How to buy an owner gas cylinder

Need some tips, and images for examples if you have them ... search and not much. Weld sites help, but might be some good info for others ...

• What does a DOT stamp look like?
• What are certification stamps? Just a date and a month?
• Can a cylinder used for one gas type be used for a different gas?
• Are the tanks color coded? how do you know what's in it?
• What size tank for a hobbyist would you recommend?

The time you spent writing that post you could have found this on google, but nevertheless.

Read this page
http://www.ehss.vt.edu/programs/CGC_cylinders.php

It's best to call the companies in town and find out driectly from the horses mouth how they deal with cylinders and the home user. It varies greatly by region.

The larger the cylinder the cheaper the gas will be per the ft^3. Not much difference in transporting or filling a 80 or 300+cf tank. IMHO a ~125cf is a good balance between portability and fill cost. That is also a common size that suppliers will differentiate between owned and leased cylinders. Again I say It's best to call the companies in town and find out driectly from the horses mouth how they deal with cylinders and the home user.

zkling said:

The time you spent writing that post you could have found this on google, but nevertheless.

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True ... but I'm sure someones searched for it on GJ

Thanks for the link ... haven't seen that.

bmxdad said:

Need some tips, and images for examples if you have them ... search and not much. Weld sites help, but might be some good info for others ...

• What does a DOT stamp look like?

Click to expand...

I think it is a numeric month/year stamp.

bmxdad said:

• What are certification stamps? Just a date and a month?
• Can a cylinder used for one gas type be used for a different gas?

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Generally no.

bmxdad said:

• Are the tanks color coded? how do you know what's in it?

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Yes the color should indicate the contents.

bmxdad said:

• What size tank for a hobbyist would you recommend?

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In this area the tanks are handled on an exchange basis. I have never had a tank filled, they just swap for another the same size that's full. If you buy from a welding supply shop, the initial buy in is expensive because you have to buy the tank, the refills are less but depend on the gas. You now own "a" tank, and they give you one. It will be used but serviceable. It's not like propane where you get your own tank refilled.

There are several shops that have tanks depending on where you live, Sumner, Tacoma, South Hill, etc.

I have one 125cf tank of 75/25 gas and this is a owner tank, and two 80cf tanks of 75/25, I use Air Gas here in Fl. You have a few Air Gas locations in Puyallup Wa. Stop by one near you one day and talk to them, they will answer your ??? or just piss you off I am not sure. All I can tell ya is that Air Gas has been good to me.... Here on my tanks I call first to see if they have any on hand and if so I just go down there and leave the emptys and pick up full tanks and pay for the gas.....Hope this helps ya...

Definitely shop around for a tank; you do need to decide on the size you want for the gas you will be using. What type of welding will you be doing and how much welding? MIG? TIG? All of that will determine the best tank size.

AirGas has stores all over, but you may find that some independent shops will have lower prices. The local AirGas store is pretty expensive.

Medical cylinders in the USA are required to have the shoulder of the cylinder a certain color. Green=Oxygen for example. Industrial gases are not required to be any special colors. Never judge a cylinder by the color, and always check the label.
Oxygen cylinders should have a CGA 540 valve. Many of the shielding gases have a CGA 580. A cylinder that had pure argon in it could be changed to a 25%CO2/Balance Argon without changing anything but the label.

As others have mentioned, figure out what your local gas supplier is willing to fill before you invest in a cylinder. In the USA, a cylinder needs to have a legible DOT/UN number, needs to be in current hydrostatic test, and has to be free of arc burns or other major damage. The DOT and Hydro stamps are two different stamps. Common pressures are 2015, 2265, and 2400psi and some vendors may 10% overfill if the cylinder has a + after the most recent hydro date. Most cylinders used for welding applications are steel.

If you are exchanging cylinders, you are more than likely paying rent/lease on that cylinder, and that is very common because that is how the gas companies make money.

This is just scratching the surface. I'm the Specialty Gas Supervisor at a large, independent welding supply company. Be careful with high pressure cylinders. When things go wrong, they can go very wrong.

Be careful buying used, you may end up buying the local gas companies leased cylinder. Make sure you get a bill of sale. My local place will fill owner cylinders, but I had to pay to have the valve updated and a hydrotest (mine was out of date). If you are looking at the small tanks, they are normal purchase and can be had reasonably. The larger ones are usually very expensive, so people lease them. A benefit to the leased tank is that you are not responsible for the hydrotesting or any other certifications. Also the longer you lease one the cheaper it will be. My local place charges about $50 per year, but a five year lease is like $130. So I always lease them for 5 years. Also you can usually exchange for any type of gas/cylinder size you want, the lease covers "a cylinder" not a specified type. That can be a bonus when you are doing some fab work that requires a gas you do not usually need, or if you wanted to get helium to fill a bunch of balloons.

I bought mine at the place I intended to go to refill it. Over time I moved up in tank size (trade in at the refill place), and the refill cost is much less per cubic foot the bigger the tank gets. When the tank gets empty I take it back and they give me another full one, I just pay for the gas. They deal with the hydro test expiration date etc.

I did originally call all the places near by to find the best deal, It varied a huge amount from company to company. Some places like customers, others not so much.

In some areas, or to people who have never bought a tank, it seem like a big deal. Around here it is not. Call around and ask.

If I needed to buy a craigslist tank, I would either have the seller meet me at the gas refill place I want to use, or take pics of the stamps on the tank and show them to the refill place before buying the tank.

It is certainly possible to buy a stolen leased tank, no good can come from that. Even a non stolen tank that the refill place will not exchange is only good to make a large cow bell.

Regards,
404

I own a 125cf bottle of 75/25 for MIG gas, I seem to go through one bottle for each 10lb roll of wire I use, your mileage will vary. The 125 is easy to handle and haul, doesn't weigh alot.
I have a 300cf of Argon for my TIG machine. Bigger is better, TIG uses more gas as a general rule, and you will use alot while learning. Bigger ***** when you have to load and handle it.

I'm just MIG welding now, but would like to try out TIG. A 125cf of C25 seems about what I'm going to look for.

Thanks guys ... going to see if I can find a local shop here in Puyallup and ask about their swap rules. If I can, I'll buy a tank off CL and see how that works out.

My local welding gas place won't fill tanks bigger than 80cf on the spot and they can't fill acetylene tanks at all! .. So I bought 2 new 80cf tanks for welding gas. I also have 145cf acetylene tank and 145cf oxygen tank. My uncle says this place is ripping me off and told me to go to another place a few towns away. Will they believe me if I tell them the tanks are mine? The only proof I have is the scribbly receipts from when I bought them. These tanks are big money and so is the pressure test but what really ***** is when I need my o/a tanks filled and I have to wait more than a week to get them back. They are just a middle-man sending them off site to get filled.

I believe that the situation varies around the country. However, here in Washington State, I know the welding cylinder game pretty well.

Many gases are delivered in high pressure cylinders. These include oxygen, nitrogen, argon, argon/CO2 mixes, trimixes, hydrogen and helium. Most vendors will sell you any gas you want that comes in a high pressure cylinder and swap it for the same size high pressure cylinder that contained any gas. For example, I can swap out an oxygen cylinder for a C25 cylinder.

High pressure cylinders have some sizes that are guaranteed to be owner cylinders no matter what is or is not cast into the neck ring. These include 150 and 92 cf cylinders. Many guys want an oxy/acetylene set but don't want 250 or 330 cf oxygen cylinders because they're too heavy. I always suggest they look for a 150 cf oxygen cylinder because then they're assured it isn't a rental. I also recommend the 92/75 cf cylinder pair (92 cf oxygen, 75 cf acetylene) which is a very common size for HVAC repair guys for whom portability is paramount.

My opinion is that there is only one reason to buy acetylene, now hyper-expensive due to a plant blowing up recently. That is to weld steel. For heating, brazing, or cutting propane is much cheaper. LP uses the same regulators and heating tips but requires different cutting tips. I have never found the "name brand" cutting tips to outperform generics so I buy cheaper tips. The savings in fuel gas will pay for a set of LP cutting tips in a year or two. Acetylene is now so expensive the best way to get it is to buy full used cylinders on CL.

Cylinders are sized in height and diameter. The height measurement is taken from the floor to the bottom of the valve, NOT the top of the valve. Here is a little table I have made up for my own reference. It will read far more easily in a fixed-width font like Courier. - metalmagpie

Welding Cylinder Data (capacity is in cubic feet @ 2100 psi)

Oxygen / Argon / Helium / Other High Pressure
Tank Designator Capacity Height Dia. (height w/o cap & valve)
T 330 55" 9 1/4"
K 251 51" 9"
S 156 46" 7 to 7 3/8" *see note at bottom
M 125 43" 7"
Q 92 30" 7 1/8"
R 20 14" 5 1/4"
65 24" 7 1/2"
Acetylene
Tank Designator Capacity Height Dia. lbs. (tare weight)
#5 350 45" 12" 171
250 12" 117 (@300: 12x42"?)
#4 150 38" 8" 75 (8.5x30-34"?)
#3 75 29" 7" 44 (7x29"?)
B 40 23" 6" 24-26 (6x19.5"?)
MC 10 15" 4" 8 (4x13"?)

One cubic foot of acetylene weighs 0.06734 pounds.
One pound of acetylene is 14.85 cubic feet.
A B bottle (26 lb tare) weighs 28.7 lbs with 40 cf acetylene.
*150 cf cylinders can be 7" OD but are 3" taller than 125 cf cylinders.

All 150 cf and 92 cf high pressure cylinders are owner cylinders.
All 75 cf acetylene cylinders are owner cylinders.

Yeah, your going to need to talk to your LWS(s). Every place seems to have different rules.

Ex - Local Praxair is who I usually deal with. They will rent anything above ~125, or you can own anything up to a T size, but it will have a metal ring that says "Customer Owned" on the neck. Smaller sizes are owned only. There is no out of date or inspection fee, the cost is just averaged in the fill cost. They don't fill on site, just exchange. You can change gases for the cost of a fill of the new gas.

But the closest place to me is a one shop place, Jasper Welding. They only deal in 3 sizes of cylinders, period. 40s, 125s and Ts. You can only own the 40s, the others have to be rented with a yearly lease. They will not fill any outside cylinders. They only get my business on emergency consumables and filler.

So YMMV applies in droves here. Also the price is going to very greatly. Expect some places to say no with a price if you tell them you are a hobbiest that only needs 1-3 tanks a year. Others understand money is money and will give you a decent price. Helps if you pick up some stuff while you are shopping (gloves, filler, clamps, etc) since it sets the idea that you will be more than a few tank swaps.

I took a gamble and bought a used cylinder for $25 from a guy who had about 10 of them. He thought they were oxygen but wasn't sure. About 3ft tall, 8-10 inches round

Did not know if it was going to work or not. I cleaned it up, took it to Northern tool and used as an exchange cylinder. They gave me a full 80# 75/25 bottle no problems.
Now when I need more argon mix I go to NT. They are open everyday and keep full cylinders on hand cost for refill if memory serves me is about $32

fred d said:

I took a gamble and bought a used cylinder for $25 from a guy who had about 10 of them. He thought they were oxygen but wasn't sure. About 3ft tall, 8-10 inches round

Did not know if it was going to work or not. I cleaned it up, took it to Northern tool and used as an exchange cylinder. They gave me a full 80# 75/25 bottle no problems.
Now when I need more argon mix I go to NT. They are open everyday and keep full cylinders on hand cost for refill if memory serves me is about $32

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You will pay a few bucks more per fill but buying a size that northern/TSC carries is a pretty sure bet, and they will almost always swap. If they don't the first time go back and try another employee.

So, would this be a bottle worth getting? They want $70 for it, and say it's a 60lb bottle.

according to the label, that is a nitrous oxide tank. NOS is filled similar to CO2, it is pumped in a liquid phase. Actually, the cylinder weight (t.w. = tare weight - empty weight) is 131.1 lbs and will accept 60lbs of NOS. The cylinder is stamped "3A2015" which means it was tested as a "high pressure" cylinder. It appears to have a current hydrostat test. The only question is usually NOS tanks are regulate as "medical use" and sometimes are not available to the general public. That is not to say it can not be re-valved for another use. As it sits, it can only be filled with NOS (medical - if you qualify - or "racing" NOS - for cars).
As far as buying it, I would wait for a better cylinder to fit your needs.

Everything looked good, except for the gas type ... so it wouldn't work as an owner bottle?

It's empty now, and only $70.

Take that pic down to Airgas/Pacific/Central supply and ask them it they'd take it. Valve doesn't match my stuff.

Bottom line is if you want a filled bottle, you either need to pay them the tank deposit (buy the first tank), or you need an equivalent tank to swap.

Yea, I passed on it. Picking up a different 125cf bottle with a Argon/CO2 mix this afternoon.

Thanks for the help all ...

Got one ... nice size @ 125cf, and even has a little gas left. Now to start practicing ..

Every customer owned bottle ive ever seen has nothing on the ring around the neck. That first bottle of NOS you showed had a company's name on the ring, that would have been a leased bottle. the one you bought appears to have a blank ring, that would be a customer owned bottle. that's the easiest way I've found to explain lease/own

Nice to know ... thanks.

.....company's name on the ring, that would have been a leased bottle. the one you bought appears to have a blank ring, that would be a customer owned bottle. that's the easiest way I've found to explain lease/own

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not universally true, maybe regional per weld gas supplier.
I currently just purchase /own a cylinder of Argon, it has a neck ring with the suppliers name embossed on it.

Another tip- There is no requirement for any LWS to accept your owner tank regardless of condition, source, or size. They are in the business to lease tanks and provide refills, not deal with owner stuff.

It's worth checking with the LWS to see what they will accept and work your plans around that since they are the ones you'll be doing business with.

I went to Pacific Welding Supply (Whom pretty much is the default in the northwest) and got a 80 cfm tank for $179 plus the first fill free. I asked about leasing, and the same tank leased would be $100 deposit, $15/mo rental, and $50 to fill up. Out the door that would have been $165 leased with $15 every month versus $179 as an owner tank and a first tank fill free. That was an easy choice to make, and only possible because they had a surplus of tanks they wanted to move.

Always work with the LWS, and you'll find life easier.

Found this in the alley one day.