ISO-5167

ISO-5167 Orifice calculates size, flow-rate or pressure drop for gas and liquid flow orifice meters based on the International Standard Organization's ISO-5167.
Orifice Size is calculated from given flow-rate and pressure drop, Flow-rate is calculated from given size and pressure drop and Pressure Drop requires orifice size and flow-rate.  
Different taps can be selected: Flange Taps, D and D/2 or Corner taps. 
Fluids include gases: Natural Gas (Specific Gravity must be provided), Air and Nitrogen, or liquids: Crude Oil, Water, Methanol, Mono-ethylene Glycol, Diethylene Glycol and Triethylene Glycol.  
In addition, selecting orifice material will adjust the sizing parameter of the orifice depending on temperature.
Customary (US-units) or SI-units can be selected.