Ganging together acetylene tanks

lastcowboy32

Well-known Member
Hi guys, I guess I'm a frequent flyer with questions here lately.

Anyway, I've had a hunch that my oxy-acetylene setup isn't performing up to snuff in some situations when I need higher flow, such as cutting and/or welding a thick piece.

So, I did a little bit of reading, and I suspect that I'm overdrawing my acetylene tank. My tank is 75 cubic feet, and, from what I've read, you shouldn't use a tip that draws any more than 1/10th of the tank per hour; otherwise the acetone used as a stabilizer in the tank starts to come out with the acetylene and you either get pressure dips and/or acetylene contaminated with acetone...which both result in crappy performance.

I have a Purox W-300 torch and I need a #15 welding tip to weld quarter inch steel. (I know...a stick welder would do this...but I don't have one and I don't have a 220 outlet where I'm working)

A #15 tip uses 15 cubic feet of acetylene per hour; which would imply that I should have 150 cubic feet of tank space feeding it. Also, looking at the charts, I believe that my cutting tip takes more than 7.5 cubic feet per hour; so I'm starving that too.

I could safely get 15 cubic feet per hour by ganging another 75cubic foot tank with my existing 75 cubic foot tank.

I would rather have two small tanks than one big one, as the smaller tanks are more easily transported. I've worked with two small oxygen tanks (60 cubic feet) ever since I've had the torch, and I like the ease of transport. I also like the fact that I can use one while having the other as a backup. Then I can continue working while I wait to get the other one filled.

Has anybody here ganged tanks together like this?

Do I need another regulator? Or do I gang the tanks together into a manifold and then put the regulator on the output of the manifold?

If I do this, do I always have to keep the tanks ganged together to keep them at identical pressure, or can I un-gang them for smaller work and/or to continue working (small work) off of one tank while the other is getting filled?
Any other tips about this that anybody would like to share?
 
"messing" with acetylene can be a life/death experience, so I would not take the advice of anyone on a forum regarding any non-standard use. now that is just me. You do as you please.
 

That's a very good point.

Ganging tanks together is standard operating procedure on construction sites and other places where large cutting/heating heads may be in use.

I did talk to the guys where I fill my tanks, but the guys at the counter didn't know much about the situation. As I was explaining the issue about how acetylene tanks are filled with a porous substrate saturated with acetone, he seemed to find that to be new information to him.

I MacGuyver a lot of things, but I try to do everything right with my oxy-acetylene setup. I invest in good quality fittings, flashback arrestors...I had my welding supply shop go through my torch and replace all of the o-rings and such.

Just trying to leave no stone un-turned.
 
I have seen non-flammable gas tanks all connected in the manifold fashion. Haven't seen acetylene like that, BUT, that does not mean it can't be done. Might try contacting manufacturers of manifolding systems. I might trust them, but sure not a counter guy that doesn't know how acetylene tanks are made/work!
 

That was an interesting angle. There was a thread here:

http://weldingweb.com/showthread.php?653591-acetylene-manifold-kits

In a welding forum. One of the replies came from a person who works for the entity that runs this web site:

http://www.regulatortorchrepair.com/

They sell kits that can be used to gang together acetylene tanks. Looking into it a little bit, I think that I may be asking the wrong question. Maybe a good compromise would be to ask my gas supplier how much it would cost to trade my 75cf tank for a 125cf tank, especially since I've seen a few references that say that drawing 1/7th of the tank per hour is OK for short bursts.

At 1/7th of the tank per hour, a 125cf tank could put out 17cfh (cubic feet per hour); which would be adequate for a #15 welding tip and run my cutting tip a little better.

Another 75cf tank would cost me 200 bucks; then the manifolding supplies aren't free...

Maybe trading in the 75cf tank for the 125cf tank is the best option for cost, simplicity of setup and safety.
 

I also would almost feel negligent if I didn't mention this for the benefit of people who might read this thread.

I read through some welding forums on this subject, and some people commented that acetylene manifolds are easily made with copper pipe.

No! No! No!

If one reads these threads thoroughly; you'll find others that are a little more experienced and savvy who remind everybody that acetylene and straight copper are no good together, as acetylene makes explosive compounds with copper. My understanding is that, yes there are some brass fittings on torches, hoses and such; but the amount of copper in these brass alloys is safe to use with acetylene...but straight copper isn't safe.
 
My two sense on this (especially if it is not a
common thing for you or you are working on
someone else's dime) is call you air gas provider
and have them come drop off a big tank and pick it
up when you are done. You're likely to be a lot safer
and time you mess with buying or building
something and another tank you will be money
ahead. At least talk to your gas provider they could
more than likely steer you in the right direction. If
you chose to do so pick the tank up in your own
truck and leave it there this way you could be as
mobile as you probably would ever need to be
 
Lastcowboy32, Probably most of us on here hasn't had the need to do this but some may have. Here's what I've seen on this subject.
Back from 1980 thru 2010 I worked for a big welding company in St. Louis Mo. Up until 1990 they produced their own acetylene in 3 big
generators. In 1990 they made the decision to use bottles. They piped 15 large acetylene tanks together. The manifold itself was made of
black pipe and each drop just had a hose to the tanks. Every 4 days those 15 bottles were empty and switched out. The acetylene was piped out
thru the plant's different departments that covered 15 acres. At each torch station there were a set of flashbacks before the regulators.
These flashbacks had to be cleaned once a month. These flashbacks weren't the kind that screwed into the end of the hose. They had a giant
float type checkvalve inside. They reminded me and looked similar to the old self waterers at each stantion in the old dairy barns on farms
years ago.
 
For all of the trouble and expense of ganging them,just rent a #4 cylinder for a month, and return it when you are done. It should be around $10.00 and the cost of gas.
 

Not sure what the cut off point is in tank size but in my area you can buy your own tanks up to a certain size, anything bigger must be rented or leased.
If it's something you don't do very often you may want to rent a tank but you stand a chance of having to take the tank back with product still in it or rent it for a longer period.
If it's something you to pretty often I'd weigh the option of tank lease on the larger tanks over the cost of more tanks and the manifold to tie them together.
I don't use my torches on a regular basis and opted to purchase the largest tanks I could buy and not have to deal with leasing tanks.
 
All good points, guys.

Monday, I'll call my gas supplier and see what they say. I do live right on a main highway. I seem to recall that they send trucks out on regular deliveries. Maybe I can just get scheduled on one of their runs and rent a bigger tank from them.

I'm also watching craigslist, because I've seen tanks and such come up on there at a reasonable cost. Even if they're out of certification, the re-cert charge is quite a bit lower than buying a new tank.

I think that I also need to seriously consider how much it would cost me to wire a 220 plug in my garage and just do what 99% of farmers do for welding...get a stick welder.

I could then take care of my cutting issue by using propane for running my cutting torch... I have the tank and tips for doing so; and propane doesn't have the same discharge volume limitations as acetylene.

Glad for the perspectives. Thanks
 

Take a look at some of the smaller mig welders, my nephew has a Hobart 145 that operates off of 120 volt and will weld 1/4" easy.
I've ran a Miller 185 220 volt machine off of a 4500 kw generator making double passes on 1/2".
I have a Miller 251 in the shop that will weld 1/2" on a single pass, but it's a 220 volt machine.
 
(quoted from post at 22:14:47 07/08/17)
Take a look at some of the smaller mig welders, my nephew has a Hobart 145 that operates off of 120 volt and will weld 1/4" easy.
I've ran a Miller 185 220 volt machine off of a 4500 kw generator making double passes on 1/2".
I have a Miller 251 in the shop that will weld 1/2" on a single pass, but it's a 220 volt machine.

Thanks. Nice to have a couple of proven options.
 
(quoted from post at 16:45:34 07/08/17)
Not sure what the cut off point is in tank size but in my area you can buy your own tanks up to a certain size, anything bigger must be rented or leased.
If it's something you don't do very often you may want to rent a tank but you stand a chance of having to take the tank back with product still in it or rent it for a longer period.
If it's something you to pretty often I'd weigh the option of tank lease on the larger tanks over the cost of more tanks and the manifold to tie them together.
I don't use my torches on a regular basis and opted to purchase the largest tanks I could buy and not have to deal with leasing tanks.

So, to close the loop on this option: I talked to my acetylene supplier. The 75cf tank is the biggest that they sell and exchange.

The next size up is a 140cf tank. If I wanted the 140cf tank, it would cost me:

$48 per year for a tank lease
around $80 to fill the tank
around $40 to $50 to have it delivered (I can't transport a tank this big safely in my car.)

So, for about the same cost of getting another 75cf tank, I can get the bigger tank safely delivered and still have my little tank for backup and smaller stuff.

Seems like a no-brainer that leasing the bigger tank is the safer and more cost effective way to do what I want to do.
 

Not the way I look at it.
$48 per year lease plus $40-50 for delivery, that second 75 cf tank will have paid for itself in two years while the 150 cf tank will never be paid for, and that's if you only use one tank per year. If you use two tanks per year that's $80-100 per year in delivery charges plus the lease, won't take long to pay for the extra plumbing at that rate or get that 220 volt plug put in.
 
(quoted from post at 21:32:52 07/11/17)
Not the way I look at it.
$48 per year lease plus $40-50 for delivery, that second 75 cf tank will have paid for itself in two years while the 150 cf tank will never be paid for, and that's if you only use one tank per year. If you use two tanks per year that's $80-100 per year in delivery charges plus the lease, won't take long to pay for the extra plumbing at that rate or get that 220 volt plug put in.

Good points. I did just hear back from the company that sells a manifolding system complete with check valves and adapters.

120 bucks...roughly...they're double-checking the fittings that they would need for my acetylene tank. I guess fittings are different here in the NorthEast, vs other areas of the country.
 

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