اورفیس پلیت – Orifice Plate

Orifice Plate

Flow measurement using an orifice flowmeter

An orifice flowmeter is one of the most common methods for measuring flow using differential pressure transmitters. The most typical type of orifice is a flat metal plate with a concentric hole, installed perpendicular to the flow direction. As the fluid passes through the orifice plate, its velocity increases due to the reduced cross-sectional area, causing a drop in pressure. Once the fluid exits the orifice, its velocity decreases again and the pressure rises.

The orifice flowmeter calculates the flow rate of the fluid using the differential pressure created by the orifice in the flow line. Pressure transmitters measure the pressure on both sides of the orifice to determine the flow rate of the passing fluid.

Orifice Flowmeter Operation

In practice, due to some pressure loss caused by friction and flow mixing, the fluid exiting the orifice is at a lower pressure than the inlet. This permanent pressure drop depends on the flow rate and the ratio of the orifice hole diameter to the pipe diameter. This ratio is called Beta (β). By measuring the pressure drop and knowing the Beta ratio, the fluid flow rate can be calculated.

One important condition for using orifices is a stable flow profile upstream. For this reason, obstacles or fittings are generally avoided at a certain distance before and even after the orifice.