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Vaisala DMT143 User Manual

Page 63

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Chapter 6 _______________________________________________________________ Maintenance

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.

NOTE

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.

If you have altered the DMT143 serial port settings, switch off the
other power supply (disconnect “Analog” cable if in use) before
powering up the MI70. Note that this powers off the transmitter,
and it will carry out the startup sequence (see section DMT143
Startup Sequence on pa
ge 17) when powered on again.

4.

Turn on the MI70 indicator. Never connect or disconnect the MI70
indicator while it is powered on, as this may cause incorrect values
to be displayed.

5.

Check and adjust the environment settings if prompted. Refer to the
DM70 User’s Guide for the settings of the DMP74B probe.

6.

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.