Orifice Plate

Orifice Plate

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

An orifice plate is also known as a diaphragm. First, the fluid passes through the orifice then the pressure builds up slightly upstream. Then, the liquid converges and passes 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 help 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 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 the actual flow rate to the flow rate with no energy losses or theoretical flow rate. Thus, an orifice plate can be inexpensive and straightforward, but high-pressure losses occur.


The membrane is a thin plate with holes, usually connected to a pipe. When liquid (liquid or gas) flows through the gap, the pressure in front of the hole increases slightly. Forced to converge through the hole, the speed increases, and the fluid pressure decreases.

The flow reaches the maximum convergence point at a point below the orifice. The convergence point is when the greatest velocity hits 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 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 mixed, and the flow is continuous rather than pulsating, orifice plates commonly measure flow in pipes.

Because the liquid occupies the entire pipeline (no debris or entrained gas), the flow profile is smooth and developed, and the fluid and flow meet some other conditions.

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

Calibrated Orifice

An orifice plate knows as calibrated orifice if calibrated with an appropriate fluid flow and a traceable flow measurement device. 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 essential standards cover these types. There are many different 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 pipeline, 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 additional conditions happen, you can predict these flow rates.

Diaphragm for an Orifice

When installing the diaphragm, 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. Thus, the uncertainty is usually tiny. Or restrict flow, in which case they are called orifice plates.

Orifice Flanges

Orifice flanges meet a pipe’s volumetric flow rate of liquid and gasses. Each flange has two pipe taps to measure the flow’s pressure drop 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 necks and slip-on flanges with extra machining.

Differential Pressure Natural Gas Flow Meter

Differential pressure (DP) flowmeters determine flow by measuring pressure drop over an obstacle inserted in the flow pathway. These flow devices are orifice plates, averaging pitot tubes, venturi tubes, and flow nozzles.

Orifice Plates

The orifice plate (orifice meter) is a differential pressure meter frequently used in natural gas measurement. It measures volumetric flow, though it can also calculate mass flow depending on the device’s calculation. It uses the same principle in suggesting a relationship between the velocity and pressure of the fluid.

That relationship is – as the velocity increases, the pressure decreases. Thus, the orifice meter determines the flow through the difference in pressure between the upstream and the downstream side of a partly impeded pipe.


The diaphragm has a long history of use and is widely used in the industry.
In addition, they are cheap and easy. They have no moving parts and are mechanically stable. The calibration is dry.
There are no temperature, pressure, or size restrictions.


On the other hand, orifice flowmeters have poor accuracy under low flow conditions. This is because they have a common flow/area and high-pressure drop, impacting operating costs. In addition, orifice plates are sensitive to flow distribution and require longer measuring tubes or flow regulators; they are not self-cleaning and may be damaged or blocked by high flow rates.

Difference Measuring an orifice plate is a natural gas flowmeter that determines the flow rate by measuring the pressure drop through the obstacle inserted into the flow path. The volume flow is measured, but you can also calculate the mass flow based on the calculation of the device, which means the relationship between fluid velocity and pressure. The association is as follows: As the speed increases, the pressure decreases. The throttle meter measures the flow rate by partially blocking the pressure difference between the inlet and outlet of the pipe.

Read about flanges.