AFA4000/E VAV Airflow Controller / p.44
Figure 8: Sash Light Curtain Transmitter and Receiver
A separate Sash Light Curtain Control Box includes a sensitivity potentiometer that allows the
beam sensitivity adjusted to sense glass or other objects that are partially transparent to infra-
red light.
Figure 9: Sash Light Curtain Control Box
4.3.4 Under Sash sensor
The Under Sash Sensor is an alternative to the Sash Light Curtain which detects whether the
opening below the sash is clear from obstructions before the sash is closed.
A sensor on one side of the fume hood detects the reflection of a beam of light from a self-
adhesive strip of retro-reflective tape mounted on the opposite inside wall of the fume hood.
The sensor incorporates a potentiometer, it allows the beam sensitivity to be adjusted to sense
glass objects.
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