Building a Vacuum Filling System: Valves & Fine Leaks

In summary, the conversation is about building a vacuum filling system for charging liquid inside a heat pipe. The person is using 1/8 inch stainless steel tubing and a Swagelok ball valve for regulating the pump flow. However, they are having trouble reaching their desired vacuum pressure of 0.1 pascal due to fine leaks. The person is considering changing to a bigger tubing size or finding a more suitable valve for the application without a high price. Some solutions mentioned include using a solder plug or a thermoplastic plug.
  • #1
Adi Wijaya
3
0
I'm building a vacuum filling system for charging liquid inside heat pipe. I am using 1/8 inch stainless steel tubing for system connecting construction and swagelok ball valve 1/8 inch for regulating the pump down flow from heat pipe to vacuum pump. The fluid regulate with micro metering valve. The goal of my vacuum pressure around 0.1 pascal but until now I could not reach that level due to many fine leaks. Unfortunately my ball valve could not stand for the vacuum condition because there is no o ring inside the valve. Also I using 1/8 inch tee swagelok for connecting three stainless steel tubing and this could be source of the leaks.
Question
What valve should I use for this application which still affordable with my budget
How can I minimize the fine leaks so when I turn off the vacuum pump the vacuum pressure still stable for hours so I could have enough time for injecting the fluid?

Thanks a lot
 
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  • #2
Regarding the Swaglok fitting, do you finger tighten the fitting then use the standard 1-1/4 turn tightening procedure? also your 1/8" tubing may not be round enough or have a too irregular surface to get an adequate seat.

I seem to remember seeing a ball valve used with a backing pump (although not as small as yours) so maybe you just chose the wrong brand. I think you can get vacuum rated manual valves with "O" ring seals but I do on think that they are made as small as you would like. Unless you have a method of locating the leaks you will have a hard time dealing with the problem.
 
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Likes Adi Wijaya
  • #3
Thank Gleem
Yes, I already tighten the fitting correctly...yes It's difficult to find the valve suit with the 1/8 inch tube...I guess I should change to bigger tubing
 
  • #4
Swagelok makes many valves in 1/8" size that can do vacuums just fine. Check the Swagelok catalog or call the local dealer. I've used Swagelok products in numerous applications, both vacuum and high pressure. Assembled correctly you should have no problem achieving 0.1 P.
 
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  • #5
OldYat47 said:
Swagelok makes many valves in 1/8" size that can do vacuums just fine. Check the Swagelok catalog or call the local dealer. I've used Swagelok products in numerous applications, both vacuum and high pressure. Assembled correctly you should have no problem achieving 0.1 P.
Thanks a lot OldYat47
I'm already contact the local dealer for the solution, they proposed Stainless Steel High Purity High Pressure Diaphragm Sealed Valve, 1/4 in. Swagelok Tube Fitting, Lever Handle
http://www.swagelok.com/en/catalog/Product/Detail?part=SS-DLS4
but the price more thank twice from my current valve (ball valve). I've been check my ball valve, that the leak came from the under the handle. When I've turn the handle to shut off the valve, my pirani gauge directly shows rapidly decrease vacuum pressure, I note it around 100 pascal.
If you don't mind my I know the right valve for this application (0.1 Pa)?with the reasonable price or I should change the tubing with 1/4 inch? Thanks a lot again
 
  • #6
A solder plug could be a cheap solution. Evacuate the tube and then melt a lump of solder, inside the tube (a U). It would be cheap. Or perhaps a thermoplastic plug.
 

Related to Building a Vacuum Filling System: Valves & Fine Leaks

1. What are the main components of a vacuum filling system?

The main components of a vacuum filling system include valves, pumps, gauges, and a chamber or vessel to hold the substance being filled. Valves are essential for controlling the flow of the substance and maintaining the vacuum pressure.

2. How do valves play a role in the vacuum filling process?

Valves are crucial for controlling the flow of the substance being filled. They allow for precise adjustments to the flow rate and can also be used to isolate different parts of the system for maintenance or troubleshooting. Valves also help to maintain the vacuum pressure by sealing off any leaks in the system.

3. What types of valves are commonly used in vacuum filling systems?

The two most commonly used valves in vacuum filling systems are gate valves and ball valves. Gate valves are used for on/off control and are ideal for high-pressure applications, while ball valves are used for throttling and controlling the flow rate.

4. How can fine leaks be detected and prevented in a vacuum filling system?

Fine leaks can be detected using a variety of methods, including helium leak testing or pressure decay testing. To prevent fine leaks, proper assembly and maintenance of the system is essential. Regularly checking and replacing O-rings and seals and ensuring all connections are tight can help prevent fine leaks.

5. What are some common challenges when building a vacuum filling system?

Some common challenges when building a vacuum filling system include finding the right balance between flow rate and vacuum pressure, ensuring all components are properly sealed to prevent leaks, and troubleshooting any issues that may arise during the filling process. It is also important to consider the compatibility of the substance being filled with the materials used in the system.

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