VESDA by Xtralis VESDAVLSProduct Guide
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2.1.4 Sector Factor
By setting appropriate sector factors it is possible to set different alarm thresholds for each of the four sectors.
The detector uses the sector factor to automatically calculate the alarm thresholds appropriate for each sector
based on the configured alarm thresholds. These are multiplied by the sector factor to set the sector alarm
thresholds.
Guidelines for setting sector factors:
l Sector factors range between 0.5 and 2.0
l Where more sensitive protection is desired for a sector (for example a critical server room where there
are relatively more sampling holes and restricted access), set the sector factor at less than 1.0
l Where less sensitive protection is desired for a sector (for example where there is a risk that a
particular local process will generate nuisance alarms), set the sector factor at greater than 1.0
l As a general rule, the difference between all pipes should not be greater than 1
Sector factors are generally optimized after a detector has been operational for a period and sufficient
historical data has been gathered in the event log to assist the decision. However, if it is required to pre-
determine the appropriate setting for sector factor the following methodology can be used:
l Use ASPIRE Pipe Modelling Software to model the intended pipe layout
l Determine the appropriate fire sensitivity required for each sector to achieve the desired hole
sensitivity in each sector
l Select an appropriate median setting for the Fire 1 threshold to be configured in the detector and
calculate the appropriate sector factor which, when multiplied by the configured Fire 1 threshold, will
give the desired fire sensitivity for each pipe
l Record the desired Fire 1 threshold setting and sector factor setting for configuration into the detector
at commissioning.
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