It's always nice to know how long your propane will last if you are out and about. And this is some quick math to get an estimate.
The first piece of the puzzle is knowing how much propane is in your RV cylinders or tank when full. Remember an RV propane cylinder or tank is full at 80% of its capacity to allow for expansion. Wait until your cylinder or tank is nearly empty and the next time you have it filled ask the attendant how much it holds.
The dimensions presented below are approximate measurements of common size propane cylinders found in service today. The measurements are not exact so contact your propane company or container manufacturer for precise cylinder dimensions.
|Capacity (gallons)||1.2 gal||2.4 gal||4.7 gal||7.1 gal||9.4 gal|
|Weight (empty)||4 lbs||13.3 lbs||18 lbs||24 lbs||29 lbs|
|Weight (full)||9 lbs||23 lbs||38 lbs||54 lbs||70 lbs|
|Overall Height||12 inches||17.43 inches||18 inches||24 inches||29 inches|
|Diameter||8.00 inches||8.87 inches||12.5 inches||12.5 inches||12.5 inches|
The next piece needs some basic propane BTU numbers - 91,502 BTUs per gallon and 21,548 BTUs per pound
Multiply your propane container capacity using one of these BTU formulas, (gallons or pounds), to determine the container BTU capacity.
Now, divide your container BTU capacity by the total BTU demand of the LP gas appliances you plan to use. [ BTU appliance demand can normally be found on the appliance itself, or in the appliance owner's manual. ]
The result will will be an estimate of how long you can expect your LP gas to last.
Why an estimate? Because there are some variables that may affect the numbers.
Calculating propane usage can give you a general idea of how long you can use your LP gas fired appliances before needing to find a propane filling station.