Project Description

Orifice Plates & Flanges

Orifice Plates & Flanges is a thin plate with a hole in it, which is usually placed in a pipe. When a fluid passes through the orifice, its pressure builds up slightly upstream of the orifice. Because the fluid is forced to converge to pass through the hole, the velocity increases and the fluid pressure decreases.  Once the flow expands, the velocity falls and the pressure increases. The pressure difference generated by the flow velocity through the hole enables the flow quantity to be measured.


Orifice plates are mainly used to achieve restricted or controlled flow of a process fluid. Therefore, the smaller the beta ratio, the higher the differential pressure generated. In working practice, the selected beta ratio is a generally compromise between the flow rate required and the desired differential pressure. It is easy to measure this decrease in pressure which can be used to determine the flow rate. Energy losses across an orifice plate can be significant. Therefore necessary to introduce a discharge coefficient which  is equal to the ratio of actual flow rate to the flow rate with no energy losses or theoretical flow rate. An orifice plate has the advantage of being inexpensive and simple to use but high-pressure losses are sustained.