Application

Sequence of Operation
Emergency Mode
11
Siemens Industry, Inc. 140-1341
Restricted 2015-11-09
Emergency Mode
The emergency mode operation overrides any other control mode in the Fume Hood
Controller. When the Emergency Purge button on the ODP is pressed, the following
sequence of events occurs.
1.
EMER ALM turns ON at BACnet priority level 1, the horn sounds, and the red
LED on the ODP illuminates. The ODP displays “EMERGENCY” mode and
indicates to close the hood.
2.
The Fume Hood Controller commands the damper/Venturi valve to fully open
for the time (in seconds) specified in EMER TIMER.
3.
After EMER TIMER has timed out, the Fume Hood Controller controls the flow
at the flow setpoint, EXH STPT, multiplied by the emergency set point
percentage, EMER STPT.
4.
When the Emergency Purge button is pressed a second time, the Fume Hood
Controller returns to normal operation for the current conditions.
Emergency Purge Schedule.
NOTE:
Norm
= Normal operation in which control is at the EXH STPT.
EMER STPT
= EXH STPT increased by the value (%) of EMER STPT.
MAX
= Maximum flow, where the damper is controlled to fully opened.
Start-up/Decommission Mode
The Fume Hood Controller contains different modes controlled by STARTUP MODE
(default is 3). These modes of operation allow the controller to be started up without
the sound of nuisance alarms at the hood. These modes are useful at different stages
of construction and after decommissioning.
The FHC also contains decommission modes and allow some or all of the functionality
of the controller to be turned off.