That chart is not helpful. Try:
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)
K 251 51" 9"
S 156 46" 7 3/8"
M 125 47" 7"
Q 92 30" 7 1/8"
R 20 14" 5 1/4"
Tank Designator Capacity Height Dia.
#5 350 45" 12"
#4 150 38" 8"
#3 75 29" 7"
From Ernie's welding class notes.
Coulple more questions....what cylinders are the most commonly used in
a home shop?
I have seen a number of different ones used.
Is it better to have more smaller cylinders or fewer larger cylinders?
This is for A/Ox, MIG and TIG setups that one finds in the home shop.
It's better to have whatever size you can get as owner cylinders,
generally the smaller-medium sizes. Pay for the cylinder once and then
just do the exchange thing whenever you need more gas (infrequently) and
not deal with cylinder lease or hydro testing. Gas may be cheaper in big
tanks, but it is typically insignificant for home shop use vs. cylinder
lease costs for big tanks.
For home hobbyist use, I'd look at trying to get a fresh tank every 3
months to a year or so. For example, the 'lugable' O2/Acetylene packages
would be great for jewelry or random odd jobs, completely unusable for
cutting the flange off a 20' steel beam. Figure out what you plan to do,
buy accordingly. Keep in mind that the K size tanks are really heavy to
transport. (Last weekend someone brought a K tank to our pit area rather
than the usual M tank. 2 wheel dolly time!)
I run the classic medium sized home outfit: #4 Acetylene with 122 cubic
foot (Size M) O2 tank. The O2 tank is a bit small if I have a project
with a lot of cutting but the Acetylene lasts forever. (but I don't have
a rosebud tip!!)
You will find that the local dealers have various contract terms and
pricing policies on the different sized tanks. This may force the
choice. I'd suggest shopping several distributors (if you have that
many) and ask for the very specific details on how they handle
cylinders. Be prepared to be confused.
Most guys get either a #3 (75 cf) acetylene tank and a 125 cf oxygen. I
had those for years, even made a rack for carrying them around on my car:
Now I have bigger ones, can't be running in to refill them all the time.
It all depends. How close is the supplier? Can you drive a few miles and
get a replacement, or do you have to drive farther? How much work do you
do? You will run out more often with the smaller ones, and work stops until
you can get another. Budget has a bit to do with it, too. Larger cylinders
cost more to lease or buy, and buying or leasing two so you never run out is
a budget buster, too. And it all has to be cost justified. How much can
you spend on cylinders? Will they be bringing any of that money back in?
Things to think about.
All good points...that is why I am asking questons.
What got this started is that I fell into a number of FREE
cylinders....CO2, He and H2.
They are all "Q" sized so I see them working better for MIG and TIG.
I will likely trade some of the cylinders for other gases and/or trade
up to larger tanks. Up to this time I have leased cylinders when they
were needed or used the welders at work to avoid actually buying my
If you had a bunch of FREE cylinders, what assortment of cylinders
would you want to trade for?
Thanks for the advice so far everyone.
WARNING, WILL ROBINSON!
Sometimes, the word "free" does not apply in the world of cylinders. Some
are stamped or cast on the collar, and forever and always belong to that
company. If you take them, they will legally and rightfully keep them, and
will thank you for returning them. Others that do not have collar
identifications may be exchanged or refilled, but it depends on the
individual company. Sometimes, you must produce proof of ownership, and I
don't know what that would entail.
In the old days of oilfield drilling, Hughes Tool Company would not SELL any
drill bits. They only leased them. If they EVER found one that was not
accompanied by the necessary paperwork, they had the right to confiscate it,
or call the law and have the person in possession arrested for possession of
stolen property. Thieves never took any Hughes drill bits because they
weren't worth a dime.
Before you take your cylinders down there, I would call ahead as a dumb
newbie and ask about it. Tell them your brother in law wants to sell you
some, or something like that. If you can get them to fill them or swap
them, it's a beautiful thing. If you beebop in there, and they confiscate
them, it can mess up your day.
It's different all over, and it's up to YOU to find out how it works in your
As to which sizes are best, it just depends on how much you use them. As
for MIG bottles, I would rather have two smaller ones rather than one large
one so I would never run out. But the smaller ones are probably more to
fill proportionately than a big one. For OA, if you're going to wheel it
around a shop, the bigger ones last a long time. If you have to wheel them
in and out of your pickup, or to a remote site, the big ones won't do.
There is no "best" size. The use will dictate the size.
Your comment could be interpreted several ways, Bob!
I only ever intended that rack for carrying my cylinders about 3 miles to the
local welding supply for refill. And I'd drive extra carefully. I did notice
some drivers giving me a lot of clearance!
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