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Flashback arrest

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First off i just want to say hello to everyone and say thank you for the abundance of information in the forum.

My question is would it be wise to install a flashback arrest ( the ones used on a cutting torch) between the gas valve and the T-burners?

 

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A flashback arrestor is only needed on oxy-fuel torches; not on air-fuel burners, where they are a complete waste of your money.

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2 hours ago, Mikey98118 said:

A flashback arrestor is only needed on oxy-fuel torches; not on air-fuel burners, where they are a complete waste of your money.

Mikey, since you reminded me of a long forgotten question with this, I figured I better ask before I forget again.

One of these days, I'm going to be modifying an old Johnson forge to blow a ribbon burner.  These introduced the propane (or natural gas) into the radial fan's intake..same general area where it's sucking air.  Usually when I see designs these days, the fuel is introduced into the air downstream stream after the blower.  

There is a gas solenoid so that if the fan's not powered, the gas is shut down..so no risk of just dumping fuel out of the system.

Just curious if there is any good reason to do one over the other:  Fuel at the air intake or further downstream?  The Johnson method would sure mix the fuel and O2 well...which is likely good for combustion but does that increase any potential dangers?  If you choke the air off too much (they have a gate at the radial intake, not in the output stream) is there a chance of the pressure/flow dropping to the point where you might get flashback?

Hope all that made some sense...

 

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3 minutes ago, Kozzy said:

Just curious if there is any good reason to do one over the other:  Fuel at the air intake or further downstream?  The Johnson method would sure mix the fuel and O2 well...which is likely good for combustion but does that increase any potential dangers?  If you choke the air off too much (they have a gate at the radial intake, not in the output stream) is there a chance of the pressure/flow dropping to the point where you might get flashback?

"Fuel at the air intake or further downstream?" Good question, and one that will continue to be debated. Why: because the closer to the air source the better it's going to mix. But the closer to the source the further into the burner system a flashback will go. On the one hand, a blown burner will provide more pressure to incoming air to counteract flashback; at the same time, this option provides an expensive target for the the minor explosion to ruin. So, it's a balancing act.

 If you choke the air off too much (they have a gate at the radial intake, not in the output stream) is there a chance of the pressure/flow dropping to the point where you might get flashback?  Another very good question, and one which the manufacture should answer :D

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I have never been a fan of introducing the gas upstream of the blown burner's blower inlet (no pun intended).  If specifically designed by the manufacturer for that I suppose it does provide additional mixing in the blower scroll, however, for the homebuilt units that most of us use I am concerned about not having a sparkproof blower in the presence of a gas/air mixture.  A little extra mixing tube (and potentially some elbows) is not a big deal.  

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