Gas Grill Safety: Propane Tanks

The summer grilling season is upon us, and that means hooking up a propane tank to your gas grill and getting the family together for an outdoor barbecue! Before you do, though, you might want to read up on some gas grilling safety tips – especially when it comes to your propane tank.

This may just be a review for some people, but I think there’s beneficial information here for anyone who uses a gas grill.

Propane Tank Safety

Bernzomatic Propane TankThat short, stout tank under your gas grill is a portable 20 pound propane cylinder, and they are the most common cylinders used today in the consumer LP gas bottle market.

So, what is propane? Propane does not occur naturally, but is refined from raw crude oil and raw natural gas.  Propane is then stored under pressure as a liquid; therefore, the name Liquid Propane (LP). LP gas is the ONLY gas that should ever be put into this cylinder.

Propane has some properties that are important for safe consumer use. Water boils at 212°F, at which point it turns to a gas. Propane boils at -44°F, so the liquid propane in your cylinder is below -44°F to maintain a liquid state.  For consumers, this means that exposure to LP gas can freeze your skin and the tissue underneath resulting in severe damage. This is also why LP gas is released from the cylinder as a gas, not a liquid, known in the industry as “vapor service.”

Propane is also heavier than air and will seek the lowest space available.  This is why consumers should never store a LP cylinder in an enclosed space, such as a garage, shed or basement.  If the cylinder leaks or if propane is expelled through the pressure relief valve, an ignition source could spark a fire or explosion. Also, the cylinder should always be stored in an upright position so the pressure release valve can function properly (it is at the top of the tank).  As propane is odorless, the manufacturer adds an odorant for obvious safety reasons.

Transporting Propane Tanks

The U.S. Department of Transportation regulates propane cylinders and they must be compliant in order to enter into U.S. commerce. I will highlight three of these requirements.

Propane Cylinder Protective Collar: The valve of a propane cylinder is required to be protected by a metal collar, also called a neck ring. The collar also serves as the location for required markings pertinent to the cylinder’s date of manufacturer and weight specifications.

Cylinder Foot Ring: This required ring ensures the LP cylinder stands in an upright position while also preventing the cylinder from making contact with the ground.

Cylinders without these two features are unfit for LP gas use and are illegal to refill.

Cylinder Certification and Recertification: Cylinders are required to be recertified (also known as requalification) twelve years from the date of manufacture and every five years thereafter. The date of manufacture is stamped on the protective collar.  The cylinder cannot be refilled until it is recertified.  Most consumers just replace it with a new one as they can be purchased for less than $40.

New cylinders need to be purged of shipping air, water vapor and other contaminates prior to filling. Most manufacturers purge the tank prior to shipping them to the retail market.  If six months have passed since the date stamped on the collar, the cylinder needs the vacuum checked and possibly re-purged prior to filling. This task can be performed by your local propane dealer.

Remove the Propane Label

Now, here is a little known fact: The labeling sleeve on the cylinder should be removed prior to use to protect the integrity of the cylinder. The sleeve contains very useful safety, valve graphics, and proper use information that should always be read prior to use.

Remove Propane Tank SleeveThe problem with cylinder sleeves is that they are made of a plastic shrink-wrap type of material that traps moisture. Any moisture that accumulates under the sleeve due to condensation and outdoor use, is trapped there and unable to evaporate. As the tank is metal, this can result in the formation of rust.  Also, rust that forms under the sleeve may not be visible to the consumer. Rust will compromise the integrity of the cylinder and shorten its useful life, and may endanger the user.

The labeling on the sleeve instructs the user to remove said label prior to using; so why do so many consumers fail to do it? You know why – they probably did not read the sleeve labeling in the first place. A lot of people simply just hook up the LP cylinder to the grill and “fire it up” just like they’ve always done. So, please read all of the operational, warning and cautionary statements reflected on the labeling.

Overfill Protection Device (OPD)

The OPD is a safety device that automatically prevents the overfilling of a cylinder with LP gas.  It was introduced in 1998 and is defined by the National Fire Protection Association (NFPA) Pamphlet 58-LP Gas Code, 1998 Edition. This code has been adopted throughout the US and pertains to all cylinders in the 4 lb. through 40 lb. propane capacity range.

The OPD provides three basic functions:

  • Prevents the cylinder from being overfilled
  • Allows room for expansion inside the cylinder due to temperature changes
  • Only allows propane vapor to exit the cylinder when it is connected to the grill or other appliance, even with the OPD valve in the “open” position.

The OPD has a float valve, similar to the one in your toilet tank.  Once the incoming liquid lifts the float to a pre-set level, typically 80% full, it automatically shuts off the flow of incoming propane. Also, the hose end connection on either a fill hose or appliance supply line is designed to work only with OPD equipped cylinders.

Consumers can identify an OPD by observing its unique identifying features.  These include brass construction, a triangular handwheel located at the top of the valve, large outer threads on the hose connection, and “OPM” is molded into the handwheel and valve body.

Propane Tank Valve

Filling/Exchanging Propane Cylinders

Consumer have two choices, either have your cylinder refilled by a propane dealer or exchange the empty for a full cylinder. A cylinder can hold 20 pounds of propane full, but that leaves no room for expansion of the LP gas as required.  The exchanged cylinder will contain 15 pounds of LP gas or 75% of capacity.  If a propane dealer refills the cylinder, they will fill it until the OPD shuts off at about 80%. The cylinder will then be weighed to determine the exact amount of LP gas put into the cylinder for billing purposes. Propane is priced by the gallon. This is also an extra safety precaution against overfilling.

Propane Tank Label

Propane Numbers and Calculations You Should Know

Tare Weight (weight of empty cylinder w/valve) indicated by a “TW” stamped on the collar followed by the weight – the weight of one gallon of LP gas is 4.24 pounds.

Let’s say the TW is 16.6 pounds and the cylinder weighs 27.8 pounds.

27.8 – 16.6 = 11.2 pounds

11.2 / 4.24 = 2.64 gallons of LP gas in the cylinder

A 20-pound cylinder has a liquid capacity of 4.7 gallons when 100% full. A 20-pound cylinder cannot be legally filled to capacity, so the choice is an exchange tank at 75% full or filling at a propane dealer where the OPD will limit capacity to about 80%.

Happy Grilling and Stay Safe!

Everyone deserves to have a safe and happy summer with their families. Barbecues are times to get together with loved ones and enjoy the nice weather. Paying attention to propane safety can help ensure that nothing goes awry and no accidents occur.

Happy grilling – and don’t forget to open the grill cover before turning on the gas and lighting the grill!