A free program for Android, by PetroSimple.

The Orifice Gas Flow App is a handy app for calculating the gas flow rate through an orifice. The calculation is based on the standard procedure described in ISO, and is used to determine the gas flow rate and pressure.

The user has the option of selecting the type of orifice, the pipe size, and the location of the orifice in the pipe. The location can be selected from the four specified by the ISO: Flange Taps, Corner Taps, D and D/2 Taps. It is also possible to manually specify the location.

The user can select the units for each of the parameters, and can change them if desired. This is done by selecting "Settings" from the menu and then selecting "Units".