NeoTechs newbie melting endevours. ;)

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NeoTech:
So the pulsejet problem is still an issue even with a filled tank.. After closer inspection firing it in my basement without any winds.. the pulsing can occur when the choke is open to wide.

With the full tank its reeeally easy to make the flame go out by opening up the valve to much. and the choke makes it pulse when opened to much.. the dangerous part is that the ignition occurs in the tube, like 1-2cm from the mig tip.. you can see the blue ball form and getting pushed forward.. so most of the ignited heat is taken up by the burner tube..

Should i start over?!? Make a new tube with smaller intake.. maybe only 1 14mm slot and make that slot like half the length??

awemawson:
To avoid 'burn back' your gas speed at the jet has to equal the flame speed. If it is slower and you get a burn back it is potentially quite dangerous. In oxy-acetylene burners it could be lethal, but as you only have a fuel gas and no oxygen other than that from the atmosphere, it is somewhat less likely to demolish your house :ddb:

NeoTech:
yeah the burn back seems to occur when i let to much air into the tube.. but if i dont it doesnt form a proper blue jet in the end of the burner tube and the heat tend to dissipate into the burner tube body instead..

Dont know if i should try a bigger or a smaller nossle.. i have 0.8 tip on it now.

tom osselton:
How big is your furnace I'm asking because the pic of your burner sitting on your lid looks like it is about 2.5 / 3" vent hole.
I think you have a backpressure problem, As you said the burner is a snug fit so the only air getting in is through it so if the lid vent is too small the pressure I think will slow the air flow basicaly making the furnace/burner gasp for air or pulse. Have you tryed slipping the lid to the side a bit? I wouldn't take this for gospel but others can put in their 2 cents or tupence for the other pond people. A furnace with a blower has the air forced into it so the lid hole isn't as critical thats the way I see it at least.

Tom

NeoTech:
yeah,. the lid hole is about 70mm, so i guess 3" is correct. The lid itself dont sit "flat" onto the furnace so there is openings around it where some eascaping is done.

But i agree i wonder if i should try to conjour 3 attempts.. one is a bigger nossle for the burner effectivl slowing the gas down and the air pull. Second is a burner tube with a lot less venting, instead of 4 slots about 50mm long and 14mm wide i should try with just one slot thats half the length for starters. And finally testing with a airpressure connector hooked up to my compressor maybe. I thought this was more for the oil burner types though.. But as you suggest the natural aspiration could be severly lacking.

Today its pouring though.. *effin weather* So i will just make parts. ;)

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