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Standard Units Do Not Have Motor Sensors
Options
Dry Contact Pressure Sensor
To insure that each fan in the system is
producing adequate pressure a dry contact diaphram style
pressure switch is
employed. It measures the differential pressure between the
fan inlet and ambient. The switch can be either normally
open or normally closed. When adequate pressure is sensed,
the condition of the switch changes. The status of the sensor
is then reported via a light or to a connector.
Cleveland
Controls Model DFS–221 (pdf)
Reporting When a High Pressure Condition
Has Been Reached
A pressure switch that reports when the internal
differential pressure reaches a pre-set limit (as in the
case of HEPA/ULPA
filter loading over time) the Cleveland Controls AFS-298-112
is provided. The status of the sensor is then reported via
a light or to a connector.
AFS
Series
Reporting When Either a High and
Low Pressure Condition Has Been Reached
Two dry contact diaphragm style pressure switches
to report via switch closure with a local display. One that
reports when the internal differential pressure reaches a
pre-set limit (as in the case of HEPA/ULPA filter loading
over time), and a second that reports if a minimum differential
pressure has not been kept (as in the case of the FFU motors
ceasing to function due to loss of power) The local display
is a magnahelic gauge on the Dwyer A3000. The position of
the dry contact(s) is then reported via a light(s) or to
a connector.
DWYER
A3000 (pdf)
Reporting Differential Pressure
as a 4-20 ma Value
Same as AFS series, above, but with the addition
of a 4-20 ma output proportional to the actual pressure
being
measured.
DWYER
3000SGT (pdf)
 Having an Analog Visual Display
of the Differential Pressure
A differential pressure gauge can be added to track
filter loading. The gauge itself can be mounted on the side
of the FFU, in an external box (often with the reporting
lights), or shipped loose for attachment by others.
Magnehelic® Differential
Pressure Gages - Indicate Positive, Negative or Differential,
Accurate within 2% (pdf)
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