Catch the Drift: An Overview of Detector Drift Compensation

Addressable fire alarm control panels provide several enhanced features that are not provided with conventional fire alarm control panels. Several of these features relate specifically to the addressable detectors, such as Drift Compensation, Maintenance Alert, and Calibrated Sensitivity testing. In this installment, we will provide an overview of Drift Compensation.

Let’s look at an addressable detector on a Silent Knight addressable fire alarm control panel. When a detector is installed and programmed, it communicates with the fire alarm control panel to determine a variety of thresholds. These thresholds determine events like trouble and alarm conditions. Once the detector reaches a specific threshold, the trouble or alarm condition would occur. Over time, detectors will accumulate contaminates such as dust, which can cause the sensitivity of the detector to change. In order to keep the sensitivity constant, the detectors adjust their internal thresholds to compensate for these contaminates. This process of adjustment is called Drift Compensation and ensures that detectors have the same sensitivity as when they were first taken out of the box.

detector values - drift compensation

Eventually, detectors will reach a point where they will not be able to compensate for contaminates. When this occurs, a Calibration Trouble will annunciate for the detector or detectors in question. It is important to note that addressable detector chambers can be cleaned. A new detector is not required when it reaches its Calibration threshold. When a clean detector is reinstalled, the panel and detector will communicate to reestablish thresholds and the Calibration Trouble will restore. Aside from keeping a constant sensitivity over time, a key benefit of Drift Compensation is that it dramatically decreases the amount of service calls as the time between cleanings increases.

Did you know the Detector Status upload with SKSS software is a U.L. listed Calibrated Sensitivity Smoke test? Please leave a comment by clicking on the Leave a Reply link above to enter your request.


About the Author
Jack Grones is an Application Engineer with Silent Knight and holds a NICET Level III certification.  Jack joined Silent Knight in 1978 and is responsible for applications and technical support.

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