Propane, that wonderful stuff

[Ralph L. Fullenwider]

Hi everyone:

Since it is a slow day on the Forum, I thought I might start a little
thread on LP gas. Ever wondered how long your tank will last during the
winter months with the LP heaters going?

Interesting facts on that:

1 gal of LP turns out 91,502 of BTU

The ASME tanks on the Birds run about 45 gallons but remember that the
tanks can only be filled to 80% of capacity so we actually have only 36
gallons available.

That means:
36 gallons X 91,502 = 3,294,072 BTU per tank fill

Now then the Lp heaters are usually 16,000 BTU units per heater, so 3
heaters would use 48,000 BTU per hour.

So 3,294.072 divided by 48,000 = 68.6 hours @ 24/7 100% run time at 70 deg
F at sea level.

Interesting:

Now we know the heaters don't run 24/7 @ 100 percent so lets say they run
25 percent of the time. This takes the BTU's used from 68.6 to 120.06 hours
and that divided by 24 hours comes to, a total of 5 days of continuous
heater run time. This does not include the refrigerator or cooking BTU's
demand.

And the colder it get's the fewer BTU's are available as pressure. Lp boils
at -44 deg F so at sea level on a 100 deg F day the available pressure from
the tank is 198 psi. then for every 10 F drop in temperature the pressure
will drop aprox 1.5 percent. So it could actually be that you have 1/4 tank
showing on the readout but 0 pressure available to feed the heaters or any
LP appliance. Hmm. if that happens, you can start the gen set and if you
have a trouble light with a 60 watt bulb and turn it on and lay the trouble
light inside the LP compartment, the heat from the lamp will actually heat
the tank to a certain degree and give you more available LP pressure for
cooking.

I have not read all of the tables on LP so am not sure how altitude would
be an effect on the BTU rate either.

Just thought this was interesting though. What do you think?

Safe travels,

Ralph and Charolette Fullenwider
Ralph's RV Solutions, Duncan, Oklahoma
http://home.swbell.net/rlf47/index.htm