Given the protection provided by today’s PPE and SCBA gear, firefighters sometimes find themselves fighting blazes in relatively high temperatures. A recently released National Institute of Standards and Technology study, however, reveals that first responders shouldn’t rely on unprotected handheld radios even in routine firefighting situations, much less in higher-temperature fires.

NIST fire engineers tested three representative portable radio models from three different manufacturers in a wind tunnel designed to simulate thermal conditions at three different degrees of intensity that firefighters are equipped to withstand: Thermal Class 1, with a maximum temperature of 212°F for 25 minutes; Thermal Class 2, with a maximum temperature of 320°F for 15 minutes; and Thermal Class 3, with a maximum temperature of 500°F for five minutes. Each of the radios tested listed their maximum operating temperatures as only 140°F.

One radio of the three samples would not transmit or receive after 25 minutes at 212°F, although it did begin working after a cooling-off period. In the 15-minute experiment at 320°F, one radio went dead in less than nine minutes. The other two radios suffered significant performance problems, ranging from transmission and reception shutdown to signal degradation or fluctuation. None survived the Thermal Class 2 test and cool-down period.

Portable radios inside pockets of turnout gear fared much better. All survived temperature tests at Thermal Class 1 and Thermal Class 2 maximum heats and times. Pocket-protected radios also survived Thermal Class 3, but exposed cords, speakers and microphones did not, effectively limiting the radios to Thermal Class 2 electronics. The NIST engineers suggest that small design changes on the speaker/microphones and cords could allow all the protected radios to reach a Thermal Class 3 rating.

NIST conducted the study to evaluate the general performance of portable radios at elevated thermal conditions, to identify shortcomings and to suggest standards for the radios. The results will be used to develop test methods and recommendations that will be submitted to the National Fire Protection Association and other appropriate standards-setting bodies. The NIST study was conducted by the Building and Fire Research Laboratory for the NIST Office of Law Enforcement Standards with funds from the Department of Homeland Security.

The full NIST report in PDF format may be viewed here.