Field calibration check of DMT340/DMT242/DMT143 - DM70

DM70 User Guide
Document code
M010091EN
Revision
G
Language
English
Product
DM70
Document type
User guide

You can use DM70 to display the reading of DMT340, DMT242, or DMT143 transmitter, and to compare the readings of DM70 and the transmitter.

Use the following cables to connect DM70 to the transmitter:
  • Connection cable 211339 with DMT340
  • Connection cable 27160ZZ with DMT242
  • Connection cable 219980SP with DMT143

To carry out a field calibration check:

  1. Turn off DM70.
  2. Connect the cable between DMT340 (service port) or DMT242/DMT143 (serial port) and DM70 (connector I or II). Turn on both devices.
  3. If you are requested to check the environment settings, press Yes. Then check the pressure settings. For instructions on setting the ambient pressure, see Configuring pressure settings.
  4. Check that the pressure units of DM70 and DMT340/DMT242/DMT143 are the same. If not, and you are checking DMT242/DMT143, change the DM70 pressure unit to bara by pressing Unit on the corresponding row. You cannot change the pressure unit for DMT242/DMT143. Adjust the values as instructed in Configuring pressure settings.

    When using DM70 to check DMT340, you can change the pressure unit of DMT340 by pressing Unit on the corresponding row. It is also possible to change the pressure unit of DMT340 through the transmitters local display/keypad interface (for instructions, see DMT340 User's Guide). Then adjust the values as instructed in Configuring pressure settings.

  5. When the pressure settings are correct, press Exit. Now the display shows the dew point readings Td/f of DM70, DMT340/DMT242/DMT143, and the difference between the readings ∆Td/f. Roman numerals (I and II) after the parameter abbreviations indicate from which port the readings are coming. You can follow the measurement trend from the graphical display.
  6. Wait until the readings are stabilized. This can take up to 1 hour in very low dew points. If the difference between the dew point readings is less than 3 ˚C, there is no immediate need for adjustment. However, in applications where optimum accuracy is essential, it is recommended to send the DMT340/DMT242/DMT143 transmitter to Vaisala if the difference is considered significant.
  7. Press the Power On/Off button.
  8. Disconnect the connection cable.