We all recognize the importance of SCBA in protecting firefighters from a wide variety of respiratory hazards beyond those experienced during structural firefighting operations. Firefighters need the respiratory protection for their response to incidents involving hazardous materials, confined space emergencies and response to possible terrorism-related events.
That’s why it got everyone’s attention when the National Fire Protection Association issued an alert on SCBA facepiece lenses in July 2012. It issued the safety alert after investigations and additional research had found that SCBA facepieces may undergo thermal degradation when exposed to intense heat.
The polycarbonate lens that’s generally used in SCBA facepieces is relatively unchanged over the last couple of decades, but the hazards to which those facepieces are exposed has changed dramatically.
For one, the more intense heat that can be encountered during interior structural firefighting can readily cause cracks, crazing, bubbling, deformation, discoloration, gaps or holes in the lens or its interface with the facepiece.
According to NFPA’s alert, “The SCBA facepiece is often considered the weakest component of a firefighter’s protective ensemble in high-heat conditions, but the level of thermal performance has not been well understood.”
As of Sept. 1, 2013, standard firefighter SCBA cannot be certified to NFPA standards unless the facepiece lens passes a new rigorous test developed by the National Institute of Standards and Technology. The NIST-developed test is designed to reduce the degradation and possible facepiece lens failure under high-heat firefighting conditions.
Changes to NFPA 1981
The 2007 edition of NFPA 1981: Standards for Open-Circuit Self-Contained Breathing Apparatus for Emergency Services did not have a specific test for the facepiece lens. When NFPA 1981 was revised for the 2013 edition, NFPA incorporated the NIST tests into the updated standard.
The new tests were designed to challenge the integrity of the lens and facepiece. SCBA manufacturers commission organizations to test their products to ensure that they meet NFPA specifications.
Remember, NFPA does not test firefighting equipment; it only establishes the standards against which equipment must be tested. In the United States, SCBA makers submit their products for certification testing before they are sold.
Here’s a look at how those tests are conducted.
A high-heat and flame test was added to evaluate convective heat loads and their effect on the integrity of the lens and facepiece — all tests are conducted using a manikin head.
First, the entire SCBA unit is subjected to a 500-degree F oven test (heat soak) for five minutes. This is followed by a flame impingement exposure at 1,800 degrees F for 10 seconds. Both elements of this test are conducted while the test manikin is breathing at a rate of 40 liters per minute for each section of the test.
Following the heat and flame exposures, the SCBA and facepiece must survive a 6-inch drop test. There are no requirements for visual acuity and a garden sprayer is permitted to extinguish any after flame. The SCBA must maintain a positive pressure for a period of 24 minutes regardless of the cylinder’s capacity.
Lens integrity
The second new test evaluates the effect of radiant heat loads on the integrity of the lens and facepiece. The SCBA’s facepiece is exposed to a radiant heat load of 15 kW/m2 for five minutes while the test manikin is breathing at a rate of 40 liters per min.
The radiant heat panel is then removed and the SCBA must maintain a positive pressure for 24 minutes regardless of the cylinder’s capacity.
The new test and test conditions are important advances in improving the performance of what has been, perhaps, the most vulnerable component of a firefighter’s protective gear in high-heat conditions.
Failure of a lens can expose a firefighter to toxic gases and can result in burns to the respiratory tract as well as asphyxiation. Documented problems include holes and extensive crazing as well as lens bubbling and deforming.
In several SCBA-related deaths, degraded facepieces were found affixed to the faces of victims who had suffered thermal burns to their airways.
These new tests are certainly welcome additions to the effort to reduce the risk to firefighters due to SCBA facepiece failures during structural firefighting.
But they should also raise a sobering question in minds of all firefighters: Why are we exposing ourselves — along with our protective firefighting ensemble — to high-heat environments? An ounce of prevention is worth more than a pound of cure.
