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Read Status
Maintenance Level
Low Chamber Value
Maintenance Alert
Maintenance Urgent
MS-9200UDLS PN 52750:A 11/04/05
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 compensation performs the following
functions:
•
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 electrical 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:
FACP Status Displays
INVREP
DIRTY1
DIRTY2
Table 4.1 Maintenance Alert Levels
Figure 4.1 illustrates a graphic representation of the maintenance levels:
Maintenance
Urgent
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
Acceptable
Range
LOW
VALUE
Operating Instructions
151
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