Determining the Gallons of Propane a Cylinder Can Hold

January 23 2018,

Determining the Gallons of Propane a Cylinder Can Hold

Written by Bobby Fisher

Pallet of 20 pound cylinders.

Yesterday I had a customer call and ask me how he could determine the gallons of propane a cylinder could hold. I thought I would share this with everyone.

The DOT cylinder has two numbers stamped into the steel usually around the collar area. One number is the TW or Tear Weight. For example, a 20# cylinder will say TW followed by the number 18. This means that when the 20# cylinder is empty it will weigh 18#.

The other number is the WC (Water Capacity). Using the same example of a 20# cylinder, the WC will be followed by the number 47.6. This means that the cylinder will hold 47.6 pounds of water.

Close up of WC and TW stamp.

Now here is where I learned something and felt the need to share. Our customer was asking how many gallons of propane a 20# cylinder would hold. Here's what I told him: take the WC and divide it by 8.345 and you'll get the total gallons of propane the cylinder can hold (or WC/8.345 = Gallons of Propane).

Now, of course, you will always have temperature compensations, but this will give you an idea of how many gallons of propane you are selling, or what it will take in gallons to fill a cylinder. Also, to determine the cylinder size you would use the formula WC x .42 = Cylinder Size (or WC*.42 = Cylinder Size). So if your WC is 47.6 multiply that by .42 and you'll get 19.992 or 20#.

Hope this helps anyone who may have forgotten these formulas.

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Outside sales rep Bobby Fisher.