15
ATMOS 14 GEN 2
4. SERVICE
This section describes the calibration and maintenance of ATMOS 14. Troubleshooting
solutions and customer service information are also provided.
4.1 CALIBRATION
The ATMOS 14 relative humidity/vapor pressure sensors receive a three-point calibration
using a METER WP4C chilled-mirror dew point sensor as the calibration standard at 20%,
50%, and 80% RH. The WP4C is calibrated every 3 months against four salt standards of
known RH (Robinson and Stokes 1970) to be accurate to within 0.2% RH.
Each ATMOS 14 barometric pressure sensor is calibrated against the average of
three secondary standard Measurement Specialties MS5611 pressure sensors. The
MS5611 sensors are calibrated every 3 months against a GE Druck TERPS 8100-series
pressure sensor. The GE pressure sensor is calibrated yearly at certified laboratory with NIST
traceability.
4.2 RECALIBRATION AND MODULE REPLACEMENT
ATMOS 14 barometric pressure and vapor pressure/RH sensors are housed on a module
that sits behind the blue elastomer cap. Sensor modules in need of calibration can easily be
removed and replaced by a module with recently calibrated sensors. METER recommends
that the sensor modules be replaced every 2 years to ensure best accuracy. Please contact
for new sensor modules.
The process for swapping modules is straightforward and can be done in the field. To replace
the module, a screwdrive (or other blade), tweezers (from the replacement kit), and gloves
are needed. Please follow the steps below.
1. Unplug the ATMOS 14 from the data logger.
2. Touch a grounded object to discharge any static electricity.
3. If the ATMOS 14 is in a radiation shield, use a screwdriver or other blade to gently pry
loose the white plastic plug where the sensor cable exits the shield. Start at the slit in
the plug and gently work around the perimeter of the plug.
4. Leave the plug attached to the sensor cable.
5. Pull the ATMOS 14 down and out of the radiation shield.
6. Use the screwdriver to gently pry the blue elastomer cap from the end of the sensor.
The sensor module sits directly behind the blue elastomer cap. It has a circular hole that
allows it to be easily removed from the sensor body.
7. Put on gloves to prevent skin oils or dirt from contaminating the sensor module.
8. Use the tweezers included in the replacement kit, a pen, or other thin object to pry the
old module away from the main sensor body.
9. Set old module aside.
