The U.S. Fire Administration and the National Institute of Standards and Technology have begun researching the potential weaknesses in the thermal performance of SCBA face pieces. The initial phase of this study will examine documented on-duty injuries and fatalities of firefighters due to thermal exposure of SCBA face pieces, said Nelson Bryner, deputy division chief of NIST's fire research division. In addition, researchers will provide regular updates on their findings to the NFPA 1981 technical committee for open-circuit SCBA.

"With the current generation of turnout gear, the firefighter is fairly well protected," Bryner said. "The weakest link in the ensemble is most probably the respiratory face piece, and the question is at what temperature they fail — when do they begin to fail and how they fail. There have been a number of recent incidents detailed in NIOSH investigations where there is sort of a hint, not an absolute link, that the face piece should be looked at a little closer."

Bryner said the first phase of the study is to examine a number of off-the-shelf face pieces and determine at what temperature they melt. He explained researchers will test the equipment in front of a radiant panel, which is a gas-fired apparatus that produces thermal flux. The thermal flux can be adjusted from temperatures that simulate "a hot day outside to like standing in a room with a fire," he said.

"So we can run less than a kilowatt per meter squared all the way up to the 20 kilowatts meter squared — which would be the radiation load you would see inside a fire room," Bryner said. "We also can look at the face piece with or without breathing. We actually have a breathing device that lets us determine breath cycle volumes and frequencies within the mask itself."

Then, researchers will determine the type of heat transfer that weakens face pieces, either through conduction, convection or radiation. Conduction is if the face mask is touching a hot surface. Convection is if hot gases are flowing past the face piece, and thermal radiation comes from the fire or hot gases. Generally speaking, thermal radiation often is a much more effective mechanism for transferring energy, Bryner said.

"Right now, we are looking to verify that the thermal radiation is the main way that energy gets transferred to the mask and that's one reason we're using the radiant panel," he said. "If it turns out thermal radiation is the major way heat gets transferred that may, and that's a big may, suggest that what you really want is a reflective coating to help reflect the thermal radiation. If it turns out that convection is the biggest contributor to the heat transfer it may suggest a different type of design. That's the type of information we intend to provide to the standards committee."

After researchers observe face pieces' performance in the lab, they will then test them at NIST's medium burn facility in Maryland. The researchers can build rooms up to a townhouse size and insert the face pieces on mannequins that are designed to breath, Bryner said. The last step will be field-testing with a chosen fire department.

"The first couple of phases help us understand the performance and then we sort of make sure that we've captured it in more realistic conditions," Bryner said.

The research will take up to 18 months, Bryner said.