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Maintenance
June 2016
Section 4: Maintenance
4.1
Cross sensitivities
Infrared sensors will react to most compounds containing a Carbon-Hydrogen bond (hydrocarbons) in
varying degrees potentially providing a response from the sensors. Other gases present within the
particular application need to be considered for their impact on this sensor. For more information,
please contact the manufacturer.
4.2
Routine inspections
The Millennium II SC311 sensor should be inspected on a routine basis to ensure that external
obstructions such as water, mud, snow, plastic bags, or other materials are not blocking the sintered
element of the sensor. If the sintered element is sprayed with water, the sintered element must be
allowed to dry to ensure specified performance.
A blocked sinter impairs sensor performance. If a sinter element is blocked, please dislodge the
material blocking the sensor to ensure sensor performance as specified.
4.3
Bump testing
As part of the site preventative maintenance program it is recommended that a bump test of the
sensor be completed every three (3) months. Bump testing consists of a visual inspection of the
sensor, applying a known gas concentration to the sensor verifying the accuracy of the response to the
specifications of the sensor, and alarm system simulation. If the response is outside of the
specifications of the sensor a calibration should be completed. Refer to
a calibration has been completed, it is recommended that a bump test be completed to verify accuracy
and response of the sensor.
4.4
Sensor replacement procedure
Sensors are pre-calibrated at the factory; however, field calibration must be performed as a part of
commissioning. When a calibration can no longer be performed or the sensor is not operating
properly, the sensor module may need to be replaced. Refer to steps below for replacing the sensor
module.
Do not open the transmitter, sensor, or junction box enclosure when in a classified area or when an
explosive atmosphere may be present unless the power to the sensor has been removed.
Avoid touching any electronic components, as they may be susceptible to electrostatic discharge
(ESD). Refer to 0 for further information and proper handling instructions of electronic components.
1. Remove power from the sensor.
2. Remove the locking ring by loosening the set crews with 1.5 mm Allen Key tool.
3. Remove the bottom part of the sensor enclosure by turning it in a counter clockwise rotation to
expose the sensor module.
14
Reference Manual
MAN-0091, Revision 8
2.7
for more information. After
Maintenance
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