Why Isn’t Propane Tank Gauge At 100%?

Why Isn’t Propane Tank Gauge At 100%?

Written on: November 20, 2023

Understanding the 80/20 Rule for Propane Tanks

propane tank georgia Have you ever noticed that right after your propane supplier delivered your fuel, they didn’t fill your propane tank all the way up to the 100% level?

Don’t worry. Your propane supplier is not doing anything wrong. Quite the contrary. They’re looking after you by following what’s known in the industry as the “80/20 rule.” This rule is followed for a very important reason: safety.

Propane: From Liquid to Gas

The propane in your tank is stored as a liquid. The liquid changes to gas before it leaves the tank. That’s why it’s called liquid petroleum gas (LPG).

Like any liquid, propane will expand when its temperature rises. The difference with propane is that it expands a lot, and quickly. Its volume increases nearly 17 times the volume of water over the same temperature increase.

This is why your propane delivery driver needs to leave extra space in your tank. This enables propane to safely expand. Aboveground propane tanks are typically filled to about 80% capacity; underground tanks can be filled slightly higher because they are insulated against the heat.

That extra space in the tank provides a cushion against the pressure that builds up inside the tank. For example, a 500-gallon tank filled to 80% will safely hold 400 gallons of propane.

This safeguard is especially important in hot weather—when liquid propane will expand the most. It’s important to note that the amount of gas in the tank doesn’t change during periods of expansion and contraction–only its density does. For example, if you notice that the tank gauge reading fluctuates slightly during quick temperature swings (hot day, cool night), again, don’t worry because that’s perfectly normal.

Propane gas expansion is also a reason why you should never paint your outdoor propane tank a dark color. This is because dark colors absorb more heat.

Propane Delivery Options

Life can get busy with work, family and other obligations. And sometimes, you might forget to regularly go outside and check your tank gauge to see how much propane is in your tank. If the reading is 30% or less, you know it’s time call your propane supplier to schedule a delivery.

If you forget to check your tank, you risk running low on or worse, completely running out of propane. That means the expense and hassle of an emergency propane delivery. And if you run out of propane, you also need a professional to pressure test your propane system and relight the pilots on all your appliances. That’s another expense.

Many of Georgia’s propane companies offer a solution with their automatic delivery service. They track your propane usage and schedule a delivery to your home before you run low.

If your local propane company doesn’t offer automatic delivery, or if you prefer the control of will-call, you need to be vigilant about monitoring your propane tank gauge levels and request a delivery when your tank is between 25% and 30% full. While your propane dealer may be able to make a delivery within a day in cases of extreme emergency, it is always best to provide a few days’ notice. This advance notice is necessary for scheduling your home into a delivery route.

Please check with your local propane dealer to find out what services and options they offer. Find propane service companies in your area.