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Chapter 6 _______________________________________________________________ Maintenance
NOTE
VAISALA ________________________________________________________________________ 61
Field Check Using the DM70 Hand-Held
Dewpoint Meter
Vaisala recommends the following equipment for field checking:
- A fully charged MI70 indicator (the measurement display that is
included in the DM70 package).
- A calibrated reference probe that is suitable for the intended
measurement environment and dewpoint range. The DMP74B probe
is recommended for checking the dewpoint and temperature
measurement accuracy.
- You also need a connection cable (Vaisala order code: 219980SP) to
connect the DMT143 to the MI70 indicator.
In the procedure below, the readings of the transmitter and the reference
probe are checked simultaneously. You can also check the reference
probe and the DMT143 separately if they cannot be connected at the
same time.
Perform the check as follows:
1.
Place the reference probe and the DMT143 in the reference
environment.
2.
Connect the reference probe and the DMT143 to the MI70
indicator:
- Reference probe to Port I
- DMT143 to Port II
3.
Turn on the MI70 indicator.
4.
Check and adjust the environment settings if prompted. Refer to the
DM70 User's Guide for the settings of the DMP74B probe.
5.
Disable the Auto power off function of the MI70 indicator to
prevent the indicator from powering off in the middle of the check.
Check the setting in the Settings - User Interface menu, and
change if necessary.
6.
The MI70 can display three parameters at one time. To compare the
readings of the DMT143 and the reference probe, select the desired
parameter from the Display – Quantities and Units menu of the
MI70. Select the same parameter from port I and II, and the delta
parameter that shows the difference between the two. For example,
∆T
shows the difference in dewpoint between the two probes.
d/f
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