# Calculation of Flow Rate - 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 internal pipe diameter at floe temperature:

2. Calculate correction factor for steam quality (For lliquid, water, and steam, Fs=1):

3. Calculate orifice diameter at flow temperature.

1. For Venturi tubes and Nozzles:

2. For orifice plates:

4. Calculate b - ratio:

5. Checking for Critical flow and some initial calculations.

Liquid /Water case

1. Calculate downstream pressure:

2. If the the flow is critical. If not then the floe is sub-critical.

1. For critical flow:

2. For sub-critical flow:

Classic Venturi tube:

1. Nozzles

2. Orifice plates:

3. Calculate first estimate for flow rate (W0 [kg/s]):

3. Gas/Steam case

1. Calculate critical pressure ratio and define whether the flow is critical.

If the the flow is critical. If not the flow is sub-critical.

4. Initial calculation for critical flow.

1. Gas Expansion factor:

2. First estimate for flow rate (W0 [1b/h], T[R], D[in], P1[psi-a])

5. Initial calculations for sub-critical flow.

Differential pressure to be used in flow rat calculation:

1. For classical Venturi tube:

2. For Nozzles:

3. For orifice plates:

6. Gas expansion factor:

1. For Venturi tubes and nozzles:

where

2. For orifice plates:

3. First estimate for flow rate (W0[kg/s]):

6. Calculate Reynolds number.

1. For gas/steam critical flow (Bore Reynolds number):

2. For liquid/water and gas/steam sub-critical flow (Pipe Reynolds number):

7. Calculate discharge coefficient. See Appendix.

8. For orifices in the case of gas/steam sub-critical flow, calculate DP and gas expansion factor:

9. Calculate new flow rate:

1. For gas/steam at critical flow:

2. For other cases (W[kg/s]):

10. Repeat steps 6 to 10 until the relative change in the flow rate is less than 0.0001.