The Thermotech heat detector Model 302 is a normally open device designed especially for fire detection and alarm systems. These rate compensation type detectors are available in either 135°F. or 194°F. ratings. All four basic models are self restoring, hermetically sealed, shock and corrosion resistant, and are tamperproof. Refer to NFPA STANDARD 72, STANDARD FOR AUTOMATIC FIRE DETECTORS for application requirements, testing and maintenance. the Thermotech heat detectors are not directionally affected, they can be mounted horizontally or vertically.