Decanting Argon to modified Scuba bottle ?? - TIG.

Decanting Ar to modified Scuba bottle - TIG.

In Australia the vendors of industrial gases do not fill user's bottles - instead you have to hire the vendor's bottle. If you are doing jobbing work, and using the TIG only once or twice a week, the hire charges can add up.

Idea -
Hire an intermediate size bottle (half G size) and decant into 72 or 80 cu ft Scuba bottle [2.25m3] (second hand - perhaps $150 AUD plus some fittings). This would result in 0.7% air contamination unless extra work were done to purge the bottle (eg. internal copper dip tube) beforehand.


Would the resultant gas be satisfactory for non structural and non pressure containing welds ?
I know the industrial Ar sold here is 99.95% Ar so clearly the vendors (BOC, Linde and so on) go to some effort in the distillation process to get near purity. Clearly none of these vendors is going to give me technical data on this proposal. It may be this lower purity mix will work for MIG but not for TIG, the latter being the only process of interest to me.

cheers, Tim F

I probably would'nt hesitate to repackage gas if i saw it enabling me to keep gas on hand that I couldn't otherwise justify having.
I don't know what you mean by a dip tube I would think pulling an initial vacuum on the receiving tank would be the way to preserve the supply bottle's purity.
I think Scuba tanks normally work at 5000 psi don't they ? Hummm now if a guy could build a scuba compressor. . . .

Dave

OzEng

G'day! I see you are from Melbourne too.

I've seen this done by an old welder guy. He made up a special adaptor and simply decanted the Argon from the big bottle to his smaller ones. If this created impurities they did not affect the quality of his welds.

He also 'acquired' gas from other people's bottles when he thought he wasn't being watched....

I hear what you are saying about the price of hire for gas bottles. It would be nice to have gas on hand for that odd occasion when you need to run the Oxy. The cost is too extortionate for this to happen. I wouldn't go without my MIG gas though.

I know some businesses, as they are members of a local chamber of commerce etc. get a sweetheart deal on their gas bottles and can pay half the price that you or I would pay. If you're chummy with the boss you might be able to get him to hire a bottle for you at this cheaper rate. However some bosses are paranoid that if you weld at home you might steal their business. Believe me, it does happen.

Whereabouts in Melbourne are you working?

Yeah,
I remember well it was 40 years ago now I was 16 and just stsrting to ga s weld I would take my 90 cubic foot oxygen bottle in to Athens elrctric Motor service and they had a manifold arrangement with 4 large bottles 300 CF I think and would valve then on one at a time to fill mine. I always watched REAL CLOSE figuring out real soon that they neededd to do them in the exact sequence of ascending pressure of the fill bottles to maximize my final pressure. Well the dudes that worked there probably didn't care as much about it as I did but I remember trying to get them to do right LOL

Then they sold me my first lathe an atlas 6" a total POS but a step up for me for sure.

AT that I had been turning metal on a sears 12" wood lathe. I been rebuilding them ever since.
The point being, when you refill sequencially from several bottles you gotta start with the lowest pressure and work up. When you add a new fill bottle you gotta put it on the top of the fill list

Dave

lalatheman

The reference to the Copper tube was with the idea of having a dual valve tree at the top and filling with the second valve open so the argon went down the copper tube to the bottom and pushed the air up and displaced it out the other valve. After x litres have flowed, you shut the second valve and let the bottle pressure up and then shut off the fill valve. This is not a 100% fix, but better than filling an air filled bottle. Frankly a bit of an overkill I would have thought (however have no specifics about the allowable amount of contamination).


Uniiqueuser - Australia

Small world - believe you also said you are in also in Melbourne. I send you a private email with some more details of sheet metal issues and so on, together with my phone number. So give us a bell if you like or leave a message on the machine. if you want you could probably come and see my humble b/yard w/shop. I am completely new to TIG and am doing a course (just started) at a Melbourne TAFE (polytech).

When decanting, you also want to note the temp rise, as heat of recomp will get bottle warm. Not that its a huge worry, in older non-pc controlled refill stations, the techs had to constantly check temp vs ambient temp, to corelate actual amount of fill in bottle.

If you want to get rid of impurities, and have relatively pure gas, the vac is the way to go. Im not sure about your corner of the world, but here in NA vac pumps are relatively cheap on ebay, abd with a bit of simple valving you could pull the cyl down to a good vac, then decant from larger bottle into yours.

Another thing to note is that some GMAW blends actualy have trace (~2%) for one common blend over here of O2 in it anyway. They are Argon,CO2,O2

Some interesting reading on what diff blends of gas can do is available at:

http://content.lincolnelectric.com/pdfs/products/literature/c4200.pdf

http://www.pc-control.net/pdf/022003/pcc_ctr_e.pdf

Happy gas scrounging !!

Tim

Could you just draw the bottle down to a good vacuum to pull out most of the air, then fill with argon? I'd think the amount of air/oxygen left would be pretty low.

Can you buy the bottle-to-bottle adapters, or is it a DIY proposition? I have a big Ar bottle, and a small empty O2 bottle, which started life as a CO2 fire extinguisher, and got a new valve, and got it recertifed for 02. What is the procedure? There are times a small Ar bottle would be very handy for site work.
Geoff

Did I miss something? If your going to buy a SCUBA tank, why not buy a small Argon tank and have it refilled/swapped out at the supply house? I rent Oxy bottles cause I use em up weekly but I own my Argon bottle. When it's used up, I take it in and they give me another one that's full. That way I always have a bottle that has a current hydrotest and don't pay rent on.
Happy New year
Tim

Tim in D,The poster has the same problem that we have in NZ - a BOC monompoly. They won't refill bottles. there are basically no owner bottles. Your only option is to rent - here it is $10/month per bottle (plus gas) - money wasted unless you are running a business and turning them over. In New Zealand I have found a company that is certified to test high pressure bottles, and isn't BOC, and found a privae refiller with a local agent. If you are out of Auckland (NZ biggest city) or Hamilton - tough luck - bend over and take it from BOC.
The local regulations, written no doubt with the help of BOC make it impossible to privately import bottles. The standard stamped on the neck on scuba bottles (ASxxxx) is the same as the O2. AR/ CO2 bottles we use.

Thats a big issue, (owner bottles) and depending on wher you live, you are just sol...

In Canada, its kinda broken up a bit, (at least here in BC) There are NO owner bottles 37 or 44 CU FT2, however they will allow small ~4 CU FT2 owner bottles.

What you need to be careful of is: (D'uh! the pressure rating on the pressure tank you wish to decant to...

Assuming you have that under control... If you dont, you on your own... .... All you need to do is go buy a high pressure hose like the one in the pictures. This one is a nice shiney SST, and has a date tag on it because it is one I hade left over from some Supplied Air breathing equipment. The ends of the hose are just NPT, and will fit the ends from replacement tank-stubs that you would buy to repair / replace the one on your regulator.

If you want to buy from your welding shop, the thing to ask for is "manifolding" equipment, as you want to connect several tanks on the high side, prior to the regulator. They will usualy be more than helpfull from that standpoint.... They just really dont like to knowingly sell you stuff to decant.

In CA, Ar/Co etc comes in various sised flasks at about 2100 psi (144.7 bar) I would double check, but I seem to remember a few years back when I was looking at purchasing my own SCBA filling station, that SCBA, and SCUBA sometimes goes as high as ~5000 psi (344.7 bar), so you should be ok pressure-wise.

It may be easier in your neighborhood to get hydraulic lines, just make sure that they are rated for the max pressure your big bottles are supplied with, and that the pressed on ends will thead onto the tank stubs.

One other thing, If you are doing this late at night... ;], you need to be aware that many times you WONT be able to get the tank stubs out of the regulator without damaging them, most are threaded into the reg body with high-grade threadloc compound....best to go buy 2 new ones ahead of time.

Decanting most non-flamables is not much of an issue, but dont try this on Acytelene, thats a whole different ballgame, it needs to be absorbed into the stone/acetone matrix very slowly.....

I have a few 44 CU FT cans that I aquired from them being left behind at a shop, so I every so often have a buddy who works at a larger plant pickup a new can, I decant 3/4 of the full bottle into my 2 bottles ( 1/2 pressure into first, then 1/2 remaining into second) I pay fopr the gas aquired, but dont get stuck with monthly rent charges.......

Hope this helps... I tried to u/l some pics, hope it worked.

Tim

Here goes 2nd try to show pics...


Tim

Hmmmm, Doesnt seem to like my big pics...

Try this

http://www.armax.ca/private/logan/blogtemp/decant.htm


Tim

Vacuuming down the bottle - that's a great idea. Makes the whole proposition sound possible.

In Australia there are three industrial gas suppliers (BOC CIG Linde) but they all have the same rules - no refills into owner bottles. (It might even be illegal to own your own bottle on the basis that it must have been stolen) Typical bottle rental is 120 dollars a year. G size bottle of Argon is around $140 I believe. You get no credit if you take a bottle back with anything in it (duh.. say intermittent work and trying to avoid rental charges). I have seen oxy sets advertised as c/w bottles but never an Argon bottle .. different threads, different colour.


What's this business about bending over for BOC in NZ about ? Like one of those Japanese bows ? Perhaps we do not understand NZ slang over here.


TEF

Over in kiwi land, Argon and O2 cylinders have the same pressure standard, and the same valve thread. Is it different in Oz?

2 countries seaprated by a common language. Regarding "bending over" ... think jail movies, showers and soap....
Geoff

after the last reply to this tread, I had the opportunity to scavenge the healthy remnants of 4 full cans of C-25 (Ar/CO2) I blew about a 150 psi Ar/CO2 into an old oxy cyl, and then vented that to dilute the O2. I managed to save about $350.00 CAD that would have gone back to the supliers, and same old same old...you do not get a refund for unused gas.

I noticed that the xfer hose wanted to freeze up a bit, I was probably trying to rush it. I walked the pressure up from 4 cans into 3 that I have, and everything went fine.

We have the same issues with threads etc, but almost all the regulator ends are 1/4" NPT, so adapting is easy as per the pics I posted earlier.

Over here bending over conjures the same idea of very bad soap-time...
Tim

backhoe-jor

I want to decant argon shielding gas /have bought a hydraulic hose rated to 4000 psi & -40 c / do i just connect bottles together & open bottle slowly or do i need to have a regulator on the donnor bottle / do it late at night to keep temp down ? Any tips appreciated thanks jor

I think your overlooking COREgas. They are owned by Coles Group and were formerly known as Linde (at least thats what its like in Sydney).

In my situation, Linde used to allow people to buy cylinders from them and then use the system as a swap and go. My local Welding Shop in brookvale (Welders Supplies) is happy to simply swap my old cylinder over for a new, full cylinder of gas for contents price. I think this is because they rent "X" number of Cylinders from Coregas, and so long as they have the right amount of Cylinders, no one seems to care.

Pity i havnt found a set of Oxy Acetylene Cylinders around without the BOC barcoding on them

At least over here in the uk the boc - air gas monopoly is finaly starting to break up :-) A local welding supplier at long last is finaly starting to supply half size tanks on a 10 year lease, basically the test certificate life of the bottle. Whilst the gas ain't much cheaper there is no bull shit handling feels or other surcharges. Add in that the 10 year bottle cost is only a nats over the boc annual rental and its a real winner. Even more so when they will deliver for sensible costs, like less than my fuel to drive to them and get it :-) Hence when the remaining 300 psi is gone in my argon i hope never to deal with BOC again, there pricing is just out of this world!

According to the company's sales rep it works well for them too, there picking up a lot of extra consumables sales as well as still making a sensible amount on the gas charges. Hence hopefully like that it will be sustainable for them to do long term.

I am agree with lalatheman. Thank you for sharing your ideas.