What’s Inside a Propane Tank?

A propane grill.

Have you ever thought about how your propane and tank work together to heat grills, space heaters and other propane-fueled appliances? The more familiar you are with your propane tank and what’s inside, the better prepared you’ll be to use it safely and effectively. Here’s an in-depth look at what’s inside a propane tank and how it all works.

What is propane?

Propane is a flammable gas that’s created from refined petroleum and natural gas that’s often used as bottled fuel. Unlike natural gas alone, propane is transportable and compact, which makes it an ideal energy source for various applications, including propane grills, water heaters, fire pits, space heaters and indoor and outdoor lighting fixtures.

What does propane look like?

Although propane comes out of the tank as an odorous gas, it’s stored in liquid form and looks a lot like water. Propane is stored as a liquid because in its gaseous state, it would be too large to fit in a portable container. Gas propane takes up 270 times more space inside a tank than liquid propane!

What does propane smell like?

Propane is an odorless and colorless gas in its natural state. The strong, “rotten eggs” odor most people are familiar with is a harmless chemical called methyl mercaptan that’s added to propane and other gasses as a safety precaution. Without it, dangerous gas leaks would be undetectable.

If you ever smell gas coming from your tank, remove any flame source and have the tank serviced at your nearest U-Haul propane refill station as soon as possible. If you’re unable to turn off the gas, call the fire department.

To stay on the safe side when using propane, follow these safety tips:

  • Do not smoke near a dispensing tank 
  • Never use, inspect or store your tank indoors 
  • Inspect your tank for leaks prior to use 
  • Do not leave your tank in your vehicle 
  • Always keep your tank upright and secured

For more propane and grilling safety tips, visit uhaul.com/propane/safety.

How is propane stored?

Whether it’s a 4 lb. tank or a 40 lb. tank, propane must be compressed into a liquid before it can be stored inside a tank. Compressing propane gas involves pressurizing it and storing it below its boiling point (-44°F) so it remains a liquid until it’s ready to be used.

Propane liquid to propane gas

When you open the valve on your tank, the internal pressure drops and the propane is exposed to outside temperatures. This causes the liquid to boil and vaporize, creating propane gas.

That vapor is the energy source that powers all your heat-powered appliances and cooks your burgers and steaks. As you turn up the heat on your grill or heater, the pressure in the tank decreases, creating more vapor and thus providing more energy to your appliance.

Whether you’re looking for a propane refill station, propane accessories or more information about propane tanks and grills, uhaul.com/propane has what you need. We know propane!

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