Differential Pressure and Orifice Plate

Orifice plates are sized according to fluid type, temperature, rate of flow (speed), pressure, size of pipe, and process system flow control requirements.

In order to accurately measure flow with an orifice plate without negatively affecting the process the flowmeter must match the plate and comply with all system parameter(s) requirements.

The manufacturer of the flowmeter and orifice will provide the proper/correct orifice based on the process information you provide to them.

If you are unsure, I suggest you contact a reputable company and ask them to review your application on-site to ensure there are no mistakes or issues.

Thanks for your kind answer ,actually the orifice plate that we are using in the our filed is local made but my problem is how can I choose the right orifice plate for example :

Air

pressure :around 3 bar

pipe :4inch

If you are an electrical engineer, you should not have much trouble learning about flow measurement.

This: flow and level measurement - Omega Engineering will give you some basic knowledge.

As SHOCKHISCAN said an instrument supplier can give you product recommendations if you don't want to learn the concepts and instruments involved.

Do you have any idea how to discuss the application with a few suppliers over the phone? Good. That's the way to do it.

In my day, Principles and Practice of Flow Meter Engineering by L. K. Spink was the standard. Later, R. W. Miller's Flow Measurement Engineering Handbook seems to have taken over. Industrial Flow Measurement by Michael Crabtree gives a good discussion of this subject.

Here's a link to a free downloadable calculator - I can't vouch for it.

Thanks for those links that you mentioned

Orifice plate and differential pressure are sooo 1973. Details of the fluid, its temperature and pressure, and the line size would help selecting an alternative.

Good Day Omar,

1. What kind of fluid are you measuring? liquid, gas, or non-newtonian
2. Does the lead in fluid conductor have sufficient length to ensure a fully developed flow at the orifice?
3. What kind of measuring accuracy is required?
4. The flow velocity is it relatively constant or varying? Because orifice have a turn down ratio of 3:1 to 4:1. You may want to investigate other primary elements such as: venturi, V-Cone (has a turndown ratio of 10:1 and it shapes the flow before measuring, and its accuracy can be pre-calibrated, google "McCrometer V-Cone"), etc.

A question I have to ask are there any mechanical engineers at your firm? Because it is my opinion that this effort is more in line with their discipline