20 \ USER OPERATION MANUAL:
FHD-400 Series
Cole-Parmer
®
coleparmer.com
6 .6 Filter Condition Monitor (Fitted as an Option)
Under normal operating conditions (if option fitted) the display will show a green filter to indicate it is safe. If the filter
display is red, the filter should be checked as follows:
•
Select a suitable test chemical (examples include alcohols, toluene, trichloroethylene or any suitable chemical
in routine use in the cabinet providing it is well adsorbed and not dangerously toxic) and a matching Gastec or
Draeger test kit
.
•
Place 6 ml of the chemical into a beaker on a hot plate inside the cabinet
. Set the hot plate to boil off the chemical
over a 2 minute period
. This should give a concentration of about 100 - 200 PPM (parts per million) challenge to
the filter.
•
If testing acid filters (acid adsorbing) or multi combination layered filters incorporating an adsorbing layer, use
sulphur dioxide gas (SO
2
) at 2 bubbles per second released through water to challenge the filter.
•
Using the test kit, take a sample reading at the outlet of the cabinet
. Follow the instructions supplied with the tubes;
i .e
. the number of strokes for each type of tube .
•
If a significant level of chemical is recorded at the outlet, the filter must be changed. It is also worth checking
the gasket condition for any damage that may result in a bypass
.
6 .7 Calibration Instructions
Testing the Filter Blockage 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 will need to be reset.
Calibration
The filter blockage 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.
•
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.
