
Calculate internal pipe diameter at flow temperature:

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

Calculate scale reading factor:

Calculate differential pressure at normal flow rate:

Calculate Pipe Reynolds number at normal flow rate:

Calculate first estimate for b ratio:

For Venturi tubes:

For other Flow meters:


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

For squareedge orifice with 21/2D and 8D pipe taps:

For LoLoss tubes, Venturi tubes and nozzles:

For eccentric orifices:

For squareedge orifices specified in ISO 51672003 (flange tappings, corner tappings, and radius tappings):

For other Flow meters:


Calculate discharge coefficient.For more information see the Appendix.

Calculate new b  ratio

Calculate the relative change in b  ratio.

Repeat steps 7 to 10 until the relative change in the b ratio is less than 0.0001.

Calculate orifice diameter at flow temperature:

For all Flow meters except Segmental orifices:

Segmental orifices:

Calculate Segmental radius:

Calculate Segmental height at flow temperature using the equation:
For further calculation of Segmental orifices, HS and HS0 are analogous to d and d0 respectivly.



Calculate orifice diameter at ambient temperature:

For LoLoss tube, nozzles and Venturi tubes:

For other orifices:


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