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Donaldson Company, Inc.
Delta P Plus Control
Description
The Delta P Plus Controller monitors the differential
pressure between the clean and dirty air plenums,
providing a visual display of the filter condition. When
combined with a pulse timer, it controls the pressure
drop by turning the cleaning mechanism on and Off at
the chosen limits. There are three (3) set points: High
Pressure On, Low pressure Off, and Alarm. The first two,
High Pressure On and Low Pressure Off, control the
filter cleaning system. The third, Alarm, provides a relay
output to activate an external alarm supplied by others.
The user can program the Delta P Plus Controller to
pulse while the collector is running, to maintain a
relatively constant pressure drop across the filters, pulse
only after the collector is shut down (after-shift cleaning),
or a combination of both, cleaning while running as well
as end of the shift.
Operation
Normal
The Delta P Plus Controller monitors the pressure on
both sides of the tubesheet while the unit is running.
As air flows through the filters, the resistance of the
media and collected dust creates a pressure difference
or "drop" between the dirty and clean air plenums. The
Delta P Plus Controller measures the pressure drop and
provides a visual display in inches water gauge or metric
(SI) units of daPa.
Filter Cleaning
The Delta P Plus Controller offers three filter cleaning
options.
1. Differential Pressure Cleaning (DFF) - When the
pressure drop across the filters reaches the
Controller's High Pressure On setpoint, the Controller
closes an output relay allowing a sequential timer
to trigger the cleaning valves. When the Controller
senses that the pressure drop has decreased to
the Low Pressure Off setpoint, the relay opens and
the cleaning cycle stops. This sequence continues
as long as the collector is in use, maintaining the
pressure drop within a narrow range.
2. Downtime Cleaning (DTC) - The Delta P Plus
Controller monitors the collection system. When
the pressure drop exceeds the Low Pressure Off set
point and then approaches zero again, the Delta P
Plus Controller runs a delay timer to allow the blower
to come to a stop and then engages the cleaning
mechanism for a preselected time.
3. Combined Differential and Downtime Cleaning
(ALL) - The Delta P Plus Controller combines the two
functions described above; maintaining the pressure
drop in a narrow band and downtime cleaning
the filters when the collector is shut down. The
downtime cleaning function can be toggled On or Off
from the keyboard.
Alarm
The Alarm setpoint is set to a higher setting than the
High Pressure On used to start the filter cleaning cycle.
It indicates situations when the cleaning system cannot
reduce the pressure drop due to cleaning system failure,
lack of compressed air, or the end of the filter's useful
life. There is a time delay prior to setting the Alarm to
prevent nuisance trips. The Delta P Plus Controller also
provides an input connection for a remote Alarm reset.
For complete information, see the most current version of
the Delta P Plus Installation, Operation, and Maintenance
manual.
Delta P Plus Control Display
