series 302 heat detectors are designed for use in normal environments as well as environments where the detectors are subject to weather, moisture (internal condensation) and explosive atmospheres. They are normally-open devices designed to close an electrical circuit upon activation. All models feature rate compensation and are available with either 135 deg F or 194 deg F ratings. They are self-restoring, hermetically sealed, shock and corrosion-resistant and are tamper-proof.