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Any of various devices used to measure the flow of a fluid through a pipe, etc.

A positive displacement flowmeter of the oval gear type. Fluid forces the meshed gears to rotate; each rotation corresponds to a fixed volume of fluid. Counting the revolutions totalizes volume, and the rate is proportional to flow.

Any of various devices used to measure the flow of a fluid through a pipe, etc.

The paddle wheel assembly generates a flow reading from the fluid flowing through the pipe instigating the spinning of the paddlewheel. Magnets in the paddle spin past the sensor. The electrical pulses produced are proportional to the rate of flow.

Any of various devices used to measure the flow of a fluid through a pipe, etc.

A propeller-type current meter as used for hydroelectric turbine testing