### Orifice Plate - an overview | ScienceDirect Topics

Orifice plates, Venturis and nozzles all provide a simple means of inducing a pressure drop to the fundamental relation u = k h 0.5 where k is a constant related to the ratio of pipe to orifice, the density and viscosity of the liquid, and h is the pressure drop in head of fluid caused by the restriction. Thus the velocity is proportional to the square root of the measured pressure drop.