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Leaf and Bud Temperature Sensor -SF 421


  • Wide Range, Accurate Measurements: Thermistor accuracy is ± 0.1 C across a range of 0 to 70 C, providing accurate measurements at temperatures near zero where frost damage is likely to occur.
  • Output Options:  Analog and digital output options include an unamplified voltage output or SDI-12
    communication protocol.
  • Typical Applications : Applications include leaf and bud temperature estimates in cropped fields, orchards, and vineyards. Leaf and bud temperatures returned by the detector can then be used to alert
    growers to the potential of frost damage to crops.

Make : Apogee Instruments

Model : SF-110


Leaf and bud temperature approximations measured with an Apogee SF-110 compared to air temperature (top
panel) and wind speed (bottom panel) on the evening of April 28, 2012. Leaf and bud temperatures were both
below air temperature after 8 P.M. and reached freezing 6 (leaf) and 4 (bud) hours before the air temperature.



Measurement Range

-50 to 70 C

Measurement Uncertainty

0.1 C (from 0 to 70 C), 0.2 C (from -25 to 0 C), 0.4 C (from -50 to -25 C) Measurement

Measurement Repeatability

Less than 0.05 C

Long-term Drift (Non-stability)

Less than 0.02 C per year (when used in non-condensing environments where the annual average temperature is less than 30
C; continuously high temperatures or continuously humid environments increase drift rate)

Equilibration Time

10 s


Less than 0.01 C

Operating Environment

-50 to 70 C; 0 to 100 % relative humidity

Input Voltage Requirement

5.5 to 24 V DC

Output Voltage Range

Current Draw

0.6 mA (quiescent), 1.3 mA (active)


570 mm length, 21 mm pipe diameter, 70 mm disk diameter


400 g


4 years against defects in materials and workmanship



Leaf and Bud Temperature Sensor Datasheet