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Operating Instructions
Drift Compensation
Drift compensation uses software algorithms that identify and compensate for long-term changes in
the data readings from each addressable smoke detector. These long-term changes in detector data
readings are typically caused by dirt and dust accumulation inside the smoke chamber. Drift com-
pensation performs the following functions:
•
Samples each photoelectric smoke detector every 6 seconds and each ionization smoke
detector every 3 seconds
•
Allows a smoke detector to retain its original ability to detect actual smoke and resist false
alarms, even as dirt and dust accumulate
•
Reduces maintenance requirements by allowing the control panel to automatically perform the
periodic sensitivity measurements required by NFPA Standard 72
The FACP software also provides filters to remove transient noise signals, usually caused by elec-
trical interference.
Maintenance Alert
The software determines when the drift compensation for a detector reaches an unacceptable level
that can compromise detector performance. When a detector reaches an unacceptable level, the
control panel indicates a maintenance alert. Table 4.1 summarizes the three levels of maintenance
alert:
Maintenance Level
Low Chamber Value
Maintenance Alert
Maintenance Urgent
Figure 4.1 illustrates a graphic representation of the maintenance levels:
172
FACP Status Displays
INVREP
DIRTY1
DIRTY2
Table 4.1 Maintenance Alert Levels
Maintenance
Urgent
Acceptable
Low Chamber
Reading
Figure 4.1 Diagram of Maintenance Levels
Indicates
A hardware problem in the detector
Dust accumulation that is near but below the allowed
limit. DIRTY 1 indicates the need for maintenance
before the performance of the detector is compromised
Dust accumulation above the allowed limit.
DIRTY
Maintenance
Alert
Range
LOW
VALUE
MS-9600LS Series Manual — P/N 52646:B2 2/12/2010
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