Operating Instructions

Fume Hood Controller Owner's Manual
16 Siemens Building Technologies, Inc.
The delay timer is adjustable and should be selected with safety in mind. Laboratory safety
procedures will not be effective if there are numerous nuisance alarms. The delay timer
should be set at a sufficiently large interval to prevent nuisance alarms. However, if the delay
timer interval is excessively large, there is a risk of having a laboratory worker standing in
front of an ineffective fume hood for a prolonged period. The delay timer interval should be
selected by the laboratory safety officer with the above considerations in mind.
Sash Area Alarms
Sash area alarms alert the user when the fume hood open sash area is above set limits. The
ODP horn will beep six one-second chirps every minute until the sash is moved within these
limits. There are limits for both attended and unattended modes of operation. This feature is
turned off by default, contact your Siemens Building Technologies, Inc. representative for
more information. The ATTN.UNATTN sash alert alarm level is controlled by either the
network or DI 1.
Emergency Purge Feature
Under certain emergency conditions, such as a spill in the fume hood, it may be necessary to
purge the air from the fume hood by pressing the Emergency Purge button. The Emergency
Purge sequence enables the fume hood user to override normal face velocity control and
temporarily increase the airflow beyond the value needed to maintain face velocity. This
increase is particularly important if the accident requires the worker to close the fume hood,
where, under normal operation, the exhaust airflow is at a minimum level. The Emergency
Purge feature will provide high exhaust airflow even when the fume hood sash is closed.
The Emergency Purge overrides any other control mode in the Fume Hood Controller and
has two modes of operation; maximum purge, and controlled purge.
The maximum purge moves the exhaust airflow control device to full open and holds it there
regardless of airflow or face velocity. This mode has the advantage of providing immediate
expulsion of the contaminating agent, but may cause airflow problems in the fume hood and
reduce the airflow capacity at other fume hoods.
The controlled purge continues to modulate the exhaust airflow control device and controls
the airflow, but at a higher than normal level.
The Fume Hood Controller can be set up to purge in either mode or to start in maximum
purge and then switch to a controlled purge after an adjustable amount of time.
Emergency Purge Operation
The Emergency Purge sequence is initiated by pressing the Emergency Purge button on the
ODP. When the Emergency Purge button is pressed, the fume hood will go to the maximum
purge for the time selected in the emergency timer. After the emergency timer elapses, the
Fume Hood Controller will begin actively controlling the airflow, but at an increased setpoint.
The Emergency Purge sequence is canceled by pressing the Emergency Purge button a
second time. The ODP indicates an Emergency Purge sequence in three ways:
 The red LED illuminates.