In 2019, an EMS crew was completing a patient transport to an emergency department in Norwalk, Conn., when the oxygen tank on their transport stretcher apparently caught fire and/or exploded. Follow-up reports from Norwalk Fire Department confirmed that there were burn marks on the walls and ceiling of the room but that the fire had been put out with a fire extinguisher. The fire department also reported that one EMT suffered minor injuries and that the patient and other EMT were uninjured.
An oxygen tank explosion really can happen
My first thought when reading this story was, “Wow, this can really happen!” I remember being taught about the possibility of an oxygen tank explosion in EMT school many years ago, but thought it was just one of those textbook things that instructors are required to tell us. A quick search found that not only has it happened, but that the FDA produced a safety video about it several years ago.
The FDA video highlighted several EMS providers that had been injured in an oxygen tank explosion/fire and cited at least one death. Considering how many tens of thousands of times oxygen tanks are used in the United States every day, these fires and explosions are extremely rare, but when they do occur, they can be extremely serious.
What is really on fire after an oxygen tank explosion?
I also remember being taught in EMT class that oxygen itself does not really burn, but that it supports the combustion of other fuels. You may have learned the fire triangle: heat, oxygen and fuel. So, what could be the fuel in these cases?
As it turns out, most instances involve the regulators and not the oxygen cylinders. Contamination in and around the regulators, or the regulators themselves are catching fire. Due to the presence of oxygen, the fires burn very quickly and appear explosive.
The details of exactly what happened in the Norwalk case have not been released, but a review of what has caused other regulator fires might help prevent more in the future.
There are two general causes of oxygen regulator fires, adiabatic heating and particle ignition. In adiabatic ignition, the increase in pressure within the regulator when the tank is opened causes a sudden, severe increase in temperature, which is transferred to the components of the regulator.
Depending on the materials used to manufacture the regulator, this moment of high temperature and high pressure may actually ignite the regulator. This is much more likely in a regulator made of aluminum that one built with brass parts. Brass requires much higher temperatures and pressures to combust. The FDA recommended back in 1999 that brass be used, but aluminum regulators are still available as they are lighter and less expensive.
Particle ignition may also cause a fire within a regulator. When the oxygen tank is opened, minuscule bits of debris get blasted up into the regulator with such force that they are heated to the point of ignition.
Both of these types of ignition can be complicated when other contaminants are present in and around the regulator. Tiny amounts of oil, grease, dirt or dust can also ignite and feed a regulator fire.
Quick steps to minimize the risk of regulator fires
Follow these steps to reduce the risk of a regulator fire or oxygen tank explosion:
- Use regulators made with brass components.
- “Crack” the oxygen tank briefly before putting the regulator on. This blasts any dust or other contaminants away, rather than introducing them into the regulator.
- Once the regulator is applied, open the oxygen cylinder slowly. It might not seem like much, but increasing the time it takes for the pressure to build in the regulator allows the heat to dissipate safely.
- Keep your regulators clean. Minimize the risk of contamination with any oils, grease or dirt. Keep any wrenches or tools used on tanks and regulators separate from any that may be used for other work.
- Use oxygen tanks that have been properly maintained, filled and stored. The company that fills your oxygen tanks should be following DOT guidelines for inspecting and testing the tanks. These tests check for structural strength of the tank metal as well as the internal cleanliness and condition of the cylinder. They must then fill the tanks will oxygen that is tested for impurities and moisture. Store your full and used oxygen tanks in an area that limits their exposure to oils, greases, dirt, dust and other grime.
- Avoid the use of two O-rings or yoke washers when putting a regulator on a tank. Whether it is done in an attempt to fix a leaky connection or inadvertently when the first O-ring was not noticed, having two can cause a leak. The high-pressure oxygen then seeps out between the washers and can create a fire if combined with a fuel and exposed to a source of heat such as a static spark.
oxygen therapy at home fire risk
Oxygen tank related fires are more common in oxygen therapy at home users. In an article for the COPD Foundation, BPR Medical’s Richard Radford shared the following statistics: each year in the U.S., there are more than 180 home fires involving oxygen therapy at home equipment, resulting in more than 70 deaths and 1,000 burns treated in emergency departments – most of these (more than 70%) are caused by tobacco smoking.
Radford noted the risks of oxygen at home therapy fires can be minimized by avoiding smoking and naked flames, and by implementing fire safety valves, called thermal fuses or firebreaks into oxygen supply tubing, which prevent fire from spreading. The Veterans Health Administration implemented steps to make thermal fuses mandatory in home oxygen equipment for veterans in 2018.
Be safe out there.
This article, originally posted in August 2019, has been updated.
