# 65 gal propane tank: How full?

• posted on May 4, 2007, 8:18 pm

I recently bought a house that has a 65 gallon LPG tank for the stove & outdoor grill. I'm trying to determine how full it is. It has a pressure guage that shows about 18 PSI at the moment. Given that the guage goes up to around 100 psi, I'm guessing this ain't toooo full. Am I right, or can you tell from the pressure reading?
TIA
Dan
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• posted on May 4, 2007, 8:35 pm

you can go to an rv place and get a stick-on temperature sensitive tape that can be used to tell how full a gas tank is.
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• posted on May 4, 2007, 8:35 pm

No in theory the pressure is the same if there is any amount of liquid in the tank...
When the liquid is all gone, the pressure of the remaining gas will decrease as you use up the remaining gas.
The pressure of the liquid /gas combination will vary with temperature, but not with the amount of liquid.
Mark
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• posted on May 4, 2007, 8:36 pm

I should add the tank has a regulator (of course) but the pressure reading is at the tank itself, not after the regulator.
Dan.
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• posted on May 4, 2007, 8:57 pm

my 250 gal tank has a gauge, that really is a % full gauge. They only fill it to 80%. Don't know if your small BBQ tank fits the same guidelines.
John
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• posted on May 5, 2007, 1:48 pm
wrote:

They are only filled to 80% so that when the tank gets hot the propane inside has some space to expand to.
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• posted on May 25, 2007, 6:55 pm
Actually, they are filled to 80% to leave room for the gas to accumulate as it is the gas that is burned, not the liquid.
--
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• posted on May 25, 2007, 7:30 pm

expansion due to temperature. If filled all the way and the temperature warms up slightly you will vent the tank through the relief valve.
From: http://www.teardropparts.com/sub-pages/propane-safety-tips.htm
By design, approximately 20% of the interior space in all propane tanks, OPD and otherwise, is reserved for expansion to safely accommodate the 1.5% increase in volume that propane experiences for every 10 degree Fahrenheit temperature increases. In an overfilled tank, insufficient space may remain as the propane warms up, expelling gas and/or liquid forcefully through the safety relief valve.
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• posted on May 4, 2007, 9:38 pm
Dan wrote: : I recently bought a house that has a 65 gallon LPG tank for the stove : & outdoor grill. I'm trying to determine how full it is. It has a : pressure guage that shows about 18 PSI at the moment. Given that the : guage goes up to around 100 psi, I'm guessing this ain't toooo full. : Am I right, or can you tell from the pressure reading? : : TIA : : Dan
Pour a kettle of boiling water down one side. You will be able to feel where the level of liquid is by where the temperature gets cool. The empty top will be warmer than where the LPG level is. Sometimes condensation will form on the cool part if it is humid.
Larry
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• posted on May 4, 2007, 10:13 pm
Dan writes:

The pressure gage reads only the saturation vapor pressure of the liquid, not the level of the liquid in the tank. The two are independent.
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• posted on May 4, 2007, 11:42 pm

OK I'm an idiot. After looking at the web site for the propane company, I realized the gauge doesn't read in PSI, it is a float gauge that reads in % full. So the tank has about 18% of 65 gallons, or about 12 gallons. Should be enough to get through the weekend, anyway ;-)
Thanks to all who replied.
Dan
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• posted on May 5, 2007, 2:35 am
Dan wrote:

While most propane tank guages read %, it's not an absolute. Mine reads gallons. Also most guages are inaccurate, giving a relatively ballbark reading.
Red
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• posted on May 6, 2007, 12:21 am
Dan wrote:

Good, because I was just about to tell you that if the tank pressure was REALLY 18 psi and the local temperature was above minus 10 F, then there was no liquid propane at all left in the tank. <G>
Jeff
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Jeffry Wisnia
(W1BSV + Brass Rat \'57 EE)
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• posted on May 25, 2007, 6:56 pm
Easily but I would set up to get a delivery.
--
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