A flow meter is a device used to measure the amount (such as 100 liters) of gas, vapor or liquid that passes through it. Also, it is used to measure nonlinear, linear, mass or volumetric flow rate (such as 100 liters per minute) of a gas or a liquid. This equipment consists of a transducer and a transmitter. A volumetric flowmeter is used to measure the volume of fluid, which is passed through it. A velocity flowmeter is used to measure the velocity of a flowing stream in order to determine the volumetric flow. A mass flowmeter is utilized to measure the mass flow of a flowing stream. Each flowmeter has its own specific installation constraints and applications. Different types of flowmeters available in market today are air flow meter, variable area meter, magnetic inductive flowmeter, vortex flowmeter, mass flowmeter and FAD meter. http://amplify.com/u/a1j7fh