Document: 333D012G
5-18-2007
- 24 -
Condition Adjustment
Down flow Inflow
Speed
control
Balancing
Damper
High High Decrease
Low Low Increase
Low High Close more
High Low Open more
OK High Decrease Close more
OK Low Increase Open more
High OK Decrease Open more
Low OK Increase Close more
Chart# 1: Type A2 Air Balancing Guidelines
As the HEPA filters load up with particulates, airflow air will be maintained automatically, at least until the down
flow filter resistance increases 60%. When airflow air eventually diminishes, you will have to increase the blower
speed in order to maintain the original volume of total airflow. If the airflow cannot be maintained, it will be
necessary to replace the HEPA filters. (See "Procedure for HEPA Filter Replacement" later in this section).
Filter Leak & Smoke Testing
The filters in your cabinet were tested at our factory before shipment to ensure that the media, gasket, and frame
were not exceeding NSF International Standard 49 allowable leak rates. Since filters may become damaged in
transport, we recommend that the filters be re-tested by qualified technicians before the cabinet is used. The filters
should also be leak tested at prescribed intervals as specified by an industrial hygienist, safety officer or other
qualified person. NSF International details the steps for performing the filter leak test in their Standard 49.
Filter leak test procedure – Down flow filter
1. Turn on cabinet blower.
2. Raise the viewscreen to the full open position.
3. Remove diffuser under down flow filter to access filter media and frame by removing two cap nuts at the
front, lowering the front and sliding the diffuser forward off rear wall mounting studs.
4. The port for measuring upstream concentration is located on the top rear left hand side of the cabinet.
WARNING
If the cabinet has been in use then it must be decontaminated before removing the plug.
5. Introduce the aerosol challenge to the cabinet blower at the front work surface perforation.
6. Perform filter leak test per NSF 49.
7. Repair any discovered leaks.
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