Look through our Flow Controls to find the right fit for you.
How to use the Orifice Flow Calculator
This Air flow calculator is based on the flow through an orifice in a common application where an orifice restrictor is supplied via a regulated pressure supply and vents to atmosphere. The Upstream pressure (PU) is gauge pressure that is set in the system. The downstream pressure (PD) is set to absolute pressure and used for the pressure differential and mass flow rate calculations.
Users will typically select an upstream gauge pressure and orifice size to determine the flow rate. Other orifice restrictor applications may require users to overwrite values in the calculator such as PD, but pay attention to the units specified.
*Results of this calculator will produce nominal values. Real world values may vary per application. If you are designing a product, we recommend using Air Logic’s Free Sample Program to test in your application.
How to Calculate Volume Flow rate
This orifice flow calculator uses the following equation to calculate the volumetric flow rate:
NFPA flow coefficient for Fahrenheit and Psi (pressure per square inch) is used to calculate CFM (cubic feet per minute). Other units are available in the calculator and are converted outside of this base equation.
Definition of terms:
Q = Air Flow in CFM
ΔP = Pressure Drop across orifice
PD = Pressure Downstream
G = Specific Gravity of the gas/air (Air = 1)
TU = Upstream Temperature
Cv = Flow Coefficient
How to Calculate Mass Flow Rate
By using a STP (standard temperature and pressure (PD)) in this calculator, a small “s” will appear in front of the flow units. The “s” stands for “standard” and indicates the output (in volumetric flow rate) may be used to calculate the mass flow rate.
To calculate the mass flow rate, multiply the density of the gas (at matching STP conditions) by the volumetric flow rate.