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350-2100 cfm Dryers Chapter 6: Maintenance 35 of 58
Chapter 6: Maintenance
6-1 Servicing the Process Air Filters (Models 350-700)
WARNING: Operating the dryer without the process air filters installed will void the warranty.
Filter Cleaning is an important part of dryer maintenance.
Dryer models 350 through 700 have single high temperature [up to 350°F] cartridge cannister-type filter
in the process air loop. It’s mounted above the process blower on the rear of the dryer. This filter
protects the centrifugal blowers from plastic fines being drawn in from the drying hopper. Regular filter
cleaning will keep your dryer operating at peak efficiency.
The filter can be washed or blown out, but remember, the filter’s dirt holding capacity is reduced with
each washing. The risk of dirt reaching the clean side of the filter during cleaning, plus possible filter
damage from high pressure washing or blowing makes washing a gamble.
Careful cleaning or washing can be done when the airflow restriction trips the dirty filter alarm. Filters
should not be washed more than six times or used for more than a year, whichever comes first.
Use a detergent that won’t damage the filter media. Such a detergent permits easy removal of dirt
particles through flushing and rinsing. An effective detergent will remove the fine particles from the
pores of the filter media.
The filter’s manufacturer recommends FM 1400 washing compound. It is formulated specifically for air
filter element cleaning. It is non-sudsing and works in hot or cold water. FM 1400 contains
biodegradable synthetic detergents and is non-phosphate, non N.T.A. It is marketed by Filter Service
Corp., 2603 A West Main, Farmington, New Mexico, [505] 326-1127.
6-2 Filter Cleaning/Replacement
• Turn off and/or lock out electrical power [and compressed air, if so equipped] to the
dryer.
• Remove the hand knobs or threaded fasteners securing the filter access cover and
remove the cover.
• Remove the nut on the center retaining rod to remove a filter cartridge.
• Inspect the filter - a damaged filter should not be washed or reused.
• Remove loose dirt from the filter with compressed air or a water hose. Compressed air
should be less than 100 psi – use a 1/8"diameter nozzle at least 2" away from the
filter. Water should be less than 40 psi – don’t use a nozzle.
• Soak the filter in FM 1400 or comparable detergent solution for at least 15 minutes.
Never soak more than 24 hours.
• Swish the filter around in the solution to agitate, loosen dirt particles, and put them in
suspension.
• Rinse the filter from the “clean” side to the “dirty” side with a gentle stream of water