Owner's manual

Chapter 7 ___________________________________________________ Calibration and Adjustment
VAISALA _______________________________________________________________________ 149
CHAPTER 7
CALIBRATION AND ADJUSTMENT
This chapter provides you with instructions on how to calibrate and
adjust Vaisala DRYCAP® Dewpoint Transmitters DMT345 and
DMT346.
Calibration
DMT345 and DMT346 are fully calibrated and adjusted as shipped from
the factory. The typical calibration interval is one year. Calibration must
always be done when there is reason to believe that the device is not
within the accuracy specifications.
It is recommended that the device should be sent to a Vaisala Service
Center for calibration and adjustment. For contact information of Vaisala
Service Centers, see www.vaisala.com/servicecenters.
NOTE
If the process is not shut down for removing the transmitter for
calibration, the hole for the probe in the cooling set must be plugged;
otherwise, there is a risk of water condensing inside the cooling pipe
(in
overpressurized processes).
User Calibration and Adjustment
When adjusting DMT345 or DMT346, the reading of the transmitter is
changed to correspond to the reference value. After the adjustment, the
original calibration certificate shipped with the product is no longer valid.
The following adjustments are possible:
- Two-point relative humidity adjustment
- One-point dewpoint adjustment
- One-point temperature adjustment
- Two-point temperature adjustment
- Analog output adjustment