Home fill station for dummies?

[rjack321]

Getting those cylinders from a commercial supplier would get cylinders of O2 at around 2400psi? He is also around 2400psi?

Would a T bottle of air be 4500? Or also 2400? Or something else?

O2 in the USA is most commonly supplied at 2200 in 250cfs, sometimes 2400 in 300cfs
helium is 2200 in 250s or 2400 in 300s

300s are much heavier than 250s and not as common either, again depending on the supplier. Many vendors have no clue what K and T etc stand for. Those are ancient codes from the Linde company. Some suppliers still reference them but many welding shops who hired their friend Bubba to work the counter will have no idea.

Air is 4500, 5000, or 6000psi depending on the vendor

 

[broncobowsher]

Oh, and @broncobowsher, you're using the dryer and dessicant to dry the air coming from the shop compressor that is going into the booster?

There is no need for a dryer or filters on the line coming from the O2/He/scuba-cylinder-of-air and the line going to the cylinder you're filling, right?

Correct. The bottled He, O2, and even air from the dive shop goes through as is. That drier would blow up if you tried to feed it high pressure gasses.

The shop compressor isn't the cleanest nor driest air. That is fixed with the drier/filter. Clean up the drive gas to keep the drive side of the booster clean.


As for getting bottles. No way would I rent. That is for a business tax write off. If I rolled into town and planned a couple weeks of diving, I might rent something. But not when it takes months to go through it. I buy bottles. Search Craig's list or whatever. It can sometimes be a bit of a mess, different gas suppliers have different rules, even the big national chains will tell you different rules from location to location. Sometimes even who is working that day. About a year ago I found a pair of Helium bottles for sale. Someone bought a shop and they were in the back. One was empty, the other had something but was also nearly empty. Out of hydro. Be sure to get the caps. I took them to one of my local welding shops. They supported my old off-road club, I'll support them. They wouldn't take them because they were marked with a different supplier's name. Odd, that is the same source on there stickers for where they get gas from. So I went a few blocks away and they had no issue exchanging them. The bottles were Ks of ballon grade. I swapped one for a K of Aviator O2 (couple bucks more and you know it is O2 intended for human consumption). But all they had for Helium in a K was balloon grade. Taking industrial grade would have required hanging around and having one made up or upgrade to a T-cylinder. You just pay the difference in the value of the bottle. The T was in stock. So pay the upgrade charge.

If you are old enough to remember getting soda in a glass bottle and taking the empties back for a deposit, its pretty much the same thing. Or like mentioned, the propane bottle at the grocery store. Usually the hydro date is ignored. One time I had a shop (different than the two above) try and stick me with a hydro. I pointed out the label on the bottle and blamed them for giving me one that was ready to be up when I got it. They dismissed it.

I have been doing welding gasses for over 20 years. The Helium and Aviator are no different. Just takes one of the bigger distributors to actually carry them. The small satellite stores don't stock it, but can if special arrangements are made. I find that to be too much trouble, just go to the big store.

I would look for used full size cylinders. K or better the T. They are about $100. Then trade them in. Once you have the process established it goes easy.

 

[rjack321]

I remember reading all about this mystical gas supplier stuff in oxyhacker's handbook way back when. Yeah none of that was accurate on this coast at all. Buy vs rent, swapping, hydros, even gas grades. NOTHING matches from region to region, dealer to dealer, or even from one employee to another. They make up even more "rules" or standards out of burps and farts than the dive industry.

As you inquire, I do recommend avoiding saying you are using anything for diving. If they think you are breathing it they will either say no or upcharge you. "Setting up some cutting and TIG welding in your garage."

 

[broncobowsher]

I've had the opposite. The weld store / gas supplier was interested in what Helium was used for in diving. I had to make a super condensed version of Trimix for the non-diver on the spot. Without wanting to take both of our days the super short version was that it is inert and being a really small molecule if flows better at high pressures.

 

[rjack321]

I've had the opposite. The weld store / gas supplier was interested in what Helium was used for in diving. I had to make a super condensed version of Trimix for the non-diver on the spot. Without wanting to take both of our days the super short version was that it is inert and being a really small molecule if flows better at high pressures.

Yeah my local store is weird, but they are welders who now happen to work behind a shop counter. The guy at their specialty gases and analysis subsidiary who gave me the rundown on exactly how the "industrial" O2 and helium are filled and differ from other grades was interested and a good resource. Best to be cautious until they know you.

 

[KentB]

i agree with rjack DO NOT say you are breathing it.....I made that mistake and it was a clusterf**k and a half

 

[GF99/99]

i agree with rjack DO NOT say you are breathing it.....I made that mistake and it was a clusterf**k and a half

Haha yeah never tell your gas supplier its for diving. If they do ask the O2 is for your torch set and the He is for Tig welding.

 

[NAM001]

First, a very fine SB'er has sent me a PDF of the VH book (3rd edition). Now I have some reading to do.

Meanwhile...

@tbone1004 Yes, I am moving to Charlotte. But, I think it will probably be easier for me to get air fills at a scuba shop than put that much effort into my relationship with my local VFD.

@kensuf My thought was to get some twinsets filled with air and then use a booster to do the air top-ups with a twinset for the source gas. Of course, in that case, maybe I would get the twinsets filled with EAN32 and just stick to Standard Gases for my dil. I normally keep my dil bottles all filled with 18/45 anyway.

@KWS I deduce that your home fill unit is something I know nothing about and that it must produce argon as a byproduct? Got a link to the kind of unit you're talking about? Regardless, I do want to be able to produce trimix for deeper diving.

A further thought I have had is (please correct me if I'm wrong) that I will need a booster, no matter what. I want to be able to fill my O2 cylinders to 3500psi (as I do now, when filling at my LDS). It occurred to me that it is probably not a good idea to attempt to do that using a Continuous Mix compressor setup. I suspect that scuba compressors are probably not safe to feed pure O2 into the intake side. So, I would need a booster to do that, regardless of what else I do.

I am curious about the (other) limitations of a continuous mix compressor setup. Like, can you easily produce TX10/70 from one? What about even more hypoxic mixes? I will get started reading the Vance Harlow book and see what I can learn from that.

Thank you all for the info so far!

I am using an invocare platinum 5 with its home fill compressor. all it appears to purge is the nitrogen and the O2 and AR gets sent to the output that goes to the compressor. the highest O2 reading I have had is a h air over 96. that should be 96 O2 and the remaining 4% is argon. with argon being 1% of air,,,, then it is 1 part AR and 21 parts O2. that is right at 4% AR in the O2 tank. Means nothing when making nitrox in the less than 40% region.

 

[happy-diver]

FR-FLM863 FILTER / REGULATOR SET & AIR CLEAN/DRYER

I've wanted to score-cobble a membrane for a while
but have neglected the friendship with the manufacturer guy


https://www.ou.edu/class/che-design/a-design/projects-2007/Oxygen Generator-Presentation.pdf




Thanks for reminding me, yeah you guys are quite exceptional

 

[broncobowsher]

If I was doing open circuit and had a home compressor, an old membrane O2 generator would be in play. The bad part is with a rebreather the Argon accumulates. Displaces the other inert gasses in the loop. I have to deal with that when I travel. But I don't need to deal with it at home. Bottles of Aviator O2 are cheap enough to get refills on.