View Full Version : Getting your propane tank - full

05-12-2012, 09:41 AM
So, yesterday I filled the Cyclone's first propane tank. The tank was full when I picked up the trailer July 2009 and it ran dry at the Delaware camp out April 2012.

I had weighed the tank at the delivery and marked it on the tank with blue tape. I weigh the tanks at the beginning of each season to make sure we have enough for any given trip.
And I use a spreadsheet I keep on the phone for capacity (see attached).

The operator noticed my blue tape and asked what the numbers were, "date and 54#'s". Told him that was what the tank weighed new, full.

He then bumped up the scale weight (after looking at a chart).

His chart listed a 30 gallon tank as 57+ pounds, which is the same as my calculation of 57.6.

"Full" tanks are really a misnomer, as they are only filled to 80% capacity (volume, not weight). You need room for vapor. Filled to 80% my tank should weigh about 51 pounds. 7.5 gallons full x 80% equals 6 gallons.

So I now wonder how many times I have gotten propane and they were not filled to the 80% full volume.
I never weigh the grill tanks.

05-12-2012, 10:10 AM
One of the places I go to runs the pump until the OPD valve in the tank shuts down the flow. I don't know if this is right or wrong..Don

05-12-2012, 10:13 AM
Porthole, Thanks for the info. Just filled my tanks yesterday. The attendant filled to a weight of 54#'s. I assumed that I got 7 gals. of propane, guess not. At least they charged for the amount of propane in gallons that was used to fill the tank rather than some that charge just by the tank, irrespective of the amount that was used to fill the tank.

Ray LeTourneau
05-12-2012, 11:01 AM
One of my tasks while work camping in CA a couple years ago was filling tanks. Both on board Motor homes and 20 or 30 pounders. The training guy actually said it was OK to open the vent and fill until liquid started to come out. I was a bit surprised at this. We didn't even have a scale at our fill station though so I guess that's a pretty valid reason. One of my own personal tanks would start to overflow at 7.1 gallons and the other at 7.4 gallons, consistently.
Around here in WI, they don't open the vents but fill by weight. Problem is, different places use different tare weights. All tanks ahve their empty weight stamped on the tank and they vary slightly from tank to tank. I guess my point is, in some places you may never get a full tank depending on how they set their scales. Some places don't even include the hose and nozzle in the tare. Gotta watch some of them. It's also funny how propane prices vary, even in the same area.

05-12-2012, 06:04 PM
Where I get my tanks filled they open the vent valve and fill the tank until propane starts to come out of the vent valve.

05-12-2012, 10:33 PM
That sounds overfilled. You have to open the vent to let the liquid in. The tank needs some of it's volume for gas.

05-13-2012, 09:43 PM
The vent (bleeder) should be set to about 80% level and will spurt liquid when the tank is at the right level. Until then it will bleed vapour. You don't actually need to open the bleeder valve to fill the cylinder, as it only contains propane vapour at the saturation temperature. Here's a useful link with info on cylinders and the OPD valve.


I agree that depending on the operator, their equipment, and method of filling, the amount of propane that you get, will vary.

05-14-2012, 07:14 AM
My guess is opening the bleeder gets a faster fill and allows a "full 80% fill.

05-14-2012, 08:41 AM
We fill ours out of one of the bulk tank used for tank heaters. The only way to fill them is to use the vapor valve. Fill until you have liquid and close. Doing it this way for the past 50 years. Works great but takes a bit of time when the temperature is cold.