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2
CNR 4 PROPERTIES
The CNR 4 consists of two pyranometers, for measuring solar radiation, and of two pyrgeometers for measuring Far
Infrared radiation. Two temperature sensors are available as standard, a Pt-100 and thermistor. The optional
ventilation unit CNF 4 is described in chapter 2.5
2.1
Properties of the CNR 4 Net-Radiometer
The properties of CNR 4 are mainly determined by the properties of the individual sensors. Generally the accuracy
of CNR 4 will be higher than that of competitive Net-Radiometers. The main reasons are that the solar radiation
measurement performed by the pyranometer is accurate, and offers a traceable calibration. Also the optionally
integrated ventilation and heating improve the accuracy significantly. Due to the fact that the Net Solar radiation
can be very intense, 1000 Watts per square metre compared to a typical -100 for the Net Far Infrared radiation, the
accuracy of the solar measurement is very critical. Wind corrections, as applied by less accurate competitive
instruments are not necessary. The robustness of the materials used implies that CNR 4 will not suffer from damage
inflicted by birds. Figure 2.1 depicts a drawing of CNR 4. From a spectral point of view, the pyranometer and
pyrgeometer are complementary. Together they cover the full spectral range: The pyranometer from 0.3 to 3
microns, and the pyrgeometer from 4.5 to 42 microns. The gap between these two produces negligible errors.
Figure 2.1 The dimensions of the CNR 4 with CNF 4 ventilation unit, side view
Figure 2.2 The dimensions of the CNR 4 with CNF 4 ventilation unit, top view
405 mm
347 mm
