Calculation of Differential Range - Intergraph Smart Instrumentation - Reference - Hexagon

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.

1. For Lo-Loss tube, Nozzles, and Venturi tubes:

   

2. For other orifices:

   

Calculate pipe Reynolds number:

*W[kg/s]

Calculate b -ratio.

1. For all Flow meters except Segmental orifices:

   

2. Segmental orifices.

   1. Calculate Segmental radius:

      

   2. 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).

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

   

2. For Lo-LOss tube, Venturi tubes and Nozzles:

   

3. For eccentric orifices:

   

4. For square-edge orifices specified in ISO 5167 - 2003 (flange tappings, corner tappings, and radius tappings):

   

5. 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: