How to measure flow using standard orifice flowmeter?
When an orifice flowmeter is placed in a pipe carrying the fluid whose rate of flow is to be measured, the orifice plate causes a pressure drop which varies with the flow rate. This pressure drop is measured using a differential pressure sensor and when calibrated this pressure drop becomes a measure flow rate.
As a standard orifice flowmeter factory, we can tell you the operation of orifice flowmeter:
1. The detail of the fluid movement inside the pipe and orifice plate has to be understood.
2. The fluid having uniform cross section of flow converges into the orifice plate’s opening in its upstream. When the fluid comes out of the orifice plate’s opening, its cross section is uniform for a particular distance and then the cross section of the fluid starts diverging in the down stream.
At the upstream of the orifice, before the converging of the fluid takes place, the pressure of he fluid (P1) is maximum. As the fluid starts converging, to enter the orifice opening its pressure drops. When the fluid comes out of the orifice opening, its pressure is (p2) and this pressure remains constant in the cross section area of fluid flow at the downstream.
This cross sectional area of the fluid obtained at downstream from the orifice edge is called VENA-CONTRACTA.
The differential pressure sensor attached between points 1 and 2 records the pressure difference (P1 – P2) between these two points which becomes an indication of the flow rate of the fluid through the pipe when calibrated.