Making a 2-point relative humidity adjustment

Making a 2-point relative humidity adjustment - DM70

DM70 User Guide

Document code

M010091EN

Revision

Language

English

Product

DM70

Document type

User guide

For the DMP74A probe, the wet point humidity reference must be > 20 %RH.

For the DMP74B and DMP74C probes , the wet point humidity reference must be < 20 %RH.

For DMP74A, humidity references of 0 % (for example nitrogen) and 30 ... 75 % are recommended. Make sure that the difference between the humidity references is more than 30 %.

For DMP74B and DMP74C, humidity references of 0 % (for example nitrogen) and 11 % are recommended.

To make a 2-point %RH adjustment:

Check that DM70 is turned on.
When using the DMP74B probe, do the manual sensor purge. For instructions, see Performing manual sensor purge .
Remove the screw from the probe handle to expose the calibration button (see Figure 1) and press the button, for example, with a small screwdriver. When pressing the button, the indicator switches into adjustment mode.
To start adjusting, press OK.
Select RH and press Select.
To check the environmental settings, press Yes. To continue without checking the settings, press No.
To select the adjustment method, press Adjust.
Select 2-point adjustment and press Select. Press OK to continue.
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.
Use the arrow buttons to give the lower reference value of relative humidity. Then press OK.
Set the probe to a higher 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.
Use the arrow buttons to give the higher reference value of relative humidity. Then press OK.
Confirm the adjustment by pressing Yes. If you press No, you return to the adjustment display and no changes are made.

DMP74A: If the difference between the 2 references is less than 30 %, the adjustment cannot be done.
The adjustment is complete. To exit the adjustment mode, press Back.
To return to the basic display, press Exit.
Place the screw back onto the calibration button after finishing dew point adjustments.

¹ If there is a temperature difference between the generated reference and the probe temperature, relative humidity must be calculated to correspond to the temperature of the probe.