19 \ USER OPERATION MANUAL:
Cole-Parmer Basic Ductless Fume Hood Series
V . Monitoring
5.1
General
The purpose of the monitoring program is to ensure consistent reliability from the system. This is achieved by
checking the following:
» If the pre-filters become blocked, the velocity of the cabinet will begin to fall and will eventually cause the
airflow alarm to illuminate.
» Manual checking of the main filters by the use of a Gastec
™
or Draeger
™
test kit will confirm the condition of
the filters.
5.2
Manual Monitoring
Manual monitoring of the cabinet should be carried out at least once per year, as this will ensure the monitoring
systems are all within calibration and performing correctly.
Airflow Measurements
The inflow velocity of the hood should be checked with the sash at the correct operating height using an
anemometer such as a hot wire, vane anemometer or propeller type. Depending on the size of the cabinet, a
series of readings are to be taken at the front opening; these are to be recorded on a service sheet or system
log sheet.
Manual Filter Testing
The condition of the filter is to be checked using a Gastec or Draeger test kit. Boiling off a suitable chemical
normally used in the cabinet or a controlled release should challenge the filter. Examples can include alcohols,
toluene and trichloroethylene.
For testing acid filters (acid adsorbing) or multi combination layered filters incorporating an acid layer, use sulfur
dioxide gas (SO
2
) at 2 bubbles per second through water.
The readings should be below your Country’s Occupational Exposure Limit (see
).
The results are to be recorded on a service sheet or system log sheet.
If a significant amount of chemical is noted at the exhaust of the system, the main filters should be changed.
