The Risk Area Heat Detector accurately senses the surrounding air temperature and actuates an electrical contact output at a pre-determined temperature. The certified SIL 2 Capable heat detector can be used as an alarm device to sense excessive heat or fire and warn personnel, or it can be used as a signaling device to sense fire and send a signal to an alarm panel for actuation of a fire suppression system. The design of the heat detector utilizes Rate Compensation, which provides enhanced performance when compared to fixed-temperature or rate-of-rise detectors. The Model HD Detector senses the surrounding air temperature and actuates its output when the temperature reaches the pre‑determined level, regardless of the fire growth rate. The unique properties of the alloy outer shell allow the Model HD to respond more quickly as the fire growth rate increases, i.e. the faster the fire grows, the sooner the unit will react. The device is furnished with an explosion-proof junction box. The detector's electrical contact is factory wired to a screw terminal block located within the junction box. All external wiring to the device is also connected to this terminal block. The screw terminals accept wiring from 12 to 24 AWG. The junction box is available in aluminum or stainless steel, with two or four conduit entries, and either 3/4" NPT or 25 mm threads.