240-8111 Pyrradiometer

WMO First Class
Long-wave and short-wave measurements
Independent from ambient temperature
Separate outputs for upward and downward radiation

The Model 240-8111 Pyrradiometer is a total hemispherical radiometer, used for exact determination of net radiation in short-wave and long-wave radiation range (0.3 to >30 µm) with two separately working receivers and with a built-in Pt-100 resistance thermometer to determine reference temperature. Two black, radiation absorbing plates act as sensors, one facing upward and one facing downward. Each transfers the energy absorbed to a separate 90-junction copper-constantan thermopile. Both of the two outputs are approximately 15 µV/Wm², one representing downward total radiation and the other representing upward total radiation. The difference between these two provides net radiation.

Lupolene domes shield the thermopiles from wind and moisture. Lupolene is essentially transparent to radiation from 0.3 to 60 microns. Two desiccant tubes are supplied to remove water vapor from inside the instrument housing. For long-term applications, fittings permit attachment of a nitrogen source for continuous purging. Levels are embedded in both the top and bottom faces of the pyrradiometer, and a 10" mounting arm is included.

Specifications

Internal temperature sensor: 100-ohm platinum resistance sensor
Spectral Sensitivity: 0.3 to >30 µm
Azimuth response: < 5% of the value
Cosine response: < 5% of the value, zenith angle 0° to 80°
Response time: < 25 sec (95%), < 45 sec (99%)
Measuring range: 0-1500 Wm²
Resolution: < 1 Wm²
Stability: < 3% per year (temporary operation)
Temperature effect: < 2% of the value between -20°C to + 40°C
Linearity: < 2% in the range 0.5-1330 Wm²
Impedance: About 190 ohm/receiver plate
Output: About 15 µV/Wm²
Ambient temperature: -40°C to + 60°C
Windshield: Lupolene dome, 2.47quot; (62 mm) diameter
Leveling: Bull's-eye levels on each face
Size: 14" L x 4" W x 3.5" H (355 x 100 x 90 mm)
Weight/shipping: 4 lbs/7 lbs (1.8 kg/3.2 kg)
Cable: 4 polar shielded, 5 m length

Ordering Information

240-8111 Pyrradiometer, including 2 desiccant tubes, silica gel, platinum resistance temperature sensor, and 5 meters of cable
240-8111-D Lupolene Dome, 2 required
240-8111-OR O-Rings, set of 4
240-8111-PT Pt-100 Platinum Element
240-8111-SG Silica Gel, 100 grams
240-8111-SGC Silica Gel Container, filled
330-0420 Additional Cable, per foot

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