Scavenging helium

[wasian]

Hello I am in need of a idea for scavenging he from the bottles at least to a few hundred psi I can’t always blend into empty tanks and I am coming back with 1500psi in my doubles right now any ideas ? I have been looking at a Sierra booster my ag30 wants way to much drive gas to get them down thanks for the ideas

 

[michael-fisch]

Use my Omnibooster.

This was originally posted by Ahmed on The Deco Stop back in 2005, after he got my writeup and instructions:

1. Hey there everyone. I got off this site plans to build a device that I have come to love very dearly. It has saved many of my clients hundreds of dollars and made me hundreds of dollars in the process! It is a very simple little thing and one can only be bewildered that one did not think of it before!
   I got the plans from Andrew Fisch (God Bless Him and may he find Islam) here on the board.
   
   Basically, it allows us to recycle the gas from the tanks that come back, into the next days tanks. It works up to 40% nitrox and equally well for Trimix with no losses or heating problems. You will be able to drain your supply tanks down to a couple of bars!
   I always come back with around 100bars in my bottom mix. So that can be pumped into another set of doubles or into storage tanks. When using standard gasses between buddies, it is most effective. This way, customers have saved money per dive, but have spent just as much, which means they dived more! Also, I have lost no profits from helium sales. Win Win!
   
   More or less it is a modifies trash bag method of filling, but much more sophisticated in idea . The British navy used to get the supply tank and connect it to the compressor via a normal regulator. This would tear the reg to shreds and get air into the mix. Andreas has refined this into a device that is ingenious in principle.
   If anyone is interested, I will also post pictures.
   
   PLEASE NOT: This will not hurt your compressor as long as you don't flow any gas with a O2 content higher than 40%, even better lower.
   But you do need some basic equipment repair skills to be able to set the contraption up to work well.
   
   Here is the shopping list:
   
   1 4" PVC t-section
   1 SS band to close on one end of T-section
   1 Piece of inner tubing that fits easily over one opening of 4" T-section.
   1 ratty 1st+second stage. (any old working one will do)
   1 SPG (without hose)
   2 PVC fitting size reducers 4" to 1" (might need a few reducers to get 1" OK)
   2 short bits of 1" pipe (or whatever fits you compressors intake hose)
   1 short bit of compressor intake hose. (30cm)
   2 SS bands the size of your compressor hose.
   1 tube of silicone adhesive
   
   Building instructions:
   
   1. Assemble the PVC fittings with proper adhesives. You should have it so that there is one side open from the T. Doesn’t matter which side. The idea behind the T is to create a compartment, to help for smooth air flow. The other 2 openings should have a bit of tubing sticking out of them that are big enough to have your compressor hose fit over them.
   
   2. Attach the rubber inner tubing over the open end of the T. You should make it tight (that’s why it should be a large piece). Fasten the rubber in place using the SS band. After it is fastened, it should feel a bit like a slightly loose drum. If you don't know what a drum feels like, then too bad
   
   3. Attach to one side of the unit the 30cm piece of intake hose.
   
   4. Now to prepare the regulator:
   a)Have only the 1st and 2nd stage with the SPG directly attached for ease of viewing.
   b)remove face of 2nd stage
   c) use silicone to seal exhaust valve shut.
   d)replace face plate
   e)remove exhaust valve cover (moustache)
   f)cut out a piece of rubber to go over the other side of the exhaust valve and seal it very well with silicone.
   g)replace the cover, so no one can see this ingenious secret that makes the whole thing tick.
   h)screw the SPG directly into the first stage.
   
   5.let everything dry!!!
   
   6. Set the second stage to free flow a bit. This will offset damaging vibration. Not to high free flow as this will cause positive pressure.
   
   7. Attach the regulator 2nd stage to the other end of the 30cm intake hose. Attach other end to the compressor intake.
   
   8.Alpha test:
   The desired result of the alpha test is to make sure everything is functioning. You should feel a slight vibration on the 2nd stage diaphragm and the rubber thingy on the T should vibrate. The compressor room will be filled with a throaty noise.
   If the 2nd stage diaphragm has more than a light vibration (ticking) then increase the free flow.
   Keep a finger on the cutoff switch to the compressor at all time. Remember to close tank straight after compressor shutdown.
   
   a)connect 1st stage to a supply cylinder.
   
   b)open cylinder and switch on compressor a second later.
   
   c) shut down and note results, correct if needed.
   
   A good Omni booster will have a good vibration going on the rubber thingy, a slight ticking sounds and vibration off the second stage diaphragm and the reg. should get cold.
   
   Beta test with nitrox 32. This way, we check for leaks.
   Use EAN32 as the supply and start filling an empty tank. If the empty has the same gas, the booster is working! if it has less than 32, it means air has gotten sucked in. Check the seal of the PVC fittings. They always leak. Silicone the hell out of them and it will work fine. even better, do it from the beginning.
   
   I am so proud of Andrew that he can come and dive for free!
   
   Any questions, feel free to blast away. As I said, I can also post photos if anyone wants.
   Reply Reply With Quote
   
   
   
   
   
   
   Re: The "Omni Booster"
   Hi Big Bubble,
   thats a great posting, the only mistake I found was that you got my name wrong! My first name isn't Andrew - it's Michael!
   Another point with the Omni Booster, I also use mine to get the last few Bars out of my Helium tanks and boost it to whatever pressure my compressors can put out. For short periods of time (less than 20 minutes) I can also boost Argon with it.
   
   Advantages:
   Cheap - Easy to make
   Works well
   No wasted Helium or Argon
   Will boost from any pressure to any pressure your compressor will pump to
   
   Disadvantages:
   Has never worked a second time while boosting Oxygen, (and I have been too scared to try pumping Oxygen the first time).
   
   All the best,
   
   Michael Fisch

and here are a few pictures:

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[michael-fisch]

Works best with a diaphram 1st stage and an old USD / Spiro 2nd stage, the coins and rubberband on the 2nd stage are used to increase the freeflow when puming Argon, without the coins the 2nd stage is adjusted to freeflow slightly with Helium.
Modern Apeks and Scubapro 2nd stages wear out rapidly if used, the old USDs just keep on chugging.
The Scubapro Mk17 1st stage is a modern addition, the original 1st stage from 1995 was a USD SE2 that lasted about 12 years before I had to replace it.
Using a compressor bigger than a Mariner is just too much work for the regulator combo,

Michael

 

[tbone1004]

Hello I am in need of a idea for scavenging he from the bottles at least to a few hundred psi I can’t always blend into empty tanks and I am coming back with 1500psi in my doubles right now any ideas ? I have been looking at a Sierra booster my ag30 wants way to much drive gas to get them down thanks for the ideas

what are you using to drive the booster? It's more than happy to run off of a standard air compressor with good filtration.

 

[wasian]

The air bank at my friends shop ( they allow me to store and keep my booster helium and stuff there ) I think the shop compressor is putting out 5 cfm right now we need to rebuild the lower pump waiting for everything to get back to normal

 

[tbone1004]

The air bank at my friends shop ( they allow me to store and keep my booster helium and stuff there ) I think the shop compressor is putting out 5 cfm right now we need to rebuild the lower pump waiting for everything to get back to normal

is that breathing gas or a "shop" compressor putting out 8ish bar?

 

[wasian]

Breathing gas from the bank it’s not producing 8 bar

 

[iain/hsm]

Another option is a small Gas Recovery Pump

Single phase 110 volt 60Hz (or 230 volt 50Hz) Gas Recovery Pump
Capable of recovering gas in a cylinder down to 25 psi and even lower at a reducing flow rate.
With a fixed charging rate of 6 LPM recompressing the gas to 2500 psi
In effect a continuous duty small 3 stage compressor.

Can be used on pure oxygen as well as Nitrox or Helium or Argon
Unlike these oil lubricated air compressor blending contraptions it doesnt oil up your gas either.

 

[iain/hsm]

Works on a standard 3 pin domestic plug US or EU with standard 3 pin internal socket into the back as illustrated
Inlet and outlet fittings are 1/4 NPT as illustrated.

Fully automatic, manual push button start and auto stop when full pressure achieved.
Fully three (3) stage compression for additional safety when compressing oxygen
Safety Pressure Relief Valves on all three stages

 

[tbone1004]

@iain/hsm when is the new one due to be released?