Chemical Resistant Wall Mount Air Conditioners & Heat Pumps


  • Stand-Alone NFPA 496 Pressurization Systems & Emergency Ventilation Fans
    Higher Air Flow Capacities for Special Needs
    – Separate Wall or Pad Mount Configurations

    – Separate or Shared Fresh Air Intake Stacks
    – Integrated or Independent Controls
  • Integrated or Stand-Alone Chemical Filtration Systems  to scrub Intake or Recirculated Air 
    – Provides a total environment control solution!


  • Meets & Exceeds all applicable NFPA 496 Chapter 7 & 9 Requirements
    – Maintains Room Pressure Automatically w/ Variable Speed Drive Technology
    – Produces required 60 FPM Velocity through all Openings

    – Maintains Dilution Rate through Room Exhaust Vents, if required
  • Ultra-Quiet Backward Inclined Blower Wheels with Venturi Inlet Cones
    – Precision balanced and mated to ensure optimum performance 
  • Integrated VFDs, Motors, Pressure Transmitters & G2 Safety Lockouts
    – All pressurization control devices, easily serviceable and within your unit!
  • Digital Pressure Indicator & Purge-Off-Auto Unit Control Switches
    – Provides inches of water reading and full control of pressurization process
  • Emergency Purge Mode Activation & Dedicated Alarm Circuits
    – Permits remote activation of purge mode in emergency conditions
    – Provides a room pressure loss alarm signal with an adjustable delay
  • 3 Express Unit Air Flow Rates or Higher Custom Unit Air Flow Rates
    – Select a Size based on the Total Square Feet of all Entry & Exit Doorways
    – Maintains Dilution Rate through Dedicated Room Exhaust Vents

Associated options
& Installation enhancements

  • Flanged Air Intake Housings – to reach remote air sources
    – External Housings with Side or Top Intake Flange & Washable Screen Filters
  • Ground Level Air Intake Housings – to use surrounding air sources
    – External Housings with Rain Shields, Bug Screens & Washable Screen Filters
    – Available in  High Velocity Air Flow Configuration
  • Installation Enhancements
    – Dual or Shared Air Intake Stack Housings for Side-by-Side Units
    – Windload Certified Free Standing Rigid Pipe Air Intake Stacks
    – Adjustable Opposing Blade Damper Room Exhaust Vents

    – Spiral Pipe Air Intake Stacks, Guy Wire & Stanchion Kits

Scroll down or contact a Bebco Sales Associate to learn more…


Click any image to enlarge…

NFPA 496 Pressurization Blowers w/ Emergency Override

– A fully integrated solution for compliance to America’s most recognized Safety Code

As a customer-driven solution that’s been provided in thousands of Units since 2001, our fully integrated variable speed blower is compact, highly efficient and fully certified!

  • Satisfies NFPA 496 Chapter 7 Control Room Pressurization Requirements
    – Quietly maintains minimum room pressure of 0.15 inches of water
    – Ramps up slowly to produce 60 FPM air velocity through open doorways
  • Satisfies NFPA 496 Chapter 9 Analyzer Room Dilution Requirements
    – Achieves constant adjustable dilution rate to maintain <25% LFL Levels
    –  Requires Bebco Room Exhaust Vents, featuring adjustable opposing blade dampers
  • Emergency Purge Mode & Dedicated Alarm Activation Circuit
    – Unit includes input terminals to demand full blower speed and quickly reduce LFL Levels
    – Intended for Room Gas or Oxygen Deficiency Detectors and Emergency Panic Switches
    – Dedicated Alarm Circuit indicates loss of room pressure and features Activation Delay Timer
  • Integrated Digital Control Platform
    – Bebco seamlessly integrates all Unit, Blower and Alarm System functions and controls
  • Safety Lockouts – provided for Units with G2 Electrical Classification Ratings
    –  Purge Mode prevents Unit operation.
    – Upon achieving safe conditions, switching to Auto Mode enables Unit

Field tested and proven components provide absolute reliability!

Click any Tab to learn more below…

More Information

System Assembly Overview & Air Flow Ratings

Major Components

Bebco’s unique Variable Speed Pressurization Systems for Express and Custom Series 1-6 Ton Wall Mount Air Conditioners and Heat Pumps are intended to satisfy NFPA 496 Chapter 7 & 9 requirements.  

The Blower Assembly includes a venturi cone to draw air into a backward inclined aluminum blower wheel.

The wheel is driven by an air-cooled sealed bearing motor that is Third Party Certified for Class I, Division 2, Group B service.  

Motor speed is controlled by a durable variable speed drive in an explosion proof housing.

The drive is controlled by a 4-20 ma signal from the Digital Pressure Transmitter to maintain a stable 0.15″ pressure with doors closed.  

What our clients like the most is that Bebco Pressurization Blowers operate smoothly to prevent sudden pressure changes and painful ear-popping sensations!

Principals of Operation

Bebco Pressurization Systems are designed to automatically establish and maintain a safe room pressure of 0.15 inches of water while all doors are closed.  When doors are opened, the drive slowly ramps the motor to full speed.  Then, as doors are closed and room pressure increases, drive speed quickly decreases to ease door closing pressure and prevent annoying ear pop sensations!

Air Flow Ratings

Our Express Unit Pressurization Systems are offered in three air velocity ratings to satisfy NFPA 496 60 feet per minute air velocity requirements through all openings simultaneously:

P1:  1,450 CFM / Maximum Opening of 24 Square Feet

P2:  2,900 CFM / Maximum Opening of 48 Square Feet

P3:  3,100 CFM / Maximum Opening of 51 Square Feet

Please use the CFM Ratings above in comparison to the dilution air flow rates required by NFPA 496 Chapter 9, for rooms contain a limited source of flammable substances.  

Cooling needs must be evaluated separately to determine Unit Size
Smaller Units may not accommodate our larger Pressurization Systems

Use our Calculator to determine your air flow requirements!

Need more air flow?

Please contact a Bebco Sales Associate…

Our Custom Units are available with larger blowers along with external, dual unit and stand-alone pressurizers!

Control Features, Alarm Contacts and Override Provisions

Standard Controls                         

Bebco Controls satisfy NFPA 496 Chapter 7 Control Room  and Chapter 9 Analyzer Room requirements.

Bebco Pressurization Controls will include a Purge-Off-Auto Unit Control Switch and a Digital Pressure Transmitter installed adjacent to your Unit Controls.

Operation Sequence

  • Prior to start-up, the Unit Control Switch must be placed in the Purge Mode, unless the surrounding area and room interior are known to be non-hazardous.
  • Upon start-up, in the Purge Mode, the Unit shall be disabled and the Blower will operate at full speed as established by adjustable VFD parameters. 
  • In the Off Mode, the Unit and Pressurization System shall be disabled. 
  • In the Auto Mode, the Unit shall be enabled and the Blower will maintain an adjustable room pressure of at least 0.15 inches of water automatically, and will slowly ramp up to full speed to achieve an air velocity of 60 feet per minute through all doors used for personnel entry and exit.

Do you have questions about
NFPA 496 Code compliance?

We offer free technical assistance and code interpretation guidance, and also conduct online and in-person seminars.
Please see below to learn more!

Dedicate Alarm Contacts

Units with this System feature dedicated alarm contacts to satisfy NFPA 496 requirements.

The contacts indicate loss of room pressure after an adjustable delay.  The delay permits entry and exit, but triggers your alarm system when doors are left open.

Emergency Override Circuits

All Units with this System will also feature an emergency purge mode activation circuit that can be triggered by room gas detectors or emergency panic switches in either local or remote locations. 

Completing the circuit by closing one or more contacts wired in parallel will activate the purge mode.   

Safety Lockout

This feature is included for all Units with G2 Electrical Classification Ratings.  When the Unit Control Switch is in the Purge Position, the Unit’s Heating and Cooling functions will be disabled. In the Auto Mode, all Unit functions will be enabled.

Analyzer Building Dilution Provisions

Satisfying Chapter 9 Air Flow Requirements                         

To satisfy air flow requirements for Limited Release under NFPA 496 Chapter 9, Bebco recommends our Model REV Adjustable Opposing Blade Damper Room Exhaust Vents.  

These Vents are provided with optional materials and finishes and come with fully detailed instructions to set a continuous dilution air flow rate.  Please note you and your associates must determine the require air flow rate.  Please learn more below and call us for more information.

We’ll help you understand all requirements
for NFPA 496 Chapter 9 Dilution!

We also offer Room Exhaust Vents along with Local and Remote Dilution Rate displays, if required by your AHJ.

Air Flow Monitoring – going beyond current requirements

While not currently required by NFPA, Bebco can furnish a variety of Air Flow Transmitters with our Custom Series Units to interface with our Smart Digital or Touch Screen Controls.  The Flow Sensors we provide may then be installed in the Air Intake Stack or at one or more points of dilution air flow discharge,  such as our Room Exhaust Vents.

Our Custom Units will also be provided with a full blower speed emergency activation circuit and a 4-20 ma output signal.  These inputs and outputs allow you to display room air flow rates and quickly purge buildings remotely during emergency conditions.

This option is intended to satisfy advanced End User or AHJ Safety Standards.  By adding a flow transmitter, the dilution requirements of NFPA 496 Chapter 9 can be monitored, and insufficient room air flow can trigger both local and remote alarm systems.

Our primary concern is for the safety and welfare of our Clients…

Bebco therefore provides a dedicated team of highly experience sales associates to assist you with understanding all requirements of NFPA 496.  We conduct training seminars and webinars regularly, and will also be pleased to provide you with one-on-one support right now, as needed.
Simply click our chat button or give us a call to start learning!

Our relationship begins with ensuring your ability to meet applicable codes…

  • Code Interpretation & Application Assistance
    – Line level review to compare known codes against your specifications
  • Critical Building Design Consideration Audits
    – Review of walls, floors, ceilings, doors, windows and vapor barriers
  • Critical Room Equipment Suitability Audits
    – Review of all installed and future equipment ratings and characteristics
  • Determining NFPA 497 Electrical Classification Ratings
    – Understanding classifications of your space and surrounding area
  • Required Door Markings & Air Velocity Calculations
    – Safety review covering markings, door areas and limited releases
  • Selecting Bebco Unit Ratings & Optional Features
    – Guidance and details on the products that best meet your needs

Need a copy of NFPA 70
NFPA 496 or NFPA 497?

Please visit the NFPA Bookstore now!

NFPA Book store

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While he’s served ASHRAE since 2004, our Founder first began by contributing 10 years of service to NFPA’s Electrical Equipment in Chemical Atmospheres Technical Committee in 1987.  During that time he and Dudley Sheffield issued significant code improvement proposals.

In regard to NFPA 496 Chapter 7, they began by requesting an exception for equipment doors from the 60 feet per minute velocity required through “all openings capable of being opened”.

Initially, their reasoning was only accepted in principal.  However, after presenting a number of negative End-User experiences with oversized equipment, the exception was finally accepted by the committee, as first published in the 1998 edition.  As a result, pressurization system airflow requirements may now be based only upon the square footage of normally operated doors!


Be sure to visit our Unit Accessories Page to learn about our complete line of Caution and Warning Nameplates for pressurized building doors and large removable access panels.

Initially, our proposal was only accepted in principal…

with persistence, the exception was published in 1998…

Associated Options & Installation Enhancements

– We provide a turn-key solution for your entire application

Pressurization System Air Intakes

Bebco offers a complete range of air intake housings that permit you to source pressurization air from ground level or remote sources.

Hi Volume Ground Level Air Intake Use
This housing is suitable if the surrounding area has been rated as Unclassified by the AHJ, while the interior of your room or building is deemed by the AHJ to be a Hazardous Location. 

Side & Top Flanged  Air Intake Use
These housings facilitate easy connection to any form of duct, including flexible duct kits, spiral pipe stacks and free-standing rigid pipe stacks.   And yes, you guessed it – we offer all that too!

Dual or Shared Air Intake Stack Housings

Bebco offers Dual Air Intake Housings that permit you to draw air into two side-by-side Units from a common source.  Material, finish and  mounting provisions are optional, and these housings can also contain one or more filters in succession, to filter and pre-treat inlet air.

Adjustable Opposing Blade Damper Room Exhaust Vents
These Exhaust Vents discharge room air to the surrounding area.  They feature opposing blade dampers to regulate dilution air flow for Pressurization Systems that must comply with Chapter 9 of NFPA Code 496.  This Vent is attached externally, and blades can be adjusted outside the building.  Optional grilles are also available at time of order to cover the interior wall cutout. 

Spiral and Free Standing Rigid Pipe Stacks
Bebco offers a comprehensive solution for all remote air intake needs.  From Flexible Duct Kits to Spiral Pipe Kits with Guy Wires or Stanchions and our Free-Standing Rigid Pipe Stacks, we have it all!  And best of all, we also provide essential engineering services, highly detailed installation diagrams and site-specific windload certifications!


Please contact a Bebco Sales Associate now to learn more about our Integrated NFPA 496 Pressurization Systems or reserve time with an Application Specialist to discuss your project!