What are Leak and Flow Measurement Units?
There are two types of SI recognized flow measurement units: mass and volumetric flow units. Mass Flow is the mass transfer over time. Units: mg/min, microgram/min, gr/hr. Volumetric Flow is volume change over time. Units: cc/min, cc/hr. At any flow path of gas (compressible fluid) – mass flow is constant, volume flow is not. Therefore specifying volume flow requires specifying pressure and temp. at the point of reference. A third type of measurement unit is commonly used with gas flow, known as “Volumetric Flow at Std. Conditions” sometimes called “standard flow” which are confusing measurement units. These measurement units are volumetric flow units with thel letter “S” in front. E.g: scc/min or sccm, scc/sec or sccs, scfm. Standard Flow is Volumtric Flow corrected to Standard Barometric Conditions yielding the same mass flow for the gas used (must use the same gas). Standard Barometric Conditions refer to standard pressure and temperature (STP) conditions.
