Author Topic: Compressed Air/ Propane Burner (Read 15367 times)

Meldonmech · « **on:** May 23, 2014, 08:47:54 AM »

Hi Guys
I was impressed with Ironman's propane burner, back in his October post. I decided that this burner was something I must have. I had aquired a small compressor a couple of years ago and never really used it. Rated at 2bar it would probably been capable of running a small engine.

Meldonmech · « **Reply #1 on:** May 23, 2014, 09:11:45 AM »

I next needed an old oxy/acetylene torch to modify, and had to wait some time before one became available on ebay at the right price, not wanting to spend too much on some thing experimental.

Meldonmech · « **Reply #2 on:** May 23, 2014, 09:18:31 AM »

I started to look for some tubing and managed to find some 35mm diameter. A small billet was then turned to fit in the back, this was threaded 1/2 inch BSF.

mattinker · « **Reply #3 on:** May 23, 2014, 09:22:18 AM »

I remember in our "metalwork" classroom, there was a town gas and compressed air torch that I used to braze the handle on to a screwdriver that I made. The nice thing about propane is that the pressure is high enough to create a "venturi" effect acelerating the air flow. Town gas isn't under sufficient pressure to do this. The compressor would get around this problem!

A couple of passing thoughts, regards, Matthew.

Meldonmech · « **Reply #4 on:** May 23, 2014, 09:24:09 AM »

A nozzle was made to screw into the torch 1/4 inch BSF, and 1/2inch BSF into the flame tube. A 1.5 mm hole was drilled for the jet.

Meldonmech · « **Reply #5 on:** May 23, 2014, 09:25:55 AM »

The torch was then assembled

Meldonmech · « **Reply #6 on:** May 23, 2014, 09:43:31 AM »

A temporary hearth was assembled on my picnic table to enable the experiments to proceed. A 4inch nail was to be heated up. I connected the propane and set it at 0.7bar, and the air at 2bar. I switched on the gas, and started the compressor, lit the gas and turned to full, turned the air on very slowly, and was amazed and surprised at the power of the jet. The nail heated up to bright red in a matter of seconds. What a difference that compressed air makes. As to the jet size, diameter of flame tube and gas and air pressure settings they were perfect. I really cannot believe what I achieved it has given me a real boost.

Thank you Ironman for your help.

Cheers David

Meldonmech · « **Reply #7 on:** May 23, 2014, 09:50:13 AM »

Hi Matthew

Thanks for comments, I to can remember the metalwork classes at school, used the brazing hearth a lot for annealing gilding metal. I was making a planished tankard which I still have.

Cheers David

Arbalist · « **Reply #8 on:** May 23, 2014, 10:05:08 AM »

As Mathew says, propane has enough pressure to produce a Venturi effect to push more air through.

http://amalcarb.co.uk/downloadfiles/amal/amal_gas_injectors.pdf

It may be more cost effective to conserve the heat by using refractive bricks rather than increasing the gas pressure. Just a thought.

vtsteam · « **Reply #9 on:** May 23, 2014, 10:27:43 AM »

Interesting!

I'm going to have to look into that besides the atmospheric torch I have for brazing

That's quite a simple torch, too -- never seen one quite like it before for oxy/acetylene. Kinda cool! Hose clamps on the fuel line, though, please.....

Meldonmech · « **Reply #10 on:** May 24, 2014, 02:50:41 AM »

Arbalist

Tried to view your reference re venturi PDF and all I got was a blank PDF page?

Cheers David

Meldonmech · « **Reply #11 on:** May 24, 2014, 02:56:30 AM »

Vt

Remiss of me to not fit the hose clamps, especially as I had them sitting there in front of me. They have now been fitted.

Cheers David

Meldonmech · « **Reply #12 on:** May 24, 2014, 03:00:50 AM »

Hi Guys

I have now included a pic, of the firebrick hearth I temporarily built on my picnic table. Can anyone suggest any improvements?

Cheers David

awemawson · « **Reply #13 on:** May 24, 2014, 03:23:28 AM »

Weld up an angle iron framework that the fire bricks sit in snugly to hold everything safely together. I did a similar thing many years ago and it evolved into a blacksmiths hearth on 'supermarket trolley' casters with a blower mounted underneith. It's also been known to double up as a barbecue on several occasions

philf · « **Reply #14 on:** May 24, 2014, 03:37:42 AM »

Quote from: Meldonmech on May 24, 2014, 02:50:41 AM

Arbalist

Tried to view your reference re venturi PDF and all I got was a blank PDF page?

Cheers David

David,

It works OK for me. A while ago I got fed up with pdfs not opening using Adobe Acrobat Reader and I've ditched it in favour of NitroReader ( http://www.nitropdf.com/pdf-reader ) which has solved the opening/stalling problems and it has the added advantage of being able to create pdfs from any package you can print from.

Cheers.

Phil.

Arbalist · « **Reply #15 on:** May 24, 2014, 05:39:12 AM »

Sometimes it's also better to right click and download the file to your HD and then open it.

Arbalist · « **Reply #16 on:** May 24, 2014, 05:48:01 AM »

Your hearth looks ok David but you can get a lot more heat if you use insulating or refractive fire bricks.

http://kilnlinings.co.uk/insulation-bricks?zenid=60ca29a57806cde5fdf9065cc18d2cde

You can sit a hard fire brick in the bottom to work on.

Meldonmech · « **Reply #17 on:** May 25, 2014, 07:24:13 AM »

Hi Guys

Thank you all for your comments.

Cheers David

ironman · « **Reply #18 on:** September 19, 2014, 02:43:02 AM »

Meldonmech

It was great to see you have a working compressed air/propane burner like mine. Buying large burners for propane can be expensive!

Can you please make a video of it running?

ironman

Meldonmech · « **Reply #19 on:** September 24, 2014, 11:24:28 AM »

Hi ironman,

Thanks for your interest, unfortunately I don't have the facilities for making videos, but am more than happy to answer any questions you may have.

Cheers David

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Author Topic: Compressed Air/ Propane Burner (Read 15367 times)