Thermotech 302 Rate Anticipation Heat Detector

In general, the Thermotech 302 heat detector operates on the principles of rate compensation detectors. Each model is a normally open device design 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 tamper-proof.

All models operate on the principles of rate compensation detectors. The Thermotech 302 detector consists of a high expansion aluminum tube that encases two insulation struts with opposing open constant points. The high expansion sensing shell and the expansion struts have a different coefficients of expansion. A slow rate of temperature rise allows the heat to penetrate the inner expansion struts. Therefore, the tubular shell and the struts expand slowly until the total device has been heated to its rated temperature level of 135°F or 194°F. At this point, the silver contact points close which initiates the alarm.

When subjected to a rapid temperature rise there is not as much time for heat to penetrate the inner strut. The rapid lengthening of the shell allows the struts to come together at a lower level which compensates for thermal lag inherent in conventional fixed temperature detectors. When the surrounding air temperatures go below the rated temperature level, the shell contracts which forces contacts to open, which automatically resets the detector.

Features / Specifications

• Hermetically sealed and explosion-proof options
• Overall Length: 4-1/8″
• Horizontal or vertical mounting
• Aluminum tubing with silver contact points