The discovery that When the flow through the pipe cross-sectional area decreases. Pressure fluid in the pipe after the cross-sectional area smaller than it would have decreased, and the difference in pressure that occurs is proportional to the square root with flow rate this phenomenon
Orifice plate has a metal plate with a hole for the fluid through. The installation will be installed between flanges of tubes perpendicular to the stream flow. Due to the relatively easy and cheap. It is used widely. Then there is the reliability of flow measurement as well. Orifice plate can be made from many materials also resistant corrosion from the fluid used. Such as 316 Stainless Steel, Monel or Inconel Orifice Plate