LaserSCANNER Product Manual
VESDA
®
4
The Scanner Valve Test
The VESDA LaserSCANNER performs a scanner valve test when first powered up. Thereafter a
valve test is performed every alternate Tuesday at 12:00 hours. During the valve test each valve
is individually closed and opened to ensure its proper functioning. Any improper functioning is
reported as a fault (refer to the VESDA Troubleshooting Guide for fault descriptions and
troubleshooting). It is possible to simulate a valve scan test by pressing the
Silence/Scan
button
on the Display Module for two seconds, or selecting the scan test option under the diagnostics
menu on the LCD programmer or the device menu on the PC software.
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:
•
Sector factors range between 0.5 and 2.0
•
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
•
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
•
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:
•
Use ASPIRE Pipe Modelling Software to model the intended pipe layout
•
Determine the appropriate fire sensitivity required for each sector to achieve the desired
hole sensitivity in each sector
•
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
•
Record the desired Fire1 threshold setting and sector factor setting for configuration into the
detector at commissioning.