97
B 2.7 Eppley Black and White Pyranometer (Model 8-48)
The Black and White Pyranometer has a detector consisting of a differential thermopile with the hot-junction
receivers blackened and the cold-junction receivers whitened. The receiver is of radial wire-wound plated
construction with the black segments coated with a flat black coating and the white with Barium Sulfate.
Built-in temperature compensation with thermistor circuitry is incorporated to free the instrument from
effects of ambient temperature. A precision ground optical glass hemisphere of Schott glass WG295 uniformly
transmits energy from 0.285 to 2.8 :m.
Specifications
Sensitivity approx. 10 :V/W m
-2
Impedance approx. 350 Ohms
Temperature Dependence ± 1.5 % over ambient temperature range -20 to +40 C
o
Linearity ± 1.0 % from 0 to 1400 W m
-2
Response time 5 seconds (1/e signal)
Cosine ± 2 % from normalization 0-70 zenith angle
o
± 5 % from normalization 70-80 zenith angle
o
Mechanical Vibration tested up to 20 g’s without damage
Calibration integrating hemisphere
Size 5.75 inch diameter, 2.75 inches high
Weight 2 pounds
B 2.8 Schenk Star Pyranometer
The measuring principle of the star pyranometer is the measurement of, the temperature difference between
white and black painted sectors so that the result is not affected by ambient temperature. A precisely cut
dome shields the sensing elements from environmental factors.
A drying cartidge keeps the interior free from hum idity. An optional protective housing enables measurements
in cold weather.
Technical Data
Measuring range 0 to 1500 W m
-2
Spectral sensitivity 0.3 to 3 :m
Output About 15 :V/W m or 4 ... 20 mA = 0 ... 1500 W m
-2 -2
Impedence About 35 Ohm
Ambient temperature -40 C to +60 C
oo
Resolution < 1 W m
-2
Stability < 1% per year ( temporary operation )
Cosine response < 3 % of the value, zenith angle 0 - 80
o o
Azimuth response < 3 % of the value
Temperature effect < 1 % of the value between -20 C to + 40 C
oo
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