Help with measure air flow rate with pressure difference in a cylinder

In summary: FLD820In summary, the speaker is looking for a way to measure the air flow rate in a pneumatic cylinder using a pressure sensor and Bernoulli's equation. They are seeking more information such as cylinder diameter, stroke, and rate of movement in order to determine the most suitable method for measuring the airflow. The suggestion is made to use a pressure independent mass flow meter and some potential options are provided.
  • #1
alexte92
1
0
Hi,

I've got a horizontally moving piston in a pneumatic cylinder, the piston is moving backward to suck the air into the cylinder from a hole at one end, this will lead to an air flow rate. I would like to measure the air flow rate at that instant. I was thinking of with a pressure sensor attach to the cylinder, i can measure the pressure difference. By using Bernoulli's equation, i can calculate the air flow rate. Is this approach correct? and what pressure sensor would be suitable?

If you need me to explain more on the details, I would be more than happy to help you.

Thx guys.
 
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  • #2
Welcome to the PF.
I think more information would help find you an answer.

It would be good to know the cylinder diameter, stroke and rate of movement?
Some idea of the orifice = hole size, would also be useful?

How you measure the airflow will depend on why you need to know it?
At what instant(s) during the retraction stroke do you need to measure the air flow?

Given that information it should be possible to get a quick answer. As the air on each side of the orifice will have a different pressure, the volume flowing will depend on the pressure where you measure it. This suggests a pressure independent mass flow meter might be appropriate.

Some light reading; http://en.wikipedia.org/wiki/Flow_measurement
 
  • #3
Given the information though it should be possible to get an answer analytically rather than by testing. You would just need to know the things Baluncore asked for. The flow in this case is almost certainly compressible, though, so it is unlikely Bernoulli's equation will be of any use.
 
  • #4
You can find some good gas mass flow meters here.

http://www.omega.com/subsection/mass-flow-meters.html

e.g.

FMA1600_l.jpg
 

What is air flow rate?

Air flow rate refers to the volume of air that passes through a specific point in a given amount of time. It is typically measured in cubic feet per minute (CFM) or cubic meters per hour (m3/h).

Why is it important to measure air flow rate in a cylinder?

Measuring air flow rate in a cylinder is important because it allows us to determine the efficiency of the cylinder and the system it is a part of. It can also help us identify any potential issues or inefficiencies in the system.

How is air flow rate measured with pressure difference?

Air flow rate can be measured with pressure difference by using a device called a manometer. This device measures the pressure difference between two points in the cylinder and uses this information to calculate the air flow rate.

What factors can affect the accuracy of air flow rate measurements?

The accuracy of air flow rate measurements can be affected by factors such as temperature, humidity, and the shape and size of the cylinder. It is important to control for these factors in order to obtain accurate measurements.

What are some ways to improve air flow rate in a cylinder?

There are several ways to improve air flow rate in a cylinder, such as using a larger cylinder, reducing air leaks, and using more efficient components in the system. Regular maintenance and cleaning can also help improve air flow rate.

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