VESDA by Xtralis VESDA VLI Product Guide
www.xtralis.com 41
5.5.2 Smoke Threshold Options
Smoke Threshold options provide the mechanism to set the smoke obscuration trigger point for each alarm
level, and the ability to assign day or night thresholds to cater for different levels of activity in the protected
area during these times.
Refer to Section 5.6 for the default settings.
Figure 5-12: Smoke Threshold Options
The Smoke Threshold configuration options are as follows:
Apply UL Limits
If checked, the fire threshold will be limited to ensure that the detector is UL compliant. Ensure that when
Apply UL limits is checked, Fire2 is set to the UL limit by exiting and then going back to the Smoke
Thresholds options.
Day Thresholds
The settings for day time smoke thresholds. The threshold and the delay are used together to decide when to
trigger the alarm condition.
Night Thresholds
The settings for night time smoke thresholds. The threshold and the delay are used together to decide when to
trigger the alarm condition.
Delay
The length of time between the alarm threshold being reached and the relay operation.
l Cumulative Delay: If checked, the delay period for alarms is set to cumulative.
l Instant Fire: If checked, the time delays are ignored when the smoke level increases rapidly.
Significant Smoke Change
The smoke change level at which an event is recorded in the Event Log. The VLIis designed for harsh
environments, so it is recommended that the Significant Smoke Change value is set to 0.05 %/m (0.015 %/ft)
or half the value of the Alert level, whichever is greater.
Changeover
l Work Days: Select which days use both day and night thresholds. Night time thresholds are used if a day
is not selected.
l Day / Night Changeover Time: The settings for the timing of the threshold changeover.
l Holidays: The settings used to define a holiday period. Use the dropdown calendars to choose the start
and end times of the holiday (or break) period. Night time thresholds are used during the holiday period.
To Next Page
Loading...
Need help?
General
