# Which Lpg Reg To Use?



## Diesel80 (13/1/12)

I have 2 LP LPG regs at home and use a 3 ring burner with approximately the following specs:
30MJ output
uses about 0.65kg gas per hour using a 2.75kpa regulator according to product spec sheet @ Auscrown.


Currently I have a 2.8kpa / 2kg/hr reg attached to it. So pretty similar to the supplier specs mentioned above.
I also have a reg off a caravan, it is 3.7kpa but only rated at 1.5kg/hr.

With 2.8kpa pressure the specs state the burner can flow 0.65kg/hr and turn this into approximate 30MJ - 32,000btu.
At 3.7kpa will this burner flow 30% more? increasing it's potential output to ~40MJ? and gas consumption to ~0.85kg /hr?

Cheers,
D80


----------



## pk.sax (13/1/12)

Higher pressure reg means that the gas coming out of the orifice will basically diffuse more on exit. PV=nRT. The greater the pressure drop, the higher the volume increase, assuming temperature on the other side remains same, the rest are constants.

In simpler words, greater increase in volume means better mixing with air and better/hotter burn. Using a high flow rate but LP reg is like driving a piece of junk antique in second gear.


----------



## Diesel80 (13/1/12)

practicalfool said:


> Higher pressure reg means that the gas coming out of the orifice will basically diffuse more on exit. PV=nRT. The greater the pressure drop, the higher the volume increase, assuming temperature on the other side remains same, the rest are constants.
> 
> In simpler words, greater increase in volume means better mixing with air and better/hotter burn. Using a high flow rate but LP reg is like driving a piece of junk antique in second gear.



By a high flow rate LP reg are you referring to the KG/hr figure as opposed to the pressure?

I have seen 3.7kpa regs at flow rates of 4Kg/hr. Is this an example of driving a piece of junk antique in second gear.

Cheers,
D80


----------



## pk.sax (13/1/12)

Nah, there, the flow rate (kg/hr) is increasing in step (or out of step) with the pressure. See, above a certain pressure level, the exiting LPG is diffused enough that you can start benefiting from an increased flow rate.

In other words, turbocharge that v6 before you think of adding a couple of cylinders (no idea about that, just linear analogy).

This is precisely why big burners like 4-ring ones seem to benefit from HP regs. You can throttle back the flow rate from the burner knob and have the HP ensure good mixing with air. Eliminating sooting in the process.

All I said was, I'd go for increasing pressure before flow rate. You will end up throttling he flow rate through the burner knob anyway. I bet you have been using them burners/regs for a while so some of this would already have been noticed. Correct me if I got carried away anywhere.


----------



## QldKev (13/1/12)

Diesel80 said:


> I have 2 LP LPG regs at home and use a 3 ring burner with approximately the following specs:
> 30MJ output
> uses about 0.65kg gas per hour using a 2.75kpa regulator according to product spec sheet @ Auscrown.
> 
> ...




I had a 2.75kpa on my old 3 ring burner, slowly it got my brew pot to the boil. zzzz.

So I wacked a 0-207kpa adj reg on it and woke the sucker up. It made a huge difference and I would never run a standard bbq reg on it ever again. 

So in your case I say go for the 3.7kpa until you can get something with some more grunt. 
_At 3.7kpa will this burner flow 30% more? increasing it's potential output to ~40MJ? and gas consumption to ~0.85kg /hr?_
I believe this would work out to be true.

I should add, I am impatient waiting for the strike water to get to temp and also the wort to get from mash out up to the boil. I see it as wasted time on brew day. I'm running my current 140L brew pot on 300,000btu...

Also if you do go to a high pressure reg you will need to drill the outlets out a bit to stop it from blowing itself out. (not needed for the 3.8kpa)

Disclaimer. I'm not LPG pro, if you blow yourself up don't blame me.

QldKev


----------



## Diesel80 (13/1/12)

QldKev said:


> I should add, I am impatient waiting for the strike water to get to temp and also the wort to get from mash out up to the boil. I see it as wasted time on brew day. I'm running my current 140L brew pot on 300,000btu...
> 
> Also if you do go to a high pressure reg you will need to drill the outlets out a bit to stop it from blowing itself out. (not needed for the 3.8kpa)
> 
> QldKev



I hear that. I run a 2400w over the side immersion element with it.

Works well for 40L boils. Will try a double soon. Should be interesting. 

thanks for input.

Cheers,D80


----------

