Mass & volumetric flowmeters

A differential pressure sensor is used to measure the pressure drop along a fixed distance of the LFE. This, along with the viscosity of the gas, is used to accurately determine the volumetric flow rate.

Separate absolute temperature and pressure sensors are incorporated and correct the volumetric flow rate to a set of standard conditions. This standardised flow rate is commonly called the mass flow rate and is reported in units such as standard cubic feet per minute (SCFM) or standard litres per minute (SLM). Standard units include a 0 to 5V output (4 to 20mA optional) and RS232 communications.