|MLA Citation:||Bloomfield, Louis A. "Question 565"|
How Everything Works 17 Jan 2018. 17 Jan 2018 <http://howeverythingworks.org/print1.php?QNum=565>.
Let me assume that you want to know about a turbine flow meter for gas. The most common of these is a device that's half filled with liquid. The "turbine" is actually a set of blades that spin in a vertical plane and spend half their times immersed in the liquid. When one of the turning blades emerges from the liquid, the empty space that appears beneath it is allowed to fill with the gas being measured. This gas flows in from the meter's inlet. Soon another blade begins to emerge from the liquid and a volume of gas is then trapped between the first blade and the second blade. Once the blades have turned almost half a turn, the first one begins to submerge again in the liquid. The gas that was trapped between it and the next blade is then squeezed out from between those blades by the liquid and flows out the meter's outlet. A geared arrangement measures how many turns the blades make and therefore how many volumes of gas have been transferred from the meter's inlet to its outlet.