Many facilities include an HVAC installation on the rooftop. These are exposed to a broad range of environmental extremes, including wide fluctuations in temperature and humidity. NEMA 4-rated InnovairFlex watertight duct smoke detectors are built to operate in the most challenging conditions without the need for bulky or costly enclosures. These detectors can operate in airflow speeds from 100 to 4,000 ft. per minute, temperatures from -4 deg. F to 158 deg. F and humidity ranges from 0 to 95 percent (non-condensing). In addition, a watertight, UV-resistant housing provides protection against dirt, rain, windblown dust, splashing and hose-directed water.