Precision Infared Radiometer
Model PIR
The Precision Infrared Radiometer, Pyrgeometer, is intended for unidirectional operation in the measurement, separately, of downwelling or upwelling longwave irradiance. Unlike instruments that measure the shortwave (short) irradiance, there is no official ISO/WMO classification of pyrgeometers which are designed to measure the longwave (infrared) irradiance from the sky. The PIR comprises the same wirewound thermopile detector and temperature compensation circuitry as found in the SPP pyranometers. This thermopile detector is used to measure the “net radiation” of the PIR and a case thermistor (YSI 44031) is used to determine the outgoing radiation from the case. A dome thermistor is also included if one wishes to measure the dome temperature as compared to the case temperature to make any “corrections” to the final result.
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| Field of View | 180° (2π sr) |
| Spectral Range | approx, 4-50 microns |
| Sensitivity | approx. 3 μV / Wm-2 |
| 95% Response Time | 5 Seconds |
| Temperature Response | 0.5% (-30°C to +50°C) |
| Linearity | 0.5% |
| Stability | 1% per year |
| Zero Offset | 2 Wm-2 |
| Tilt Response | 0.5% |
| Uncertainty | 5 Wm-2 |
| Operating Temperature | |
| Range | -50° to +80°C |
| Operating Humidity | |
| Range | 0 to 100% RH |
| Traceability | World Infrared Standard Group (WISG) International Practical Temperature Scale (IPTS) |
| Application | Working Standard or Network Mesurements |