Calculation of safety valve nozzle area

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I. Determination of operating conditions
1. Constant pressure Ps (MPa): 1.38
2. Accumulation pressure Pa (MPa): 0.276
- Safety valve for pressure vessels without fire risk: 0.138
- Safety valve for pressure vessels at risk of explosion in case of fire: 0.276
- Safety valve for steam boilers: 0.0414
3. Maximum discharge pressure Pm (MPa): 1.656
4. Critical flow pressure of the gas Px (MPa): 0.935
- Adiabatic index of the gas K (Cp/Cv): 1.2
- Critical flow ratio of the gas: 0.564
5. Back pressure P2 (MPa): 0.138

II. Calculation of nozzle area (in cm2)
3.7864, 21.96
Calculation formula: Ao = 0.4 * Gv / (C * KF * Pm * Kb) * (Z * T1 / M) ^ 1/2
Nozzle diameter (mm):
Gv: Maximum gas discharge rate, kg/h: 1111
KF: Flow coefficient; 0.7 for fully open nozzles, 0.4–0.5 for slightly open nozzles with adjustment rings, and 0.25–0.35 for slightly open nozzles without adjustment rings.
Pm: Maximum discharge pressure (MPa): 1.656
T1: Temperature of the medium at the inlet, in K: 313
M: Molecular weight of the gas: 49.69
Z: Compression factor of the gas at Pm: 0.9755
C: Characteristic coefficient of the gas: 250.9816
kb: Back pressure correction coefficient: 1