REV 8

SEPTEMBER 19,2002

MET ONE DELTA TEMPERATURE

The following calibration may require two individuals to complete, depending on the proximity of the tower to the shelter and DAS.

1. Record the appropriate site, date, sensor and calibration device information on the calibration spreadsheet for ambient temperature and for delta temperature.

2. Disable channels 11 (delta temp) and 13 (ambient temp) in the data logger.

3. Disable those other data logger channels utilized for other meteorological parameters which are affected by the lowering of the tower.

4. Carefully lower the tower and rest the top of the tower on a support to prevent damage to any of the tower sensors.

5. Check the operation of the aspirator motors, then unplug the power supply to the aspirator motors. (Repair the motors if inoperative.)

6. Disconnect the wires from inside the aspirator housing.

7. Remove the temperature/delta temperature probes from their housings. It will be necessary to remove signal wire straps from the tower leg to allow the placement of the probes in a water bath.

8. Place the probes in the water bath.

9. Allow the bath to cool to 32oF.

10. Once the DAS readings are stable, record the bath temperature and the DAS values on the spreadsheets. (in oF.)

11. If both the temperature and delta temperature are within the PSD Tolerance(s), proceed to Step 13. If one or both exceed the Tolerance, continue with Step 12.

12. If the ambient temperature response (DAS) exceeds the PSD tolerance, adjust R602 and/or R702 to bring readings in specifications.

13. Adjust the water bath to near 25oC (75oF).

14. Once the DAS readings are stable, record the bath temperature and the DAS values on the spreadsheets. (in oF.)

15. Adjust the water bath and heat the water to near 50oC (122oF).

16. Once the DAS readings are stable, record the bath temperature and the DAS values on the spreadsheets. (in oF.)

17. If either the temperature or delta temperature are outside of the PSD Tolerance(s), or if probes cannot be brought into specifications at zero point translator box must be returned to vendor for calibration.

18. If the observed DAS values are within the PSD Tolerances, return the system to its normal configuration.

19. Enable the appropriate data logger channels.

20. Place a copy of the calibration spreadsheets in the equipment file.