NFPA Journal

BY BRIAN O'CONNOR 

In recent months there have been several major hospital fires around the world related to the treatment of COVID-19 patients. These events all involved the delivery of oxygen to patients and underscore the reason oxygen must be handled carefully in health care environments.

Many of the safety considerations related to oxygen delivery also apply to hyperbaric chambers, enclosures that allow patients to breathe pure oxygen in a pressurized environment. Hyperbaric chambers are typically used to treat decompression sickness, but they have an array of other applications; studies are examining ways they could be used to treat COVID-19 patients. There are three classes of hyperbaric chamber: Class A for multiple occupants, Class B for single occupants, and Class C for animal (nonhuman) occupants. Requirements for hyperbaric facilities and the chambers within are found in Chapter 14 of NFPA 99, Health Care Facilities Code.

There are several distinct hazards associated with hyperbaric facilities that require unique fire protection features. The most obvious hazard is the environment of increased pressure and the presence of elevated oxygen levels. While oxygen itself is not flammable, it is an oxidizer that supports combustion and can increase the flammability of other materials. This means that care must be taken to prevent any means of ignition from entering the oxygen-enriched environment, since the conditions exist for a fire to grow rapidly. In fact, some materials—including silicone rubber and certain lubricants and flame-resistant fabrics—that will not burn at atmospheric pressure and corresponding oxygen levels can ignite in the increased pressure and oxygen levels found in a hyperbaric chamber.

Another fire and life safety challenge for hyperbaric facilities is evacuating the chamber. Since these chambers are pressurized, they must undergo a decompression process before occupants can safely exit. The process is required to take no more than six minutes for class A chambers and two minutes for Class B when returning from three times standard atmospheric pressure.

To help mitigate the effects of a fire in the hyperbaric chamber, Class A chambers require a deluge sprinkler system to be installed in each portion of the chamber designed for occupants. In addition to the deluge system, an independently supplied handline is also required to be installed within the chamber.

Since Class B or Class C chambers are single-occupant vessels, deluge systems are not required. This is because the occupant should be able to leave the chamber more quickly when compared to Class A chambers. The higher levels of oxygen found in Class B and C chambers would also cause a fire to burn too rapidly to allow time for intervention. The current recommended procedures for a fire in a single occupancy chamber are to stop the flow of oxygen and follow emergency decompression procedures.

Any room housing Class A, Class B, or Class C chambers needs to be protected by either an automatic sprinkler system, a water mist system, or a clean agent fire protection system. This can protect patients and staff from fires originating outside the chamber. A 2-A:10B:C portable fire extinguisher is also required to be installed in the room housing the hyperbaric chambers.

While designing a fire protection system to protect life and property is essential, another crucial safety element is ensuring that proper operational procedures are developed and followed by the administrative and maintenance staff. Preventing potential ignition sources from entering the chamber and only permitting certain fabrics to be worn or brought into the chamber are some examples of the safety precautions that should be taken. Staff must also be aware of the hazards and properly trained on how to respond during an emergency.

While the use of oxygen therapy equipment such as hyperbaric chambers comes with associated hazards, having the right fire protection system design and emergency procedures means these facilities can continue to help patients recover in a safe and controlled manner.