Envirco NSF Biohazard Cabinet - Manual (Page 28)

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XV. CABINET PRESSURE TESTING
The ENVIRCO Biohazard Cabinet is designed so that there are no contaminated
plenums under positive pressure when the cabinet is operating. The entire outer
shell of the cabinet and the work area are at negative pressure with respect to the
laboratory. Therefore, any leakage at the cabinet penetrations or at the access
panels is "inward" and thus not a contamination hazard.
The outside access panel is sealed and the cabinet is designed to be airtight at two
(2) inch water gauge over-pressure when the open face and the exhaust openings
are sealed off.
A test of the cabinet seals after removal of the access panel can be accomplished
using the following procedure:
Suggested Equipment
1. Heavy vinyl sheeting and two-inch plastic or rubberized tape to seal off the
cabinet openings.
2. A small compressor or the building’s compressed air source.
3. A detergent solution or other liquid leak detector solution in a hand-held spray
bottle.
Test Procedure
1. Seal off the front opening of the cabinet and the exhaust opening. When taping
the plastic in place, ensure that a complete pressure-tight seal is formed.
2. Connect the pressure source to the drain valve fitting located on the bottom of
the cabinet. The valve can be used to control the air pressure feed into the
cabinet.
3. Using the magnehelic gauge mounted on the front of the unit to monitor the
pressure, pressurize the cabinet to two-inch water gauge.
4. Using the soap solution, spray around the access panel opening and other
cabinet penetrations. The formation of soap bubbles indicates an air leak that
may be sealed off by tightening the fasteners or by using a silicone rubber
construction joint adhesive.
NOTE: The Electrical Control Compartment may be completely removed by
unplugging the wiring spade connectors from the terminal block on the
right side and removing the hinge screws. Unplug the power cord before
attempting to remove the compartment.