bikingman

Part 2, Tanks
I'm looking at investing in tanks from my local supplier so I can be sure they'll switch them out when I need more fuel. I'd also like to minimize the number of trips to the supplier through the years.

1. What oxygen to acetylene tank size ratio should I use? From my understanding for every 2 parts acetylene, I need 5 parts oxygen. But the balance won't ever be perfect in practice. I would guess a 2:1 ratio or an oxygen tank twice the size of the acetylene tank is good.

Look forward to reading this discussion and feel free to answer questions if you need any clarification.
Dan

JohnDThompson 

Keep in mind that oxygen tanks are much higher pressure than acetylene tanks and thus hold more gas.

unterhausen

oxy/acetylene are going to be more tightly controlled in the future. I suggest looking up how to use propane and an oxygen concentrator. I own oxygen and acetylene tanks, and am considering the switch.

wsteve464

bikingman

Oh right, thanks for that information. I missed that in my reading. Shows that I have much more to read.

bikingman

Interesting - who will be turning up the control: OSHA, state, national, or other agencies? Would this be in the US? Any reliable information I could use to read up on this? Regulatory changes to limit acetylene use would certainly play a role in the direction I go. Thanks again unterhausen

bikingman

Thanks, wsteve464 - I am looking into a truck for another project and could rig up brackets on that to use with a trolly for transport. Otherwise, they would travel in the back of a hatchback with seats that fold to be at grade with the floor. Either way, ease of transportation is certainly on the radar. Thanks

TiHabanero

"I use fairly small tanks, don’t recall the size, acetylene is about 2 1/2 feet tall oxy about 3 feet tall. They are good for about 2 frames."

I use the same size tanks and have just completed a 3rd frame without recharging the tanks. Still have 400psi on both tanks respectively. This last frame I started with 450psi in the Acetylene tank. I have also repaired 3 frames with bad drop outs and cut down a basket ball hoop stand next to the driveway on the same charge. Unless I am doing something out of the ordinary, one should get more than 2 or 3 frames from this size tank and a full charge.

unterhausen

The problem is two-fold. It's likely that having oxy acetylene in a house or attached garage is not covered by homeowners and is probably not allowed by local ordinance. My gas supplier now makes me sign a waiver saying I know it's not safe to transport gasses in my vehicle. I have heard that some gas supply places will not allow you to transport in an enclosed vehicle. Not sure if that is a state regulation or what. I'm almost positive that my gas supplier will not deliver to a residential address. When I tried to rent larger tanks, they wouldn't do it. I have the largest tanks I could buy.

The last acetylene tank I got was leaking pretty quickly. It was a little scary. Fortunately, they exchanged it without question. Customer in front of me got acetylene and threw (literally threw) the tank loose in the back of his truck. It's guys like him that are driving stricter regulation. I have been in the same building (the infamous Trek red barn) as an acetylene explosion, and it's something I still remember. That is not a small building, and the whole thing shook.

bikingman

Good to know the timeframes you expect with those tanks (cool job with the BB hoop). The supplier I had in mind isn't on my normal commute, so perhaps I'll consider a closer one or one on a more direct route from my place. Not sure how much longer the propane tanks would last relative to ace. Either way, the accessibility of propane is nice.

bikingman

hm, this is important. I'll look into this for my area and have conversations with local suppliers. Given your observations with the loose tanks in trucks, maybe better to consider a OP setup for that reason alone... Wonder if oxy tanks are treated similarly.. Huge thanks.

unterhausen

I have to get my oxygen tank refilled, so I'll report back. I think it may just be acetylene though. I'm pretty sure most states require pressurized tanks to be securely fastened to the vehicle though.

Nessism

Reading some of the comments here scared me since I live in So. Calif. where laws are tight, and my tanks haven't been filled/tested for quite some time. The local welding supply house said the tanks will have to be tested, or they will do an exchange come refill time, but there are no restrictions against selling/trading out the bottles for a hobbiest type person. I asked about transportation of bottles and they said there are no specific restrictions in that regard (at least to the point where they are going to get involved with).

Now to figure out how much gas I have left? Googling turned up some info related to the translation between pressure and gas remaining, for oxygen anyway, but acetylene seems less inclined to follow the same direct relationship? Guess I'll have to break out the scale and see if I can weigh the acetylene cylinder...

unterhausen

acetylene gas is dissolved in acetone. The so as it is used, it's coming out of solution. But the pressure does reflect how much acetylene is in there. If you see purple in the flame, that's bad. You can always overdraw the acetylene, even if you have plenty. There used to be a rule of 7, now they recommend using a rule of 10. That is, whatever the cubic inches of your tank, you should draw no more than 1/10th of that per hour. Most tips are rated as to max flow rate. I have tips for my A1WA that will over-draw my tank, which holds 75 cu in.

I found this, it suggests that gas cylinder transportation is more restricted in commercial vehicles. PDF warning. https://www.lindeus.com/en/images/298...138-276010.pdf

It also suggests that the guy that threw the acetone tank in his truck horizontally was defeating the pressure relief system. One guy like that rear-ending a school bus and causing a fatality is all it takes for a state to heavily regulate gasses. So it could happen in any state, no matter what the political situation might be. I know Texas had a pretty well publicized incident of a welding supply blowing up

Doug Fattic 

I've said it elsewhere in another subject thread but I get about 3 times as much burn time with a BBQ tank that costs me less than $20 a refill compared to the biggest acetylene tank I could buy ($65 a refill) and not rent from my local welding supply store. A BBQ tank of propane will last just about forever for a hobbyist.

In fact there is enough propane to build a frame or 2 in those small containers sold for a variety of purposes like torches and portable stoves. The problem with them is that their fittings are not compatible with regulators used in welding. A BBQ tank has the same GCA-510 fittings.

Andrew R Stewart 

I remember watching that vid 10 or 15 years ago. Mighty eye opening.

Side bar story. There's a reason that Acetylene gages have a red line on them. It becomes unstable above 15PSI. When I took the Eisentraut frame class (1979 in Rutland VT) Al mentioned he once shared a building with a guy who did large scale OA cutting of plate steel. One day he was visiting his neighbor and noticed that the A pressure gages were at 15PSI... Al went back to his side of the building knowing that all the separated them was a thin brick wall. Andy

unterhausen

I got my oxygen cylinder exchanged today. Going to take a while to pay for a oxygen concentrator at these rates, $18 + $3 for hazardous gas fee. Maybe I'll make the change to propane first and keep looking for a deal on oxygen concentrators.

I had to sign something, but it wasn't a page of tightly spaced lawyerese like it was with the acetylene.

Note that you should probably store propane outdoors, it is heavier than air

Doug Fattic 

Of course the advantage of getting an oxygen concentrator goes to a new set up. One can most likely be bought for less (and probably much less) than a tank and regulator and flashback arrestor. Then there is the matter of greater safely and convenience.

A concentrator has its issues. It probably doesn't have the output for rosebuds and it takes a couple of minutes to purge the line until nearly pure oxygen is coming out. Also they make a racket if the line is cut off to warn Grandma she is about to die because her O2 isn't getting to her. This can be annoying if you turn off the knob by mistake.

unterhausen

Doug, I seem to remember that you said that propane takes more oxygen?

David Tollefson

I've actually never run out a BBQ bottle propane tank framebuilding. My wife steals them for the smoker (when it runs out) long before I get to the empty mark.
I paid $350 off a CL ad for my medical oxygen unit 5 years ago. Only thing I've done to it is vacuum off the foam intake filter a few times. 5Lpm capacity, and I run maybe 2Lpm max (propane at about 3.5psi) using a #4 tip.

unterhausen

there is something to be said for ease of purchase of gas and not having to get more in the case of oxygen. One of Doug's favored oxygen concentrator suppliers is a couple of hours drive from here, I'll have to come up with an excuse to go down there sometime.

Doug Fattic 

My preference for an oxygen concentrator manufacturer is DeVilbiss. I have an older model 515 with 18,000 operating hours. It is still working fine. The newer 525 is supposed to be quieter and is dark gray instead of beige. It can have a higher oxygen output than a couple of Invacare models I also own (so I can have several torches in my classes operating at once if necessary) even though they all are rated at 5 liters per minute.

Another reason I like the DeVilbiss better is because its output fitting is a standard B that a welding hose can directly screw into. The Invacare has a barb fitting designed to hold those clear plastic hoses that carry oxygen to a patient. Often they come with a plastic adaptor that has a barb on one end and a B fitting on the other. So it works to attach a separate plastic hose to the unit and the plastic adaptor which allows a welding hose to screw into the adaptor. But this extra stuff seems unnecessarily complicated even though it works okay.

And the 3rd reason I like my DeVilbiss better is because the warning signal on my Invacare – when I accidentally shut off the oxygen flow after doing a braze – is more piecing loud. And it won’t shut off when I open the oxygen knob again on my torch handle. I have to turn the machine off and on again. The Develbiss stops yelling at me when I open the flow knob again. None of those preferences would matter much to me if I got a really good price on another brand.

I bought my 1st oxygen concentrator from M&M Medical Repair in Beaverdale, PA (a very small town in the middle of nowhere). I discovered they were the source for various used Oxygen concentrator suppliers. I paid $300 + $30 shipping. It came with a 3 year guarantee. After a couple of years my concentrator wasn’t putting out enough pure oxygen and they repaired it for free (I paid for a new filter). The reason this might be a sensible option for some just getting their brazing equipment is that one can choose a Devilbiss 525 and have the assurance of the guarantee. In bigger cities oxygen concentrators can be randomly found for $150 to $200 (and some of my students have paid less) but sometimes they have some issues that have to be sorted out and repaired. They are pretty complicated inside. Those that are mechanical can figure out how to get them fixed while others just want something that works. $300 is not much different than what the cost of a oxygen tank and regulator would be and of course there is no cost of refills. For some this is really the only option because of pressurized tank restrictions where they are located. Where I live I haven't seen one on Craigslist within 50 miles of me for as cheap as $200 for a long time. So how long someone is willing to wait for the right machine is part of decision on where to buy.

unterhausen

I get the impression that the place to find them cheap is at estate auctions. Need to start looking for those. I use search tempest for CL and the closest $300 units are further from me than Beaverdale.

Nessism

Exchanged my tanks yesterday. Cost $126.64. There are very few places in my area that sell gas. It's been a while since I've exchanged but I'm positive there were far more places a decade or so back. The guy at the shop seemed almost apologetic, and asked me "is this okay" (regarding the price). What to do? Go somewhere else and most likely pay just as much? I was charged $22.50 for "hydrotest fee" for the O2 bottle and $27 for "requalification on acetylene" bottle. The O2 is (I think) 80 CF, along with some reference to Refill 2.2 (5.1). Not a large tank. The Acetylene is (I think) a 2A tank, which I can't find much of any info on. Most likely an old outdated standard size. There is some mention of 2.1 on the bill but I don't know what this means. At any rate, NOT CHEAP!

Doug Fattic 

That is interesting and informative information, thanks for sharing. Just so everyone knows, it is possible to use acetylene mixers/elbows/tips with propane. It works okayish. I made a number of frames in Ukraine doing just that. However, It just doesn't work as well as propane specific equipment. Older acetylene regulators should be rebuilt with new seals. This is a service available in many locations but might involve shipping. Rubber hoses should be T grade and not acetylene only R grade. The ultra light hoses are T grade. The problem is that a propane flame is harder to light and blows out more easily with acetylene mixer/elbow/tips. This is not as much a problem when silver brazing because the flame isn't usually held as close to the work as when brazing with brass. It is the flame pressure bounce back that might extinguish the flame. It is possible to get around that problem by adjusting the angle of the flame to the work.

The reason to use propane is because of its greatly cheaper cost and much higher availability at stores closer and open way longer than a welding supply store. I have counted 7 locations reasonably close to me that sell propane BBQ tanks and provide trade-ins with empties. A refill costs less than $20 and buying a full tank that you own is less than $50. There is enough fuel in one of those tanks to last hours and hours and hours of brazing. For most beginners its slightly cooler flame gives them a few seconds longer to asses what to do.

A propane mixer/elbow like a Victor UN-J or a Smith AT-61 has a different fuel to gas ratio mix. Victor TEN tips have a recess to help keep the flame attached and Meco or Paige multi-port tips stabilize the flame even more making it harder to blow it out. So if one is beginning from scratch, it makes sense to use propane with propane specific equipment but if one inherits or finds oxyacetylene equipment cheap, it is possible to start out using it with propane and making the switch when funds are more readily available.