Pressure Measurement for Flow rates : Generally
this method is used for measuring flow of gas, steam
and liquids of low viscosity. An obstruction in
the pipeline is generated by an element (orifice
plate) creates pressure difference before and after
the element. This differential pressure (pressure
low) is proportional to square of the flow rate.
magnetic flow measurement : This method is used
in application where liquid is electrically conductive.
E.g. water, acids, alkalis, milk, beer, pulp slurry
etc. Faraday's law of induction is the principle
used. Electromagnetic Force (E.M.F) is induced when
conductive material passes through a magnetic field.
The flowing medium is conductor and induced voltage
is proportional to flow velocity.