Vaisala DM70 - Manual (Page 71)

Chapter 9 _______________________________________ Calibration, Adjustment, and Maintenance
For DMT340 M-sensor, humidity references of 0 % (for example
Nitrogen) and 10 ... 20 % are required.
NOTE For the DMT340 M-sensor both reference humidities must be below
20 %RH.
To make the adjustment, follow the instructions below:
1. Turn off DM70.
2. Connect the cable 211339 between DMT340 (service port) and
DM70 (connector I or II). Turn on both the devices.
3. With DMT340 series transmitters with the M-sensor, perform
the manual purge. Also, if you are using DMP74B probe as
reference, perform the manual purge on the reference probe as
well.
4. Press the ADJ button on the DMT340 motherboard to enable the
adjustment mode.
5. From the list of parameters, select RH
I/II
6. You are prompted to check the settings, make sure that the
pressure units of DM70 and DMT340 are the same. If not,
change the unit by pressing Unit on the corresponding row.
7. Continue with the adjustment by pressing Adjust. Select 2-
point adjustment. A note is displayed on the screen reminding
you to follow the adjustment procedure described in the User's
Guide. Press OK to proceed with the adjustment.
8. Set the probe to a lower reference value of relative humidity 1) .
You can follow the stabilization from the graph display by
pressing Graph. When the reading has stabilized, press
Ready.
9. Use the arrow buttons to give the lower reference value of
relative humidity. Then press OK.
10. Set the probe to a higher reference value of relative humidity 1) .
When the reading has stabilized, press
Ready. You can follow the stabilization from the graph
display by pressing Graph.
11. Use arrow buttons to give the higher reference value of relative
humidity. Then press OK.
VAISALA _______________________________________________________________________ 69