Forma Scientific, Inc.___________________________________________________Introduction
2-1
Section 2 - Introduction
2.1 Description
The 1184/1186/1188/1190/1194/1196 Series is a Class II, Type A/B3 cabinet. The "Type
A/B3" designation indicates two alternative uses of the cabinet. When vented directly into the
laboratory room, the unit serves a "Type A" unit. When vented to the outside atmosphere,
through an in-house exhaust system, it serves as a "Type B3" unit. Either usage of the cabinet
offers both personnel and product protection.
The cabinet can be used in low-to-moderate risk environments and are designed to
National Sanitation Foundation Standard #49. Class 1, 2, and 3 (low-to-moderate risk) agents are
described in the "Biosafety In Microbiological And Biomedical Laboratories"; CDC NIH
Publication No. (NIH) 88-8395, 2nd Edition, May 1988.
The cabinet is available in a sliding or hinged window version. The cabinet's window
permits the user to place auxiliary equipment and research implements in the work area. The
work opening must be held to 10" during all work procedures. If the window is raised higher than
the designated 10", the air barrier at the front of the cabinet will be weakened and containment
will be seriously impaired.
2.2 Theory of Operation
Figure 2.1 shows the general airflow pattern of the cabinet.
Clean, filtered air descends through the work zone with approximately 40% being
discharged through the exhaust HEPA filter with the remaining air recirculating through the
supply HEPA filter into the work area. Exhausted air is replaced by room air entering the system
through the front access opening.
Room air entering the work zone, through the front access opening, completes the air
barrier at the unit face and is responsible for the containment properties of the unit. All work
must be performed beyond the intake grille, on the solid work tray.
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