CVF4

The CVF4, manufactured by Kipp & Zonen, is a ventilator/heater for our CMP6, CMP10, CMP11, CMP21, and SMP10 pyranometers. The ventilation unit improves the reliability and accuracy of the measurement by reducing dust, raindrops, and dew on the dome. The integrated heater can be used to disperse precipitation and melt frost, or even melt snow and ice in cold climates.

The CVF4 uses a fan and inlet filter to draw clean air over the pyranometer’s domes. The fan runs continuously to reduce dust and dirt settling, to dissipate rain drops, and to stabilize the dome temperature.

The flow that the CVF4 creates is unique. At the top of the pyranometer dome, the flow is very high, and it swirls to improve the air distribution over the dome. The position of the heaters and the new cover material ensure that only half the heating power is needed to melt frost and snow compared to older ventilation units.

The CVF4 is meant to run continuously. The heater can either be switched on permanently for cold regions, or it can be switched by a Campbell Scientific data logger to remove dew in the morning and then be switched off afterward. In that scenario, the heater could operate for a period before and after sunrise. This saves power in situations where power is limited, such as PV-operated systems.