What are the different types of orifice plates and state their uses?

Orifice plates are commonly used in industrial flow measurement applications to restrict fluid flow and measure the pressure drop across the plate, which can then be used to calculate the flow rate of the fluid. There are several types of orifice plates, each with its own unique design and applications.

Orifice plates often come in the following varieties:

  1. Concentric Orifice Plate:

A concentric orifice plate is a circular plate with a concentric circular hole in the center. It is the most commonly used type of orifice plate and is suitable for use in a wide range of applications. For excellent liquid, gas and steam service, a concentric orifice plate is used. For liquids, this orifice plate beta ratio ranges from 0.15 to 0.75; for gases, including steam, it ranges from 0.20 to 0.70. The optimal range is between 0.4 and 06.

Beta ratio is the ratio of the internal pipe diameters to the orifice bore (450 bevelled edges are frequently utilised to reduce friction resistance to flowing fluid).

  1. Eccentric Orifice Plate:

Similar to a concentric orifice plate, an eccentric orifice plate has a hole that is offset from the plate’s centre. This design helps to reduce the effects of pipe and plate wear, making it ideal for use in applications where abrasion is a concern. An eccentric hole exists in the eccentric orifice plate. Use fully for measuring items that contain particles, liquid oil, or moist steam. Flange or vena contracta taps can be used on eccentric plates, however they must be positioned either 1800 or 900 millimeters from the eccentric opening. ‘ Eccentric orifices feature a bore that is off-center to reduce issues when working with materials that contain particles.

  1. Segmental Orifice Plate:

A segmental orifice plate has a flat plate with a segmental opening in the center. This design is suitable for use in applications where the fluid contains solid particles or debris that could damage the orifice plate. Measurement of colloidal and slurry flow is performed using the segmental orifice location, which has a hole in the form segment. The tap should be placed 1800 from the center of tangency for maximum precision. Another type of plate that is practical for materials containing solids is one with segmented orifices.

  1. Quadrant Edge Orifice Plate:

A quadrant edge orifice plate has a sharp edge around the perimeter of the orifice. This design is typically used in applications where high accuracy is required, such as in custody transfer applications. It is widely used in Europe and is especially helpful for pipes less than 2 inches. For low Reynolds numbers in the region of 100,000 to 5,000, quadrant edge orifices give a comparatively consistent coefficient of discharge.

  1. Conical Entrance Orifice Plate

A conical entrance orifice plate has a conical inlet that gradually tapers to a circular orifice. This design helps to reduce fluid turbulence and pressure loss, making it ideal for use in applications where energy efficiency is a concern.

The choice of orifice plate type depends on the specific application and the flow conditions of the fluid being measured. The use of the appropriate orifice plate type can help to ensure accurate flow measurement and prevent damage to the orifice plate and the flow metering system.

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The right type of orifice plate has to be chosen depending on the application and flow conditions. The selection helps to ensure accurate measurements and minimise damage to the orifice and the metering system.

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