Scooper

I'm a hobbyist framebuilder whose only experience has been silver brazing lugged frames using oxy-acetylene. I have a Bernzomatic OX2550KC kit, which includes a torch and cylinders of oxygen and "Max Power Propylene" gas (my understanding is that they stopped producing MAPP gas). According to the Bernzomatic website, the Max Power Propylene maximum flame temperature in oxygen is 5,193º F, which should be sufficient for silver brazing.

I'd like to use Oxy-Max Power Propylene rather than Oxy-Acetylene since I'm pursuing this as a hobby and am concerned about the safety of having large O-A cylinders in my garage workshop.

The torch that comes with the Bernzomatic kit is pretty basic, and I'd like to know if I could use a Smith AW1A torch or similar O-A torch with the oxygen and Max Power Propylene cylinders that came with the kit. It seems like I'd have much better flame control.

I e-mailed Bernzomatic with this question and got a one sentence reply, "We do not recommend altering any of our products." I suppose that reply was to be expected.

Has anyone used a decent O-A torch with the Bernzomatic gas cylinders?

TIA.

GrayJay

Given that it burns hotter than oxygen/propane 4580°F (which is sucessfully used), it should be plenty hot for brazing. Given than the Berz formulation MAPP subsititution has BTU density inbetween Acetylene and Propane, it seems reasonable to think that it could be used with most any torch that has been proven sucessfull with both Propane and Acetylene. I suspect that you will go through the tiny Max Propylene cylinders very quick and it will be expensive fuel for more than a frame or two. The one time I long ago played with a O2/mapp setup I depleted the tanks in about 10 minutes of use. Have you considered a BBQ propane/oxygen system instead? Use either larger bottled O2 tank or a concentrator if you have safety reservations about O2 tanks.

Scooper

Thanks for the quick reply. I'm also considering propane with an O2 concentrator, but I bought 12 of the 17 oz. "Fat Boy" Max Power Propylene cylinders for $123.00 and want to see how many I go through in building a frame and how well a Smith torch works with the Bernzomatic gas first.

unterhausen

it might be easier to go with a propane bottle from a gas grill, most LWS can supply you with an adapter for that. I don't know what to tell you about the oxygen, regulation is nice.

Scooper

You're right; I probably should have just gone with propane and O2 to begin with instead of messing around with the Bernzomatic stuff.

squirtdad

you will go through a lot more of the Oxygen bottles than you will the fuel bottles, if your experience is anything like mine has been with the oxy/mapp setup. I have not done frames, but have taking bits off frames and used the oxy/mapp for other light brazing.

tuz

Yeah I guess once you've invested in the torch, hoses and regulators, you are better off getting larger cyclinders. That being said, as long as you can find a way to connect the torch to those small cyclinders, it should work. Most torch nozzle/mixers work for many types of fuels.

Scooper

Thanks, squirtdad and tuz.

I'm beginning to think I should just invest in an O2 cylinder I can have refilled at the local Airgas welding supply and use bottled grill propane from Lowe's or Home Depot. My biggest concerns with acetylene are its instability and the legality of using it in a residential garage; propane OTOH is relatively safe and legal. Oxygen-Acetylene flame temperature is ~5,615° F while Oxygen-Propane is only ~4,579° F, but that should still be plenty adequate for silver brazing.

tuz

I've been working with propane for a bit over a year and I'm used to it. Propane yields a higher BTU actually, so in a way preheat is smoother with less chance of local overheating. It's fine for bronze lugwork, and I'm getting better for the fillets. So don't worry. Get many tips and change them depending on the work. And while propane is more readily accessible, it is still hazardous. It is denser than air and leaks will fill basements...

GrayJay

Bit of reading I did suggested that an injection torch would be better for propane due to its greater density. In this type of torch, the pressurized O2 stream travels through a venturi creating a vacuum that pulls-up the propane from a relativly low pressure source, mixing it more thouroughly. Anyone have comparitive experience using propane with both standard and injection torch types? Suggestions for a suitable injector torch for brazing?

Back to Scoopers current situation, I would think that the density and heat content of the replacement pseudo-Mapp gas is closer to Acytylene than propane and most any Acytylene torch would work with the Burz-max.