Binder- A substance used to bond the glass fibers together that gives some structural strength to the media. The binder is a normal part of HEPA filter manufacturing.
During burn off procedure ,There will be smoke, possibly a pungent odor, and a residue on interior surfaces. This is a result of oxidation of the binder, and the evaporation/decomposition of any challenge agents.
Check the oven for particles or the exhaust for smoke and odor to determine that the burn-off is finished. the burn-off should be done at or above the maximum process temperature. The filter should not be cooled faster than 1 degree C per minute. Burn off the filter until the downstream air is clean enough for the process.
The completion of the burn-off period should be based on the particle level in the oven. Laminated media will take longer than the standard HEPA media to burn off to a particular cleanliness level, at the same temperature. Both types of media will burn off faster at higher temperature.
If it is necessary to move the equipment after the burn-off process (which is not recommended),considerable care should be used. The binder which gives strength to new filters is now gone and the media is very fragile. Any handling of either the filter alone or the equipment with the filter installed is strongly discouraged. The media may crack or tear (leak).
For best clean oven processing, it is recommended that the oven be thoroughly cleaned after the burn-off period and at regular intervals thereafter.
The filter hold-down nuts should be checked after burn-off and tightened again, if necessary. For best results, this step should also be repeated on a regular basis. Most oven gaskets are known to take a set, and thus require tightening after heating.