Basic Documentation

Differential Pressure Monitors
Double door interiors are maintained at a lower
negative pressurization level as indicated by a single
negative sign (-). Although not specifically required,
it is desirable to use electrically interlocking doors so
that only one door may be open at a time. This helps
maintain containment even when a door is opened.
Differential Pressure Monitors are located at
doorway
s where lab users can confirm proper
pressurization. These monitors indicate the static
pressure difference and warn of a loss of required
differential pressure at that location. While a door is
open, the differential pressure level across it drops
until the door is again fully closed. Therefore,
differential pressure alarms must have an adjustable
alarm delay to prevent nuisance alarms during
passage through doors.
LABORATORY ROOM
-0.10 TO -0.15 iNCHES
NEGATIVE PRESSURIZATION
ROOM SUPPLY
AIR TERMINAL
100%
OUTSIDE AIR
'BUBBLE TIGHT'
ISOLATION DAMPER
ROOM VENTILATION RATE
4 TO 8 AIR CHANGES PER HOUR
B1 OR B2
BIOSAFETY
CABINETS
HEPA
FILTERS
'BUBBLE TIGHT'
ISOLATION DAMPERS
CEILING
EXHAUST
FLOOR
EXHAUST
EXHAUST TO
OUTSIDE
BAG IN / BAG OUT
HEPA FILTERS
Figure 4
. Room Ventilation for a BSL-3 Laboratory Room.
Page 8 of 10 Siemens Industry, Inc.
Document No. 149-997