Posted: August 12, 2024
At Callahan’s Gas, we often hear this concern from our loyal customers after they receive a propane delivery: Why doesn’t my propane tank gauge read 100%?
It’s true that a full aboveground propane tank will typically read approximately 80% on its gauge. But that doesn’t mean you’re getting shortchanged on your propane delivery. In this article, we’ll explain how your tank gauge measures the amount of fuel you have and why propane companies follow an “80/20 Fill Rule.”
Your tank uses what’s called a float gauge. As that name suggests, there is a float that rests on top of your liquid propane. A stem connects the float to gears that cause the gauge on the outside of your tank to provide a reading.
Your tank gauge provides information about the percentage fill of the tank based on the volume of the liquid propane it contains. It doesn’t tell you the number of gallons inside.
And speaking of volume, propane tanks are viewed and sized through two different lenses simultaneously. The gauge measures the liquid level of propane. The total water capacity (WC) of the tank is how much water (or liquid) it would take to fill the tank to the brim. However, as mentioned above, a full tank of propane will sit at approximately 80% of that mark.
So, if the gauge on your 500-gallon (WC) propane tank reads 50, it is at 50% of its total water capacity and contains roughly 250 gallons of propane.
Liquid propane’s volume (the amount of space it takes up) expands as outdoor temperatures rise and contracts when temperatures drop. Water’s volume expands and contracts with temperature changes, too. However, propane expands nearly 17 times more than water with the same temperature change.
This can affect your tank gauge reading. If you have 250 gallons of propane in a 500-gallon tank, the gauge will read 50 on a moderate afternoon. If temperatures drop considerably at night, the gauge reading may be several percentage points lower, even though the number of gallons hasn’t changed.
This brings us to why your tank isn’t 100% full after a propane delivery. All responsible propane companies leave 20% empty space in aboveground propane tanks to allow for the safe expansion of propane. Doing so prevents unsafe pressure levels on hot days. As such, a full 500-gallon (WC) aboveground propane tank will contain approximately 400 gallons of fuel. (Underground tanks can be filled higher since they are less exposed to direct sunlight.)
Still, you don’t need to worry about being charged for that 20% of empty space. We only bill you for the propane gallons that we add to your tank at each delivery.
Throughout Maryland’s Kent, Queen Anne’s, Caroline and Talbot counties, families trust the Callahan’s Gas team to keep their propane tanks reliably filled. We are dedicated to providing dependable and safe delivery service.
With our free Automatic Delivery schedule, you can count on Callahan’s Gas to do all the planning for you. Our state-of-the-art computerized system uses a tried-and-tested process to calculate your propane usage. Then, we pre-schedule your next propane delivery so you never run low. Automatic Delivery frees you from ever needing to run outside and check your tank gauge, and it’s also totally fee-free.
Come to Callahan’s Gas to get the reliable propane delivery you deserve. Become a customer today.
