Operating Instructions

Laboratory Room Controller Owner's Manual
3-6 Siemens Building Technologies, Inc.
Table 3-2
Descriptor Number Function
OCC SUP MAX 31 Maximum supply in occupied mode.
OCC SUP MIN 32 Maximum supply in occupied mode.
OCC GEX MAX 33 Maximum general exhaust in occupied mode.
OCC GEX MIN 34 Minimum general exhaust in occupied mode.
OC V ALM LVL 90 Ventilation alarm level in occupied mode.
UOC SUP MAX 71 Maximum supply in unoccupied mode.
UOC SUP MIN 72 Minimum supply in unoccupied mode.
UOC GEX MAX 67 Maximum general exhaust in unoccupied mode.
UOC GEX MIN 68 Minimum general exhaust in unoccupied mode.
UC V ALM LVL 91 Ventilation alarm level in unoccupied mode.
Using an Unoccupied Mode
One of the tasks of a laboratory ventilation system is protecting the laboratory workers by
diluting air contaminants with a supply of fresh air. Often this air supply is expensive to
deliver. Energy-conscious managers can reduce this expense by reducing the ventilation rate
when there are no people in the laboratory. Without a room occupant to protect, the same
dilution and the same supply airflow may not be required. This is called
ventilation setback
.
There are two issues involved: the potential to save energy and the safety of people who use
the building.
The first issue is for the facility's Safety Officer to determine whether a reduced ventilation
rate is acceptable when the room is unoccupied. This person should consider the sources of
contaminants in the rooms, permissible concentrations, and the corresponding air change
rates. The necessary information and philosophy should be found in the site's Chemical
Hygiene Plan. The Safety Officer will then state if reducing the ventilation rate is safe and
what ventilation rate is required during the unoccupied period.
The second issue is to decide how the LRC should determine when the laboratory is
occupied and when it is not. Possibilities include either one or more of the following:
schedules, switches and buttons in the room, as well as using the fume hoods. For more
details, refer to the section
Determining Occupancy
in this chapter.
W
WW
WAR
ARAR
ARN
NN
NI
II
ING
NGNG
NG:
::
:
Regardless of how the LRC selects unoccupied mode; it is essential that the
system clearly indicates that mode to occupants of the building. When a room is
in unoccupied mode, there must be an indicator, such as a light, visible to
anyone in the room or entering the room. Any workers who have occasion to
enter the room must be trained to observe the indicator and know what it means
to them. This is a critical part of laboratory safety training.