Calculation of Pressure Loss - Intergraph Smart Instrumentation - Reference - Hexagon

Calculate internal pipe diameter at flow temperature:

Calculate correction factor for steam quality (for liguid, water, and steam, Fs=1):

Calculate orifice diameter at flow temperature.

1. For Venturi tubes and nozzles:

   

2. For orifice plates:

   

Calculate pipe Reynolds number (W[kg/s]):

Calculate b - ratio:

Calculate discharge coefficient. See Appendix.

Calculate critical flow rate.

1. For liquid/water:

   

2. For gas/steam

   

Checking for critical flow and pressure loss calculation.

1. Case A - Critical flow: W>0.999*Wcr and W<1.001*Wcr.

   For this case, pressure loss:

   

2. Case B - Wrong data: W=>1.001*Wcr. Flow rate cannot be achieved, check data.

3. Case C- Sub-critical flow: W<=0.999*Wcr:

   First estimate for differential range:

   

4. Calculate discharge coefficient. See Appendix.

5. Calculate gas expansion factor (for liguid and water, Eps=1).

   1. For Venturi tubes and nozzles:

      

   2. For Orifice plates:

      

6. Calculate new differential range (W[kg/s]):

7. Calculate the relative change in the differential range:

   

8. Repeat steps e to g until the relative change in the DP is less than 0.0001.

9. Calculate pressure loss: