MAPP + O2?

Figured I needed to see if anyone still read this NG!
My O/A rig was not getting much use, then my gas supplier changed the
lease terms, made it MUCH more expensive per month, I sent the tanks
back. But I still have occasional needs for braze repairs and cutting
off the stray bolt or two. MY BIL had a long unused O2 and Mapp gas tote
setup that he was willing to donate. I checked around this afternoon,
The O2 bottle is an 'R' size @ 20 cubic feet, my local supplier will
take it with no questions asked for about $20 per fill. Mapp gas is
running about $8 per 1 pound cylinder.
Is this thing worth the time and effort to get it running right? I know
that the O2 tank won't last at all for any cutting but does it cut at
all? Lightweight brazing (mostly small castings and thin sheet metal)
should be fine. Welding is pretty iffy from what I've read.
Reply to
RoyJ
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No substitute for O/A, consider purchasing some mid sized cylinder and not leasing. Can normally to the swap thing and not deal with hydrotesting and waits for cylinders to be sent out for filling.
Reply to
Pete C.
Oxy / Acetylene is only NECESSARY for gas welding. For everything else (cutting, soldering, brazing, heating) LP fuels are much much cheaper and more efficient.
All you need is a small O2 bottle, and a 5 gallon BBQ Propane bottle. Acetylene regulators have the same fitting as Propane regulators. It is called a POL fitting. Even the newer BBQ bottles with the quick connectors have a POL fitting receiver in the middle of the valve stem. Acetylene regulators work fine for propane.
I teach with acetylene at school, but I haven't had an acetylene bottle in my home shop in 6 years.
Reply to
Ernie Leimkuhler
snip What's the consensus on the safety of storing MAPP vs acetylene in a home?
I am not aware of MAPP's specifics, but doubt that it could possibly be worse than acetylene. All flammable gases have the power to cause serious damage when their containment fails in an enclosed space, but acetylene's range of explosive concentration is much larger than any other gas that I am aware of (with the exception of ethylene oxide).
It is probably worth commenting that we are now in the season where we often hear about someone killed while attempting to thaw the frozen lock on a tool box containing an acetylene torch or bottle that has leaked. Current practice requires that tool boxes containing pressurized gases be very well ventilated and that regulators be removed when not in use.
Good luck, YMMV
Reply to
Private
From that it sounds like I should get the O2 cylinder filled, try out the MAPP gas as a first step, then try out the O2 with a propane cylinder and one of the spare acet regulators from the welding supplies box, see how I like it. Heating, brazing, and short cuts (bolt heads and such) would be just fine.
Reply to
RoyJ
?
Don't forget to get some propane tips for your cutting torch, they are different than the standard O/A cutting tips.
Best Regards Tom.
Reply to
azotic
There's more - acetylene can become spontaneously unstable and explode - that not needing the presence of any oxygen or anything else to happen. Conditions:
- pressure - yes we can control that - but a "flashback" - oops!
- heat / raised temperature - after a fire incident, acetylene is the only gas in bottle where if the cylinder has survived the fire you cannot yet know whether you are "in the clear".
Acetylene auto-decomposition is exothermic. So if you have got any instability in a cylinder, the temperature will rise, the reaction will speed up and spread, ...., ..., and before long - bang!
So you seriously need to respect acetylene. On the other hand - acetylene is very special for what it can do. So we have to live with it - carefully!
Hear's some good (?) guidance from the UK "Health and Safety Executive"
formatting link

"Take care with acetylene"
INDG327 - File Format: PDF/Adobe Acrobat
"There are a number of incidents each year where a flashback into an acetylene cylinder triggers decomposition, leaving the cylinder in a dangerous, unstable ...
Reply to
Richard Smith
After changing to LPG and changing back, I will go with acetylene any day, no matter the cost. That would be unless I was using it in mass quantities, which I am not.
Steve
Reply to
Steve B
It is just so natural and intuitive getting to know the acetylene flame. Anyone who knows it likes it. Also for easily igniting a cut there is nothing like it - and that is the recognised view. And I know from physical principles that nothing can come close.
Now, the one time I met oxy-propane, I could never get on with it. But there was no-one to show me how to rightly use it.
I have this assurance: with a good oxy-propane set up you will like it.
The oxy-propane nozzle with the removable core with groove passages fitting into a conical plain out nozzle - I am told this design is good.
And I was told - don't be offput by seeing cold black dots on the steel plate perfectly mirroring the shape of the nozzles - that is apparently normal.
Maybe there are fans of oxy-propane who could speak-up? For brazing it would be ace and the OP could have cutting as well.
Richard S
Reply to
Richard Smith
While I do prefer OA for most work, mostly due to its higher heat and ability to focus this heat on a much smaller area which enables much quicker and cleaner starts when cutting/burning particularly when cutting thick material or for cutting bolt or rivet heads and such. The tips are much smaller (easier to access and see the cut) and are available in many specialized types optimized for gouging and cutting rivet or bolt heads. Propane tips are too big to do a really clean job of bolt/rivet head cutting. It is also superior when heating/removing rust frozen nuts or for shrinking rust frozen bolts (although stick welding is superior to both for this) as the speed of heating allows primarily heating the nut without excessively heating or weakening the bolt or stud.
There are some advantages to OP for cutting thin plate and it often causes less slag on the back side of the cut, especially when compared with an OA tip of the wrong size or dirty or using poor technique. I much prefer OP when cutting very thin sheet steel but the tip must be angled forward (just like with OA) and travel speed as high as possible. The larger tip can make it easier to 'lose the cut'.
OP is generally considered to be cheaper but the acetylene suppliers claim that O2 consumption is increased, YMMV. A lot depends on the cost of cylinder rental especially for low volume users. The general rule is to always be on the lookout for bargain priced owned? (use caution) or 'stray' cylinders.
IMHO, OP is much superior for soldering as OA is usually too hot, but a simple adapter tip on an OA welding tip allows the use of pure acetylene and this is very good for soldering and light brazing or silver soldering/brazing.
OP works for general heating but supplies no where near as much focused heat as an OA rosebud. I have never seen an OP rosebud heating tip but suspect it would be great from a cost viewpoint. I have always said that OA suppliers should give away rosebuds and gouging tips due to the large amounts of acetylene they consume. A large rosebud requires a very large acetylene cylinder or multiple cylinders connected with a manifold especially in cold weather as the tip can overdraw the acetylene cylinder. A plain propane 'tiger' torch is great for most general heating jobs and is much cheaper to operate than OA or OP and IMHO is definitely worth carrying in the colder months to remove frost and dry or preheat before cutting or welding.
Once you have propane AND acetylene on the job it is easy to use the best for the specific job. IMHO, all welders should have a propane cutting tip for emergency use as it is usually possible to use/borrow/refill a BBQ tank.
Good luck, YMMV
Reply to
Private
x2, this seems to be the 'cause of death' for many OP tips. I have never seen the outer tips available for purchase separately.
Hope you are having good luck nursing 'Sally'.
Good luck, YMMV
Reply to
Private
"Private" wrote
Sally runs good enough that it would run longer than me unless I pressed it into daily service. The rebuild may consist of just dropping the pan, changing the main seals if they are easy to drive out, getting a new circuit board, and a valve job. I'd love to putz with it, but at my stage of life, there are ten other things I'd rather do in the same time frame.
Steve
Reply to
Steve B
The first time I recall seeing propane used for cutting was 1959. They were cutting up scrap steel. At the time the yard manager told me that Propane was less expensive than Aceteline but did not burn as hot, so they had to use special tips.
From reading the posts here, he must have been right.
Reply to
Nadogail
MAPP is generally considered safer than acetylene.
Thank You, Randy
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Reply to
Randy
In the meantime, I imagine you're doing what I'm doing. Buying cheap 40 wt. oil by the 55 gallon barrel......................
Steve
Reply to
Steve B
I have heard here many times that Propane is used for lots and lots of cutting, and is cheaper. I'm not impressed with it for what I do, and am not crazy about the results I got. Notice past tense.
The only good thing is that the hoses are usable with acet, and not the other way around.
Steve
Reply to
Steve B

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