Flow measurement methods other than positive-displacement flowmeters rely on forces produced by the flowing stream as it overcomes a known constriction, to indirectly calculate flow. Flow may be measured by measuring the velocity of fluid over a known area. For very large flows, tracer methods may be used to deduce the flow rate from the change in concentration of a dye or radioisotope.

Flow Meter

A flow meter is a device used to measure the volume or mass of a gas or liquid.
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SWK 13

Flow Switch/Gauge

Flow switches are typically used to control the flow of liquid or gas through a designated channel.
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