# Thick Orifice

Thick orifice plates are used for measuring the volumetric flow rate of a fluid and may also be used to reduce the pressure in a flowing system and for flow balancing. They use the same principle as the Bernoulli's principle which states that there is a relationship between the pressure of the fluid and the velocity of the fluid. When the velocity increases, the pressure decreases and vice versa. When the fluid reaches the orifice plate, the fluid is forced to converge through the small opening in the middle. The point of maximum convergence occurs just downstream of the physical orifice. As it does so, the velocity and the pressure changes. Beyond the opening, the fluid expands and the velocity and pressure change once again. By measuring the difference in fluid pressure between the normal pipe section and at the opening, the volumetric and mass flow rates can be obtained using Bernoulli's equation. The calculation standard detailing the pressure loss over thick orifice plates is found in Pipe Flow - A Practical & Comprehensive Guide - AIChE [24].