Any of various devices used to measure the flow of a fluid through a pipe etc(noun)
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Use "flowmeter" in a sentence
"Endress and Hauser will also showcase its Promass 83F Coriolis mass flowmeter, which is said to be ideal for oil and gas applications."
"Next, he attached a flowmeter to the pump to register the speed of the liquid."
"(All of the cells that have exploded were open; that is, the D2 and O2 gas was exhausted, and sent through a gas flowmeter and mass spectrometer in the case I mentioned.)"