Field Check Using DM70 - DMT132

DMT132 User Guide
Document code
M211289EN
Revision
B
Language
English
Product
DMT132
Document type
User guide
To check the accuracy of the DMT132 in the field, you need the following equipment:
  • A fully charged MI70 indicator (the measurement display that is included in the DM70 and HM70 hand-held indicator products).
  • A calibrated reference probe that is suitable for the intended measurement environment and dew point range.
    • DMP74A probe from the DM70 is the recommended choice, as it offers the best accuracy in the measurement range of the DMT132.
    • All probes compatible with the DM70 and HM70 hand-held indicators may be used as a reference.
    • You can also use a second DMT132 transmitter.
  • A connection cable between DMT132 and the MI70 indicator (Vaisala order code 219980).
  • A reference environment with a stable dew point and temperature in a suitable range for both devices. The normal measurement environment of the transmitter can also be used, if it meets these criteria.
In the procedure below, the readings of the devices are checked individually. You can also perform the field check so that you connect the reference probe simultaneously with the DMT132 you are checking. In this case, you need two of the connection cables if you are using a DMT132 also as the reference probe.
Make sure that the measurements are made in the same pressure.

Perform the check as follows:

  1. Place the DMT132 in the reference environment (unless it is there already). You can perform the check even if the DMT132 is currently being powered and used, as long as there is no cable or LED indicator plug connected to connector II. However, external powering is not needed when using the MI70 indicator with DMT132.
  2. Connect the MI70 connection cable between the MI70 indicator and connector II of the DMT132.
  3. Turn on the MI70 indicator.
  4. Check and adjust the environment settings if prompted. You can only change the pressure compensation value that is used for dew point temperature calculation.
  5. If the desired measurement 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/f reading after the measurement has stabilized.
  8. Turn off the MI70 indicator and disconnect the DMT132.
  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.
  11. Wait for the reference probe to provide a stable reading, and compare it with the reading from the DMT132.

    The difference between the readings should be within the combined accuracy of the reference probe and the DMT132 in the measured temperature and dew point. If the difference is more, the DMT132 is in need of adjustment.

You can send the DMT132 to be adjusted at Vaisala, or adjust the transmitter yourself.

Notes on using the MI70 indicator with the DMT132:
  • If you disconnect the DMT132 while the MI70 indicator is on, the measurement parameters will remain on the screen, but no measurement will be shown.
  • Notification messages from the transmitter will appear in English even if the MI70 has been set to another language.