Operating Instructions

Fume Hood Controller Owner's Manual
18 Siemens Building Technologies, Inc.
If a sequence initially employing maximum purge with a switch to controlled purge is desired,
set the emergency setpoint as described for the controlled purge. Select a value for the
emergency timer to tell the system how long to leave the damper open before switching to
controlled purge. Base this on the types of accidents anticipated, the reason you require a
maximum purge, and the reason you want to switch it down to a controlled purge.
In addition to setting up the purge sequence to effectively handle the exhaust needs,
decisions must be made on how to use the information available at the central reporting
station. Consult your local Siemens Building Technologies, Inc. representative for more
information on central reporting and trending of emergency purge information.
Fail-safe Operation
If the Fume Hood Controller or one of its accessories fails, then a failure mode sequence will
be initiated.
Fume Hood Controller
If the Fume Hood Controller power fails, the exhaust damper will go to the full open position.
Since there would be no power to the controller, no LEDs or display will be available on the
ODP.
NOTE: If the power fails to both the exhaust fan and the controller, there will be no
indication except for the absence of the noise that the air makes during
normal operation.
Sash Sensor
If the sash sensor fails, the controller will maintain airflow through the fume hood at an
exhaust setpoint calculated using 50% of the maximum open sash area. The ODP will
display FFF and GENERAL FAILURE.
ODP
If the ODP fails, the controller will continue to control the fume hood face velocity. However,
no display or audible alarming will be available.
Differential Pressure Transmitter
If the differential pressure transmitter fails, the controller will control the exhaust damper or
valve to the fully open position. The ODP will display FFF and GENERAL FAILURE.
Electronic Actuator Assembly
If the electronic actuator or interface board fails then alarms are displayed on the ODP
indicating unsafe operating conditions.