The EWT Series of THERMOFLEX™ heat detectors for fire alarm systems are Explosion proof, Weather proof,  Water-tight and Dust-tight.
Hazardous Environments

With its non-metallic diaphragm, the detector can operate normally at low temperatures, making it suitable for non-heated, exposed or chilled spaces including garages, boat decks, engine rooms, tunnels, etc., or in corossive or high humity environments.


        Class I, Group C - atmospheres containing ethyl ether vapours, ethylene, cyclopropane
        Class I, Group D - atmospheres containing gasoline, hexane, naphtha, benzene, butane,  propane, alcohol, acetone, lacquer solvent vapours, or natural gas.
        Class II, Group E - atmospheres containing metal dust, including aluminum magnesium and their commercial alloys, and other metals of similarly hazardous characteristics
        Class II,  Group F - atmospheres containing carbonaceous dusts including carbon black, coal or coke dust
        Class III,  Group G - atmospheres containing flour starch or grain dust
        Class III, A location where there is a danger of explosion due to the presence of flammable fibers or flyings

Rate-of-Rise & Fixed Temperature

The Model Number prefix “CR” indicates that the detector is a combination Rate-of-Rise and Fixed Temperature,(often referred to as “Dual-action”), unit.  The Rate-of-Rise function allows the detector to close its contacts when the temperature at the ceiling increases at a rate of 8.4 Celsius degrees (15 Fahrenheit degrees) per minute. The closure of the contacts initiates the Fire Alarm sequence.  The Fixed Temperature portion consists of a spring-loaded plunger held in place by a eutectic solder that will fuse at the specific temperature (in Fahrenheit degrees) as indicated by the Model Number i.e. 135, 165, and 200.

Fixed Temperature Only

The Model Number prefix “CF” indicates that the detector is Fixed Temperature Only, and will therefore not respond to a rate of temperature increase but will operate when the detector fuses at the prescribed (Fahrenheit) temperature as indicated by the model number, i.e. 135, 165, 200 and 285 degrees.  This detector is referred to as “Fixed Temperature Only, non-restorable”.