TEL AFA4000/2, Installation And Operating Manual

Page: 37 / 177

AFA4000/2 Airflow Monitor / p.37
4.3.2 Personnel sensor
Figure 5: Detection area clear Figure 6: Obstruction present
The Personnel Sensor is a Passive Infra-Red (PIR) occupancy detector which detects the
presence / absence of the fume hood user.
Note: If the user is detected, the sash will not automatically close. The Sash can be
opened / closed manually or using the Up / Down pushbuttons.
On power up, the Personnel Sensor ‘learns’ the reflection characteristics of the
environment within its field of view and stores this information as reference background
data. The sensor then 're-learns' the background every three minutes. A stationary
object, such as a stool, that is left in the field becomes part of the background and is
'ignored' by the sensor. When the user is not present at the fume hood, the sash will
close automatically. This follows a pre-set delay time, if the Sash Light Curtain is not
broken and the sash is open.
Green LED Red LED