Scavenging helium

[rjack321]

What is the reasoning behind sealing the exhaust valve shut?

Michael has passed away since this was written and can't answer your question personally

I think I got it, the idea is you want to see the rubber innertube expand if the flow is to high, which you would not if the exhaust was allowing He to escape.

There is only one outlet from the 2nd stage and it's into the intake for your compressor. The second stage regulates only delivers what the compressor intake vacuum pulls.

You can do the same thing as the omnibooster with a trash bag. Use any pressure reducing regulator to keep the bag partly filled as your compressor sucks your leftover gas from it. Oxyhacker wrote about this approach 20 years ago.

 

[InWay2Deep]

You can do the same thing as the omnibooster with a trash bag. Use any pressure reducing regulator to keep the bag partly filled as your compressor sucks your leftover gas from it. Oxyhacker wrote about this approach 20 years ago.

Yea I read those chapters this morning. I get the concept behind the omnibooster, once I understood it wanted a very slight positive pressure inside the "Tee" it made sense why you need the exhaust plugged and the "inner tube diaphragm" blocking the other side of the Tee, my compressor is small so not worried about over driving the reg. I've got some old regs and plenty of 1/2 used 1st stage diaphragms so not to worried about wearing them out even though, I have the 2nd stage set for slight free flow now. Do you use the trash bag version?

 

[rjack321]

Yea I read those chapters this morning. I get the concept behind the omnibooster, once I understood it wanted a very slight positive pressure inside the "Tee" it made sense why you need the exhaust plugged and the "inner tube diaphragm" blocking the other side of the Tee, my compressor is small so not worried about over driving the reg. I've got some old regs and plenty of 1/2 used 1st stage diaphragms so not to worried about wearing them out even though, I have the 2nd stage set for slight free flow now. Do you use the trash bag version?

1. I put a hole in a wine cork, shoved a tube though it and duct taped a bag to the end of the tube
2. Put the cork into the inlet of the compressor
3. Turn on a cheap O2 regulator off ebay with the orifice drilled out
4. Let the bag fill with whatever leftover gas I am boosting (Not O2)
5. Turn on the compressor and keep the bag partly filled by adjusting the flow rate

Pump away. If pumping 100% helium I recommend sticking below around 2200psi. The blow by becomes extreme. Don't go too crazy. After 20-30 mins your oil will be getting foamy and losing some lubrication so take a break for a bit and finish later.

 

[InWay2Deep]

Pump away. If pumping 100% helium I recommend sticking below around 2200psi. The blow by becomes extreme. Don't go too crazy. After 20-30 mins your oil will be getting foamy and losing some lubrication so take a break for a bit and finish later.

When doing this do you disable the PMV?

 

[rjack321]

When doing this do you disable the PMV?

There's no need to. It should be set at about 1800psi anyway.