Testing for Rate Compensation

HST Series Operation with Rate Control:

1. Turn on HST by pressing the power button. Hold tester firmly over detector.
2. The temperature will begin to rise to approximately 65% of the detectors set point. The temperature will then be held at 65% for about 3 minutes.
If there is an "initial trip" trip before hold temperature is reached, continue holding tester over the detector and note the "initial trip" temperature when detector tripped. Detector should "auto reset" in about 1 minute. (try resetting alarm every 30 seconds until alarm resets).
3. After the 3 minute hold time, the temperature will begin to rise slowly at a rate of about 10-15°F per minute.
4. Watch the remote temperature readout and note the temperature when detector trips.
This will most likely NOT be exactly at the temperature set point of the detector.
See Appendix A for information on Rate Compensated detector set point.
5. When temperature is close to the detectors set point the LED will begin slow flash.
Slow flashing LED indicates that detector should be very close to trip point if not already tripped.
6. The temperature will continue to rise until 5° to 30°F above detector set point.
7. Completely cool the tester before starting on next test.

Interpretation of test results
1. An initial trip followed by a second trip at higher temperature after 3 minute timer is indicative of rate compensation working properly.
2. If detector does not trip below hold temperature, you may still verify rate compensation by allowing detector to heat for a few minutes, followed by 1 minute rest then starting test over again, watching for higher trip point on second test.
3. If detector is heated longer and re-tested. The trip point will continue to slowly rise.
4. A detector which continues to trip below 3 minute hold temperature may indicate a low-shift in set point.
5. A detector which fails to trip after full temperature is reached may indicate a high-shift in set point.

Example test results:
Detector type: Fenwal DAF 140F
Ambient temperature: 88 Degrees F
Initial trip point:110 F Degrees
Compensated trip point (second trip):132 Degrees F

After noting trip points for all detectors, it is recommended to use manufacturers +/- tolerances and good judgment to determine Pass/Fail criteria for your particular environment. Detectors should be within similar +/- tolerances. A device which falls outside of this parameter may require replacement or further evaluation. Results will vary somewhat depending on ambient temperature, battery charge, etc. The HST can accurately determine if detector set point has shifted low or high. However these limitations should be considered when interpreting test results.
Detector calibration requires specialized laboratory-type equipment and is performed on new detectors at the manufacturers factory. The HST will help to detect major shifts in set point but is not intended to be used to calibrate heat detectors. To meet listing requirements, detector manufactures do not usually provide a way to field adjust heat detector set point.
The material presented in this document is for informational purposes only. Follow the manufacturer's specific testing instructions. Detectors may require additional tests, especially if open flame or other uncontrolled source of heat has been used in the past for testing purposes. See Fenwal® Operation, Maintenance and Installation manual for complete testing instructions.