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1.0 BASIC OPERATION
The Guardian is a complete system package consisting of space and reference pressure se
nsors and the
central signal processing module. The central module measures and displays the pressure differential
with a resolution of up to one ten thousandth of an inch water column. The LED display can be factory
set for engineering units of either Inches Water Column or Pascals. An analog output which is linear to
the pressure differential is provided for remote monitoring, control and data logging. An alarm
condition will occur when the space pressure falls outside the preset operating range. During an alarm
condition a local LED will illuminate, a local audible alarm circuit will be enabled, and an alarm relay
shall energize for remote alarming purposes. An optional remote auxiliary alarm is available with an
adjustable delay which will activate a local LED and the audible alarm. A key locked front panel
allows for controlled access to the field configurable functions of the Guardian. These functions
include pressure alarm setpoint adjustment, audible alarm on/off selection, adjustable delay of the
pressure alarm to prevent nuisance alarms which would occur due to normal foot traffic, and
differential pressure transducer calibration.
2.0 GUARDIAN FEATURES
2.1 POWER SUPPLY
The Guardian utilizes an isolated linear type power supply generating +15vdc and ∀5vdc to
power the pressure transducer sensor, scaling and digit circuitry. Input power to the Guardian
is 24VAC. The power supply is fused with a 3/8 Amp Slow Blow Pico fuse, located near the
input power terminal.
2.2 ALARM STATUS
Both Normal and Alarm operating status is locally indicated via LED•s on the Guardian face
plate.
2.3 ALARM SELECTION
The Guardian can be field configured to provide either Positive or Negative room pressure
alarming function. In the Positive mode the alarm activates when space pressure falls below
the alarm setpoint value. When in the Negative mode the alarm activates when space pressure
rises above the setpoint value.
2.4 AUDIBLE ALARM ACKNOWLEDGE
Muting of the local audible alarm during a loss of the required pressurization level. The
audible alarm circuit shall be reset once the monitored pressurization level is within the
acceptable operating range.
2.5 REMOTE ALARM RELAY
A single-pole double-throw relay is energized whenever the space pressurization level is
outside of the acceptable operating range.
2.6 REMOTE ROOM PRESSURE SELECT
The Room Pressure Monitor can be configured for positive or negative room monitoring
remotely by the closure of a dry contact.
2.7 REMOTE AUXILIARY ALARM
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