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16th Mar 2013, 06:24 PM #31Senior Member
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- May 2012
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- Melbourne, Australia
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- 155
I hate this weight system for cylinders. My scuba cylinder was always measured in cubic feet although it's probably metric now. I think it was how many cubic feet of air at atmospheric pressure was compressed into the tank at its rated pressure. Knowing the internal volume of a tank and its pressure rating should allow us to calculate how much gas you can get inside. 6.8 kg of CO2 doesn't really tell us this.
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16th Mar 2013, 07:48 PM #32Golden Member
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- Feb 2010
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- Ballina, NSW
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- 900
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17th Mar 2013, 07:57 AM #33Senior Member
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- May 2012
- Location
- Melbourne, Australia
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- 155
Thanks for all your input Mick.
At least I've got a basis to work things out on now.
Just for the hell of it I might even look at the figures for using LPG bottles. Of course due to the much reduced pressure I,d need a lot more volume and that would mean more unused gas once the pressure has dropped to an unuseable level.
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17th Mar 2013, 10:15 PM #34Senior Member
- Join Date
- Aug 2009
- Location
- Quindanning, WA
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- 175
I'm near collie and just go to perth for refills. I use pressure testing service on campbell st in belmont.
I have 2 cylinders so theoretically i shouldn't run out but still do sometimes when i'm busy or havent been to perth for a while. You can exchange cylinders at the homebrew places in bunbury if you have one of their cylinders otherwise they have to send your cylinder to perth then wait for it to come back. Bloke in perth does it in 10 min while you wait and is a lot cheaper... But obviously you have to go to perth
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18th Mar 2013, 12:23 PM #35New Member
- Join Date
- Aug 2012
- Location
- margaret river
- Posts
- 6
Buying Cylinders
Can i ask where you got your cylinder and appx what you paid for what size? i think this is defo the way to go. i used co2 years ago when i used mig a fair bit and found it to be great for my use, maybe not for a pro but plenty strong, pretty and cheap for the property! im nearish to margaret river, whereabouts did you find $30 fills? and whos best to contact do you think? brewshops, aquarium places, etc but do gas exchange places generally do fill on a non swap bottle? also whats the go with bottle testing, where and who and how much? if i buy a bottle from us ebay will the test be valid, can i get it retested here easily, who do i ask about this?
####!!! sorry, 1000000 questions! well, i guess you dont have to answer!!!
any advice greatly welcomed!
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18th Mar 2013, 12:28 PM #36New Member
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- Aug 2012
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- margaret river
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- 6
er, perhaps one should read back to the end before posting! my bad!!!
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18th Mar 2013, 03:35 PM #37Senior Member
- Join Date
- Aug 2009
- Location
- Quindanning, WA
- Posts
- 175
I have the 6kg 'keg king' steel cylinders, they cost $250 each. I bought mine online but can't seem to find them now... but I'm pretty sure if you google keg king they have distributors in perth who sell cylinders and do refills too.
not sure about overseas cylinders but i would suspect they would probably be ok... not sure its worth the risk though.
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18th Mar 2013, 07:03 PM #38New Member
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- Aug 2012
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- margaret river
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- 6
cool, thanks, ill look in to it more. best price so far is $300+ +fill so am a bit pained when theyre less than $150 on fleabay i just still wonder if id get it filled and when the time came, tested. hmmm, its often tough being a skint tight ####!!!
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2nd Aug 2013, 01:13 PM #39New Member
- Join Date
- Jul 2013
- Location
- Brisbane
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- 1
I know I'm a little late, but I'm in the same boat. My MIG doesn't get enough use to justify over $100 per year in rental.
Empty cylinders do come up from time to time on Ebay and in the local paper. It has already been noted that you can connect the two cylinders together with a high pressure hose and get the pressures to equalize. If you go from a E to an E you get half and half, which still leaves the previously full cylinder with a lot of gas in it still, a waste to return it like this. If you have a big welding job to do, hire the bottle, drain half off into your cylinder and use up the rest of the hire one on the job.
You can buy high pressure compressors that can draw from the rental and fill your own cylinders, but they aren't cheap. There are details on the internet of people that have built their own to fill cylinders, mainly for diving cylinders and oxygen. I'm not brave enough to do this, as any hydrocarbons in the area of pure oxygen can cause a violent explosion.
I built my own compressor for MIG welding gas, it's crude, but does the job very well. It es essentially two hydraulic cylinders joined from end to end. There is the cylinder that does the work, the other holds the gas that is compressed. The compressed cylinder has one way valves to allow gas in from the filling cylinder and out via the filled cylinder. It does generate quite a bit of heat when running too.
Again, this is not for oxygen, oxygen needs special seals and non sparking metals in the compressor. You don't want to become a gooey mark on the shop wall.
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27th Sep 2013, 05:39 PM #40Intermediate Member
- Join Date
- Aug 2008
- Location
- Perth
- Posts
- 26
You are looking for a Haskel pump (brand name) or similair to transfer gas between cyclinders with out contaminating it. These all cost quite a few $, I have one but it would be over $6k to replace. They occasionally come up for sale second hand but there are a lot of different sizes, which changes the pressure range in which they are most efficient. Once you are out of that range you sit there a long time before you move much gas.
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27th Sep 2013, 07:27 PM #41
Or buy a swap-over-able cylinder - Speed Gas - Products - Argon.
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28th Sep 2013, 07:03 AM #42Banned
- Join Date
- Jul 2013
- Location
- Perth
- Posts
- 77
Many
Many years back when I mig welded up my first alloy kit boat - I had to hire pure argon bottles for the mig..., and a bottle was lucky to last 2 days use, They cost around $90 for the gas back then, plus rental, and I used 2 full bottles from memory (might have been 3 - can't remember now) and 2 rolls of 1.5km alloy wire.
Decanting from big to small bottles... would be the way...and use the balance in the hire bottle and then return it to save rent.
You can occasionally pick up scuba fill compressors (Bauer?) which should be fine for just straight CO2 - but as others have said, they aren't cheap.... (~$6K last I looked)
Back when I scuba dived (we are talking the 1970's here) the allowable pressures in scuba tanks was lower than today (2250psi was common for a full 70 cubic foot steel tank - Alloy tanks were just becoming popular).
The dive club I was in, we had a plumber member who welded up a decanter out of heavy walled high pressure copper pipe... and "fittings" to go into the large medical air cylinders from CIG. When we went away on a club dive - we'd take 3 of the large medical air cylinders and the decanter device... and all take turns filling our tanks for each days diving.
Unbeknownst to us, CIG at some point, uprated their medical air cyclinders from the usual 2500 psi - 3500 psi.... so when we filled the first tank, and checked it with a pressure gauge... - we all were a little shocked at the 3000+psi reading. Really speaking it wasn't such a big issue - they pressure test them to something like 5000psi, so it really just meant we got more air for our buck..(and could stay down longer on 1 tank)...which CAN become an issue for decompression limits at depths below 1 atmosphere water pressure >32feet).
Anyway - that's besides the point......
But yes Argons used for welding aluminium (Along with a special plastic insert sleeve in the tube and hand piece to stop the aluminium wire kinking inside the feed line or hand-piece from friction and when it occasionally splatters across to the sheild piece and sticks.
Wasn't wealthy enough to have a push pull hand-piece back then to draw the wire thru...rather than just push it.
Even the gravity of pushing the wire up over the gunnel to weld down inside the bilge area etc would sometimes make it kink... so we hung the welder overhead from the roof truss on a rope so it was all downhill feed. Managed to bang our heads on it frequently tho.
Must tell the bro in law about this home brew cylinders of CO2 idea... he always winging about the gas bottle rental bills, when its not used much and just sits in his garage.
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29th Sep 2013, 05:39 PM #43Most Valued Member
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- Aug 2009
- Location
- Sydney, NSW, Australia
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- 1,844
i purchased a speed gas cylinder about 5-6 months ago, its a bought cylinder not hired, i took mine in for the first refill the other day u make the $88 payment (D size cylinder) and they give u another filled cylinder, the way it works if u take in a nice new looking cylinder u get that back if u take in a trashed ratty looking cylinder u get a similar one back so look after it
mine cost $314 outright, filled, $88 a refill, D size tank and supposedly last 4 hours of tig welding aluminium but i think i have another leak as ive gone thru that whole bottle already
u can buy the small cylinders on ebay for $200 these can be sent anywhere in australia specialtygasesptyltd items - Get great deals on items on eBay Stores!
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3rd Oct 2013, 10:54 PM #44Member
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- Mar 2013
- Location
- Ningi Qld Australia
- Posts
- 64
Hi, although this was posted a while ago, I thought that I would throw my 2 cents in on this one for clarity, despite what the "gas manufacturers suggest" you use, in the forty odd years of MIG welding I have never had the need to go more than 6-10lts/minute on a regular basis indoors, when outside the shed and a bit of wind blowing using a large torch I once used 12lt/min, that was it, indoors no need as it just wastes gas and forces you to have to refill more often; ie they make more money! With using MIG outside you generally need to protect the welding area from the wind or use different wire.
I have 3 torches, a tiny 180A North torch 6-8lt/min, and the Binzel 350A and the 400A Bernard both get 8-10lt/min, works for me! Then again, I might have been doing it wrong all these years! .
Cheers
Ed.
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6th Oct 2013, 06:57 PM #45Member
- Join Date
- Mar 2013
- Location
- Ningi Qld Australia
- Posts
- 64
I rang Speedgas the other day enquiring about their E size gas cylinders (4.0 cubic mts) and that cylinder to buy was $496 ( D size to buy is $376 and 1.7 cubic mts) and I don't think it included the first fill, the E size fill of 93%Ar 5% CO2 and 2%O2 was $184 delivered. BOC was charging $198 rental per year and about $104 for a refill. So with speedgas you are paying the equivalent of 2.5 years rental up front and then you are almost paying double for the gas refill than what BOC charges forever. Probably after 4-5 years you may get slightly ahead by owning your bottle, also I live near Caboolture and they deliver about every 3-4 weeks to my area, so I wouldn't want to run out in the middle of a job! Looks like I am going to stay with yearly rental as I live within 15 minutes of a BOC dealer. Supagas rental is the same but they charge about $141 for the gas delivered. If you don't use much gas and take several years to empty an E or D size then Speedgas may work out better as you don't pay yearly rental anymore.
I have almost emptied my bottle so I think I will switch from Supagas and back to BOC.
Cheers
Ed.
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