ORIFICE PLATES often provide flow measurements in plants. If manufactured to ISO or equivalent standards, they generate specific pressure drops for a given flow rate. However, their accuracy varies with the flow profile (see: "Think Straight About Orifice Plates," www.ChemicalProcessing.com/articles/2013/think-straight-about-orifice-plates/). Depending upon the situation, getting accurate readings may require from 10 to 90 diameters of straight pipe run upstream of the orifice plate and an additional five diameters downstream. Flow conditioners can reduce the necessary straight piping runs. With proper conditioners, upstream piping runs of 10-15 diameters often will suffice.
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