In the procedure described here, the readings of the probes are checked
individually. You can also perform the field check so that you connect the
reference probe simultaneously with the DMT152 you are checking. In this case,
you need two connection cables if you are using a DMT152 also as the reference
probe. Also, you must power one of the transmitters by other means than the
MI70 indicator.
1. Place DMT152 in the reference environment (unless it is there already). You can perform
the check even if DMT152 is currently being powered and used, as long as there is no cable
connected to connector II.
2. Connect the MI70 connection cable between the MI70 indicator and connector II of
DMT152.
3. Turn on the MI70 indicator. If the analog channels of your DMT152 are configured to use
the current output, and if DMT152 is powered by MI70, you will see an error message that
indicates the supply voltage is too low for running the actual analog output. This is
expected behavior; press
OK
to acknowledge the error and continue the field check.
4. Check and adjust the environment settings if prompted. You can change the pressure
compensation value (only needed for ppm calculation) and the molar mass of the
measurement gas. The pressure must be entered in bar
a
; to enter the value in psi
a
, use the
serial line. For more information on these settings, see the following sections:
•
Set Pressure Value for ppm Calculation (page 44)
•
Set Molar Mass for ppm w Calculation (page 45)
5. After a brief delay, DMT152 should provide an approximate measurement reading of the
selected parameters. Remember that it takes up to 15 minutes for the transmitter to start
the active measurement. If the desired parameters are not shown on the display, select
them from the
Display – Quantities and units
menu.
6. The
Auto power off
function should be disabled on the MI70 indicator to prevent the
indicator from powering off in the middle of the check. While waiting for the active
measurement to start, check the setting in the
Settings - User Interface
menu, and
change if necessary.
7. Write down the
Td
reading after the measurement has stabilized.
8. Turn off the MI70 indicator and disconnect DMT152.
9. Insert the reference probe to the measurement environment, and connect it to the MI70
indicator.
10. Turn on the MI70 indicator. Check and adjust the environment settings if prompted.
Chapter 6 – Maintenance
55
Summary of Contents for Drycap DMT152
Page 1: ...M210865EN J User Guide Vaisala DRYCAP Dew Point Transmitter DMT152...
Page 8: ...DMT152 User Guide M210865EN J 6...
Page 68: ...DMT152 User Guide M210865EN J 66...
Page 70: ...DMT152 User Guide M210865EN J 68...
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