Donaldson Company, Inc.
34
Delta P Control
Description
The Delta P Control 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.
Operation
Normal
The Delta P Control monitors the pressure in the
clean and dirty air plenums while the unit is
running. The blower draws air through the filters,
creating a pressure drop. The Delta P control
measures the pressure drop and provides a visual
display in inches water gauge or metric (SI) units.
Filter Cleaning
When the pressure drop across the filter bags reach
the control's High setpoint, the control closes an
output relay allowing a timer to trigger the cleaning
valves sequentially. When the control senses that the
pressure drop has decreased to the Low 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.
Alarm
The alarm setpoint is set to a higher setting than
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 Control
also provides an input connection for a remote
alarm reset.
For complete information, see the most current
version of the Delta P Installation, Operation, and
Maintenance manual.
Delta P Control Display
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