Gas Orifice Flow Meter Calculator - Maple Help
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Gas Orifice Flow Meter Calculator

This application calculates the flow rate through a large-diameter orifice using the approach outlined in ISO 5167 2:2003.

Orifice meters use the pressure loss across a constriction (that is, the orifice plate) in a pipe to determine the flow rate.  

The formulas are valid for the following parameters:


Pipe diameters between 50mm and 1000 mm


Pressure ratios greater than 0.75



Pipe Diameter D1 (m)

Molecular Weight

Orifice Diameter D2 (m)

Compressibility Factor

Upstream Pressure P1 (Pa)

Specific Heat Ratio

Downstream Pressure P2 (Pa)

Fluid Viscosity (Pa s)

Upstream Temperature (K)

Tap Type


 m3 s-1




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