Despatch LCC1-87NV-2 - Manual (Page 25)

16
 Check the corner joints of the frame for adhesive sealing and tightness.
 Check that the gaskets are cemented firmly to the filter frame and that the
gasket pieces are butted or mated at the joints.
3.
Remove the old HEPA filter.
a. Unscrew the four (4) brass nuts on the left side of the work chamber.
b. Remove the perforated duct exposing the filter.
c. Remove and discard the old HEPA filter.
4.
Install the filter with the gasket centered around the hole in the side wall of the
oven. Be sure to install the filter with pleats and separators running from top to
bottom.
5.
Install and tighten the perforated duct. Be sure to compress the gasket evenly
and equally at all points with the filter frame completely covering the opening.
HEPA Filter Burn-off
The burn-off process will take place in any
piece of equipment where a new HEPA filter
is used at temperatures above 150 C /
300 F. There will be smoke, possibly a
pungent odor, and a light residue on interior
surfaces. This is the result of oxidation of
the binder and the evaporation/
decomposition of any D.O.P.. Most of the
binder will leave the filter after running at a
temperature of 260 C/500 F for eight (8) to 48 (forty-eight) hours. After eight hours
6.7% of the total media weight is lost, 11.2% after 24 hours and 16.0% after 48 hours.
Check the oven for particles or the exhaust for smoke and odor to determine that the
process is finished.
Significant advantage in paper strength and shedding characteristics is obtained for
some filters if some of the binder is left on the media (burn-off done below 220 C/428 F
and lower.) Lower burn-off temperature are more advantageous. However, the
burn-off should be done at or above the maximum process temperature. If the binder
is burned off in the range from 150 C/300 F to 220 C/428 F, it is wise to remember that
additional binder will be given off if the oven is ever heated above this temperature.
Select a location for this process where the smoke and odor generated will be
ventilated with the least amount of interruption and inconvenience. Ideally this will be in
NOTE: If it is necessary to move the
equipment after the burn-off process,
considerable care should be used.
The binder which gives strength to new
filters is now burned-off and the media
is very fragile. Rough handling of
either the filter alone or the equipment
with the filter installed is not
recommended as it may tear the
media and lose its efficiency rating.