Labconco Type C1 Biosafety Cabinet Models 30468 - Manual (Page 29)

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Theory of Operation
Background
The Axiom Type C1 BSC was the result of a customer request for a Type B
(directly exhausted) cabinet that could operate at a constant exhaust system
vacuum of only 0.25 inches of H
2
O. Realizing that this was impossible for
existing Type B technologies, Labconco developed a new type of BSC; The
proposed Type C1.
Figure 1-8
Airflow Patterns and Features
The overall airflow pattern in the Type C1 is similar to a Type B1, with three
important differences:
1. In the C1, the directly exhausted portion of downflow air is
taken from the center of the work area (The Chem-Zone TM ).
2. An inlet relief valve, unique to the Axiom, stabilizes the inflow
as exhaust system airflows fluctuates, and closes during an
exhaust system failure, signaling the Axiom to initiate a timed
“Active Protection” of the user and their work.
3. A constant volume exhaust blower upstream of the Exhaust
HEPA maintains constant inflow, and allows the unit’s blowers
to continue to operate during an exhaust system failure
(Active Protection), maintaining safe inflows and downflows
while the user secures any hazardous materials in the work
area.