DewPro<Superscript>® MMR31 Installation & Operation Manual
17
Chapter 3. Calibration and Troubleshooting
Note:
For successful calibration, it is important that the temperature in the salt solution and in the enclosed
atmosphere above the solution reach equilibrium at the same value. After waiting for approximately two
hours, the ammeter reading should stabilize.
3.
If the meter reading is stable at 5.80 mA (or 11.3% on a display), press
Sl
for at least one second. This assigns the
11.3% RH value. If only the low RH calibration will be performed, return
Switch S3
to position 0 (see
). Otherwise, continue to the next section to calibrate the high RH reading.
3.2.2
Calibrating the High RH Reading
Note:
For the high RH reading, a saturated salt solution of sodium chloride is used to provide an 75.4% relative
humidity reference.
1.
Insert the probe into the calibration bottle, almost to the bottom.
2.
Observe the ammeter. The reading will change toward 16 mA (or 75.4% on a display) after insertion of the probe.
Note:
For successful calibration, it is important that the temperature in the salt solution and in the enclosed
atmosphere above the solution reach equilibrium at the same value. After waiting for approximately two
hours, the ammeter reading should stabilize.
3.
If the meter reading is stable at 16 mA (or 75.4% on a display), press
S2
for at least one second. This assigns the
75.4% RH value. Return
Switch S3
).
4.
After successful calibration, remove the ammeter, reconnect the negative (-) lead and reinstall the cover.
Note:
During calibration, if the wrong key is pressed, the value will not be accepted due to a plausibility check