Thermal Vac chamber pressure gain question

In summary, the chamber was pumped down to a pressure of 3.7E-7, and a release of gas into the chamber abruptly caused the pressure in the chamber to rise to 5.0E-7. My question is how can I tell in liters how much gas was released into the chamber to cause this amount of rise in chamber pressure, based on the starting pressure and the ending pressure?
  • #1
loctwo
1
0
Hi group, I work at Thermal Vacuum Chamber, and we had an incident last night where our chamber, Which is 70' H x 30' D, was pumped down to a pressure of 3.7E-7. There was a release of gas into the chamber abruptly last night that caused the pressure in the chamber to rise to 5.0E-7, before it recovered back to it's original pressure. My question is How can I tell in liters how much gas was released into the chamber to cause this amount of rise in chamber pressure, based on the starting pressure and the ending pressure?
 
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  • #2
Wow! both # are so far below viscus flow, it might be worth thinking about how many atoms we are talking about. (it's been over 30 years since I did vacuum stuff.)
From the interweb, http://en.wikipedia.org/wiki/Mean_free_path
In a chamber that size, I am thinking some type of contamination, even roughing pump oil out gases at 10 -7. I have seen a case where diffusion pump could not get to a high vacuum. It turned out that the diffusion pump oil was contaminated with another oil.
 
  • #3
loctwo said:
Hi group, I work at Thermal Vacuum Chamber, and we had an incident last night where our chamber, Which is 70' H x 30' D, was pumped down to a pressure of 3.7E-7. There was a release of gas into the chamber abruptly last night that caused the pressure in the chamber to rise to 5.0E-7, before it recovered back to it's original pressure. My question is How can I tell in liters how much gas was released into the chamber to cause this amount of rise in chamber pressure, based on the starting pressure and the ending pressure?

Use the ideal gas law (PV=nRT) with a pressure of 1.3E-7.
 
  • #4
Calculate the volume of the chamber in liters.
Divide by the standard molar volume of a gas at STP (22.41 liters)
Multiply this volume by 3.0E-7/760 and 5.0E-7/760 to get moles of gas before and after.
Subtract and get gas released into chamber, in moles (e.g., 29 grams per mole of air).
 
  • #5
Did the incident occur while the evacuation was going on?
 

1. What is a Thermal Vac chamber?

A Thermal Vac chamber is a specialized type of chamber used for testing and simulating the extreme temperatures and vacuum conditions of outer space. It is commonly used in the aerospace industry for testing spacecraft and their components.

2. What is pressure gain in a Thermal Vac chamber?

Pressure gain in a Thermal Vac chamber refers to an increase in pressure within the chamber during testing. This can occur due to the heating of gases or materials inside the chamber, causing them to expand and increase the overall pressure.

3. Why is pressure gain important to consider in Thermal Vac testing?

Pressure gain is important because it can affect the accuracy of test results. If the pressure increases beyond the desired levels, it can impact the behavior of materials and components being tested, leading to inaccurate data and potentially causing damage to the chamber or its contents.

4. How is pressure gain controlled in a Thermal Vac chamber?

Pressure gain can be controlled through various methods, such as adjusting the temperature and flow of gases within the chamber, using pressure relief valves, and monitoring and adjusting the vacuum pumps. Proper calibration and maintenance of the chamber are also crucial in controlling pressure gain.

5. What are the potential risks associated with pressure gain in a Thermal Vac chamber?

If pressure gain is not properly controlled, it can lead to equipment failure, inaccurate test results, and potential safety hazards. It can also result in delays and additional costs in the testing process. Therefore, it is important to carefully monitor and manage pressure gain in Thermal Vac testing.

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