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The SI-111-PW, manufactured by Apogee, is a version of our SI-111 that is fitted with a connector for attachment to a prewired enclosure. This precision infrared radiometer determines the surface temperature of an object without physical contact. The SI-111-PW measures both the subject's surface temperature and the sensor-body temperature. A Campbell Scientific data logger uses these measurements to calculate the correct temperature of the subject.
Leia maisThe SI-111-PW consists of a thermopile, which measures surface temperature, and a thermistor, which measures sensor body temperature. The two temperature sensors are housed in a rugged aluminum body that contains a germanium window.
Both the thermopile and the thermistor output a millivolt signal that most of our data loggers can measure. The data logger uses the Stefan-Boltzman equation to correct for the effect of sensor body temperature on the target temperature. The corrected readings yield an absolute accuracy of ±0.2°C from -10° to +65°C.
The SI-111-PW has a 22-degree half-angle field of view (FOV). The FOV is reported as the half-angle of the apex of the cone formed by the target (cone base) and the detector (cone apex). The target is a circle from which 98% of the radiation viewed by the detector is being emitted.
Input Power | 2.5 V excitation (for thermistor) |
Response Time | < 1 s (to changes in target temperature) |
Target Temperature Output Signal | 60 μV per °C difference from sensor body |
Body Temperature Output Signal | 0 to 2500 mV |
Optics | Germanium lens |
Wavelength Range | 8 to 14 μm (corresponds to atmospheric window) |
Field of View (FOV) | 22° half angle |
Operating Temperature Range | -55° to +80°C |
Operating Relative Humidity Range | 0 to 100% RH |
Cable Description | 4.5 m (14.76 ft) twisted, shielded 4-conductor wire with Santoprene casing, ending in pigtails |
Absolute Accuracy |
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Uniformity |
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Repeatability |
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Diameter | 2.3 cm (0.9 in.) |
Length | 6 cm (2.4 in.) |
Weight | 190 g (6.7 oz) |
Please note: The following shows notable compatibility information. It is not a comprehensive list of all compatible products.
Product | Compatible | Note |
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21X (retired) | ||
CR10 (retired) | ||
CR1000 (retired) | ||
CR10X (retired) | ||
CR200X (retired) | ||
CR206X (retired) | ||
CR211X (retired) | ||
CR216X (retired) | ||
CR23X (retired) | ||
CR295X (retired) | ||
CR3000 (retired) | ||
CR500 (retired) | ||
CR5000 (retired) | ||
CR510 (retired) | ||
CR800 (retired) | ||
CR850 (retired) | ||
CR9000 (retired) | ||
CR9000X (retired) |
The SI-111-PW is often fastened to a CM200-series crossarm, a tripod or tower mast, or a user-supplied pole using a CM230, CM230XL, or CM220 mount. The CM230 and CM230XL are adjustable inclination mounts that allow the SI-111-PW to be mounted perpendicular to the target surface when the target surface is on an incline. The CM230XL is similar to the CM230, but the CM230XL places the SI-111-PW further from the pole or crossarm. The SI-111-PW may also be attached directly to a user-supplied camera tripod.
The cable on the SI-111-PW is fitted with a connector that attaches to a prewired enclosure.
Number of FAQs related to SI-111-PW: 7
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The window in the Apogee infrared sensor is inset and protected, but it can become partially blocked in three ways:
Clean the inner threads and sensor window using a cotton swab dipped in the appropriate solvent. For additional cleaning information, see the Maintenance section of the instruction manual.
As a general recommendation, recalibration should be done every two years.
There are two accuracy specifications listed for the SI-111:
Using a radiation shield with the sensor helps keep the sensor body temperature in close approximation to the ambient air temperature. Ultimately, the need to protect the sensor from short-wave radiation is dependent on what is being measured and under what conditions. For example, Campbell Scientific recommends using a radiation shield for canopy measurements.
The SI-111 has been successfully calibrated with a maximum cable length of 100 m without a loss in accuracy. Ideally, the sensor is calibrated with the overall cable length already configured. Our tests have shown, however, that adding a few meters of cable in the field has a negligible effect on the calibration, provided the measurement device has significantly high input impedance, such as with the CR1000.
The SI-111 can be used to measure a wide variety of surfaces, including water and snow. When measuring objects with low emissivity, however, it is particularly important to apply corrections to the measurement.
The information included on a calibration sheet differs with each sensor. For some sensors, the sheet contains coefficients necessary to program a data logger. For other sensors, the calibration sheet is a pass/fail report.
This depends on the information contained in the calibration sheet: