16
SERVICE
10. Orient the replacement module so that the female 4-pin connector on the sensor body
aligns properly with the male connector on the module. The module will sit diagonally
across the opening in the sensor body when properly aligned.
11. Insert the module into the sensor body opening, mate the two halves of the connector,
and firmly press the module against the sensor body until the connector is fully seated.
12. Replace the blue elastomer cap and firmly seat it into the sensor body
13. Plug the ATMOS 14 back into the data logger and scan its output to make sure the
electrical connections have been made and the sensor is functioning properly.
14. Reinstall the into the radiation shield (if radiation shield is being used).
15. Replace the white plastic plug in the radiation shield, pressing it into place with a
thumb. Begin pressing at the slit and working around the perimeter of the plug.
4.3 CLEANING AND MAINTENANCE
The ATMOS 14 sensor does not require any regular cleaning or maintenance. The radiation
shield should be cleaned with a damp cloth to remove dirt, debris, and nesting insects
or webs as these will reduce the airflow through the radiation shields and may reduce
its effectiveness.
However, the polymer RH sensing element in the ATMOS 14 can be poisoned by exposure
to volatile organic compounds, solvents, and other chemicals. The effects of exposure
to these chemicals can range from subtle loss of accuracy to catastrophic failure.
If the ATMOS 14 may have suffered chemical exposure (evident in questionable RH
measurements), check the sensor accuracy using known RH conditions.
A convenient method for generating known RH conditions is through the use of salt
solutions. For an initial check, prepare a saturated NaCl solution, which has an equilibrium
RH of 0.75 (75%):
1. Pour laboratory-grade NaCl into a sealable container that is large enough to
accommodate a salt solution and the ATMOS 14.
2. Mix in enough water that there is a thin layer of liquid water present over a thick slurry of
NaCl crystals.
3. Seal the ATMOS 14 sensor into the container, making sure that the ATMOS 14 is held or
suspended above the salt solution .
NOTE: Ensure the ATMOS 14 sensor is at the same temperature as the salt solution or large errors in the
measured RH occur.
Salt solutions in a wide range of RH can be carefully prepared with pure, dry salts using the
ratios in
or are available from METER. METER salt solutions are specified accurate to
within ±0.3% RH.
