Where Can I Find Baseline Data for Air Flow vs. Pressure in Valve Testing?

Click For Summary

Discussion Overview

The discussion revolves around finding baseline data for air flow versus pressure in the context of valve testing. Participants explore the setup of a flow test bench involving a PVC pipe, air compressor, and various measurement instruments, while seeking comparative data for their experiments.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Experimental/applied

Main Points Raised

  • One participant is seeking baseline data for air flow versus pressure for various valve components, describing their specific experimental setup.
  • Another participant suggests obtaining a calibration curve from the flow meter manufacturer as a check on the measurements.
  • There is a discussion about the purpose of the setup, with one participant confirming it is intended to determine the Cv of the valves being tested.
  • Standards for flow rate testing of valves are mentioned, which involve measuring upstream and downstream pressures and applying equations to determine Cv.
  • Concerns about the accuracy of the flow meter readings due to setup variations are expressed, with one participant emphasizing the importance of the measurement location within the tube.
  • Suggestions are made for alternative flow measurement devices, such as rotameters and orifice measuring stations, to validate the existing flow meter readings.

Areas of Agreement / Disagreement

Participants express varying opinions on the reliability of the current flow meter setup and the need for additional measurement devices. There is no consensus on a single method or source for baseline data, indicating multiple competing views remain.

Contextual Notes

Participants acknowledge that the inherent chaos in the system could affect readings, and the accuracy of measurements may vary depending on the valve in use. The discussion highlights the complexity of measuring flow in a constrained environment.

wxrocks
Messages
130
Reaction score
0
I am working on an air flow vs pressure chart for a variety of valve components for work and I am hoping someone may know where I could get some comparative baseline data.

My setup is a 4' long, 2" diameter PVC pipe with one end connected to a large air compressor tank with a ball valve for regulating the flow. Near the other end, I have an air flow transducer (Omega FMA-906) and a pressure transducer (Omega PX303). The end of the pipe is reduced by a series of graduated fittings that terminate at different ends that are designed to fit the valves I am testing.

I am able to check my pressure readings with an analog pressure gauge, but I don't have the same ability with the flow without significant setup changes. I am hoping there is some type of baseline data available for typical flows in a pipe with a constricted end. If anyone could point me to a resource for that data, that would be great!
 
Engineering news on Phys.org
What is the signal output from the flow meter? You should get a calibration curve from Omega. That's your check. Is there a reason why you don't trust the cal cert?
 
It sounds like you're trying to set up a flow test bench to determine the Cv of your valves, is that right? From reading this it sounds like you have an air tank, a ball valve on the tank outlet to regulate pressure or flow, a 2" pipe leading to a point that a valve is being tested, and I assume the outlet of the valve is venting to atmosphere.

There are some standards which cover flow rate testing for valves if that's what you're looking for. They basically tell you to measure upstream and downstream pressure on your valve and apply the equation to determine Cv. If your valves are various sizes such that your flow meter can't handle the full range, you should probably purchase a few different flow meters to handle the range. Electronic air flow meters of any kind are not cheap, so if you're concerned about cost, I'd suggest a rotometer.
 
turst in calibration

I do trust the calibration of the instrument -- It has more to do with the setup. Any setup will have different amounts of chaos and thus could affect the instrument reading depending on where it is located in the tube. I can certainly use the data I have, but I thought a "second" opinion would be nice.

Yes, this is venting to the atmosphere. And yes, my flow meter is sufficient to cover the flow amounts I need to test.
 
Last edited:
If you're just looking to back up the meter you have, a rotameter might suffice. It will get you to within a few percent for less than $100. Check out http://www.mcmaster.com/".
 
Last edited by a moderator:
Granted your uncertainty will change slightly depending on the valve that is in line. However the "chaos" as you state it, inherent in the system will be eclipsed by the error in the measurements.

Depending on the expected range of velocities, you could also employ an orifice measuring station as a check.
 

Similar threads

Relationship between flow and pressure in a valve
  • · Replies 5 ·
Replies
5
Views
3K
Modeling Air Compression Cylinder
  • · Replies 45 ·
2
Replies
45
Views
7K
Mass Flow Rate of Pressure Regulator
  • · Replies 3 ·
Replies
3
Views
4K
Caculate air flow using tank pressure
  • · Replies 2 ·
Replies
2
Views
2K
Underground pump vault airflow considerations
  • · Replies 15 ·
Replies
15
Views
4K
How can I accurately measure the mass air flow in my intercooler heat exchanger?
  • · Replies 5 ·
Replies
5
Views
2K
How to calculate flow loss between 90 and 45 degree fittings
  • · Replies 3 ·
Replies
3
Views
17K
Can the Pressure Rise in a System be Calculated When Leakage Changes?
  • · Replies 6 ·
Replies
6
Views
5K
How to increase pressure in a pipe ?
  • · Replies 1 ·
Replies
1
Views
4K
Engineering Water Flow from Pressurized Tank through Heat Exchanger
  • · Replies 56 ·
2
Replies
56
Views
6K