New pressure pot and vacuum chamber

[ni9eofse7en]

Advise please.

I picked up a second hand pressure pot at the weekend, similar to Resin Model Moulding Casting Tank 10Litre.

A quick test. I pressurised to 4 bar, about 60psi. 4 hours later it was down to 2 bar, and now 24 hours later 0. I know no pressure pot is 100% sealed so there must be a leak somewhere. So

1. I read its an idea to seal the rubber lip seal with vaseline, any thoughts?
2. I intend to try a soap ans water mix to test the joints. Assuming I find a leak I thought about resealing joints with either PTFE tape or threadlock or both or, what would anyone suggest.
3. The pot is about a year old and very clean so I am hoping its not the pot itself.

Now the vacuum chamber is a small plastic 2ltr unit, with a generic PRC 2cfm pump.

4. Before I tried it the gauge read 0.2 bar or 6hg, under vacuum this rises to about 0.4 bar about 12/13hg. Now here is where I am truly clueless. Should the gauge start at 0 or is this reading a natural air reading????
5. The lid has a foam pad to seal, now this looks original, but surely foam is full of holes?
6. I filled the tank about a third of the way with water, I put in a small scrap of beech, which floated and was then held down with a lump of ali. I ran the pump for about a min, and the water bubbled (Do you keep pumping till all bubbling stops?). Stopped the pump and opened the release valve, the water dropped a couple of mills and the wood sank. So it appears to work fine.
7 Would you recommend a chamber between the pump and the liquid filled chamber to avoid any liquids getting in to the vacuum chamber.

Thanks in advance lots of questions but I appreciate advice, tips or vids, etc

 

[Ray7756]

Pressure pot you need to bring it up to pressure and test all penetrators and valves with a mix of soap and water in a spray bottle, this will show up any leaks they will show up as bubbles at the leak site, you then need to sort out the leaks, ptfe tape should sort out most of them, but also remember to test all valves for leaks, if its the valves its easier to change them out, I take it the main pot seal is a rubber gasket so remove it totally and clean all mating surfaces then carefully check the gasket for damage them replace Them after applying a thin layer of silicon grease

The vacuum chamber is a lot more dificult to leak test, but as you keep the pump running and you get the vacuum you need its not a problem, and yes your gauge should read zero to start with, new gauge its sorted, or just use it the way it is, as it sounds like its working just fine
Cheers
Ray

 

[ni9eofse7en]

Cheers Ray, appreciate your advise.

 

[Bucks]

John, Does the gauge on the vacuum chamber have a rubber bung on it? If so just use your finger nail to pull the bung to one side to equalise the pressure, then the needle should drop down to zero.

 

[ni9eofse7en]

Paul,

Thanks, I will check this later.

 

[ni9eofse7en]

Well, tested pressure pot for leaking and found three, the air inlet, outlet and handle. PTFE failed so looking for some loctite thread sealer for next week and hopefully will have a sealed pot that holds pressure for longer. Thanks for the help guys.