
Calculate internal pipe diameter at floe temperature:

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

Calculate orifice diameter at flow temperature.

For Venturi tubes and Nozzles:

For orifice plates:


Calculate b  ratio:

Checking for Critical flow and some initial calculations.
Liquid /Water case

Calculate downstream pressure:

If the the flow is critical. If not then the floe is subcritical.

For critical flow:

For subcritical flow:
Classic Venturi tube:



Nozzles

Orifice plates:

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


Gas/Steam case

Calculate critical pressure ratio and define whether the flow is critical.
If the the flow is critical. If not the flow is subcritical.


Initial calculation for critical flow.

Gas Expansion factor:

First estimate for flow rate (W0 [1b/h], T[R], D[in], P1[psia])


Initial calculations for subcritical flow.
Differential pressure to be used in flow rat calculation:

For classical Venturi tube:

For Nozzles:

For orifice plates:


Gas expansion factor:

For Venturi tubes and nozzles:
where

For orifice plates:

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



Calculate Reynolds number.

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

For liquid/water and gas/steam subcritical flow (Pipe Reynolds number):


Calculate discharge coefficient. See Appendix.

For orifices in the case of gas/steam subcritical flow, calculate DP and gas expansion factor:

Calculate new flow rate:

For gas/steam at critical flow:

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


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