A flow meter is a device which is used for measuring the quantity or flow rate of a liquid or gas in a pipe. Flow measurement applications are very varied; regard these examples: water flow via an open channel, fuel measurement through a fuel injector, respiratory flow through a peak expiratory flow meter or hydraulic valve leakage.
Though there are loads of technologies used for measuring the flow, the positive displacement flow meter is exceptional since it is the only one to straight away measuring the actual volume. All other kinds deduce the flow rate by making some other kind of measurement and equating it to the flow rate. Flow meters are referred to by a lot of names, like, flow gauge, liquid meter, flow indicator, etc. dependent on a specific industry; nevertheless the function, for measuring the flow, stays the same. It is the duty of the Flow Meter Supplier that they sternly select the most reliable and durable flow meter so that they may function properly.
Flow Meter Source 