Air Filtration Units

Gaffco BDU-48 Nuclear, Biological, and Chemical Overpressure Filter/Ventilation System Installation & Operation Manual


The Gaffco BDU-48 is a portable, positive pressure, emergency air filtration system is designed to offer protection in the event of a nuclear, biological, or chemical event when installed in a protected space (room) with a maximum volume of 3,500 cubic feet (99 cubic meters). When properly installed, this system is capable of giving adequate supply of filtered air for up to 12 occupants, according to Israeli standards.

The system works by drawing outside air through its bank of six filter medias and introducing it into the protected space creating a slight overpressure (positive pressure). This overpressure is designed to deny access to any unfiltered air that would migrate back into the shelter area through small openings such as cracks or electrical outlets and conduit.

This overpressure relieves the occupants from wearing gas masks and protective clothing, enabling them a safe and comfortable environment.

The system operates from any standard 110-240 volt AC, 50/60 hertz power source.

In the event of a line power failure the unit has two emergency backup systems:

The first backup is an automatic switching power supply that trickle charges a user-supplied battery and then automatically draws power from that battery in the event of a power outage. In other words, if you were to “pull the plug” the blower will continue to operate and maintain an overpressure in your protected space. When the electricity comes back on line, it will automatically revert to drawing from the AC power and recharging the battery.

The second backup is an optional manual (hand pumped) blower that can be used in the event of a long-term power outage.

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