Flow metering instrumentation for measuring the mass of a substance that has passed a particular point in a specified time period.
A mass flow meter is an instrument which can measure either directly or indirectly the mass of a substance which is passing through a specific location in a set period of time.
Mass flow meters can provide an instantaneous analogue, digital or pulse output of the mass flow rate.
A mass flow meter may also include additional electronics such as a digital indicator for displaying the total mass measured to date.
The measurement of mass flow is called the mass flow rate, and this is defined as the amount of mass that will be transferred in a unit period of time i.e. ṁ = m / t.
Mass flow can be measured either directly using a mass flow meter, or indirectly by combining other parameters such as flow velocity, area, density, temperature and pressure.
There are many different units used for measuring mass flow rate. The type of substance, size of cross sectional area, flow speed, and geographic region, will all dictate the mass and time units which are the most convenient to use for particular flow measurement. The mass flow rate unit derived from SI units is kilograms per second (kg/s).