Orifice Plate Flow Meter

Introduction and applications

The orifice plate flow meter is a differential-pressure meter and the most widely used type of flow meter. It combines a standard orifice plate with a multivariable differential-pressure transmitter (or separate DP, temperature and pressure transmitters) to form a wide-turndown DP flow device that can measure gas, steam and liquid flow.

The meter is based on Bernoulli's equation and the continuity equation: as fluid passes the restriction, a differential pressure develops across it that is proportional to the square of the flow rate. The orifice plate is the most standardised throttling device and the simplest and most adaptable of them, widely used for all kinds of fluid measurement and especially gas. Design, manufacture and use comply with ISO 5167, with calibration to the Chinese national standard JJG 640-2016.

Orifice meters are mainly used to measure volumetric flow of liquids, gases and vapours. In industry they are found in petroleum, chemical, power, metallurgy, medical, food and papermaking plants; in laboratories they are commonly used to measure air, gas and liquid flow. They are also valuable in agriculture and environmental protection.