The Almighty Orifice Plate Flow Meter
2019-06-18
The orifice plate flow meter is commonly used in clean liquid, gas, and steam services.
It is available for all pipe sizes but it is very cost-effective for measuring flows in larger ones. The orifice plate is also approved by many organizations for custody transfer of liquids and gases.
The orifice plate calculations used nowadays still differ from one another, although various organizations are working to adopt an universally accepted orifice flow equation. Orifice plate sizing programs usually allow the user to select the flow equation desired.
The orifice plate meter can be made of any material, although stainless steel is the most common. The thickness of the plate usedis a function of the line size, the process temperature, the pressure, and the differential pressure.
The traditional orifice flow meter is a thin circular plate, inserted into the pipeline between the two flanges of an orifice union. This method of installation is cost-effective, but it calls for a process shutdown whenever the plate is removed for maintenance or inspection. In contrast, an orifice fitting allows the orifice to be removed from the process without depressurizing the line and shutting down flow. In such fittings, the universal orifice plate, a circular plate with no tab, is used.