Digital flowmeter

They are electronic flow-measuring instruments, usually installed in line with the pipe carrying the fluid. They have no internal moving parts and therefore require no maintenance.

Electromagnetic flowmeters are based on Faraday’s law: a conductor moving within a constant magnetic field induces a voltage proportional to the speed of the movement and to its length.

The instrument consists of coils that create the magnetic field, a conductor passing through it — the moving fluid — in which the potential difference is induced, and electrodes that measure it. That difference is proportional to fluid velocity, so flow is obtained by multiplying it by the pipe cross-section. These flowmeters require the liquid to have a minimum conductivity.

Mass flowmeters measure the mass flowing per unit of time. The most widely used types are Coriolis-principle and thermal mass flowmeters.

The Coriolis effect occurs when an object moves radially on a rotating disc: as a body of mass “m” travels from the centre towards the edge, its tangential velocity increases. Because it does not depend on the conductivity of the liquid, the mass flowmeter greatly widens the range of products that can be packaged.