104
e) Calibrating the rain collector
The rainfall measuring gauge is extremely accurate upon delivery; therefore it is normally not necessary
to calibrate it.
A calibration is only necessary if utmost accuracy is required.
The calibration process is rather long (at least 10 minutes) and must be carried out with extreme
diligence and care or the accuracy will be poorer than before.
Before starting the calibration of the rain collector, reset the rain quantity at the display console to zero
(total rain display reads zero) in normal display mode.
And the unit for the rain quantity must be set to “mm” or “l/m²” for the calibration. Set the display unit
correctly.
Make also sure that the rain collector is clean (collection funnel, drain hole, tipping bucket) and that the
tipping bucket is dry.
To accurately calibrate the unit, then proceed as follows:
1. Pour in 100 ml of water very slowly into the collection funnel of the rain collector over a period of 10 minutes.
Caution!
If you pour in the water too quickly, the measuring result will become inaccurate. Pour in the water so
slowly that the water is never standing in the funnel.
Please remember that even in heavy rain only a few raindrops will fall into the opening of the rain
collector.
2. The total quantity should now be 6.5 l/m².
3. If a different value is displayed, the so-called tipping value must be recalculated as follows:
6.5 x present tipping value
New tipping value =
Actual value (display after filling in the water)
4. Now enter the new tipping value in the configuration menu (RAIN CAL system menu). It is indicated in ml/tipping
scoop.
The ex-factory setting is 295 ml/tipping scoop.