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Inflow Velocity
All models of Labconco biosafety cabinets are tested per the current NSF/ANSI
Standard 49. This section describes how to prepare and test the inflow velocity on all
Types of biosafety cabinets.
The front Dress Panel must be installed on the biosafety cabinet to obtain accurate
inflow results. If the biosafety cabinet is connected to a remote (building) exhaust
system, ensure the remote exhaust system is on.
Primary Method
NSF/ANSI Standard 49 now requires the Primary Method for determining inflow be
utilized unless there is less than 41 inches (104 cm) clearance between the front of the
biosafety cabinet and the nearest physical, permanent obstruction.
The Primary Method requires the following:
DIM (Direct Inflow Meter), such as a Shortridge
TM
Labconco Holder Bracket Assembly (Catalog Number 3836405), shown below in
Figure 10-28.
Thin, rigid plastic (or similar material) blocking plates, to close off front work
opening on either side of the DIM so all inflow air is directed through the DIM.
Removable tape to secure the plastic blocking plates.
1. Start the blower(s), ensure the sash is at the correct operating height.
2. Attach the Labconco Holder Bracket Assembly to the front grille centered left-to-
right on the biosafety cabinet. Loosen the two Thumbnuts to create a gap
between the two plates.
3. Place the DIM’s skirt frame into the gap between the two plates on the Bracket
Assembly.
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