21 \ USER OPERATION MANUAL:
Cole-Parmer Basic Ductless Fume Hood Series
6.6
Calibration Instructions
Testing the Low Airflow Alarm
» Ensure the fitted pre-filters are new. Switch on the cabinet; the red/amber neon should not be
illuminated.
» Switch the unit off. Block the pre-filter using paper or cardboard to permit airflow of <0.3 m/sec or 60 fpm.
» Switch the unit on. The red/amber neon should illuminate. If not, the calibration should be reset.
Calibration
The low airflow alarm operates using a differential pressure switch to detect
a “high vacuum” situation when the
pre-filter is blocked or blocking up. The pressure switch is calibrated and tested prior to leaving our factory and
under normal circumstances will not require any adjustment.
» With the cabinet running and the pre-filter blocked as described above, locate the grey pressure switch
through the hole in the right hand sidewall. Adjustment is made by turning the small screw in the end of the
switch. (
See Photograph #16 - page 14
).
» Adjust the screw to make the alarm show. You may have to repeat these steps to ensure an accurate
setting has been achieved.
» Remove the blockage and restart the machine. The red/amber neon should not be illuminated.
