Siemens 125-5033 - Manual (Page 18)

Fume Hood Controller Owner's Manual
10 Siemens Building Technologies, Inc.
NOTE: While the pneumatic actuator is being commanded, you may hear a hissing or
clicking sound coming from the AO-P module. This is due to the movement of the
air valves and the bleeding of air from the actuator. This is normal operation.
Differential Pressure Transmitter
The differential pressure transmitter is used to send a signal that represents the velocity of air
in the duct to the controller. The differential pressure transmitter receives the velocity
pressure signal from the airflow sensor (orifice plate). The transmitter is a dead-end device
which prevents the exhausted fume hood air from flowing through the transmitter or the
sensor.
NOTE: In accordance with laboratory ventilation safety standards and regulatory
agencies, the performance of the fume hood should be checked annually, as a
minimum, to ensure continued safe and proper operation. Consult Siemens
Building Technologies for more information about a comprehensive laboratory
ventilation system evaluation and associated test programs.
Airflow Sensor
Airflow sensors are used in conjunction with the differential pressure transmitter. The airflow
sensor senses an average air velocity across the duct section. Using the average air velocity
and the duct area, the controller calculates the airflow.
CAUTION:
Ensure that the sensor and exhaust system materials match the fume hood usage.
Exhausting corrosive fumes may corrode the sensor and exhaust system.
Cables
The Fume Hood Controller connects to the portable operator's terminal with the controller
interface cable (P/N 540-143). This cable has an RJ-11 connector (similar to a phone jack)
on one end, and a larger, 9-pin connector on the other end. The RJ-11 connector plugs into
the bottom of the ODP. For more information, see the Fume Hood Controller Operator
Display Panel User's Card (125-1976). The 9-pin connector plugs in the communication port
of the portable operator's terminal. For more cable information, contact your local Siemens
Building Technologies, Inc. representative.