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/diy/ - Do It Yourself

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1281406 No.1281406 [Reply] [Original]

Hey /diy. I need som help. Im a blacksmith whose used coal and charcoal for many years. And im switching to propane for a more efficient smelting method. Problem is the pin hole for the gas to escape. Whats the correct drill bit to use? Ill have oxygen control. So i can get the ratios right. But i dont want too much propane. Ive heard 1/32, but i dont know it thats just common hearing because its conveinient. Is there a more efficient size? Thanks~

P.s. pic is my current setup.

>> No.1281412

>>1281406

I AM NOT AN EXPERT.

but. a few years ago I replaced the main burner in my propane (LPG) furnace. the old one had an orifice of about 0.093. (1/32 is 0.031, and keep in mind that area is proportional to the diameter squared).

the optimum orifice, I believe, is when the flame is mostly blue, and not yellow. Yellow means too much gas or not enough oxygen.

I reduced mine to 0.062 (1/16 drill bit) and the flame is nice and blue and looks to be the right size for the combustion chamber. This was 4 winters ago, and it has seemed fine since.

So, if 0.031 gives you a nice sized blue flame then it's fine in my amateur opinion. If you can go to a larger diameter and still have a blue flame you might get higher temperatures with similar efficiency.

And someone who knows will eventually tell us both what we need to know.

>> No.1281417

>>1281412

I should add that my furnace has a plate that says the orifice should be #41 which, if it's a drill size, is 0.096 and I measured the old orifice to be very close to that.

However, the plate also says the manifold pressure should be 11" W.C. which I think means 11 inches of water on a manometer.

So I made a manometer which you may already know is simply a U shaped tube of water with one end connected to the pipe leading to the burner. In my case the valve has a plug you remove and install a standard pipe fitting. The other end of the tube is open to atmospheric pressure, and the water will be pushed by the manifold pressure and the difference should be 11 inches for me. I could not get the pressure that high which is part of the reason I went to a smaller orifice, but the main reason as mentioned above was that the flame was rather yellow before.

Does manifold pressure matter to you? I don't know, but it's easy to rig up and test if you are the type who likes to do that sort of thing. Maybe some HVAC guy will tell us. Back when I was trying to burn my place down I asked on an HVAC forum but once they figured out that I was not licensed they banned me.

>> No.1281423

Start small and then widen it if needed

>> No.1281556

>>1281423
I might. I just dont want to buy a bunch of tiny as bits that i probably wont use again. I dont do micro work often, at all

>>1281412
>the old one had an orifice of about 0.093.

>I reduced mine to 0.062 (1/16 drill bit) and the flame is nice and blue

So stepping it up in opening made the flame stronger?

>>1281417
>Does manifold pressure matter to you?

Not at all

>> No.1281560
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1281560

I drilled a 1/64" hole for my venturi style burner based on the RR ez burner design. It works really well, shown here running at 12 psi its producing a really nice jet.

Im in the middle of rebuilding my forge and making new burners for it. Old one had a 1/32" hole and didn't burn as nice as the new one.

>> No.1281563

>>1281406
Also that coupling on the end of your mixing tube needs to be tossed out or reworked. It needs to be flared or use a 3/4"-1" reducer.

>> No.1281567

>>1281563
Fair point. Ill throw it in the forge and open it up a bit. Thanks

>> No.1281568

>>1281560
1/64 yeah? Hmm... I actually may have to get a micro set and just see what works best for my set up

>> No.1281569

>>1281556
>I might. I just dont want to buy a bunch of tiny as bits that i probably wont use again.
You can get a set of tiny drill bits for like 3 bucks at harbor freight.

>> No.1281571

>>1281567
>>1281568
What size is the nipple for your mixing chamber? 3/4"x8"?

>> No.1281575

>>1281571
1" x8"

>> No.1281581
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1281581

>>1281575
The size of your mixing tube might be hold you back a little bit. It will require more volume of fuel/air then may be economical. Previously I could run a 20lb tank of propane dry in about 4 hours of continuous usage. Im expecting to get close to double the use now with the new burners.

>first rendition of the burner, lousy flame as you can see.
1 1/2"x3/4" red-3/4"x8"nipple-3/4"x1"red
Fuel supply is all 1/8" brass pipe. This burner has a 1/32" outlet hole and you can see how anemic the jet is. When I built the new burners all I did was swap out the 1/8" brass nipple for one with a 1/64" hole and ground the threads off the outlet reducer to lessen turbulance.

>> No.1281611

>>1281581
>It will require more volume of fuel/air then may be economical.

Hmm.. Okay, ill keep that in mind. Ill watch how it goes and change it accordingly.

>>1281581
>all I did was swap out the 1/8" brass nipple for one with a 1/64"

Okay, ill try 1/64. Thank you very much~

>> No.1281637

>>1281611
Good luck with your project anon. One last question because it often gets overlooked, do you have an adjustable propane regulator for your setup? Bbq regulators wont work.

>> No.1281641

>>1281637
Indubidubly. You can see it in the original post picture

>> No.1281647

>>1281641
Oh yea... Silly me. Hah

>> No.1281669
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1281669

>>1281647
Lol, no biggie. P.s. added the oxygen regulator. Very fancy and super complicated. Harhar

>> No.1283361

Okay! I did a test. The flame is just reds and yellows with a hint of blue.

>>1281581

>mixing tube might be too big

I think youre right. I got a smaller pipe and ill try, asap.

>> No.1283830
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1283830

Made some adjustments and bam. It still gets flicks of yellow/red a bit. Also, it doesnt sound too strong. I turn my reg. Up to about 25 psi and i get it. Any more and theres a lot of yellow red flicker.

>> No.1283873

>>1283830
It looks pretty good. How well is the port centered in relation to the tube?

>> No.1283877

>>1283873
Very well. I made sure of that before i tacked it in place. Why do you ask?