safety valve|Common technical terms of safety valve

1. Nominal pressure of safety valve: indicates the maximum allowable pressure of the safety valve at room temperature. The safety valve used in high temperature equipment should not consider the reduction of the allowable stress of the material at high temperature. The safety valve is designed and manufactured according to the nominal pressure standard.
Opening pressure: also called rated pressure or set pressure, it refers to the inlet pressure when the safety valve disc starts to rise under operating conditions. Under this pressure, there is a measurable opening height, and the medium is visually or audibly perceivable. Continuous discharge state.
Discharge pressure: the inlet pressure when the valve disc reaches the specified opening height. The upper limit of discharge pressure shall comply with the requirements of relevant national standards or regulations.
Excess pressure: The difference between the discharge pressure and the opening pressure, usually expressed as a percentage of the opening pressure.
Re-seat pressure: After discharge, the valve disc contacts the valve seat again, that is, the inlet pressure when the opening height becomes zero.
Opening and closing pressure difference: The difference between the opening pressure and the re-seat pressure, usually expressed as a percentage of the re-seat pressure and the opening pressure, and only when the opening pressure is very low, the difference between the two pressures is used to express.
Back pressure: The pressure at the outlet of the safety valve.

2. Rated discharge pressure: the standard specifies the upper limit of discharge pressure.

3. Sealing test pressure: the inlet pressure for the sealing test, under which the leakage rate through the sealing surface of the closure member is measured. Opening height: the actual lift of the disc from the closed position.

4. Flow channel area: refers to the minimum cross-sectional area of ​​the flow channel between the inlet end of the valve clack and the sealing surface of the closing member, which is used to calculate the theoretical displacement without any resistance.
Runner diameter: the diameter corresponding to the area of ​​the runner.

5. Curtain area: when the valve flap is above the valve seat, the cylindrical or conical channel area formed between its sealing surfaces.
Discharge area: The minimum cross-sectional area of ​​the fluid passage when the valve is discharged. For the full enlightenment safety valve, the discharge area is equal to the flow channel area; for the micro-lift safety valve, the discharge area is equal to the curtain area.

6. Theoretical displacement: it is the calculated displacement of an ideal nozzle with the cross-sectional area of ​​the flow passage equal to the flow passage area of ​​the safety valve.
Displacement coefficient: the ratio of actual displacement to theoretical displacement.
Rated displacement coefficient: the product of the displacement coefficient and the reduction coefficient (take 0.9).
Rated displacement: refers to the part of the actual displacement that is allowed as a reference for the safety valve.
Equivalent calculated displacement: refers to the calculated displacement of the safety valve when the conditions such as pressure, temperature, and medium properties are the same as the applicable conditions of the rated displacement.

7. Frequency jump: The safety valve disc moves back and forth quickly and abnormally, and the disc contacts the valve seat during the movement.

8. Flutter: The safety valve disc quickly and abnormally moves back and forth, and the disc does not touch the valve seat during the movement.