SI-131 Ultra-Narrow Field of View Infrared Radiometer Sensor 14º APOGEE


Apogee Instruments


915,00 €

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Spec Sheets:SI Series Owner's Manual:SI Series Sample Programs:Edlog,CRBasic,LoggerNet Short Cut Instructions Infrared Temperature Sensor

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The SI-131 14º sensor provides accurate measurement of the leaf-to air temperature gradient is important for irrigation scheduling and the determination of energy transfer, transpiration rate, and stomatal conductance in both single leaves and plant canopies.


Apogee infrared radiometers are the most accurate non-contact temperature sensors available anywhere. The SI-131 has a 14 degree half angle field of view. The sensor has tinned leads for connecting to a datalogger. Applications include measuring the temperatures of road surfaces, plant canopies, and soil, snow and water surfaces. Measurement of surface temperature is a crucial component of energy transfer. Accurate measurement of the leaf-to-air temperature gradient is essential to the determination of transpiration rate and stomatal conductance in both single leaves and plant canopies.

Approximate Sensitivity: 20 μV per C

Output from Thermistor: 0 to 2500 mV (typical, depends on input voltage)

Input Voltage Requirement: 2500 mV excitation (typical, other voltages can be used)

Calibration Uncertainty (-20 to 65 C): 0.3 C, when target and detector temperature are within 20 C

Calibration Uncertainty (-40 to 80 C): 0.5 C, when target and detector temperature are different by more than 20 C

Measurement Repeatability: < 0.05 C

Stability (Long-term Drift): less than 2 % change in slope per year when germanium filter is maintained in a clean condition

Response Time: 0.2 s

Field of View: 14° half angle

Spectral Range: 8 to 14 μm; atmospheric window

Operating Environment: -55 to 80 C, 0 to 100 % relative humidity (non-condensing)

Dimensions: 2.3 cm diameter and 6.0 cm length

Mass: 190 g (with 5 m of lead wire)

Cable: 5 m of four conductor, shielded, twisted-pair wire. Additional cable available in multiples of 5 m. Santoprene rubber jacket (high water resistance, high UV stability, flexibility in cold conditions). Pigtail lead wires.

The AI-100 radiation shield improves the performance of Apogee infrared sensors in applications where there is a significant solar load on the sensor housing.
This shield is included on all new infrared sensors and is offered as an accessory for customers wishing to retro-fit previously purchased infrared sensors.


Solar Radiation protector AI-100
Included with every SI-111

Protector AI-100


Apogee Mast Bracket AM-210

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