Building and Fire Research Laboratory engineers at the National Institute of Standards and Technology have embarked on a project to assess current PASS technology by examining specific enhancements, including elimination of false alarms, improved accuracy, links to the Global Positioning Systems and/or fireground personnel tracking systems, and the incorporation of additional technologies, such as thermal sensors or toxic gas analyzers.

“We're putting the PASS devices through their paces to see how well they perform,” said Nelson Bryner, group leader of NIST's Firefighting Technology Group. “There's an NFPA standard test that they all must pass, but the question is, ‘In a real fire how, do they perform?’”

To find out, BFRL has devised a series of evaluations to characterize PASS devices from different vendors. These include laboratory trials that expose the devices in ovens to test thermal radiation sensors. They also have an apparatus that shoots hot toxic gases toward the PASS devices to see how well they sense convector heat.

Outside the laboratory, BFRL exposes the devices to a series of controlled townhouse and apartment burns. During these controlled field burns, a mannequin named Fred is outfitted with instruments and placed on a dolly in furnished rooms that are set afire. The dolly and Fred are withdrawn before flashover.

Placement of the PASS devices on turnout gear can be critical. “We have an instrumented mannequin on which we installed six PASS devices,” Bryner said. “We're tracking the temperature in front and back of the firefighter, and on the top of the helmet.

“Typically, firefighters wear just one PASS device,” Bryner said. “Some wear them on the front. If you're just beginning to fight a fire, that may be the most appropriate place. However, if you're retreating from a fire or crawling along on your hands and knees, the PASS device itself may be protected from the fire and therefore may not sense the amount of ambient energy.”

Conversely, some PASS devices are worn on the back, integrated into the SCBA. “If you're facing the fire, this may not be the best location if you're trying to get a thermal signal,” Bryner said. On the other hand, if you're crawling along the floor, that may be the optimum place for it to be.

“We're looking at the performance,” he said. “For instance whether the PASS devices on the front alarm at the same time that the ones on the back do, and whether there are scenarios where the ones on the back may alarm more quickly.”

The NIST tests aren't attempting to determine which model outperforms another; rather, they're evaluating overall performance of all devices. Also, part of the project will attempt to gauge whether other technologies, such as toxic gas sensors, can be effectively incorporated into PASS devices to make them even more useful.

Results of the evaluations will be published later this year. The NIST work is funded by the U.S. Fire Administration.