Since the introduction of the Americans With Disabilities Act in 1990, the number of visual fire alarm signals installed in the United States has grown exponentially. Virtually all of these fire alarm visual signals consist of the Xenon gas fiashtube type. This technology offers high intensity along with moderate cost in a relatively small package. Typical intensities offered range from 15cd (candela) up to 185cd. With the recent advances in solid state LEDs (Light Emitting Diodes) the possibility exists to develop visual fire signals using this technology. When used in lower intensity visual appliances, LEDs offer comparable light output with much smaller optical footprints (albeit at somewhat higher estimated costs). This paper will examine the optical performance of a prototype LED visual fire signaling appliance as compared to a more conventional device. It will also evaluate a series of tests, which were run in an office environment to compare the response time of workers for both the conventional Xenon fire signal appliance as well as the prototype LED device. Measurements for each test subject were taken over a two to three day period. Parameters measured included time of day, size of office and general ambient lighting. Results of these experiments indicate that the general response times of the test subjects were similar for the two types of fire signals. The paper concludes with a discussion of the potential for LED-type fire signaling devices as well as some of the potential technology obstacles still to be overcome.
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