Blocked Flow - Gas Relief - Intergraph Smart Instrumentation - 13.1 - Reference - Hexagon PPM

Integraph Smart Instrumentation Sizing Equations

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Intergraph Smart Instrumentation
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Reference
Smart Instrumentation Version
13.1
  1. Calculate upstream relieving pressure:

    *Pa [psi-a]

  2. Calculate total back pressure:

  3. Calculate critical flow throat pressure:

  4. Effective coefficient of discharge: Kd = 0.975.

  5. The condition Pb < P(Pb [psi-a]) 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).

      For conventional and Pilot operated valves, Kb = 1.

      For Bellows valve:

      Y= Pb / Ps

    3. Estimate required effective discharge area:

Case B - Sub-critical flow: Bellow 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].

  2. Estimate required effective discharge area:

6. For Rupture disk application, calculate required effective discharge area:

A = A0 /Kcc