Envirco NSF Biohazard Cabinet - Manual (Page 14)

14
External Exhaust Connection (Optional)
Under normal conditions, the Class II Type A Cabinet does not require external
exhaust from the laboratory. However, when used in the Type B3 configuration, the
cabinet must be connected to an external laboratory exhaust system with the use of
a thimble connection. This ensures that the exhaust air balance of the Biohazard
Cabinet is not disturbed by fluctuation in the external exhaust system.
In order to assure a negative pressure exhaust system, the external exhaust
capacity should be sized as follows:
10448 - EBC 47, 4-Ft Type A/B3: 305-cfm minimum
10451, 6-Ft Type B3: 460-cfm minimum
Since the exhaust transition is a thimble connection, the exhaust motor/blower need
only be sized to overcome the resistance of the facility exhaust system.
NOTE: The customer must install the thimble connector suspension and provide
the external exhaust system fan and damper.
Transition Dimensions
10448 - EBC 47 Thimble
14-¼” W x 22-¼” D
to 10” round
10451 Thimble
26-½
” W x 20-¼” D
to 10” round
Figure 5: External Exhaust Through Ceiling
External Exhaust Through Ceiling