A Restriction Plate is a device used to restrict flow, or for reducing pressure. It decreases pressure and flows from the upstream side to the downstream side. Restriction Plates are beneficial to protect downstream equipment and are helpful in order to reduce noise.
Restriction Plates are widely used for numerous applications in the industry. The design of the Restriction Plate is very similar to an orifice plate, but the function is different. Restriction plates are used to fulfill a number of purposes, which include:
Orifice Plates are used for measuring flow rate, while a restriction plate is used to drop upstream pressure. The restriction plate is similar to an orifice plate but it is thicker. When the fluid passes through thick plate energy is lost in heat and friction resulting significant pressure drop.
There are many important factors to look at when selecting and sizing restriction plates. Although there are highly advanced control valves available in the market; there is a remarkable usage of restriction plates in the piping industry. A restriction plate is mainly used to control the flow of the fluid or to achieve pressure restriction. Based on the requirements, the Restriction plate should be sized for critical or pre-critical conditions.
In general, pressure control restriction plates are sized by considering the maximum pressure drop lesser than the critical pressure. And, the flow-controlling restriction plates are sized for critical pressure drops. The thickness of the plate is calculated as per the R.W. Miller handbook and sizing is conducted as per ISO 5167-2.
Types of Restriction Plates
The Restriction plate should be selected based on the flow rate and required pressure drop. Following are the types of restriction plates:
Orifice plate or restriction device is used for measuring the volumetric flow rate in a pipe. Orifice plate function is based on Bernoulli’s principle. Bernoulli’s equation says that when the pressure drops across the restriction plate is directly proportional to the volumetric flow rate that passes through the orifice plate.
A restriction plate also works on the same principle but provides a different purpose. The main difference between the orifice plate and restriction plate is their usage. A restriction plate is used for overcoming pressure in a pipe by raising fluid velocity. Restriction plates and orifice plates are similar in structure and both are based on Bernoulli’s equation.