Grilling accidents involving fires and explosions are tragically common in the US. Roughly 76% of American households own propane gas grills, and according to the National Fire Protection Association, grilling accidents accounted for at least 16,900 emergency room visits and tens of millions of dollars in property damage in 2012 alone. The US Fire Administration reports that propane grill fires result in about 10 fatalities every year. As more people buy grills and switch from charcoal to gas-powered cooking devices, these numbers have tended to increase.
The two most common causes for gas grill fires and explosions are termed “venting” and “odor fade” but there are other issues as well. Venting refers to a propane tank or canister releasing some gas through a safety valve as the pressure inside the tank increases. The internal tank pressure can increase in several circumstances, including when the tank is exposed to sunlight or direct heat. This can become more dangerous when the company servicing the propane tanks overfills them with gas. If a propane tank is venting in an enclosed space, such as the cabinet underneath a grill or inside a garage, the gas can build up over time. The propane, which is heavier than air, cannot escape in a closed area, and can be ignited by any nearby spark or static charge. This can lead to an extremely hazardous situation in which a large pool of propane can suddenly catch fire and explode, creating a fireball reaching temperatures at thousands of degrees Fahrenheit.
Gas grill explosions are usually the result of venting, odor fade, and connection problems between the propane canister and the grill. Explosions occur when unsuspecting people ignite a grill without realizing that gas has leaked from the propane canister, becoming highly concentrated in the surrounding area.
Venting becomes even more dangerous due to odor fade. Unlike methane, propane gas has no odor in its natural state, so companies selling and servicing propane for gas grills add an extra compound to the gas called ethyl mercaptan. This additive is the real cause of the “rotten eggs” type smell that people associate with propane. Studies have shown that ethyl mercaptan can start to dissipate in as little as 5 days after a propane tank is refilled, but most people replace the canisters only once or twice a year. The rapid deterioration of the ethyl mercaptan odor leaves grill users with a container full of undetectable, explosive gas. When combined, venting and odor fade have led to catastrophic accidents in which grillers unwittingly ignite a huge cloud of invisible gas.
Another problem with propane grills is the connection between the propane canister and the barbeque grill, called the regulator. The regulators are typically made of rubber but the propane canister value is brass. Rubber connectors cannot be made to the same specific tolerance as brass, in other words, there is more “give” in the rubber than the brass. When the unsuspecting user is attaching the regulator between the grill and the canister, it is can be mis-threaded and a propane leak can occur. And once again, the leaking propane can build up and eventually reach the barbeque flame or other ignition source.