# Flow Equations for ASME Type Gas Flow Nozzles

(Adopted from "Fluid Meters - Their Theory and Application")To compute mass flow rate (lb/sec) using the precision air flow nozzle (ASME long-radius flow nozzle, Beta <= 0.5, where Beta is defined as throat diameter to duct diameter)

Measure: D, upstream pipe diameter, in d, nozzle throat diameter, in p_{1}, upstream static pressure, lb/in2 δp, differential pressure (p_{1}- p_{2}), in H_{2}O T_{1}, upstream gas temperature, deg F

Inputs required are the type of gas (air, CO_{2},
H_{2}, etc.), the upstream static temperature, upstream static pressure and the
differential pressure. The procedure incorporates real gas effects (variation of gas viscosity
with temperature, boundary layer, etc.), determines whether the flow is choked or subsonic
and computes the exit velocity, the volumetric flow rate and the mass flow rate.

For flow computation, written in BASIC and running under MS-DOS, go to software.