Chapter 5 ___________________________________________ CALIBRATION AND ADJUSTMENT
Calibration and Adjustment of MM70 Series
Probes
General about Calibrations
The MM70 is fully calibrated as shipped from factory. Adjustment
should be done if there is a reason to believe that device is not within
the accuracy specifications. The recommended calibration interval is
one year.
It is recommended to send the device to Vaisala Service Centre for
calibration and adjustment, see contact information in section Vaisala
Service Centers on page 61. Alternatively, user can calibrate and
adjust MM70 by following the instructions below.
Preparations before the Calibration
Before calibration the used sensor should be cleaned with instrument
air to blow out existing oil or gently first flush with hepthane (C7H16)
and dry with instrument air. This is to decrease response time and to
prevent contamination of the salt bath and change of the reference
condition. See section MAINTENANCE on page 59.
NOTE
It is important to clean the sensor before calibration as the dirty
sensor can contamine the salt bath and change the reference
condition.
When using Vaisala humidity calibrator HMK15, use the adapter
fitting (13.5 mm hole). Before starting the adjustment mode, take out
the screw vovering the calibration button (item 3 in Figure 2). See
Figure 2 on page 11.
Relative Humidity Adjustment
Li-Cl-NaCl Automatic Adjustment
LiCl-NaCl automatic adjustment is a two-point adjustment in
reference humidities of 11.3 % (LiCl) and 75 % (NaCl). You don't
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