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Chapter 6: Maintaining Your Filtered Enclosure
Routine Maintenance Schedule
Weekly
• Wipe down the interior surfaces of the enclosure with a
disinfectant or cleaner, depending upon the usage of the
unit and allow to dry.
• Using a damp cloth, clean the exterior surfaces of the
enclosure, particularly the front and top to remove any
accumulated dust.
• Operate the exhaust system, noting the airflow velocity
through the enclosure using a source of visible smoke.
Airflow monitors are recommended for constant
monitoring.
Monthly (or more often as required)
• Determine the actual face velocity through the sash opening
of the enclosure where the average reading should be at the
specified velocity. (Use calibrated thermal anemometer or
other approved apparatus). Airflow alarms are
recommended for constant monitoring.
• The enclosure rear baffle should be checked for any
blockage to ensure that the enclosure is maintaining proper
airflow.
• All weekly activities.
• Check face velocity. Increase speed control or change
HEPA filter when face velocity of the enclosure drops
below the recommended speed for your facility or if the
airflow alarm monitor alerts you. Airflow monitors are
recommended.
• While the enclosure is filled with the contaminant, test
filter condition on Odor Control carbon filters using the
appropriate gas detector tube at intervals of 20% of the total
estimated time. The exception to the 20% recommendation
is formaldehyde or any carcinogen or suspected carcinogen.
These hazardous chemicals must be checked at least every
10% of the total estimated time. Gas detector tubes for the
specific chemicals that are being used in the enclosure can
be obtained from your laboratory supply dealer.
• Replace Odor Control carbon filters when chemical
breakthrough is indicated by odor, time, detector tube, or
for some chemicals, analytical instrumentation. See
“Replacing Odor Control Carbon Filters” section of this
manual in Chapter 6.
HEPA
CARBON
CARBON