INSTALLATION
MAN0987_Iss 2_09/16
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FSL100 Series Flame Detectors
Technical Handbook
4.7 Vote Count
FSL100 flame detectors will not give an alarm until several different alarm criteria occur at the same time, and the probability of
a false alarm is very low. The flame detector is therefore suitable for relay activated actions (i.e. drenching) based on the signal
of one flame detector.
However, ‘voting’ may be demanded in a functional specification, in which case the ‘voting-system’ may be applied; i.e., the
flame detectors may be mounted in multiples, as shown in the example below where an alarm output would be dependent on
the controller receiving confirmatory alarm inputs from at least two of the available detectors.
Figure 8.
Voting Arrangement Using Four Detectors
A good example of voting would be in a Server room or process room that uses inert gas drenching to replace oxygen in the
atmosphere, and the voting of any 2 out of the 4 flame detectors should be mandated before the relay output can be triggered.
Note:
The fire control panel or PLC must be able to support the two detector voting system.
Caution
A flame detector is a line of sight detector so voting with just two flame detectors in not reliable. The redundant
flame detector in the opposite corner cannot be used for a 2 detector dependent output because a flame
occurring in a shadow area would not be seen by the second detector until the fire is well established. In this
case the second flame detector will give an alarm too late or not at all.
Monitored object
