pure He through compressor

offpro

hi


has anyone bagged pure He through the compressor up to 300bar over time.. ? have bagged He to my twinsett, but only up to 200 bar with good result.. but im worried that the compressor will take damage over time..


was thinking about using a 300bar tank for storage of He..

my compressor is lenhardt & wagner 100l/min


mats

decoweenie

I only pumped pure Helium thru compressor to 125 bar (to mix 10/50), and 10/50 to 250 bar (to top off Rebreather tanks). Both for ~6 years for mostly CC tanks with a few occasional bail-out stages.

The friend who showed me how to do it been doing even earlier and at higher volume since dives OC, and also pump to his Helium bank. Not sure if he pumped Helium to 300 bar though.

wizbang

Hi Phi, would you mind fleshing out some more details.
Comp Type & size?
Bag or Stick?
In a room or out side?
Extra cooling from external source or not?

You have a booster but still use the compressor for this type of work?

Thanks Wiz.

decoweenie

Using Bauer Junior-2 compressor, I originally used a modified second-stage reg to feed into a tube which feeds into the compressor inlet.

The second-stage was modified by the same friend who showed me how to pump Helium, Michael Fisch:

• the purge valve of the second stage is epoxied shut.
• the inlet is standard via LP hose connects to the feed tank 1st stage.
• the mouthpiece is zip-tied to a hose feeding to the inlet of compressor.

The 2nd stage is set to free-flow slightly so it will feed the compressor continuously, and also allows the 2nd stage diaphgram to make up as needed.

I used that system for a few years, wrapped a rubber band around the purge button and kept adding coins on the purge button to press it more to increase the flow as I was too lazy to adjust the second stage (free) flow rate...

Michael eventually changed the design to make the second stage adds easier. Look it up under "Omni booster" in The Deco Stop forum, it has been discussed extensively as well as a lot of details and pictures.

Now, I am too lazy to make the Omni booster modification so I made a modified version of the French trashbag method:

• bought a couple of the rubber bouncy exercise balls with rubber handles stuck out of them.
• cut the handles off.
• stick an aluminum tube in the remaining of the handles, zip tie, use same as before to feed compressor.
• connect a used wing inflator to the other handle, zip tie, use as injection source to pump up ball.

All I have to do is:

• connect the gas source to the wing inflator, pump up the ball.
• connect the feed tube to the compressor inlet.
• start the compressor.
• make sure doesn't get completely deflated.

It takes just a few minutes to pump up a 3L Rebreather tanks so I don't get too bother, but Michael dives OC and pumps a lot more gas.

Another method that a friend in Belgium does is using a (new) welding reg to the 50L source, adjust the feed rate and feed that straight into the compressor. It is the most elegant solution, I have the parts to do it but not the time to try yet. He is on Rebreather World so he might want to add some info. Davy ?

Everything is inside the house, in a dedicated dive room so the temperature is controlled (21C or less if desired). Pump never operate very long so no need for extra cooling.

I use the booster to boost O2, and the compressor to pump Helium/Trimix normally.

I would like to build the stick someday when I get time...

offpro

got pics of the modified second-stage?



we normaly use welding regularor on the supply tank and a 150liter garbage bag on the compressor inlet as a buffer...

Dave & Sandy

We use this method as well. Industrial Welding Reg (Co2/Argon) attached to the G of He. The compressor inlet has a machined plastic three way inlet attached which allows the He in, gas to be sucked out (attached to the comp inlet) and a ballon to be attached to the top of it to monitor that your pumping with slight positive pressure. If the ballon begins to collapse you just increase the flow from the industrial reg. Too much pressure and decrease.

We can remove the ballon, attach our air snorkel and then continuous blend which is our prefered method of pumping He.

This set up allows us plenty of flexibilty. We never waste gas. We can pump gas out of SCUBA cylinders into other storage G's, use stored gas to reblend straight into a cylinder.

We've being doing this for years now and use to fill large numbers of OC cylinders both at home and in the field.

__________________
Cheers,

Dave & Sandy

Atvar shows Dave & Sandy testing their new habitat 101 and home build RBMK69's

Shawn

I'm not sure what you mean by Bag He, but this is what i have done with it.

I have a bank of 4500 psi tanks that I often boost full with He and O2. The only thing that I have ever had to keep an eye on was the spped at which I fill the tanks...The He would heat the tanks up a lot!

Usually I will fill and Al 80 to 3300 psi using a standard mix set and my doubles to 3442psi using the same mix set.

I basically use the compressor to run the boster and I try to stay away from the death gas as much as possible. Kinda of hard with the price of He these days...

I don't know if that helped at all, but I feel better getting it off my chest

Have a good one!

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decoweenie

Thanks for the idea guys.

I surely will be implementing the buffer/balloon indicator idea when it is time for me to use the O2 welding reg method.

Dave, I might contact you later to get more details about the plastic part unless you already have the picture/details ready to send. Thanks...

davy

Hi Phi,

I made a small write up about it here:

However, I don't often use it anymore...
At the moment I have 2 sticks in series to pre-mix trimix and pump whatever I want through the compressor as long as the FO2 is less then 36%

PS. Missed you last week when we paid a visit to the mike fisch scooter cemetery.

(Steve was there too)

davy

Hi Dave.
I really like this idea... should take all the stress off the regulator AND the compressor!