Introducing Our New Payment Portal. More Information →

Why Isn’t My Propane Tank 100% Full After Delivery?

Written on: January 29, 2024

It’s Chemistry 101—and It’s for Your Safety!

propane tank Loxahatchee, FL Every so often, a customer will call us after a propane delivery to ask why the gauge on their propane tank indicates that it’s not completely full. Often, it’s a customer who is new to propane. It’s a good question—we get it: If you’ve called us to come fill your tank, why isn’t it full? The answer is right out of your high school chemistry book.

Propane, also called LPG or liquid propane gas, is transported and stored in a liquid form. If you paid attention in chemistry, you know that liquids expand when they are heated. What you may not know is that liquid propane expands a lot more, and a lot faster, than some other liquids. Propane will expand nearly 17 times more than water heated the same amount. For your safety, an aboveground propane tank, which is exposed to the sun, is considered “full” at about 80% to provides a cushion against the pressure that builds up inside the tank. Underground tanks are typically filled to about 85% because they are insulated.

This so-called “80% rule” is especially important in places like here in southern Florida, where warmer weather means liquid propane is prone to expansion year-round.

Keep in mind that the amount of gas in the tank doesn’t actually change when propane expands or contracts–only its density does. You might notice that the tank gauge reading fluctuates slightly during quick temperature swings (hot day, cool night), don’t worry, that’s perfectly normal.

Reading Your Tank Gauge

If you have an above-ground propane storage tank, the gas gauge is right at the top of the tank, under a lid or dome. If you have an underground tank, the gauge will be near the fill pipe.
You’ll see a gauge that looks a lot like a speedometer, with numbers going around the edge, and a single pointer. The numbers indicate what percent of gas is in your tank.

Remember, although your tank will never be filled to more than 80%, you should always call for a fill-up before your tank falls below 20% so we have time to schedule a delivery. If your tank falls below that level, you could lose pressure, which can lead to problems with equipment.

Of course, it’s good to know how to check your tank level, but it’s an easy task to forget about. That’s why we give you easier ways to make sure you get propane deliveries when you need them—without having to remember to check your tank and call us for delivery.

Automatic Delivery & Tank Monitoring

We know you’re busy—with plenty of things on your to-do list besides checking your propane tank gauge. That’s why we offer two convenient services to help. Automatic delivery uses a proven system based on your previous usage and other factors to let us calculate when you will need a propane delivery. Not only does it eliminate the need to call for a delivery, but it makes things easier on our end, too: We’re better able to plan deliveries, using the most efficient routes to get to everyone quickly. That saves time and money—savings we can pass on to you.

For seasonal homeowners—and anyone who’s propane usage fluctuates a lot—we recommend our wireless propane monitor. It tracks the level of propane in your tank in real time, and transmits your usage via wireless cellular technology. When the tank gauge reaches a pre-set level, the monitor alerts us—and you—directly via a wireless mobile app.

Of course, we still believe in old-fashioned customer service. That’s why we’re always happy to take your call and answer any questions. Contact us today to sign up for worry-free automatic deliveries or ask about our propane monitors.