Plastec Airflow Monitor A - Manual (Page 3)

When the fume extraction fan is running, it causes negative pressure inside
the fume cupboard. If the sash is lowered, the negative pressure becomes
more intense causing air to be drawn through the sash opening at an increased
velocity. Conversely, if the sash is raised, the negative pressure becomes less
intense and air velocity reduces.
If an opening is made in the wall of the fume cupboard, air will enter it at a
velocity determined by the same negative pressure that is drawing air into the
sash opening. By sensing the air velocity through an opening, we can determine
its level at the sash opening.
PLASTEC ® AirControl exploits this by the placing of a numerical sensor into a
hole in the cupboard and sending the air velocity measurement obtained to a
display on the fascia panel.
The air velocity level is displayed on the fascia either by LED illumination or
digital read-out. An audible alarm will also sound if the air velocity is too low.
SENSOR
Airflow Monitor
www
.plas
tecv
ent.net
2216 60th Drive East • Bradenton, Florida 34203
(941) 751-7596 • Fax (941) 751-7598 • www.plastecvent.net 3
Operating Principle
Laboratory Airflow Monitors & Controls
TYPE A STANDARD & NIGHT SETBACK
LED & DIGITAL