Vaisala hmdw110 series - Adjustment Types

n Always wait for measurement instruments to stabilize in the ambient
temperature. Temperature differences are a major source of measurement
error.
n Check that there are no heat or moisture sources near the transmitter.
n Check that the transmitter is not in direct sunlight or close to the discharge of
the supply air ducts.
n Check that there is no moisture on the probe. If the sensor has become wet,
you must allow it to dry before you can measure.
Adjustment Types
You can perform a one-point calibration and adjustment with Vaisala hand-held
meters that utilize the MI70 measurement indicator (for example, HM70). See the
following sections:
n Calibration and Adjustment Using a Hand-Held Meter and a Reference
Probe on the facing page
n One-Point Humidity Calibration and Adjustment Using a Hand-Held Meter
and HMK15 Humidity Calibrator on page45
Connecting to the service port using a computer and a terminal program allows
you to perform calibration and adjustment tasks using serial commands. You
can, for example, perform a two-point humidity calibration and adjustment, or
clear the existing user adjustments (factory calibration will remain). See the
following sections:
n Calibration and Adjustment Commands on page36
n Two-Point Temperature Calibration and Adjustment using a Computer on
page49
n Two-Point Humidity Calibration and Adjustment using a computer and a
HMK15 Humidity Calibrator on page46
If you replace the HUMICAP
®
humidity sensor of the
transmitter, you must perform the two-point humidity calibration
afterward.
Adjustment Points
HMDW110 series transmitters have two adjustment points for both humidity
measurement and temperature measurement:
n The first point (low point) affects offset across the entire measurement range.
For humidity adjustment, the low point must be < 50 %RH.
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