Trying out oxy-propane

[evfreek]

Hi. I bought a drill from a flea market vendor, and she was also selling a National hand torch with a small oxygen cylinder. She said she'd sell it to me for $65, so I figured it was worth a try. I connected it up to a 20 lb. propane tank, and although adjusting the fuel was kind of tricky, it made a nice blue flame . I tried it out for making some minor adjustments on my plant stand, especially on the hook ends and collared leaves and vines. Wow, this thing is great . It really beats jockying things into the ground forge!

I saw something on the web about using forge burners, firebricks and an acorn table to save a factor of 10 over the cost of a torch, but I don't think so. The venturi propane burner is cheap ($1 per 9 cu ft), but you have to run it a lot longer and heat up a lot more stuff. But, this little torch does eat up the oxygen. When using propane, you need more than 4X the oxygen flow rate over the propane flow rate to achieve a neutral flame. The torch had the OX-3 tip, which worked for 1/2", but was great for the 1/8" vines and 1/4" leaves. This meant 3 CFH propane and 12 CFH of oxygen. That's a lot of oxygen for one of those small tanks. So, I started looking into other gases. Acetylene is not allowed near my house, so I looked into MAPP. This requires only 2-2.5X oxygen for about the same heating rate. But, the MAPP is much more costly. It is about $9 per pound (8.7 cu ft) in the disposable tanks, and $29 for a 7.5 lb tank with $55 refills. If one approximates $10 for 40 cu ft oxygen, this is still more expensive than the propane per BTU or per hour.

So, I wonder if any of those brazing fuels are better. Especially the ones that are mainly propane. Oddly enough, these advertise lower oxygen ratios and substantially higher flame temperatures than propane. Does this make sense in theory or practice? I am looking at things like propylene, chemtane, flamex, hydroflame, FC-2 or razor gas. Has anybody tried these out for heating, and if so, how good are they?

[irnsrgn]

Have you ever been in a steel rolling plant that makes structural shapes, They use Natural gas/Oxygen torches, the designated cutting only torches are about 6 feet long and are left burning at designated areas so when something happens and a billet is being rolled and it jumps out of the trough, its impossible to stop the rollers till the billet has been completely rolled to shape. Then in come the torch men wearing wooden soles and cut the tangled hot mess into pieces and a loader then scoops the cut up scrap up and its loaded back into a pot for remelting.

Its another alternative but rather impractical for most shop users, most of the alternative gases to Acetylene work well to some degree for cutting, but just don't have the oompf for torch welding, but some such as Mapp do get hot enough for brazing or heating.

the normal air you breath is only 21% Oxygen at best, so compressed air is out as an oxidizer for use with alternative gases. Fuel gases are designated by there burn time in feet per second from the ignition source in free air and this is governed by there access to Oxygen, the slower the burn time the more oxygen they consume.

sorry for the rambling, I guess I should not have replied in the first place.

[tbrforge]

worked a few years in a steel wharehouse, cutting scrap from the oxy-fuel burney multi head cutters and plasma torches. Cut scrap up to six inch thick "cobble" (contents unknown but I'm sure thats where all those lost files went. Used oxy-natural gas. Got paid by the ton so learned to be as fast as could be with natural gas cutting. Ended up modifying tips larger. Normal Oxy pressure. As is usally the case all data must be considered. Price, availability, permission, safety, etc. in the end things balance out. The smaller the container the more cost though eh?

[Candidquality]

Might try a search for gasoline fueled cutting torch. I know they are used in disaster areas as it's usually easy to find more fuel. Supposed to completely oxidize the metal as it cuts. Never used one personally but I've heard good things from a few that have. Sorry I can't be of more help, but I d all my cutting with a chisel.

[Dale Russell]

" sorry for the rambling, I guess I should not have replied in the first place "

Jr , not rambling .. good down to earth info . I for 1 wouldn't think twice ( about being wrong ) about any of your posts mate



Dale Russell

[evfreek]

Hi. Thanks Irnsrgn and tbrforge for the interesting application stories. I have a coworker whose dad works in a scarfing mill, and he has some interesting experience too. Yes, natural gas is cheap, but it uses more oxygen. I suspect that if the usage rate is high, natural gas-oxygen is the way to go. Especially, if you have a deal on the oxygen. A lot of the big factories use PSA or on-site liquefaction which is much cheaper per cu ft than tanks. I got a quote from the local gas shop on plumbing a natural gas line: $800. I will have to monitor gas usage for a while before considering this. Also, around here, it seems that you cannot have an open gas tap like you see in laboratories. The installation has to be permanent.

[irnsrgn]

me thinks you making a mountain out of a mole hill, Oxy Acet is the way to go and if you get decent sized tanks the cost is far less than the toy ones most people get to try and save money, but just blow it trying to be cheap.

[J W Bennett]

I use O/A for welding,spot heating and heavy cutting. I bought a plasma cutter early last year and cut my O/A bill down by almost 1/2 what it was. I use the plasma for anything under 3/8" and have cut 1/2" with it. It has almost paid for itself already.
The gasoline torches were popular around here among junkers about 15 years ago but don't hear much about them anymore.

It all boils down to what your application is, how oftenyou will use it, Fuel consumption vs time and what is readily available.

John

[ThomasPowers]

Re bottle size: Getting in good with the local gas suppier can help too. I once had to cut up about 10 tons of wrought iron plate and the friendly welding supply company allowed me to "borrow" the large tanks and only pay for the gas used. I did have to put down a deposit for the tanks on a credit card but they refunded it when I returned the tanks.

[Bentiron1946]

Oxy-propane set ups are popular for small work with jewelers. They seem to be OK for silver soldering rings and such but melting gold and silver for casting where you need a lot of heat in hurry nothing beats o/a. For work around the shop I use o/a for twists and curls using a rose bud or just stick it back in the forge that uses an atmospheric propane burner.

[evfreek]

That's a good idea, Thomas. I also have a good relationship with the local welding supply, and I can rent tanks at a pretty good short term rate. That would be good for a cutting "party". But, I don't have a pickup truck or trailer, so hauling those big tanks can be a chore. There is a local arts consortium which always has 5 240's filled up. I can go there to do bigger work. They offered me one of their "restricted bottles". You can only fill at one dealer, and they charge double. That tank almost never gets used, since the deal is so unfavorable. I need a truck ;)