Blocked Flow - Liquid Relief - Intergraph Smart Instrumentation - Reference - Hexagon

Requiring ASME capacity certification

1. Calculate total back pressure:

   

2. Effective coefficient of discharge: Kd =0.65 (if Kd is not entered by user).

3. Determine correction factor for back pressure:

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

   2. For Bellows valve:

      Case Pb / Ps <0.16:	Kw =1
      Case 0.16 < Pb / Ps < 0.5:	Kw = 1.152 -- 0.95•Pb / Ps
      Case Pb / Ps >0.5:	Kw = 0.677

4. Calculate upstream relieving pressure:

   *Pup[psi-g]

   

5. Estimate required effective discharge area:

   *W[US gal/min], Pup [psi-g]

   

6. Calculate Reynolds number:

   

7. Calculate correction factor for viscosity:

   

8. Calculate required effective discharge area:

   1. With Rupture disk:

      

   2. Without Rupture disk:

      

Not requiring ASME capacity certification

1. Calculate total back pressure:

   

2. Effective coefficient of discharge: Kd =0.62 (if Kd is not entered by user).

3. Determine correction factor for back pressure:

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

   2. For Bellows valve:

      Case Pb / Ps <0.16:	Kw =1
      Case 0.16 < Pb / Ps < 0.5:	Kw = 1.152 -- 0.95•Pb / Ps
      Case Pb / Ps >0.5:	Kw = 0.677

4. Calculate correction factor for overpressure:

   

5. Estimate required effective discharge area:

   *W[US gal/min]

   

6. Calculate Reynolds number:

   

7. Calculate correction factor for viscosity:

   

8. Calculate required effective discharge area:

   1. With Rupture disk:

      

   2. Without Rupture disk: