Drip counter rain gage
The ClimaVue 50 has a 9.31-cm diameter rain-collection funnel. A spring in the funnel acts as a filter to keep out large particles while allowing enough flow so water does not back up. Rain collected by the funnel exits the funnel through a precision flared hole that forms the rain into drops of a known size. The falling drops hit and momentarily bridge the gap between two gold pins, creating an electrical pulse.
The ClimaVue 50 counts the pulses (drops) and calculates the water volume based on 0.017 mm of rain per drop. The resolution of the drip counter allows light precipitation events and heavy dew accumulations to be recorded.
The accuracy decreases during high-intensity rain storms (greater than 50 mm/hr). For applications that require accurate, long-term accumulation measurements, Campbell Scientific recommends using a standard, tipping-bucket rain gage, such as the RainVue 10.
To test the rain sensor before installation, slowly (~5 ml/min) drip water into the funnel to mimic rainfall. Pouring water too fast will result in inaccurate pulse measurements.