FILTER CLEANING
Filter cleaning is accomplished by actuating a short burst of air that blows back-ward
from the clean side of the cartridge. This dislodges the caked dust that then drops into
collection drawers or optional dust collection hoppers. Each pulse cleans two to six filter
cartridges, depending on scrubber type, leaving the remaining cartridges available to
continue filtering the ventilation air. This allows the cleaning to take place without the
need to stop the air ventilation system.
Descriptions of certain main filter cartridge cleaning system components are as follows:
1.
Pulses of compressed air automatically clean the cartridges by reverse
pressurization. A preset solid state timer with digital display, controlling
both frequency and duration of the pulses, controls cleaning. A pressure
transducer monitors differential pressure across the filter section. When
the pressure differential reaches a pre-set value, the reverse pulse system
will automatically dislodge dust from the cartridges using compressed air
stored in an integral header tank inside the clean air plenum. Since the
header tank is protected from uv and moisture the service life of the
reverse components is several time longer than competitors units where
the header tank is mounted externally.
2.
Timer Control Board. This solid state device controls the cleaning cycle of
the filter cartridges. When the pre set pressure differential setting has
been reached, an output signals the timer control board to start the
cleaning cycle. The timer control board then initiates a series of timed
pulses, cleaning a single row of filter cartridges with each pulse. This
sequence starts left-to-right (facing the air inlet). The length of each pulse
is adjustable from .05 to .5 second with the normal pulse time being 0.3
second.
A time delay between each pulse allows the air accumulator tank to
recharge for the next pulse. This delay is adjustable between 8 and 180
seconds with the normal delay for the standard system being 8 seconds.
During the cleaning cycle, the controller will pulse each set or filter
cartridges in turn until the pressure differential drops below the LOW set
point. When the LOW set point is reached, the cleaning cycle stops until
the HIGH set point is again reached.
The timer control board’s memory feature remembers which filter cartridge
set was the last one cleaned. The next cleaning cycle will start with the
next filter element in line. This feature ensures that all filter cartridges
receive the same cleaning regardless of their position in the cycle.
