Fire Case - Liquid Filled Vessel - Intergraph Smart Instrumentation - Reference - Hexagon

1. Calculate maximum discharge:

   

2. Calculate upstream relieving pressure:

   

3. Calculate Total back pressure:

   

4. Calculate Critical flow throat pressure:

   

5. Effective coefficient of discharge: .

6. The condition determines:

   Case A - Critical flow

   1. Calculate Coefficient for critical flow equation:

      

   2. Calculate Capacity correction factor due to back pressure (if Kb is not entered by user).

      1. For conventional and Pilot operated valves,.Kb =1.

      2. For Bellows valve:

         

   3. Estimate Required effective discharge area:

      

Case B - Sub-critical flow: Bellows Valve.

1. Calculate Cr:

   

2. If Capacity correction factor due to back pressure is not entered by user, Kb =1.

3. Estimate Required effective discharge area:

   

Case c - Sub-critical flow: Conventional and Pilot operated valves..

1. Calculate Coefficient for sub-critical flow equation: *Pb [psi-a]

   1. 

   2. 

2. Estimate Required effective discharge area:

   

7. For Rupture disk application, calculate Required effective discharge area:

A = A0 / Kcc