A, P-B, A-B

   Neutral spool position open connections to:

   • P-A, P-B, A-B

   Negative spool position open connections to:

   • P-A, P-B, A-B

Programmatic Use

Parameter: Kv_TLU_AB

A-B orifice spool travel vector — Vector of spool opening distances relative to fully closed position

[0, .00125, .0025, .00375, .005] m (default) | 1-by-n vector

Vector of spool travel distances for the tabular parameterization of the valve area. List the values in ascending order. The first element must be 0. The block uses linear interpolation between table data points.

Dependencies

To enable this parameter, set Area characteristics to Different for each flow path, Opening characteristic to Tabulated, and one of the following parameters:

Positive spool position open connections to:

• P-A, P-B, A-B

Neutral spool position open connections to:

• P-A, P-B, A-B

Negative spool position open connections to:

• P-A, P-B, A-B

Programmatic Use

Parameter: del_S_Cv_TLU_AB

Parameter: del_S_Kv_TLU_AB

Parameter: del_S_C_TLU_AB

Parameter: del_S_orifice_area_TLU_AB

A-B maximum orifice area — Maximum orifice opening area

1e-4 m^2 (default) | positive scalar

Largest open area of the A-B orifice during the operation of the valve.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Orifice area

3. Opening characteristic to Linear

4. One of the following parameters:

   Positive spool position open connections to:

   • P-A, P-B, A-B

   Neutral spool position open connections to:

   • P-A, P-B, A-B

   Negative spool position open connections to:

   • P-A, P-B, A-B

Programmatic Use

Parameter: orifice_area_max_AB

A-B orifice area vector — Vector of valve opening areas

[1e-10, 1e-05, 4e-05, 6e-05, .0001] m^2 (default) | 1-by-n vector

Vector of opening areas for the tabular parameterization of the valve area. The vector elements must correspond one-to-one with the elements in the A-B orifice spool travel vector parameter. The elements must be greater than 0 and listed in ascending order. The first element of this vector is the leakage area.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Orifice area

3. Opening characteristic to Tabulated

4. One of the following parameters:

   Positive spool position open connections to:

   • P-A, P-B, A-B

   Neutral spool position open connections to:

   • P-A, P-B, A-B

   Negative spool position open connections to:

   • P-A, P-B, A-B

Programmatic Use

Parameter: orifice_area_TLU_AB

A-B constant orifice area — Cross-sectional area for constant orifice

1e-4 m^2 (default) | positive scalar

Orifice area when the positive and negative spool positions include the same orifice.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Orifice area

3. One of the following settings in each parameter:

   Positive spool position open connections to:

   • P-A, P-B, A-B

   Neutral spool position open connections to:

   • P-A, P-B, A-B

   Negative spool position open connections to:

   • P-A, P-B, A-B

Note:

This parameter is enabled only when the A-B orifice settings appear in all three spool position parameters: Positive spool position open connections, Neutral spool position open connections, and Negative spool position open connections.

Programmatic Use

Parameter: orifice_area_const_AB

A-B orifice xT pressure differential ratio factor at choked flow — Ratio of pressure differentials

0.7 (default) | positive scalar

Ratio between the inlet pressure, p_in, and the outlet pressure, p_out, defined as $$(p_{in}-p_{out})/p_{in}$$ where choking first occurs for the A-B orifice.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Kv flow coefficient or Cv flow coefficient

3. At least one of the following parameters:

   Positive spool position open connections to:

   • P-A, P-B, A-B

   Neutral spool position open connections to:

   • P-A, P-B, A-B

   Negative spool position open connections to:

   • P-A, P-B, A-B

Programmatic Use

Parameter: xT_Cv_AB

Parameter: xT_Kv_AB

A-B constant orifice sonic conductance — Sonic conductance for constant orifice

12 l/(bar*s) (default) | positive scalar

Sonic conductance when the positive and negative spool positions include the same orifice. This value is the ratio, measured at the onset of choking, of the mass flow rate through the resistive element to the product of the upstream pressure and mass density at standard conditions as defined in ISO 8778. This parameter determines the maximum flow rate allowed at a given upstream pressure.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Sonic conductance

3. One of the following settings in each parameter:

   Positive spool position open connections to:

   • P-A, P-B, A-B

   Neutral spool position open connections to:

   • P-A, P-B, A-B

   Negative spool position open connections to:

   • P-A, P-B, A-B

Note:

This parameter is enabled only when the A-B orifice settings appear in all three spool position parameters: Positive spool position open connections, Neutral spool position open connections, and Negative spool position open connections.

Programmatic Use

Parameter: C_const_AB

A-B constant orifice critical pressure ratio — Ratio of downstream and upstream pressures at which the flow first chokes for constant orifice

0.3 (default) | positive scalar

Critical pressure ratio when the positive and negative spool positions include the same orifice. This value is the pressure ratio at which flow first begins to choke and the flow velocity reaches its maximum, given by the local speed of sound. The pressure ratio is the outlet pressure divided by inlet pressure.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Sonic conductance

3. One of the following settings in each parameter:

   Positive spool position open connections to:

   • P-A, P-B, A-B

   Neutral spool position open connections to:

   • P-A, P-B, A-B

   Negative spool position open connections to:

   • P-A, P-B, A-B

Note:

This parameter is enabled only when the A-B orifice settings appear in all three spool position parameters: Positive spool position open connections, Neutral spool position open connections, and Negative spool position open connections.

Programmatic Use

Parameter: B_crit_const_AB

A-B orifice maximum sonic conductance — Sonic conductance corresponding to maximally open orifice

12 l/(bar*s) (default) | positive scalar

Value of the sonic conductance when the A-B orifice is fully open and the area available for flow is at a maximum.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Sonic conductance

3. Opening characteristic to Linear

4. One of the following parameters:

   Positive spool position open connections to:

   • P-A, P-B, A-B

   Neutral spool position open connections to:

   • P-A, P-B, A-B

   Negative spool position open connections to:

   • P-A, P-B, A-B

Programmatic Use

Parameter: C_max_AB

A-B orifice critical pressure ratio — Ratio of downstream and upstream pressures at which the flow first chokes

0.3 (default) | positive scalar

Pressure ratio at which flow first begins to choke and the flow velocity reaches its maximum, given by the local speed of sound. The pressure ratio is the outlet pressure divided by inlet pressure.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Sonic conductance

3. Opening characteristic to Linear

4. One of the following parameters:

   Positive spool position open connections to:

   • P-A, P-B, A-B

   Neutral spool position open connections to:

   • P-A, P-B, A-B

   Negative spool position open connections to:

   • P-A, P-B, A-B

Programmatic Use

Parameter: B_crit_linear_AB

A-B orifice sonic conductance vector — Sonic conductances corresponding to values in spool travel vector

[1e-05, 2.4, 4.8, 7.2, 9.6, 12] l/(bar*s) (default) | 1-by-n vector

Vector of sonic conductances inside the resistive element. Each conductance corresponds to a value in the A-B orifice spool travel vector parameter. The size of the vector must be the same as the A-B orifice spool travel vector parameter.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Sonic conductance

3. Opening characteristic to Tabulated

4. One of the following parameters:

   Positive spool position open connections to:

   • P-A, P-B, A-B

   Neutral spool position open connections to:

   • P-A, P-B, A-B

   Negative spool position open connections to:

   • P-A, P-B, A-B

Programmatic Use

Parameter: C_TLU_AB

A-B orifice critical pressure ratio vector — Critical pressure ratios corresponding to values in spool travel vector

0.3 * ones(1, 6) (default) | 1-by-n vector

Vector of critical pressure ratios at which the flow first chokes, with each critical pressure ratio corresponding to a value in the A-B orifice spool travel vector parameter. The critical pressure ratio is the fraction of downstream-to-upstream pressures at which the flow velocity reaches the local speed of sound. The size of the vector must be the same as the A-B orifice spool travel vector parameter.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Sonic conductance

3. Opening characteristic to Tabulated

4. One of the following parameters:

   Positive spool position open connections to:

   • P-A, P-B, A-B

   Neutral spool position open connections to:

   • P-A, P-B, A-B

   Negative spool position open connections to:

   • P-A, P-B, A-B

Programmatic Use

Parameter: B_crit_TLU_AB

A-B orifice subsonic index — Exponent used to characterize mass flow in subsonic flow regime

0.5 (default) | positive scalar

Empirical value used to more accurately calculate the mass flow rate in the subsonic flow regime.

Dependencies

To enable this parameter, set Area characteristics to Different for each flow path, Orifice parameterization to Sonic conductance, and at least one of the following parameters:

Positive spool position open connections to:

• P-A, P-B, A-B

Neutral spool position open connections to:

• P-A, P-B, A-B

Negative spool position open connections to:

• P-A, P-B, A-B

Programmatic Use

Parameter: m_AB

A-B orifice ISO reference temperature — ISO 8778 reference temperature

293.15 K (default) | scalar

Temperature at standard reference atmosphere, defined as 293.15 K in ISO 8778.

You only need to adjust the ISO reference parameter values if you are using sonic conductance values that are obtained at difference reference values.

Dependencies

To enable this parameter, set Area characteristics to Different for each flow path, Orifice parameterization to Sonic conductance, and at least one of the following parameters:

Positive spool position open connections to:

• P-A, P-B, A-B

Neutral spool position open connections to:

• P-A, P-B, A-B

Negative spool position open connections to:

• P-A, P-B, A-B

Programmatic Use

Parameter: T_ref_C_AB

A-B orifice ISO reference density — ISO 8778 reference density

1.185 kg/m^3 (default) | positive scalar

Density at standard reference atmosphere, defined as 1.185 kg/m3 in ISO 8778.

You only need to adjust the ISO reference parameter values if you are using sonic conductance values that are obtained at difference reference values.

Dependencies

To enable this parameter, set Area characteristics to Different for each flow path, Orifice parameterization to Sonic conductance, and at least one of the following parameters:

Positive spool position open connections to:

• P-A, P-B, A-B

Neutral spool position open connections to:

• P-A, P-B, A-B

Negative spool position open connections to:

• P-A, P-B, A-B

Programmatic Use

Parameter: rho_ref_C_AB

A-T Orifice

Spool position at maximum A-T orifice area — Spool offset for fully open A-T orifice

5e-3 m (default) | positive scalar

Spool offset from the neutral position for a fully open A-T orifice.

Dependencies

To enable this parameter, set one of these parameters.

• Positive spool position open connections to P-B, A-T.

• Neutral spool position open connections to:

  • P-A, P-B, A-T, B-T

  • P-B, A-T

  • A-T, B-T

  • P-A, A-T

  • A-T

  • P-A, A-T, P-T

  • P-A, P-B, A-T, B-T, P-T

• Negative spool position open connections to P-B, A-T.

Note:

This parameter is enabled only when the A-T orifice settings do not appear in all three spool position parameters: Positive spool position open connections, Neutral spool position open connections, and Negative spool position open connections.

Programmatic Use

Parameter: S_max_AT

A-T spool travel between closed and open orifice — Maximum spool stroke

0.005 m (default) | positive scalar

Maximum distance of spool travel. This value provides an upper limit to calculations so that simulations do not return unphysical values.

Dependencies

To enable this parameter, set Area characteristics to Different for each flow path, Opening characteristic to Linear, and one of the following parameters:

• Positive spool position open connections to P-B, A-T.

• Neutral spool position open connections to:

  • P-A, P-B, A-T, B-T

  • P-B, A-T

  • A-T, B-T

  • P-A, A-T

  • A-T

  • P-A, A-T, P-T

  • P-A, P-B, A-T, B-T, P-T

• Negative spool position open connections to P-B, A-T.

Programmatic Use

Parameter: del_S_max_AT

A-T constant orifice Cv flow coefficient — Flow coefficient

4 (default) | positive scalar

Value of the constant C_v flow coefficient for the A-T orifice. This parameter measures the ease with which the vapor traverses the resistive element when driven by a pressure differential.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Cv flow coefficient

3. One of the following settings in each parameter:

   • Positive spool position open connections to P-B, A-T.

   • Neutral spool position open connections to:

     • P-A, P-B, A-T, B-T

     • P-B, A-T

     • A-T, B-T

     • P-A, A-T

     • A-T

     • P-A, A-T, P-T

     • P-A, P-B, A-T, B-T, P-T

   • Negative spool position open connections to P-B, A-T.

Note:

This parameter is enabled only when the A-T orifice settings appear in all three spool position parameters: Positive spool position open connections, Neutral spool position open connections, and Negative spool position open connections.

Programmatic Use

Parameter: Cv_const_AT

A-T orifice maximum Cv flow coefficient — C_v coefficient that corresponds to maximally open component

4 (default) | positive scalar

Value of the C_v flow coefficient when the A-T orifice is fully open and the area available for flow is at a maximum. This parameter measures the ease with which the vapor traverses the resistive element when driven by a pressure differential.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Cv flow coefficient

3. Opening characteristic to Linear

4. One of the following parameters:

   • Positive spool position open connections to P-B, A-T.

   • Neutral spool position open connections to:

     • P-A, P-B, A-T, B-T

     • P-B, A-T

     • A-T, B-T

     • P-A, A-T

     • A-T

     • P-A, A-T, P-T

     • P-A, P-B, A-T, B-T, P-T

   • Negative spool position open connections to P-B, A-T.

Programmatic Use

Parameter: Cv_max_AT

A-T orifice Cv flow coefficient vector — C_v coefficients for values in member position vector

[1e-06, .8, 1.6, 2.4, 3.2, 4] (default) | 1-by-n vector

Vector of C_v flow coefficients. Each coefficient corresponds to a value in the A-T orifice spool travel vector parameter. This parameter measures the ease with which the vapor traverses the resistive element when driven by a pressure differential. The size of the vector must be the same as the A-T orifice spool travel vector parameter.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Cv flow coefficient

3. Opening characteristic to Tabulated

4. One of the following parameters:

   • Positive spool position open connections to P-B, A-T.

   • Neutral spool position open connections to:

     • P-A, P-B, A-T, B-T

     • P-B, A-T

     • A-T, B-T

     • P-A, A-T

     • A-T

     • P-A, A-T, P-T

     • P-A, P-B, A-T, B-T, P-T

   • Negative spool position open connections to P-B, A-T.

Programmatic Use

Parameter: Cv_TLU_AT

A-T constant orifice Kv flow coefficient — Flow coefficient

3.6 (default) | positive scalar

Value of the constant K_v flow coefficient for the A-T orifice. This parameter measures the ease with which the vapor traverses the resistive element when driven by a pressure differential.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Kv flow coefficient

3. One of the following settings in each parameter:

   • Positive spool position open connections to P-B, A-T.

   • Neutral spool position open connections to:

     • P-A, P-B, A-T, B-T

     • P-B, A-T

     • A-T, B-T

     • P-A, A-T

     • A-T

     • P-A, A-T, P-T

     • P-A, P-B, A-T, B-T, P-T

   • Negative spool position open connections to P-B, A-T.

Note:

This parameter is enabled only when the A-T orifice settings appear in all three spool position parameters: Positive spool position open connections, Neutral spool position open connections, and Negative spool position open connections.

Programmatic Use

Parameter: Kv_const_AT

A-T orifice maximum Kv flow coefficient — K_v coefficient that corresponds to maximally open component

3.6 (default) | positive scalar

Value of the K_v flow coefficient when the A-T orifice is fully open and the area available for flow is at a maximum. This parameter measures the ease with which the vapor traverses the resistive element when driven by a pressure differential.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Kv flow coefficient

3. Opening characteristic to Linear

4. One of the following parameters:

   • Positive spool position open connections to P-B, A-T.

   • Neutral spool position open connections to:

     • P-A, P-B, A-T, B-T

     • P-B, A-T

     • A-T, B-T

     • P-A, A-T

     • A-T

     • P-A, A-T, P-T

     • P-A, P-B, A-T, B-T, P-T

   • Negative spool position open connections to P-B, A-T.

Programmatic Use

Parameter: Kv_max_AT

A-T orifice Kv flow coefficient vector — K_v coefficients for values in member position vector

[1e-06, .72, 1.44, 2.16, 2.88, 3.6] (default) | 1-by-n vector

Vector of K_v flow coefficients. Each coefficient corresponds to a value in the A-T orifice spool travel vector parameter. This parameter measures the ease with which the vapor traverses the resistive element when driven by a pressure differential. The size of the vector must be the same as the A-T orifice spool travel vector parameter.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Kv flow coefficient

3. Opening characteristic to Tabulated

4. One of the following parameters:

   • Positive spool position open connections to P-B, A-T.

   • Neutral spool position open connections to:

     • P-A, P-B, A-T, B-T

     • P-B, A-T

     • A-T, B-T

     • P-A, A-T

     • A-T

     • P-A, A-T, P-T

     • P-A, P-B, A-T, B-T, P-T

   • Negative spool position open connections to P-B, A-T.

Programmatic Use

Parameter: Kv_TLU_AT

A-T orifice spool travel vector — Vector of spool opening distances relative to fully closed position

[0, .00125, .0025, .00375, .005] m (default) | 1-by-n vector

Vector of spool travel distances for the tabular parameterization of the valve area. List the values in ascending order. The first element must be 0. The block uses linear interpolation between table data points.

Dependencies

To enable this parameter, set Area characteristics to Different for each flow path, Opening characteristic to Tabulated, and one of the following parameters:

• Positive spool position open connections to P-B, A-T.

• Neutral spool position open connections to:

  • P-A, P-B, A-T, B-T

  • P-B, A-T

  • A-T, B-T

  • P-A, A-T

  • A-T

  • P-A, A-T, P-T

  • P-A, P-B, A-T, B-T, P-T

• Negative spool position open connections to P-B, A-T.

Programmatic Use

Parameter: del_S_Cv_TLU_AT

Parameter: del_S_Kv_TLU_AT

Parameter: del_S_C_TLU_AT

Parameter: del_S_orifice_area_TLU_AT

A-T maximum orifice area — Maximum orifice opening area

1e-4 m^2 (default) | positive scalar

Largest open area of the A-T orifice during the operation of the valve.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Orifice area

3. Opening characteristic to Linear

4. One of the following parameters:

   • Positive spool position open connections to P-B, A-T.

   • Neutral spool position open connections to:

     • P-A, P-B, A-T, B-T

     • P-B, A-T

     • A-T, B-T

     • P-A, A-T

     • A-T

     • P-A, A-T, P-T

     • P-A, P-B, A-T, B-T, P-T

   • Negative spool position open connections to P-B, A-T.

Programmatic Use

Parameter: orifice_area_max_AT

A-T orifice area vector — Vector of valve opening areas

[1e-10, 1e-05, 4e-05, 6e-05, .0001] m^2 (default) | 1-by-n vector

Vector of opening areas for the tabular parameterization of the valve area. The vector elements must correspond one-to-one with the elements in the A-T orifice spool travel vector parameter. The elements must be greater than 0 and listed in ascending order. The first element of this vector is the leakage area.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Orifice area

3. Opening characteristic to Tabulated

4. One of the following parameters:

   • Positive spool position open connections to P-B, A-T.

   • Neutral spool position open connections to:

     • P-A, P-B, A-T, B-T

     • P-B, A-T

     • A-T, B-T

     • P-A, A-T

     • A-T

     • P-A, A-T, P-T

     • P-A, P-B, A-T, B-T, P-T

   • Negative spool position open connections to P-B, A-T.

Programmatic Use

Parameter: orifice_area_TLU_AT

A-T constant orifice area — Cross-sectional area for constant orifice

1e-4 m^2 (default) | positive scalar

Orifice area when the positive and negative spool positions include the same orifice.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Orifice area

3. One of the following settings in each parameter:

   • Positive spool position open connections to P-B, A-T.

   • Neutral spool position open connections to:

     • P-A, P-B, A-T, B-T

     • P-B, A-T

     • A-T, B-T

     • P-A, A-T

     • A-T

     • P-A, A-T, P-T

     • P-A, P-B, A-T, B-T, P-T

   • Negative spool position open connections to P-B, A-T.

Note:

This parameter is enabled only when the A-T orifice settings appear in all three spool position parameters: Positive spool position open connections, Neutral spool position open connections, and Negative spool position open connections.

Programmatic Use

Parameter: orifice_area_const_AT

A-T orifice xT pressure differential ratio factor at choked flow — Ratio of pressure differentials

0.7 (default) | positive scalar

Ratio between the inlet pressure, p_in, and the outlet pressure, p_out, defined as $$(p_{in}-p_{out})/p_{in}$$ where choking first occurs for the A-T orifice.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Kv flow coefficient or Cv flow coefficient

3. At least one of the following parameters:

   • Positive spool position open connections to P-B, A-T.

   • Neutral spool position open connections to:

     • P-A, P-B, A-T, B-T

     • P-B, A-T

     • A-T, B-T

     • P-A, A-T

     • A-T

     • P-A, A-T, P-T

     • P-A, P-B, A-T, B-T, P-T

   • Negative spool position open connections to P-B, A-T.

Programmatic Use

Parameter: xT_Cv_AT

Parameter: xT_Kv_AT

A-T constant orifice sonic conductance — Sonic conductance for constant orifice

12 l/(bar*s) (default) | positive scalar

Sonic conductance when the positive and negative spool positions include the same orifice. This value is the ratio, measured at the onset of choking, of the mass flow rate through the resistive element to the product of the upstream pressure and mass density at standard conditions as defined in ISO 8778. This parameter determines the maximum flow rate allowed at a given upstream pressure.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Sonic conductance

3. One of the following settings in each parameter:

   • Positive spool position open connections to P-B, A-T.

   • Neutral spool position open connections to:

     • P-A, P-B, A-T, B-T

     • P-B, A-T

     • A-T, B-T

     • P-A, A-T

     • A-T

     • P-A, A-T, P-T

     • P-A, P-B, A-T, B-T, P-T

   • Negative spool position open connections to P-B, A-T.

Note:

This parameter is enabled only when the A-T orifice settings appear in all three spool position parameters: Positive spool position open connections, Neutral spool position open connections, and Negative spool position open connections.

Programmatic Use

Parameter: C_const_AT

A-T constant orifice critical pressure ratio — Ratio of downstream and upstream pressures at which the flow first chokes for constant orifice

0.3 (default) | positive scalar

Critical pressure ratio when the positive and negative spool positions include the same orifice. This value is the pressure ratio at which flow first begins to choke and the flow velocity reaches its maximum, given by the local speed of sound. The pressure ratio is the outlet pressure divided by inlet pressure.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Sonic conductance

3. One of the following settings in each parameter:

   • Positive spool position open connections to P-B, A-T.

   • Neutral spool position open connections to:

     • P-A, P-B, A-T, B-T

     • P-B, A-T

     • A-T, B-T

     • P-A, A-T

     • A-T

     • P-A, A-T, P-T

     • P-A, P-B, A-T, B-T, P-T

   • Negative spool position open connections to P-B, A-T.

Note:

This parameter is enabled only when the A-T orifice settings appear in all three spool position parameters: Positive spool position open connections, Neutral spool position open connections, and Negative spool position open connections.

Programmatic Use

Parameter: B_crit_const_AT

A-T orifice maximum sonic conductance — Sonic conductance corresponding to maximally open orifice

12 l/(bar*s) (default) | positive scalar

Value of the sonic conductance when the A-T orifice is fully open and the area available for flow is at a maximum.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Sonic conductance

3. Opening characteristic to Linear

4. One of the following parameters:

   • Positive spool position open connections to P-B, A-T.

   • Neutral spool position open connections to:

     • P-A, P-B, A-T, B-T

     • P-B, A-T

     • A-T, B-T

     • P-A, A-T

     • A-T

     • P-A, A-T, P-T

     • P-A, P-B, A-T, B-T, P-T

   • Negative spool position open connections to P-B, A-T.

Programmatic Use

Parameter: C_max_AT

A-T orifice critical pressure ratio — Ratio of downstream and upstream pressures at which the flow first chokes

0.3 (default) | positive scalar

Pressure ratio at which flow first begins to choke and the flow velocity reaches its maximum, given by the local speed of sound. The pressure ratio is the outlet pressure divided by inlet pressure.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Sonic conductance

3. Opening characteristic to Linear

4. One of the following parameters:

   • Positive spool position open connections to P-B, A-T.

   • Neutral spool position open connections to:

     • P-A, P-B, A-T, B-T

     • P-B, A-T

     • A-T, B-T

     • P-A, A-T

     • A-T

     • P-A, A-T, P-T

     • P-A, P-B, A-T, B-T, P-T

   • Negative spool position open connections to P-B, A-T.

Programmatic Use

Parameter: B_crit_linear_AT

A-T orifice sonic conductance vector — Sonic conductances corresponding to values in spool travel vector

[1e-05, 2.4, 4.8, 7.2, 9.6, 12] l/(bar*s) (default) | 1-by-n vector

Vector of sonic conductances inside the resistive element. Each conductance corresponds to a value in the A-T orifice spool travel vector parameter. The size of the vector must be the same as the A-T orifice spool travel vector parameter.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Sonic conductance

3. Opening characteristic to Tabulated

4. One of the following parameters:

   • Positive spool position open connections to P-B, A-T.

   • Neutral spool position open connections to:

     • P-A, P-B, A-T, B-T

     • P-B, A-T

     • A-T, B-T

     • P-A, A-T

     • A-T

     • P-A, A-T, P-T

     • P-A, P-B, A-T, B-T, P-T

   • Negative spool position open connections to P-B, A-T.

Programmatic Use

Parameter: C_TLU_AT

A-T orifice critical pressure ratio vector — Critical pressure ratios corresponding to values in spool travel vector

0.3 * ones(1, 6) (default) | 1-by-n vector

Vector of critical pressure ratios at which the flow first chokes, with each critical pressure ratio corresponding to a value in the A-T orifice spool travel vector parameter. The critical pressure ratio is the fraction of downstream-to-upstream pressures at which the flow velocity reaches the local speed of sound. The size of the vector must be the same as the A-T orifice spool travel vector parameter.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Sonic conductance

3. Opening characteristic to Tabulated

4. One of the following parameters:

   • Positive spool position open connections to P-B, A-T.

   • Neutral spool position open connections to:

     • P-A, P-B, A-T, B-T

     • P-B, A-T

     • A-T, B-T

     • P-A, A-T

     • A-T

     • P-A, A-T, P-T

     • P-A, P-B, A-T, B-T, P-T

   • Negative spool position open connections to P-B, A-T.

Programmatic Use

Parameter: B_crit_TLU_AT

A-T orifice subsonic index — Exponent used to characterize mass flow in subsonic flow regime

0.5 (default) | positive scalar

Empirical value used to more accurately calculate the mass flow rate in the subsonic flow regime.

Dependencies

To enable this parameter, set Area characteristics to Different for each flow path, Orifice parameterization to Sonic conductance, and at least one of the following parameters:

• Positive spool position open connections to P-B, A-T.

• Neutral spool position open connections to:

  • P-A, P-B, A-T, B-T

  • P-B, A-T

  • A-T, B-T

  • P-A, A-T

  • A-T

  • P-A, A-T, P-T

  • P-A, P-B, A-T, B-T, P-T

• Negative spool position open connections to P-B, A-T.

Programmatic Use

Parameter: m_AT

A-T orifice ISO reference temperature — ISO 8778 reference temperature

293.15 K (default) | scalar

Temperature at standard reference atmosphere, defined as 293.15 K in ISO 8778.

You only need to adjust the ISO reference parameter values if you are using sonic conductance values that are obtained at difference reference values.

Dependencies

To enable this parameter, set Area characteristics to Different for each flow path, Orifice parameterization to Sonic conductance, and at least one of the following parameters:

• Positive spool position open connections to P-B, A-T.

• Neutral spool position open connections to:

  • P-A, P-B, A-T, B-T

  • P-B, A-T

  • A-T, B-T

  • P-A, A-T

  • A-T

  • P-A, A-T, P-T

  • P-A, P-B, A-T, B-T, P-T

• Negative spool position open connections to P-B, A-T.

Programmatic Use

Parameter: T_ref_C_AT

A-T orifice ISO reference density — ISO 8778 reference density

1.185 kg/m^3 (default) | positive scalar

Density at standard reference atmosphere, defined as 1.185 kg/m3 in ISO 8778.

You only need to adjust the ISO reference parameter values if you are using sonic conductance values that are obtained at difference reference values.

Dependencies

To enable this parameter, set Area characteristics to Different for each flow path, Orifice parameterization to Sonic conductance, and at least one of the following parameters:

• Positive spool position open connections to P-B, A-T.

• Neutral spool position open connections to:

  • P-A, P-B, A-T, B-T

  • P-B, A-T

  • A-T, B-T

  • P-A, A-T

  • A-T

  • P-A, A-T, P-T

  • P-A, P-B, A-T, B-T, P-T

• Negative spool position open connections to P-B, A-T.

Programmatic Use

Parameter: rho_ref_C_AT

B-T Orifice

Spool position at maximum B-T orifice area — Spool offset for fully open B-T orifice

5e-3 m (default) | positive scalar

Spool offset from the neutral position for a fully open B-T orifice.

Dependencies

To enable this parameter, set one of these parameters.

• Positive spool position open connections to P-A, B-T.

• Neutral spool position open connections to:

  • P-A, P-B, A-T, B-T

  • A-T, B-T

  • P-A, B-T

  • P-B, B-T

  • B-T

  • P-B, B-T, P-T

  • P-A, P-B, A-T, B-T, P-T

• Negative spool position open connections to P-A, B-T.

Note:

This parameter is enabled only when the B-T orifice settings do not appear in all three spool position parameters: Positive spool position open connections, Neutral spool position open connections, and Negative spool position open connections.

Programmatic Use

Parameter: S_max_BT

B-T spool travel between closed and open orifice — Maximum spool stroke

0.005 m (default) | positive scalar

Maximum distance of spool travel. This value provides an upper limit to calculations so that simulations do not return unphysical values.

Dependencies

To enable this parameter, set Area characteristics to Different for each flow path, Opening characteristic to Linear, and one of the following parameters:

• Positive spool position open connections to P-A, B-T.

• Neutral spool position open connections to:

  • P-A, P-B, A-T, B-T

  • A-T, B-T

  • P-A, B-T

  • P-B, B-T

  • B-T

  • P-B, B-T, P-T

  • P-A, P-B, A-T, B-T, P-T

• Negative spool position open connections to P-A, B-T.

Programmatic Use

Parameter: del_S_max_BT

B-T constant orifice Cv flow coefficient — Flow coefficient

4 (default) | positive scalar

Value of the constant C_v flow coefficient for the B-T orifice. This parameter measures the ease with which the vapor traverses the resistive element when driven by a pressure differential.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Cv flow coefficient

3. One of the following settings in each parameter:

   • Positive spool position open connections to P-A, B-T.

   • Neutral spool position open connections to:

     • P-A, P-B, A-T, B-T

     • A-T, B-T

     • P-A, B-T

     • P-B, B-T

     • B-T

     • P-B, B-T, P-T

     • P-A, P-B, A-T, B-T, P-T

   • Negative spool position open connections to P-A, B-T.

Note:

This parameter is enabled only when the B-T orifice settings appear in all three spool position parameters: Positive spool position open connections, Neutral spool position open connections, and Negative spool position open connections.

Programmatic Use

Parameter: Cv_const_BT

B-T orifice maximum Cv flow coefficient — C_v coefficient that corresponds to maximally open component

4 (default) | positive scalar

Value of the C_v flow coefficient when the B-T orifice is fully open and the area available for flow is at a maximum. This parameter measures the ease with which the vapor traverses the resistive element when driven by a pressure differential.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Cv flow coefficient

3. Opening characteristic to Linear

4. One of the following parameters:

   • Positive spool position open connections to P-A, B-T.

   • Neutral spool position open connections to:

     • P-A, P-B, A-T, B-T

     • A-T, B-T

     • P-A, B-T

     • P-B, B-T

     • B-T

     • P-B, B-T, P-T

     • P-A, P-B, A-T, B-T, P-T

   • Negative spool position open connections to P-A, B-T.

Programmatic Use

Parameter: Cv_max_BT

B-T orifice Cv flow coefficient vector — C_v coefficients for values in member position vector

[1e-06, .8, 1.6, 2.4, 3.2, 4] (default) | 1-by-n vector

Vector of C_v flow coefficients. Each coefficient corresponds to a value in the B-T orifice spool travel vector parameter. This parameter measures the ease with which the vapor traverses the resistive element when driven by a pressure differential. The size of the vector must be the same as the B-T orifice spool travel vector parameter.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Cv flow coefficient

3. Opening characteristic to Tabulated

4. One of the following parameters:

   • Positive spool position open connections to P-A, B-T.

   • Neutral spool position open connections to:

     • P-A, P-B, A-T, B-T

     • A-T, B-T

     • P-A, B-T

     • P-B, B-T

     • B-T

     • P-B, B-T, P-T

     • P-A, P-B, A-T, B-T, P-T

   • Negative spool position open connections to P-A, B-T.

Programmatic Use

Parameter: Cv_TLU_BT

B-T constant orifice Kv flow coefficient — Flow coefficient

3.6 (default) | positive scalar

Value of the constant K_v flow coefficient for the B-T orifice. This parameter measures the ease with which the vapor traverses the resistive element when driven by a pressure differential.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Kv flow coefficient

3. One of the following settings in each parameter:

   • Positive spool position open connections to P-A, B-T.

   • Neutral spool position open connections to:

     • P-A, P-B, A-T, B-T

     • A-T, B-T

     • P-A, B-T

     • P-B, B-T

     • B-T

     • P-B, B-T, P-T

     • P-A, P-B, A-T, B-T, P-T

   • Negative spool position open connections to P-A, B-T.

Note:

This parameter is enabled only when the B-T orifice settings appear in all three spool position parameters: Positive spool position open connections, Neutral spool position open connections, and Negative spool position open connections.

Programmatic Use

Parameter: Kv_const_BT

B-T orifice maximum Kv flow coefficient — K_v coefficient that corresponds to maximally open component

3.6 (default) | positive scalar

Value of the K_v flow coefficient when the B-T orifice is fully open and the area available for flow is at a maximum. This parameter measures the ease with which the vapor traverses the resistive element when driven by a pressure differential.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Kv flow coefficient

3. Opening characteristic to Linear

4. One of the following parameters:

   • Positive spool position open connections to P-A, B-T.

   • Neutral spool position open connections to:

     • P-A, P-B, A-T, B-T

     • A-T, B-T

     • P-A, B-T

     • P-B, B-T

     • B-T

     • P-B, B-T, P-T

     • P-A, P-B, A-T, B-T, P-T

   • Negative spool position open connections to P-A, B-T.

Programmatic Use

Parameter: Kv_max_BT

B-T orifice Kv flow coefficient vector — K_v coefficients for values in member position vector

[1e-06, .72, 1.44, 2.16, 2.88, 3.6] (default) | 1-by-n vector

Vector of K_v flow coefficients. Each coefficient corresponds to a value in the B-T orifice spool travel vector parameter. This parameter measures the ease with which the vapor traverses the resistive element when driven by a pressure differential. The size of the vector must be the same as the B-T orifice spool travel vector parameter.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Kv flow coefficient

3. Opening characteristic to Tabulated

4. One of the following parameters:

   • Positive spool position open connections to P-A, B-T.

   • Neutral spool position open connections to:

     • P-A, P-B, A-T, B-T

     • A-T, B-T

     • P-A, B-T

     • P-B, B-T

     • B-T

     • P-B, B-T, P-T

     • P-A, P-B, A-T, B-T, P-T

   • Negative spool position open connections to P-A, B-T.

Programmatic Use

Parameter: Kv_TLU_BT

B-T orifice spool travel vector — Vector of spool opening distances relative to fully closed position

[0, .00125, .0025, .00375, .005] m (default) | 1-by-n vector

Vector of spool travel distances for the tabular parameterization of the valve area. List the values in ascending order. The first element must be 0. The block uses linear interpolation between table data points.

Dependencies

To enable this parameter, set Area characteristics to Different for each flow path, Opening characteristic to Tabulated, and one of the following parameters:

• Positive spool position open connections to P-A, B-T.

• Neutral spool position open connections to:

  • P-A, P-B, A-T, B-T

  • A-T, B-T

  • P-A, B-T

  • P-B, B-T

  • B-T

  • P-B, B-T, P-T

  • P-A, P-B, A-T, B-T, P-T

• Negative spool position open connections to P-A, B-T.

Programmatic Use

Parameter: del_S_Cv_TLU_BT

Parameter: del_S_Kv_TLU_BT

Parameter: del_S_C_TLU_BT

Parameter: del_S_orifice_area_TLU_BT

B-T maximum orifice area — Maximum orifice opening area

1e-4 m^2 (default) | positive scalar

Largest open area of the B-T orifice during the operation of the valve.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Orifice area

3. Opening characteristic to Linear

4. One of the following parameters:

   • Positive spool position open connections to P-A, B-T.

   • Neutral spool position open connections to:

     • P-A, P-B, A-T, B-T

     • A-T, B-T

     • P-A, B-T

     • P-B, B-T

     • B-T

     • P-B, B-T, P-T

     • P-A, P-B, A-T, B-T, P-T

   • Negative spool position open connections to P-A, B-T.

Programmatic Use

Parameter: orifice_area_max_BT

B-T orifice area vector — Vector of valve opening areas

[1e-10, 1e-05, 4e-05, 6e-05, .0001] m^2 (default) | 1-by-n vector

Vector of opening areas for the tabular parameterization of the valve area. The vector elements must correspond one-to-one with the elements in the B-T orifice spool travel vector parameter. The elements must be greater than 0 and listed in ascending order. The first element of this vector is the leakage area.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Orifice area

3. Opening characteristic to Tabulated

4. One of the following parameters:

   • Positive spool position open connections to P-A, B-T.

   • Neutral spool position open connections to:

     • P-A, P-B, A-T, B-T

     • A-T, B-T

     • P-A, B-T

     • P-B, B-T

     • B-T

     • P-B, B-T, P-T

     • P-A, P-B, A-T, B-T, P-T

   • Negative spool position open connections to P-A, B-T.

Programmatic Use

Parameter: orifice_area_TLU_BT

B-T constant orifice area — Cross-sectional area for constant orifice

1e-4 m^2 (default) | positive scalar

Orifice area when the positive and negative spool positions include the same orifice.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Orifice area

3. One of the following settings in each parameter:

   • Positive spool position open connections to P-A, B-T.

   • Neutral spool position open connections to:

     • P-A, P-B, A-T, B-T

     • A-T, B-T

     • P-A, B-T

     • P-B, B-T

     • B-T

     • P-B, B-T, P-T

     • P-A, P-B, A-T, B-T, P-T

   • Negative spool position open connections to P-A, B-T.

Note:

This parameter is enabled only when the B-T orifice settings appear in all three spool position parameters: Positive spool position open connections, Neutral spool position open connections, and Negative spool position open connections.

Programmatic Use

Parameter: orifice_area_const_BT

B-T orifice xT pressure differential ratio factor at choked flow — Ratio of pressure differentials

0.7 (default) | positive scalar

Ratio between the inlet pressure, p_in, and the outlet pressure, p_out, defined as $$(p_{in}-p_{out})/p_{in}$$ where choking first occurs for the B-T orifice.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Kv flow coefficient or Cv flow coefficient

3. At least one of the following parameters:

   • Positive spool position open connections to P-A, B-T.

   • Neutral spool position open connections to:

     • P-A, P-B, A-T, B-T

     • A-T, B-T

     • P-A, B-T

     • P-B, B-T

     • B-T

     • P-B, B-T, P-T

     • P-A, P-B, A-T, B-T, P-T

   • Negative spool position open connections to P-A, B-T.

Programmatic Use

Parameter: xT_Cv_BT

Parameter: xT_Kv_BT

B-T constant orifice sonic conductance — Sonic conductance for constant orifice

12 l/(bar*s) (default) | positive scalar

Sonic conductance when the positive and negative spool positions include the same orifice. This value is the ratio, measured at the onset of choking, of the mass flow rate through the resistive element to the product of the upstream pressure and mass density at standard conditions as defined in ISO 8778. This parameter determines the maximum flow rate allowed at a given upstream pressure.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Sonic conductance

3. One of the following settings in each parameter:

   • Positive spool position open connections to P-A, B-T.

   • Neutral spool position open connections to:

     • P-A, P-B, A-T, B-T

     • A-T, B-T

     • P-A, B-T

     • P-B, B-T

     • B-T

     • P-B, B-T, P-T

     • P-A, P-B, A-T, B-T, P-T

   • Negative spool position open connections to P-A, B-T.

Note:

This parameter is enabled only when the B-T orifice settings appear in all three spool position parameters: Positive spool position open connections, Neutral spool position open connections, and Negative spool position open connections.

Programmatic Use

Parameter: C_const_BT

B-T constant orifice critical pressure ratio — Ratio of downstream and upstream pressures at which the flow first chokes for constant orifice

0.3 (default) | positive scalar

Critical pressure ratio when the positive and negative spool positions include the same orifice. This value is the pressure ratio at which flow first begins to choke and the flow velocity reaches its maximum, given by the local speed of sound. The pressure ratio is the outlet pressure divided by inlet pressure.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Sonic conductance

3. One of the following settings in each parameter:

   • Positive spool position open connections to P-A, B-T.

   • Neutral spool position open connections to:

     • P-A, P-B, A-T, B-T

     • A-T, B-T

     • P-A, B-T

     • P-B, B-T

     • B-T

     • P-B, B-T, P-T

     • P-A, P-B, A-T, B-T, P-T

   • Negative spool position open connections to P-A, B-T.

Note:

This parameter is enabled only when the B-T orifice settings appear in all three spool position parameters: Positive spool position open connections, Neutral spool position open connections, and Negative spool position open connections.

Programmatic Use

Parameter: B_crit_const_BT

B-T orifice maximum sonic conductance — Sonic conductance corresponding to maximally open orifice

12 l/(bar*s) (default) | positive scalar

Value of the sonic conductance when the B-T orifice is fully open and the area available for flow is at a maximum.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Sonic conductance

3. Opening characteristic to Linear

4. One of the following parameters:

   • Positive spool position open connections to P-A, B-T.

   • Neutral spool position open connections to:

     • P-A, P-B, A-T, B-T

     • A-T, B-T

     • P-A, B-T

     • P-B, B-T

     • B-T

     • P-B, B-T, P-T

     • P-A, P-B, A-T, B-T, P-T

   • Negative spool position open connections to P-A, B-T.

Programmatic Use

Parameter: C_max_BT

B-T orifice critical pressure ratio — Ratio of downstream and upstream pressures at which the flow first chokes

0.3 (default) | positive scalar

Pressure ratio at which flow first begins to choke and the flow velocity reaches its maximum, given by the local speed of sound. The pressure ratio is the outlet pressure divided by inlet pressure.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Sonic conductance

3. Opening characteristic to Linear

4. One of the following parameters:

   • Positive spool position open connections to P-A, B-T.

   • Neutral spool position open connections to:

     • P-A, P-B, A-T, B-T

     • A-T, B-T

     • P-A, B-T

     • P-B, B-T

     • B-T

     • P-B, B-T, P-T

     • P-A, P-B, A-T, B-T, P-T

   • Negative spool position open connections to P-A, B-T.

Programmatic Use

Parameter: B_crit_linear_BT

B-T orifice sonic conductance vector — Sonic conductances corresponding to values in spool travel vector

[1e-05, 2.4, 4.8, 7.2, 9.6, 12] l/(bar*s) (default) | 1-by-n vector

Vector of sonic conductances inside the resistive element. Each conductance corresponds to a value in the B-T orifice spool travel vector parameter. The size of the vector must be the same as the B-T orifice spool travel vector parameter.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Sonic conductance

3. Opening characteristic to Tabulated

4. One of the following parameters:

   • Positive spool position open connections to P-A, B-T.

   • Neutral spool position open connections to:

     • P-A, P-B, A-T, B-T

     • A-T, B-T

     • P-A, B-T

     • P-B, B-T

     • B-T

     • P-B, B-T, P-T

     • P-A, P-B, A-T, B-T, P-T

   • Negative spool position open connections to P-A, B-T.

Programmatic Use

Parameter: C_TLU_BT

B-T orifice critical pressure ratio vector — Critical pressure ratios corresponding to values in spool travel vector

0.3 * ones(1, 6) (default) | 1-by-n vector

Vector of critical pressure ratios at which the flow first chokes, with each critical pressure ratio corresponding to a value in the B-T orifice spool travel vector parameter. The critical pressure ratio is the fraction of downstream-to-upstream pressures at which the flow velocity reaches the local speed of sound. The size of the vector must be the same as the B-T orifice spool travel vector parameter.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Sonic conductance

3. Opening characteristic to Tabulated

4. One of the following parameters:

   • Positive spool position open connections to P-A, B-T.

   • Neutral spool position open connections to:

     • P-A, P-B, A-T, B-T

     • A-T, B-T

     • P-A, B-T

     • P-B, B-T

     • B-T

     • P-B, B-T, P-T

     • P-A, P-B, A-T, B-T, P-T

   • Negative spool position open connections to P-A, B-T.

Programmatic Use

Parameter: B_crit_TLU_BT

B-T orifice subsonic index — Exponent used to characterize mass flow in subsonic flow regime

0.5 (default) | positive scalar

Empirical value used to more accurately calculate the mass flow rate in the subsonic flow regime.

Dependencies

To enable this parameter, set Area characteristics to Different for each flow path, Orifice parameterization to Sonic conductance, and at least one of the following parameters:

• Positive spool position open connections to P-A, B-T.

• Neutral spool position open connections to:

  • P-A, P-B, A-T, B-T

  • A-T, B-T

  • P-A, B-T

  • P-B, B-T

  • B-T

  • P-B, B-T, P-T

  • P-A, P-B, A-T, B-T, P-T

• Negative spool position open connections to P-A, B-T.

Programmatic Use

Parameter: m_BT

B-T orifice ISO reference temperature — ISO 8778 reference temperature

293.15 K (default) | scalar

Temperature at standard reference atmosphere, defined as 293.15 K in ISO 8778.

You only need to adjust the ISO reference parameter values if you are using sonic conductance values that are obtained at difference reference values.

Dependencies

To enable this parameter, set Area characteristics to Different for each flow path, Orifice parameterization to Sonic conductance, and at least one of the following parameters:

• Positive spool position open connections to P-A, B-T.

• Neutral spool position open connections to:

  • P-A, P-B, A-T, B-T

  • A-T, B-T

  • P-A, B-T

  • P-B, B-T

  • B-T

  • P-B, B-T, P-T

  • P-A, P-B, A-T, B-T, P-T

• Negative spool position open connections to P-A, B-T.

Programmatic Use

Parameter: T_ref_C_BT

B-T orifice ISO reference density — ISO 8778 reference density

1.185 kg/m^3 (default) | positive scalar

Density at standard reference atmosphere, defined as 1.185 kg/m3 in ISO 8778.

You only need to adjust the ISO reference parameter values if you are using sonic conductance values that are obtained at difference reference values.

Dependencies

To enable this parameter, set Area characteristics to Different for each flow path, Orifice parameterization to Sonic conductance, and at least one of the following parameters:

• Positive spool position open connections to P-A, B-T.

• Neutral spool position open connections to:

  • P-A, P-B, A-T, B-T

  • A-T, B-T

  • P-A, B-T

  • P-B, B-T

  • B-T

  • P-B, B-T, P-T

  • P-A, P-B, A-T, B-T, P-T

• Negative spool position open connections to P-A, B-T.

Programmatic Use

Parameter: rho_ref_C_BT

P-T Orifice

Spool position at maximum P-T orifice area — Spool offset for fully open P-T orifice

5e-3 m (default) | positive scalar

Spool offset from the neutral position for a fully open P-T orifice.

Dependencies

To enable this parameter, set Neutral spool position open connections to:

• P-T

• P-A, A-T, P-T

• P-B, B-T, P-T

• P-A, P-B, A-T, B-T, P-T

Programmatic Use

Parameter: S_max_PT

P-T spool travel between closed and open orifice — Maximum spool stroke

0.005 m (default) | positive scalar

Maximum distance of spool travel. This value provides an upper limit to calculations so that simulations do not return unphysical values.

Dependencies

To enable this parameter, set Area characteristics to Different for each flow path, Opening characteristic to Linear, and Neutral spool position open connections to:

• P-T

• P-A, A-T, P-T

• P-B, B-T, P-T

• P-A, P-B, A-T, B-T, P-T

Programmatic Use

Parameter: del_S_max_PT

P-T orifice maximum Cv flow coefficient — C_v coefficient that corresponds to maximally open component

4 (default) | positive scalar

Value of the C_v flow coefficient when the P-T orifice is fully open and the area available for flow is at a maximum. This parameter measures the ease with which the vapor traverses the resistive element when driven by a pressure differential.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Cv flow coefficient

3. Opening characteristic to Linear

4. Neutral spool position open connections to:

   • P-T

   • P-A, A-T, P-T

   • P-B, B-T, P-T

   • P-A, P-B, A-T, B-T, P-T

Programmatic Use

Parameter: Cv_max_PT

P-T orifice Cv flow coefficient vector — C_v coefficients for values in member position vector

[1e-06, .8, 1.6, 2.4, 3.2, 4] (default) | 1-by-n vector

Vector of C_v flow coefficients. Each coefficient corresponds to a value in the P-T orifice spool travel vector parameter. This parameter measures the ease with which the vapor traverses the resistive element when driven by a pressure differential. The size of the vector must be the same as the P-T orifice spool travel vector parameter.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Cv flow coefficient

3. Opening characteristic to Tabulated

4. Neutral spool position open connections to:

   • P-T

   • P-A, A-T, P-T

   • P-B, B-T, P-T

   • P-A, P-B, A-T, B-T, P-T

Programmatic Use

Parameter: Cv_TLU_PT

P-T orifice maximum Kv flow coefficient — K_v coefficient that corresponds to maximally open component

3.6 (default) | positive scalar

Value of the K_v flow coefficient when the P-T orifice is fully open and the area available for flow is at a maximum. This parameter measures the ease with which the vapor traverses the resistive element when driven by a pressure differential.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Kv flow coefficient

3. Opening characteristic to Linear

4. Neutral spool position open connections to:

   • P-T

   • P-A, A-T, P-T

   • P-B, B-T, P-T

   • P-A, P-B, A-T, B-T, P-T

Programmatic Use

Parameter: Kv_max_PT

P-T orifice Kv flow coefficient vector — K_v coefficients for values in member position vector

[1e-06, .72, 1.44, 2.16, 2.88, 3.6] (default) | 1-by-n vector

Vector of K_v flow coefficients. Each coefficient corresponds to a value in the P-T orifice spool travel vector parameter. This parameter measures the ease with which the vapor traverses the resistive element when driven by a pressure differential. The size of the vector must be the same as the P-T orifice spool travel vector parameter.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Kv flow coefficient

3. Opening characteristic to Tabulated

4. Neutral spool position open connections to:

   • P-T

   • P-A, A-T, P-T

   • P-B, B-T, P-T

   • P-A, P-B, A-T, B-T, P-T

Programmatic Use

Parameter: Kv_TLU_PT

P-T orifice spool travel vector — Vector of spool opening distances relative to fully closed position

[0, .00125, .0025, .00375, .005] m (default) | 1-by-n vector

Vector of spool travel distances for the tabular parameterization of the valve area. List the values in ascending order. The first element must be 0. The block uses linear interpolation between table data points.

Dependencies

To enable this parameter, set Area characteristics to Different for each flow path, Opening characteristic to Tabulated, and Neutral spool position open connections to:

• P-T

• P-A, A-T, P-T

• P-B, B-T, P-T

• P-A, P-B, A-T, B-T, P-T

Programmatic Use

Parameter: del_S_Cv_TLU_PT

Parameter: del_S_Kv_TLU_PT

Parameter: del_S_C_TLU_PT

Parameter: del_S_orifice_area_TLU_PT

P-T maximum orifice area — Maximum orifice opening area

1e-4 m^2 (default) | positive scalar

Largest open area of the P-T orifice during the operation of the valve.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Orifice area

3. Opening characteristic to Tabulated

4. Neutral spool position open connections to:

   • P-T

   • P-A, A-T, P-T

   • P-B, B-T, P-T

   • P-A, P-B, A-T, B-T, P-T

Programmatic Use

Parameter: orifice_area_max_PT

P-T orifice area vector — Vector of valve opening areas

[1e-10, 1e-05, 4e-05, 6e-05, .0001] m^2 (default) | 1-by-n vector

Vector of opening areas for the tabular parameterization of the valve area. The vector elements must correspond one-to-one with the elements in the P-T orifice spool travel vector parameter. The elements must be greater than 0 and listed in ascending order. The first element of this vector is the leakage area.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Orifice area

3. Opening characteristic to Tabulated

4. Neutral spool position open connections to:

   • P-T

   • P-A, A-T, P-T

   • P-B, B-T, P-T

   • P-A, P-B, A-T, B-T, P-T

Programmatic Use

Parameter: orifice_area_TLU_PT

P-T orifice xT pressure differential ratio factor at choked flow — Ratio of pressure differentials

0.7 (default) | positive scalar

Ratio between the inlet pressure, p_in, and the outlet pressure, p_out, defined as $$(p_{in}-p_{out})/p_{in}$$ where choking first occurs for the P-T orifice.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Kv flow coefficient or Cv flow coefficient

3. Neutral spool position open connections to:

   • P-T

   • P-A, A-T, P-T

   • P-B, B-T, P-T

   • P-A, P-B, A-T, B-T, P-T

Programmatic Use

Parameter: xT_Cv_PT

Parameter: xT_Kv_PT

P-T orifice maximum sonic conductance — Sonic conductance corresponding to maximally open orifice

12 l/(bar*s) (default) | positive scalar

Value of the sonic conductance when the P-T orifice is fully open and the area available for flow is at a maximum.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Sonic conductance

3. Opening characteristic to Linear

4. One of the following parameters:

   Positive spool position open connections to:

   • P-A, B-T

   • P-A, P-B

   • P-A

   • P-A, P-B, A-B

   Neutral spool position open connections to:

   • P-A, P-B, A-T, B-T

   • P-A, A-T

   • P-A, B-T

   • P-A, P-B

   • P-A

   • P-A, A-T, P-T

   • P-A, P-B, A-B

   • P-A, P-B, A-T, B-T, P-T

   Negative spool position open connections to:

   • P-A, P-B, A-T, B-T

   • P-A, A-T

   • P-A, B-T

   • P-A, P-B

   • P-A

   • P-A, P-B, A-B

Programmatic Use

Parameter: C_max_PT

P-T orifice critical pressure ratio — Ratio of downstream and upstream pressures at which the flow first chokes

0.3 (default) | positive scalar

Pressure ratio at which flow first begins to choke and the flow velocity reaches its maximum, given by the local speed of sound. The pressure ratio is the outlet pressure divided by inlet pressure.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Sonic conductance

3. Opening characteristic to Linear

4. Neutral spool position open connections to:

   • P-T

   • P-A, A-T, P-T

   • P-B, B-T, P-T

   • P-A, P-B, A-T, B-T, P-T

Programmatic Use

Parameter: B_crit_linear_PT

P-T orifice sonic conductance vector — Sonic conductances corresponding to values in spool travel vector

[1e-05, 2.4, 4.8, 7.2, 9.6, 12] l/(bar*s) (default) | 1-by-n vector

Vector of sonic conductances inside the resistive element. Each conductance corresponds to a value in the P-T orifice spool travel vector parameter. The size of the vector must be the same as the P-T orifice spool travel vector parameter.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Sonic conductance

3. Opening characteristic to Tabulated

4. Neutral spool position open connections to:

   • P-T

   • P-A, A-T, P-T

   • P-B, B-T, P-T

   • P-A, P-B, A-T, B-T, P-T

Programmatic Use

Parameter: C_TLU_PT

P-T orifice critical pressure ratio vector — Critical pressure ratios corresponding to values in spool travel vector

0.3 * ones(1, 6) (default) | 1-by-n vector

Vector of critical pressure ratios at which the flow first chokes, with each critical pressure ratio corresponding to a value in the P-T orifice spool travel vector parameter. The critical pressure ratio is the fraction of downstream-to-upstream pressures at which the flow velocity reaches the local speed of sound. The size of the vector must be the same as the P-T orifice spool travel vector parameter.

Dependencies

To enable this parameter, set:

1. Area characteristics to Different for each flow path

2. Orifice parameterization to Sonic conductance

3. Opening characteristic to Tabulated

4. Neutral spool position open connections to:

   • P-T

   • P-A, A-T, P-T

   • P-B, B-T, P-T

   • P-A, P-B, A-T, B-T, P-T

Programmatic Use

Parameter: B_crit_TLU_PT

P-T orifice subsonic index — Exponent used to characterize mass flow in subsonic flow regime

0.5 (default) | positive scalar

Empirical value used to more accurately calculate the mass flow rate in the subsonic flow regime.

Dependencies

To enable this parameter, set Area characteristics to Different for each flow path, Orifice parameterization to Sonic conductance, and at least one of the following parameters:

Neutral spool position open connections to:

• P-T

• P-A, A-T, P-T

• P-B, B-T, P-T

• P-A, P-B, A-T, B-T, P-T

Programmatic Use

Parameter: m_PT

P-T orifice ISO reference temperature — ISO 8778 reference temperature

293.15 K (default) | scalar

Temperature at standard reference atmosphere, defined as 293.15 K in ISO 8778.

You only need to adjust the ISO reference parameter values if you are using sonic conductance values that are obtained at difference reference values.

Dependencies

To enable this parameter, set Area characteristics to Different for each flow path, Orifice parameterization to Sonic conductance, and at least one of the following parameters:

Neutral spool position open connections to:

• P-T

• P-A, A-T, P-T

• P-B, B-T, P-T

• P-A, P-B, A-T, B-T, P-T

Programmatic Use

Parameter: T_ref_C_PT

P-T orifice ISO reference density — ISO 8778 reference density

1.185 kg/m^3 (default) | positive scalar

Density at standard reference atmosphere, defined as 1.185 kg/m3 in ISO 8778.

You only need to adjust the ISO reference parameter values if you are using sonic conductance values that are obtained at difference reference values.

Dependencies

To enable this parameter, set Area characteristics to Different for each flow path, Orifice parameterization to Sonic conductance, and at least one of the following parameters:

Neutral spool position open connections to:

• P-T

• P-A, A-T, P-T

• P-B, B-T, P-T

• P-A, P-B, A-T, B-T, P-T

Programmatic Use

Parameter: rho_ref_C_PT

Plots

Valve characteristics — Generate valve characteristics plot

button

Use the Plot button to generate the valve characteristics plot.

References

[1] ISO 6358-3. "Pneumatic fluid power – Determination of flow-rate characteristics of components using compressible fluids – Part 3: Method for calculating steady-state flow rate characteristics of systems". 2014.

[2] IEC 60534-2-3. "Industrial-process control valves – Part 2-3: Flow capacity – Test procedures". 2015.

[3] ANSI/ISA-75.01.01. "Industrial-Process Control Valves – Part 2-1: Flow capacity – Sizing equations for fluid flow underinstalled conditions". 2012.

[4] P. Beater. Pneumatic Drives. Springer-Verlag Berlin Heidelberg. 2007.

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.

Version History

Introduced in R2025a