Leak rate correlation between different gases

[djsnow]

Hi
I am i new member, i hope i am posting in the correct forum. I require some help i with a problem i am trying to solve in my work. Currently we have 3 separate leak test methods specified for a part all with different working gases and pressures. If possible, i would like to correlate this data so that i can determine that a specified leak rate of "X" with Helium at 700kPa is equal to a leak of "y" with Air at 1.0MPa is equal to a leak of "Z" with R134a at 2.1MPa. The aim being to commonise to one spec (preferably air).
I have done some work on this to based on info in found around the web, in particular this site:
www.air-dispersion.com/msource.html
I am struggling with a few variables used in the formula, in particular compressability factor and real gas density and a few others of R134a.
My question, is there another way to go about solving this problem that anyone might be able to help me with? Does anyone know where i can get some properties tables on the web on R134a at different pressures and temps (and helium for that matter) that could also assist me.
Thanks in advance, any help you can offer will be greatly appreciated.

Michael
Australia

 

[AndyW]

Dear Michael,

Thank you for reaching out to our forum for help with your problem. I can understand the importance of standardizing leak testing methods to ensure accuracy and consistency in your work. I would be happy to offer some suggestions and assistance.

Firstly, I would recommend consulting with an expert in gas properties and leak testing methods. They may be able to provide you with more specific and accurate information and guidance. Additionally, they may have access to specialized resources and databases that can help you in your research.

In terms of finding properties tables for R134a and helium, I would suggest looking for reputable sources such as scientific journals or books. You can also try contacting manufacturers or suppliers of these gases as they may have this information readily available.

In terms of approaching your problem, one way to correlate the data would be to use the Ideal Gas Law (PV=nRT) to calculate the volume of gas needed to achieve a certain pressure and flow rate. This can help you determine the equivalent leak rate for each gas at the specified pressures. However, as you mentioned, this may not take into account factors such as compressibility and real gas density. In that case, you may need to use more complex equations or simulations to accurately compare the leak rates.

I hope this helps guide you in the right direction. Best of luck with your research and standardization efforts.
[Your Title/Expertise]

 

[sir-pinski]

Hi Michael,

Welcome to the forum! It sounds like you have a challenging problem to solve. It's great that you have already done some research and found some helpful resources.

One way to approach this problem is to use the ideal gas law, which states that the pressure, volume, and temperature of a gas are related by the equation PV = nRT, where P is pressure, V is volume, n is the number of moles of gas, R is the gas constant, and T is the temperature in Kelvin.

To compare the leak rates of different gases at different pressures, you will need to calculate the number of moles of each gas leaking through the part per unit time. This can be done by rearranging the ideal gas law equation to solve for n, and then plugging in the values for pressure, volume, and temperature of each gas.

You can also use the ideal gas law to calculate the compressibility factor, which is a measure of how much a real gas deviates from ideal gas behavior. This factor will affect the leak rate of each gas, so it is important to take into account when correlating the data.

As for obtaining properties tables for R134a and helium at different pressures and temperatures, you may be able to find them through a quick internet search or by consulting a thermodynamics textbook. You can also try reaching out to experts in the field or contacting companies that specialize in gas properties.

I hope this helps and good luck with your research!