
Calculate internal pipe diameter at flow temperature:

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

Calculate orifice diameter at flow temperature.

For LoLoss tube, Nozzles, and Venturi tubes:

For other orifices:


Calculate pipe Reynolds number:
*W[kg/s]

Calculate b ratio.

For all Flow meters except Segmental orifices:

Segmental orifices.

Calculate Segmental radius:

Calculate b ratio:
HS is calculated with the help of HS0 in accordance with step 3b.



Calculate Discharge coefficient, see Appendix.

First estimate for Differential range:

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

For square edge orifice with 2½D and 8D pipe taps:

For LoLOss tube, Venturi tubes and Nozzles:

For eccentric orifices:

For squareedge orifices specified in ISO 5167  2003 (flange tappings, corner tappings, and radius tappings):

For other Flow meters:


Calculate new Differential range:
*W[kg/s]

For liquid and water, got to step 13.

Calculate the relative change in differential range:

Repeat steps 8 to 11 until the relative change in the differential range is less than 0.0001.

For quarter of circle (Quadrant Edge) orifice, calculate radius of upstream profile: