Bebco Building Pressurization Unit, Air Stack

Bebco 4 Inch Diameter Room Pressurage Gauge       

All Bebco Model WDP Whisper-Drive™ Building Pressurization Units  feature 

necessary indicators and controls to maintain room or building pressurization 

or outward velocities through openings automatically upon loss of pressure. 

Operation is easy, beginning with startup. Once doors are sealed and the secondary 

fan control switch is placed in its automatic mode, the unit is started by engaging 

the primary fan control switch. 

The green primary fan engaged indicator will then illuminate to indicate the unit is running, 

as it establishes a safe pressure within the room automatically.  From that point forward, the 

unit maintains NFPA 496 Code compliance with no need for further adjustments!  If pressure 

is lost, the secondary fan will engage and the alarm signal will be activated immediately 

or as permitted by settings of their separate corresponding delay timers and the red alarm 

engaged indicator will illuminate to confirm loss of pressure. 

When doors must be left open for a prolonged period of time, the secondary fan control switch may be placed in its 

manual mode and the alarm signal bypass switch may be used to disable the alarm signal, which in turn will be 

indicated by flashing of the red alarm engaged indicator. In essence, you’ll find our pressurization units extremely 

easy to operate, but for more information on how to utilize these controls to your benefit, 

please contact a Bebco Sales Associate!