BG12 burner air / fuel setup for keggle

[garage_life]

Hi all, I've got a keggle with BG12 cast "banjo" style burner I'm fabricating a frame for.
Having a bit of drama getting the air fuel ratio sorted.

I haveve increased the jet to 2.0, reduced to 1.8 then 1.6 and have remover the air baffle / valve plate and tidied up the casting and enlarged a bit.


Bestformance I've had was with the 2.0 size jet but the flame has been pretty much the same combustion and only varied in size (bigger with the bigger gas orifice) with big light yellow tips -too much fuel, incomplete combustion and light sooting.

Removing the air valve plate cleaned up the flame a bit, previous owner clearly had it too rich as the bottom of the keg is heavily sooted.

My theory is I need more gas pressure to pull more air and reduce the gas flow with a needle valve (have one need a few extra fittings). Is a high pressure adjustable reg the way to go?

It seems the only variable I haven't messed with is gas pressure as I'm using a standard cheapo bbq 2.75KPa reg, haven't checked the output pressure yet.

Anyone got decent output and running clean let me know and also the best budget solution for an adjustable reg. I work with hydraulics so getting fittings is no problem.

Some pics although they look richer than IRL.

Cheers!

 

[garage_life]

Sorry about typos, on the app and can't figure out the edit....

 

[Sidney Harbour-Bridge]

Looks like it's missing a tap to regulate gas flow, I find with mine I need to turn the taps down to about 75% for a clean burn.

 

[garage_life]

Yep that's what I'm planning to do, needle valve tap to reduce amount of gas but keep it at full pressure. Are you using a standard bbq regulator or an adjustable one?

 

[garage_life]

Just added a needle valve to regulate flow, can get a clean burn but virtually no output... Looks like a high pressure reg is in order and more jet tuning

 

[Sidney Harbour-Bridge]

Yep that's what I'm planning to do, needle valve tap to reduce amount of gas but keep it at full pressure. Are you using a standard bbq regulator or an adjustable one?

Yes I have the low pressure regulator, I am thinking of a high pressure burner next. The low pressure one will just hold a simmer with 40+ L in the pot and it takes an age to get there.

 

[Sidney Harbour-Bridge]

Just added a needle valve to regulate flow, can get a clean burn but virtually no output... Looks like a high pressure reg is in order and more jet tuning

I'm not game to play with jets and pressure but I think the jet and valve regulate the gas flow and you have found the optimum setting, increasing the gas pressure will add more gas so probably make it richer again.

If you can entice more air into the flame you may be able to burn more gas cleanly, I did think of fabricating a conical duct to add below the burner to accelerate the airflow through the middle of the ring but I think without a fan it would not increase the amount of air coming in.

 

[garage_life]

Ive turned the gas pressure up with some ehhh, creative pretengineering -see photo, don't do what Donny Don't Does.

With a slightly reduced 1.8mm jet sizing and the air valve removed and ports enlarged slightly (the "neck of the casting is the biggest restriction now) it's running almost perfectly.

I'll have to dead head the gas line and put a gauge on it to check the pressure and be careful of what the shitty hose is rated too.

The needle valve has been removed as it was causing too much pressure drop, it needs to be before the reg to work correctly for what I want it to do.

I'll post pressure and jet sizing after I get it happy, not any regulator mods though, if you can't figure it out and know what your doing, don't do it! .

 

[garage_life]

FYI 0.9 - 1.4mm seems to be the sweet jet size for the BG12 burner on LPG at most pressures which I think is around what most are stock, the output is unusable with a standard BBQ regulator though.
To reduce the size after I've drilled mine I simply used some flux and a butane torch to solder the hole back up and redrill. During testing the fitting and end of the burner isn't even touching 60 deg so melting (plus the gas cooling) isn't a problem with the lead / tin solder.