Vaisala MMT330 - Manual (Page 141)

Chapter 7 ___________________________________________________ Calibration and Adjustment
VAISALA _______________________________________________________________________ 141
CHAPTER 7
CALIBRATION AND ADJUSTMENT
This chapter provides information that is needed in calibration and
adjustment of the product.
The MMT330 is fully calibrated and adjusted as shipped from factory.
The calibration interval depends on the application. When measuring
moisture in transformer oil, the recommended calibration interval is
3 years. It is recommended that calibration is done always when there is a
reason to believe that the device is not within the accuracy specifications.
The user can calibrate the MMT330 or send it to Vaisala for calibration.
For contact information of Vaisala Service Centers, see
www.vaisala.com/servicecenters .
Calibration and adjustment is carried out either by using the push-keys on
the motherboard, through the serial port or with the optional
display/keypad.
Before the calibration the used sensor should be cleaned with instrument
air to blow out existing oil or gently first flush with hepthane (C
7
H
16
) and
dry with instrument air to decrease response time.
The cleaning must be done as the oily sensor can contamine the salt bath
and change the reference condition.
NOTE It is important to clean the sensor before calibration as the oily sensor can
contamine the salt bath and change the reference condition.
Vaisala HUMICAP® hand-held moisture and temperature in Oil meter
MM70 can also be used for calibration.