acetylene vs propane

[Jonny Cycles]

However I have a hard time finding the UN-J universal nozzle

I had an unused tip laying around that I simple brazed the Paige adaptor to -

[Guillaume]

I had an unused tip laying around that I simple brazed the Paige adaptor to -

Ho! I have two No2 and two No4 so I can sacrifice one of them. Thanks for the tip.

However, yesterday I brazed a IS disc mount to a fork with a Victor 2 tip and it went really well. Better than with acetylene.

[Doug Fattic]

Just as a reminder the best possible results come from using a UN-J (or its clone the Gentic 881). The oxygen supply holes in the UN-J mixer/elbow are bigger and more plentiful than a unit dedicated to acetylene use (like say a Victor 2-W-J). Propane gobbles up more oxygen. Of course it is possible to make use of what we have to avoid the expense of buying new. As you have discovered, your acetylene equipment worked okay with propane.

I'll add that I like to use a 3 or 4 TEN tip if I am working with a fork crown or BB shell. The Paige tips were designed for the jewelry trade and their biggest #5 tip is not always big enough for me (even though I can make it work). Richard at Paige says they are coming out with a bigger tip recognizing that there are applications where a bigger tip is desired. I'd suggest that if you can afford it, I would buy a 3-TEN and 4-TEN tips when ordering the 881 from Torch Tools. I've gotten to like swapping out different sized tips for different applications.

[classtimesailer]

It took me so long to finally start acquiring my equipment that all the parts are now available to put together a "perfect" beginner set up:AW1A, AT-61, Paige Kit, TM-hose, Arrestors at the regulators, and a pair of Harris 25GX regulators. I'm considering the recommended rubber hose to hang from the ceiling, check valves at the torch, and I'm leaning towards a 40 ft. oxygen tank.
Propane tanks are confusing me. How does Cyberweld get $113.00 for a 5 lb. tank? And my local Ace Hardware has a 11 lb. tank for $65.00. Then there is a 20 lb. Bernzomatic from Lowes for $35.00 Aside from capacity, is there any difference?

[Doug Fattic]

Propane tanks are confusing me. How does Cyberweld get $113.00 for a 5 lb. tank? And my local Ace Hardware has a 11 lb. tank for $65.00. Then there is a 20 lb. Bernzomatic from Lowes for $35.00 Aside from capacity, is there any difference?

Congratulations on collecting the brazing equipment you need to get started. Where do you plan on getting a refill? I think the tanks you listed come empty and somewhere you have to get them filled. Buying one of those tanks may not be your cheapest or most convenient option. Where I live 15 lb BBQ tanks are sold everywhere around me. At my local grocery store, almost every gas station and every other kind of store that carries tools or farm supplies. Even the drug store. A full one costs $50 or less and a refill $20 or less. A refill is actually just an exchange of my empty tank for another full one. Some of these stores are open before I wake up and after I go to bed. A BBQ tank also has the right fitting for a typical regulator.

While not technically necessary, it is smart to extend your TM hoses away from the tanks with a T rated 3/16" rubber hose. Probably 12 1/2" length is all you need. Hooking it up to the ceiling keeps the hose from dragging on the floor or getting drops of hot flux from falling on it. And keeps your tanks a safe distance from your hot action.

[classtimesailer]

I'll put the extra hose on my list. There is a propane seller about 6 blocks from me. I'll see what the local welding supply store recommends for my oxygen tank. The idea of owning and caring for my own tanks and having them refilled appeals to me despite the inconvenience. Thanks Doug--for the thread and your attention to it. I can act a little smarter because of it.

[Doug Fattic]

I'll put the extra hose on my list. There is a propane seller about 6 blocks from me. I'll see what the local welding supply store recommends for my oxygen tank. The idea of owning and caring for my own tanks and having them refilled appeals to me despite the inconvenience. Thanks Doug--for the thread and your attention to it. I can act a little smarter because of it.

All the welding supply stores in my area just trade tanks with a already filled full tank when you bring yours in for a refill. Buying a tank from a local welding supply store just means that you get to use tanks in their system and not that the one you buy is actually yours. Lots of places also rent tanks for a certain amount per month. This can be a good option starting out so you don't have to pay that much in the beginning. It also allows you to use your brazing equipment to get started if you will be looking to find a good used oxygen concentrator. At any time they let you buy instead of rent. Keep in mind that in some bigger cities welding supply stores won't allow transportation or delivery of pressurized tanks to non business locations. That is one of the reasons a concentrator is popular.

[Jim Gourgoutis]

I’d recommend just renting a 20lb propane tank from Blue Rhino or similar. Keep in mind that if you buy your own tank, it will need to be tested and recertified every 10 years or so (there’s a date code stamped on the collar around the valve) before you can get it refilled. Swapping a rental tank avoids this hassle.

[classtimesailer]

Somewhere in this thread, I thought that I read that the oxygen regulator should have a 0-50 psi delivery gauge. Should I also seek a 0-50 or narrower 0-15 gauge propane regulator?
My local family owned welding supply will refill my tanks while I wait and while I have so much to learn, I'd rather not mess with a used oxygen concentrator that may need my "attention".

[Doug Fattic]

Somewhere in this thread, I thought that I read that the oxygen regulator should have a 0-50 psi delivery gauge. Should I also seek a 0-50 or narrower 0-15 gauge propane regulator?
My local family owned welding supply will refill my tanks while I wait and while I have so much to learn, I'd rather not mess with a used oxygen concentrator that may need my "attention".

The narrower the operating range on either the fuel or oxygen regulator the better. The operating range you will using to run your brazing equipment will typically be at 5 psi or less. That means any pressure setting much beyond that is useless for our purposes. A regulator that has a narrower pressure range can provide finer adjustment when the control T knob is being turned. That just makes it easier to adjust the pressure to exactly what you want.

Some newer acetylene regulators will work fine for propane. Propane is more corrosive on seals and the newer regulators can handle both fuels. While we are talking about regulators, a 2 stage regulator is better than a single stage. A larger diaphragm is better than a smaller one and a 2 1/2 diameter gauge is easier to read than a 2" one. Propane however seems less sensitive to fine pressure settings than acetylene so a cheaper one makes less difference in being able to get a stable setting.

A student in my current framebuilding class picked up in IL a practically new Devilbiss 525 oxygen concentrator for $125 this last week end. It had been listed for $200 for a long time with no takers. So there are deals out there but it is just by lucky chance one is in your area. A more common asking price is $400. M&M Medical in Beaverdale PA sells refurbished ones with a 3 year guarantee for $300 if one doesn't want to wait to get locally lucky and can be assured it will run properly.

[jclay]

Somewhere in this thread, I thought that I read that the oxygen regulator should have a 0-50 psi delivery gauge. Should I also seek a 0-50 or narrower 0-15 gauge propane regulator?
My local family owned welding supply will refill my tanks while I wait and while I have so much to learn, I'd rather not mess with a used oxygen concentrator that may need my "attention".

Doug and I are kinda the Brooks and Shields of the regulator discussions around here so the following information isn’t news to him (hi Doug!). There were some very informative regulator discussions on the original framebuilders list a couple of decades ago but I think that the material is no longer available. I had fairly lengthy conversation with a Smith Equipment regulator engineer two decades ago when I started framebuilding because I was having gas flow problems (defective lightweight hose) and was curious about the opinions that were being aired on the forum; certain things didn’t make sense. Here’s an abridged summary of the high points:

Normal welding regulators are commodity items and have coalesced on a standard design for decades. Any single stage unit from a reputable mfg will provide adequate pressure/flow of the gasses for our purposes.

Even if you choose LP I’d get an acetylene regulator that’s listed as being compatible with LP/alternate fuels; at this point I think that most major’s offerings are, but confirm. Reason: They’re gauged and possibly set up (different spring) for operating at lower pressures.

With the enormous decline in industrial oxy/fuel welding (actually it's the utter demise of aircraft oxy/fuel welding) you may be hard pressed to find a low pressure oxygen regulator (like 0-20psi or 40, thereabouts). If you end up with a 0-150 psi oxygen unit then a lower pressure gauge might be helpful. It won’t change actual regulator performance but it will make it easier to set the low pressures we use. In the old days, as I recall, the spring in better lower pressure regulators was of a different constant to provide better performance at those lower pressures. You might get lucky with a regulator rebuilding outfit; they might have a refreshed, lower pressure oxygen regulator for sale. I see 0-100psi units for sale, now.

Regulators with larger diaphragms don’t deviate from setpoint as much as those with smaller diaphragms. It doesn’t really matter much; plenty of folks use compact (small diaphragm) regulators. I find them a little annoying but a large diaphragm won’t really make you a better brazer; practice will. My oxygen regulator is an old medium diaphragm (2.25” I think, neoprene) Smith; my acetylene is now a used Victor SR 450 (3” or so, stainless) and extremely stable. I often think about getting an SR 460 for oxygen but the low pressure ones are hard to find….and it doesn’t really matter. The neoprene units do drift a fair bit at startup, while the rubber stretches to conform to the change in pressure so be attuned to that.

Regulators with smaller diaphragms waste less gas on bleed-down though, and on the oxygen side that can be surprisingly meaningful (which is why I don’t bleed the primary side of my oxygen unit...but I am NOT recommending others do the same).

Definitely get conventional 3/16” Grade T twin welding hose (suitable for alternate fuels) so you never have to think about fuel compatibility, whether you use that alone or attach a 10-ish foot ultra lighweight hose for connection to the torch.

I rapidly went through two sets of lightweight Smith (now Miller) Kevlar hoses and don’t use’em anymore because they’re too fragile. I’m happy with the stiff, tough, B/B, 1/4” (wish it was 3/16”) T grade I bought when my second lightweight hose failed and that was all that was available on a Saturday….but what makes that OK for me are the A/B adapters to my round body AW1A; they give me, effectively, a flat surface with which to grip the torch, at the connectors. I don’t hold it by the body but by the connectors. I think the ULW hoses that tinmantech.com sells are probably quite good but personally I don’t find them compelling; many do.

Two Stage Regulators: Changes in cylinder pressure during operation cause the secondary pressure (delivery to torch) to change (rise); two stage regulators reduce that effect but in framebuilding we’re not brazing continually for nearly a long enough time for that to matter; aside from that it’s a simple matter to adjust the flame. Two stage regulators are more expensive and completely unnecessary outside of serious production where primary gas pressures change rapidly. We’re on the other side of the Earth with respect to that Zip Code.

If you want the most stable gas delivery possible for our purposes, the Victor SR 450 and 460 (low pressure version) are pretty much impossible to beat and the SS diaphragms will outlast you....BUT they are in no way necessary.

GET TRAINING on safe the use of the equipment.

For my money, the Meco Midget is far and away the best torch going for aircraft or bicycle framebuilding if using compressed gas cylinders (not an oxygen concentrator). Ready to light it's lightest and if you orient the bend in the tip tube (get the longer one) to be in plane with the body then the valves are positioned perfectly for thumb & forefinger and the torch won't rotate in the hands. With ULW hoses you hardly know it's there. I settled on the AW1A because I occasionally need the cutting head (thought not in years....), which isn't available for the midget. Wish I'da kept my Meco Aviator Jet for posterity but the Midget is better.

[jclay]

Somewhere in this thread, I thought that I read that the oxygen regulator should have a 0-50 psi delivery gauge. Should I also seek a 0-50 or narrower 0-15 gauge propane regulator?
My local family owned welding supply will refill my tanks while I wait and while I have so much to learn, I'd rather not mess with a used oxygen concentrator that may need my "attention".

The Miller Smith 30-20-540 is an example of a nice, medium diaphragm regulator; it's a 2" or 2.25" diaphragm, neoprene or some elastomer (not SS). I use the older version, before Smith was purchased by Miller. Here's the new version on ebay: https://weldfabulous.com/miller-smit...uty-regulator/

Series 30 (medium diaphragm)
-20 is the intended operational range in psi
-540 is the connection spec.

It, like others from the majors, is an excellent little regulator. The nice thing for us about this particular model is that it's the low pressure version. As a nice surprise, I see that it's a current product but doesn't appear to be available in the twin pack (fuel + oxygen units) which would have saved a few bucks.

[classtimesailer]

Thanks Jon. Good to know that the all the major manufacturer' regulators are dependable. The Harris 25GX is available in 1-15 psi delivery pressure in oxygen and propane versions and at $75 with a 7 year warranty is attractive. My local family owned gas and welding supply store doesn't carry Harris but maybe they carry Smith (Miller) and the price looks reasonable enough to buy local. I received my ultra lite and 12.5 hoses from Tinmantech. Ultra lite is exactly that!

[jclay]

Thanks Jon. Good to know that the all the major manufacturer' regulators are dependable. The Harris 25GX is available in 1-15 psi delivery pressure in oxygen and propane versions and at $75 with a 7 year warranty is attractive. My local family owned gas and welding supply store doesn't carry Harris but maybe they carry Smith (Miller) and the price looks reasonable enough to buy local. I received my ultra lite and 12.5 hoses from Tinmantech. Ultra lite is exactly that!

I didn't see a 25GX oxygen with such a low secondary pressure range in the Harris catalog so if you've found one, jump on it; particularly at that price!

Also, if using acetylene, understand that there is a max withdrawal rate that's a function of cylinder size. Check me but I think the accepted ratio these days is 1/10 of the cylinder volume expressed as SCFH; a 75 cf acetylene cylinder would have a max withdrawal rate of 7.5 std cu feet/hr so an AW205 (6 scfh consumption at "proper" max fuel setting) would be the largest tip you could drive if adjusted as per the instructions (get the acetylene only soot to disappear, then adjust the O2 for the type of flame you want). It used to be 1/7th but was revised in the not too distant past. Do your due diligence on that.

[Jim Gourgoutis]

The Miller Smith 30-20-540 is an example of a nice, medium diaphragm regulator; it's a 2" or 2.25" diaphragm, neoprene or some elastomer (not SS). I use the older version, before Smith was purchased by Miller. Here's the new version on ebay: https://weldfabulous.com/miller-smit...uty-regulator/

Series 30 (medium diaphragm)
-20 is the intended operational range in psi
-540 is the connection spec.

It, like others from the majors, is an excellent little regulator. The nice thing for us about this particular model is that it's the low pressure version. As a nice surprise, I see that it's a current product but doesn't appear to be available in the twin pack (fuel + oxygen units) which would have saved a few bucks.

National make an oxygen regulator with a 0-30psi dial. https://nationaltorch.com/?page_id=428. I use an oxygen concentrator so I have no need for an oxy regulator, but I use their 2300.510 fuel/gas regular and have been happy with it (https://nationaltorch.com/?page_id=423).

-Jim G

[bikebones]

Thank you very much to everyone to shared their knowledge in this thread. It helped lots of people like me to get a decent set up with oxypropane and saved lots of time and money for us.

Also I have a technical question. As someone mentioned the primary flame of propane has not the same concentration of heat as acetylene, should we use the secondary flame for fillet brazing with propane? how far from the fillet ? I find a lot harder to keep consistency of my fillets with the primary flame of propane than acetylene.

[e-RICHIE]

Thank you very much to everyone to shared their knowledge in this thread. It helped lots of people like me to get a decent set up with oxypropane and saved lots of time and money for us.

Also I have a technical question. As someone mentioned the primary flame of propane has not the same concentration of heat as acetylene, should we use the secondary flame for fillet brazing with propane? how far from the fillet ? I find a lot harder to keep consistency of my fillets with the primary flame of propane than acetylene.

I'll wait for others to reply to you but in the meanwhile, welcome here and please use a first and last name in all comments and threads on the Frame Forum.

Thank you

[bikebones]

Thank you Richard

I wont forget to sign my posts from now


Francisco Serrano

[Doug Fattic]

Francisco, I'm going by memory but what I think I recall is that the hottest part of a propane flame tip is a couple of mms beyond the visible flame tip. I'm not sure what you mean when you say "secondary flame"? Unlike an acetylene flame where the inner flame can have 2 visible different cones, I can only see one inner cone on a propane flame. The secondary flame extends well beyond the inner flame so it can't be used as a length guide for anything.

By the way, it is as easy for me to use propane for fillet brazing as acetylene It just requires a slightly different technique. Most students have an easier time with propane because it slightly lower temperature doesn't require quite as quick reflexes. With more practice you probably wouldn't notice much difference either.

[bikebones]

Doug

that was exactly what I needed to know. 2mm beyond the visible cone flame tip on oxy propane.

I do have a compilation text file that includes some of your answers in this and other threads for sharing on a facebook new framebuilders group everytime someone request technical data about torch, gas pressure, flame adjustment and tips for oxypropane.

thanks again for sharing your knowledge

Francisco Serrano