Umwelt-Geräte-Technik GmbH
| Eberswalder Str. 58 | D-15374 Müncheberg | phone: +49 (0) 33 43 2 - 89 575 |
6.1.
Rezero of the Full Range Tensiometer
The Full Range Tensiometer is factory calibrated that the measured tension equals 0 kPa at a water
temperature of 20 °C when the ceramic cup is saturated and placed on the free water surface (please
see calibration certificate).
A drift in the measurement readings for long measurement periods can be corrected by determining
the
maximum pressure (P
ref
at 20°C)
before and after the measurement campaign. To determine the
maximum pressure value put the tensiometer at least for 3 hours in water with a free surface (e.g.
water filled beaker) and a constant temperature of 20 °C. Note that the ceramic is not allowed to touch
the bottom of the water tank and that the ceramic cup should not be touched by any holding device.
Comparing both values, the offset can be determined and the data set can be adjusted.
Note:
If you expect a high ion concentration in the surroundings (e.g. soil or irrigation water) while
operating the Full Range Tensiometer a calibration (rezero) under the expected site conditions is
highly recommended. The set to zero can be carried out by following the instruction or by our trained
UGT staff.
Correct (left) and incorrect (middle and right) positioning of the Full Range Tensiometer for the determination of
the maximum pressure in a temperature controlled water bath
