Continuing advances in infrared technology have resulted in fail-to-safe hydrocarbon gas point detectors that continuously monitor combustible gases and vapors within the lower explosive limit (LEL) and provide alarm indication. Other features of these detectors include operation in oxygen deficient or enriched areas, lack of routine calibration, immunity to poisons and RS-485 communications link along with 4-20 mA output. Another application of infrared technology is open path detection, which complements point detection. With an open path system there is no definite fixed path length for measuring gas leaks so the measurement is expressed in terms of concentration times path length. The open path system incorporates many of the same advantages of the optical point detector and includes a dual range, ppm.m for small hydrocarbon leaks and LEL.m for more catastrophic leaks.

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