VDOT-ASD-400 Aspiration Detector
Velocity Detection
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VDOT-ASD-400 Aspirating Smoke Detector User’s Manual V1
Appendix
Pipe Scan
VDOT-ASD-400 aspirating smoke detector consists of four individual aspirators, connecting to its
pipe inlet port and one high sensitivity smoke detector. All the air samples from the four pipes are
mixed and go to a single exhaust port. The mixed air samples are then drawn into the high
sensitivity smoke detector on the way to the exhaust port.
Taking advantage of the four individual aspirators, the VDOT-ASD-400 can turn each aspirator on
and off in sequence when there is a smoke alarm to “identify” the pipe having the most smoke. We
call this process pipe scan.
For example, when there’s smoke goes into the sampling points on pipe 3, the VDOT-ASD-400 will
detect the smoke and generate alarms when the smoke alarm levels have been reached and
appropriate time delay expired. At this time, the VDOT-ASD-400 cannot identify which pipe the
smoke is from. When the alarm reaches the scan level setting (can be alert, action, fire 1, or fire 2),
besides the activation of alarm LED on the display and relay output on the termination board, the
pipe scan process will be activated.
The scan process starts to scan pipe 1 (turn on fan 1 and turn off fan 2, 3, 4), collect the smoke level
for pipe 1 for a time interval call scan time. When the pipe 1 scan time is completed, it will move to
scan pipe 2 (turn on fan 2 and turn off 1, 3, 4) and then scan pipe 3 and scan pipe 4 respectively,
finally all the fans will turn on to flush out the possible smoke contained inside the detector and
then complete a pipe scan cycle. During the scan process the 6 digits Numerical Display will flash
and show the scanned pipe number and its smoke level. After the scan cycle, the smoke data of
each pipe is calculated and analyzed, and the pipe with the most smoke will be identified. The
Aspirator #1~#4
