Project Description

Orifice Plate

Orifice Plates

Orifice Plates have many uses: power generation, oil production, refining, water treatment and distribution, gas processing and transmission, chemical, and petrochemical industry. An orifice plate is a thin plate with a hole in it, usually placed in a pipe.

First, the fluid passes through the orifice then the pressure builds up slightly upstream of the orifice. Then, the fluid is forced to converge to pass through the hole, the velocity increases, and the fluid pressure decreases.

When the flow expands, the velocity falls, and the pressure increases. The pressure difference generated by the flow velocity through the hole enables the flow quantity to be measured. Orifice plates are mainly used to achieve the restricted or controlled flow of a process fluid. Therefore, the smaller the beta ratio, the higher the differential pressure generated.

The selected beta ratio is a general compromise between the flow rate required and the desired differential pressure in working practice. It is easy to measure this decrease in pressure which can be used to determine the flow rate.

Energy losses across an orifice plate can be significant. Therefore, it is necessary to introduce a discharge coefficient equal to the ratio of actual flow rate to the flow rate with no energy losses or theoretical flow rate. An orifice plate has the advantage of being inexpensive and simple to use, but high-pressure losses are sustained.


The membrane is a thin plate with holes, usually connected to a pipe. When liquid (liquid or gas) flows through the hole, the pressure in front of the hole increases slightly. Forced to converge through the hole, the speed increases, and the fluid pressure decreases. At a point below the orifice, the flow reaches the maximum convergence point, at which time the velocity reaches the maximum, and the pressure reaches the minimum.

The flow expands, the speed decreases, and the pressure increases. By measuring the liquid pressure difference between the inlet and outlet of the bottom, the flow velocity can be derived from the Bernoulli equation using coefficients established by extensive research.


When the liquid is single-phase (not a mixture of gas and liquid or liquid and solid) and is well mixed, and the flow is continuous rather than pulsating, orifice plates are most commonly used to measure flow in pipes. The liquid occupies the entire pipeline (no debris or entrained gas), the flow profile is smooth and developed, and the liquid and flow meet some other conditions.

In these cases, and when designing and installing membranes according to relevant requirements. You can easily determine the flow rate from published formulas based on extensive research and published in industry, national and international standards.

If an orifice has been calibrated for the proper liquid flow rate and the flow rate has been monitored, the orifice is called a calibrated orifice. The measuring device plate is usually designed with round, sharp-edged holes and installed concentrically with the pipe and the pressure connection of one of the three pairs of standard holes on the front and back of the plate; ISO 5167 and other important standards cover these types. There are many other options.

The edges can be rounded or tapered, and the plate can have holes the same size as the pipe, except for the clogged part at the top or bottom. The hole can be eccentric to the pipe, making the pressure connection at another location. Variants of these functions are described in various standards and guidelines. Each combination will produce a different flow rate. When different conditions are met, you can predict these flow rates. Meet different types of conditions.

Once the diaphragm is designed and installed, it is usually possible to specify the flow rate by taking the square root of the pressure drop across the diaphragm pressure connection and applying an appropriate constant. The uncertainty is usually small. Or restrict flow, in which case they are often called orifice plates.

Orifice Flanges

Orifice flanges are for metering the volumetric flow rate of liquid and gasses through a pipe. Each flange comes with two pipe taps for measuring the pressure drop of the flow through an orifice plate. Orifice Flanges are used with orifice meters to measure the flow rate of either liquids or gases in the pipeline.

They are also used with orifice meters to measure the flow rate of either liquids or gases in the respective pipeline. Orifice flanges usually come with either raised faces or ring-type joint facings. Therefore, they are essentially the same as weld neck and slip-on flanges with extra machining.

Read about flanges.