Except where noted here, this link is identical to the GunnsFluidRegulatorValve.

This link models a pressure relief valve, which modulates its position to maintain a sensed control pressure below a crack pressure. This model is identical to the regulator valve except in the direction of pressure control: whereas the regulator tries to prevent under-pressure by maintaining pressure above the crack pressure, the relief valve prevents over-pressure by maintaining pressure below the crack pressure.

The valve position behaves opposite of the regulator valve with respect to the control pressure, as shown below. As the control pressure rises above the "crack" pressure (1), the valve quickly opens towards the "pop" position (2). As control pressure continues to rise, the valve will continue to open (along 3a) until it either reaches full open at the "full-open" pressure, or until the control pressure begins to decrease again. In the former case, once control pressure begins to decrease below the full-open pressure, the valve will begin to close (along 4) until it reaches the pop pressure. In the latter case (shown by the blue line 3b), which happens when the control pressure starts to decrease before the valve reached full-open, the valve holds its current position as control pressure decreases until it picks up the closing slope (4) and begins to close again. When closing past the pop pressure, the valve quickly closes to fully closed (5). These paths are all determined by config data as described below.

The most common way to use a relief valve is in an assembly with a regulator valve as shown below. The relief valve is usually there to prevent bursting the lines if the regulator valve fails open. In this example we have the regulator and relief valve both regulating the gauge pressure of Node 1 relative to the ambient Node 2. Relief flow goes out of the lines to the ambient environment. To avoid the relief and regulator valves fighting each other over control of the Node 1 pressure, the crack & reseat pressures of the relief valve are set higher than the reseat pressure of the regulator.

As with the regulator valve, the relief valve's pressure ports can be hooked up to any combination of nodes in the network, for maximum flexibility.

Port Connection Rules (These are limitations on the port connection to nodes that the link enforces in run-time):

• Ports 0 and 1 (the flow ports) cannot connect to the same non-Ground node.
• Ports 2 and 3 (the control pressure ports) cannot connect to the same non-Ground node.

Other Rules (These are extra rules you should always try to follow):

• Same as GunnsFluidConductor.

Configuration Data Parameters:

• maxConductivity: Same as GunnsFluidConductor.
• expansionScaleFactor: Same as GunnsFluidConductor.
• rateLimit: Same as GunnsFluidCheckValve.
• thermalLength: Same as GunnsFluidValve.
• thermalDiameter: Same as GunnsFluidValve.
• surfaceRoughness: Same as GunnsFluidValve.
• reseatPressure (default = 0.0 (kPa, must be < crackPressure)): This is the control pressure at and below which the valve will move to fully closed.
• crackPressure (default = 0.0 (kPa, must be < fullOpenPressure)): This is the control pressure at and above which the valve will begin to open.
• fullOpenPressure (default = 0.0 (kPa)): This is the control pressure at and above which the valve will move to fully open.
• popPosition: Same as GunnsFluidRegulatorValve.
• popSlopeScale: Same as GunnsFluidRegulatorValve.
• inletDependencyCoeff0 Same as GunnsFluidRegulatorValve, applying this bias to the relief pressure.
• inletDependencyCoeff1 Same as GunnsFluidRegulatorValve, applying this bias to the relief pressure.

Input Data Parameters:

• malfBlockageFlag: Same as GunnsFluidValve.
• malfBlockageValue: Same as GunnsFluidValve.
• position: Same as GunnsFluidValve.
• malfLeakThruFlag: Same as GunnsFluidValve.
• malfLeakThruValue: Same as GunnsFluidValve.
• malfPressureBiasFlag: Same as GunnsFluidRegulatorValve.
• malfPressureBiasValue: Same as GunnsFluidRegulatorValve.
• setPointPressureBias: Same as GunnsFluidRegulatorValve.
• wallTemperature: Same as GunnsFluidValve.
• malfPreviousFlag (malfStuckFlag): Same as GunnsFluidCheckValve.
• malfCurrentFlag (malfFailToFlag): Same as GunnsFluidCheckValve.
• malfCurrentValue (malfFailToValue): Same as GunnsFluidCheckValve.

• Valve Chatter: Same as GunnsFluidRegulatorValve.
• Pressure Overshoot: Similar to GunnsFluidRegulatorValve, this happens when the control pressure is decreasing and overshoots the reseat pressure before the valve can fully close. This has the same fixes as the regulator valve.

• N/A