On Sat, Apr 2, 2011 at 10:02 AM, Jack Brooks <jibjib@att.net> wrote:
> My neighbor converted his propane grill to natural gas, drilling out the
> orifices. B It took a while to dial in the correct heat output on the
burners
> due to the operating pressures of each fuel and the energy content. B He
> continued to open up the orifices until the burners fired correctly. B You
> may not have sufficient pressure on your natural gas line. B Here are your
> variables.
>
>
>
> Propane contains about twice the energy in a given volume of gas.
Which is a pretty silly way to measure, since mass/volume varies with
pressure. Propane suppliers like it, because of the higher normal
working pressure makes propane look better.
The useful figure is energy content per unit of mass, and by that
measure, natural gas is about
7% higher energy denser (49 MJ/kg for NG, compared to 46 MJ/kg for
propane). Actual numbers vary
a fair amount, since the constituents in the gas change based on
supplier and time of year.
>
> Propane normally works at about 11 inches of water column.
>
> Natural gas "typically" runs at around 7 inches of water column.
With a lot of variation. In the stupid mcmansions around here, a 2
psig system is pretty common. Meter regulator cuts supply pressure
from tens of psi to 2 psi, the house pipes are 2 psi, and a regulator
at each appliance cuts it to about 7 inches of water. That lets them
use smaller pipe on the long runs to things like the pool heater and
the grill.
>
>
>
> I'd check your natural gas pressure (with burners lit) and insure it meets
> the requirements of the grill. B Alternatively, you could light one burner,
> note the flame size, then light the other four and see if the first one
gets
> smaller, but a pressure test is the best.
>
>
He doesn't need to do that: his pipe is undersized. 20 feet of 1/2"
pipe has a capacity of about 45 cubic feet, 45,000 btu/hr, but he
doesn't have that, he's got a 1/4" pipe. I don't have a chart for the
capacity of 1/4 pipe, but I'm sure it's not 45Kbtu/hr.
--
David Scheidt
dmscheidt@gmail.com
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