METER ATMOS 41 - 4.2 RECALIBRATION RECOMMENDATIONS; 4.3 CLEANING AND MAINTENANCE

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SERVICE
• Wind Direction: The ATMOS41 wind direction measurement depends on the geometry
of the ultrasonic transducers and the north orientation indicator on the ATMOS41 body.
This geometry is held to within 0.025-mm specifications through CNC milling procedures.
Orientation of the ATMOS 41 toward North will introduce more error in the wind direction
measurement than sensor geometry.
• Sensor Tilt: The ATMOS41 tilt sensor is zeroed against the primary bubble level on the
bottom side of the upper anemometer housing.
• Lightning Strike Counter: Calibration on ATMOS41 lightning strike detector is performed
by the original manufacturer of the lightning detection chip prior to integration into the
ATMOS41. Verification that the lightning strike sensor meets specification is performed on
each ATMOS 41 unit during QA procedures.
• Lightning Distance: Calibration on ATMOS41 lightning distance detector is performed
by the original manufacturer of the lightning detection chip prior to integration into the
ATMOS41. No further calibration is performed during sensor integration.
4.2 RECALIBRATION RECOMMENDATIONS
Table 4 lists the recommended sensor calibration frequencies.
Table 4 Sensor calibration frequencies
Sensor Function Calibration Frequency
Solar radiation Every 2 years
a
Barometric pressure Every 2 years
b
Relative humidity (RH) Every 2 years
b
All other sensors Not needed
a
Calibrated, field-swapable replacement pyranometers are available from METER. Contact Customer Support
to purchase a new funnel and consult Instructions for swapping ATMOS 41 funnel (metergroup.com/swapping-
atmos-41-funnel-pyranometer-sensor) for instructions on field swapping the pyranometer.
b
ATMOS41 barometric pressure and vapor pressure/RH sensors and their respective calibrations are housed
on a module that sits behind the circular Teflon membrane in the same housing as the sonic transducers
(Figure8). This module is field-swappable, so sensors in need of calibration can be removed and replaced
by a module with calibrated sensors. Please contact Customer Support for new sensor modules and consult
Instructions for swapping ATMOS 41 daughterboard (metergroup.com/swapping-atmos-41-rh-temperature-
barometric-pressure-module) for instructions on swapping the module.
4.3 CLEANING AND MAINTENANCE
For more information on thoroughly cleaning the ATMOS 41, see ATMOS cleaning instructions
(metergroup.com/meter_knowledgebase/atmos-41-cleaning-instructions/).
1. Make sure nothing is obscuring the temperature sensor or the sonic transducers shown
in Figure13 (cobwebs, leaves, wasp nests, etc.).
2. Check the following areas to make sure they are clear of miscellaneous environmental,
animal (specifically bird droppings) and insect debris, or spider webs: