Pessl Instruments iMETOS - Leaf Wetness Sensor; Maintenance; Troubleshooting

iMETOS Maintenance & troubleshooting 6
4. LEAF WETNESS SENSOR
4.1 Maintenance
The sensing element (paper) should be checked periodically/every 3 months depending on the rain fre-
quency. If this sensing element (paper) is dirty, soiled by bird droppings, coated by spray materials (copper
fungicide, etc.), physically damaged, or worn out, it should be replaced. The sensing element will eventually
dissolve after long exposure. As replacement, you can use an other lter paper, if it is thin you should put it in
2 pcs of paper. Filter size is 18 x 25 mm.
The sensor works by measuring the conductivity in a lter paper. The lter paper is held by two stainless steel
electrodes in a transparent holder. The use of transparent Lucite plastic as a holder reduces the warm up of
the sensor when it is exposed to direct sunlight.
Note: do not clip the leave into the sensor the lter paper is simulating the green tissue of the leave.
Installation tip: To avoid premature ageing of the cable, check that the 5m cable is xed and that is not aect-
ed by wind.
Life expectancy: Over ten years in very hummed micro-climates (worst case). Check it every 4 years.
4.2 Troubleshooting
• It always shows wet or dry data: cable is cut.
• Leaf wetness period shorter than expected: no lter or pure rain.