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SF-421-SS Radiation Frost Detector (SDI-12)

Updated:2025-03-13

Brand: APOGEE
Model: SF-421-SS Radiation Frost Detector (SDI-12)
Description: The SF-421-SS has SDI-12 digital outputs and high-quality cable terminations with pre tinned pigtail leads for easy connection to data recorders and controllers. The detector contains a precision ther
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Product Details

Overview of SF-421-SS Radiation Frost Detector (SDI-12)：

User's Manual

The SF-421-SS has an SDI-12 digital output and high-quality cable terminating in pre-tinned pigtail leads for easy connection to dataloggers and controllers. The detector contains a precision thermistor that mimics a leaf. The SF-421-SS provides close approximations of leaf temperatures and has a temperature measurement range of -50 to 70 ℃. Typical applications include leaf temperature estimates in cropped fields, orchards, and vineyards. Leaf temperatures returned by the detector can then be used to alert growers to the potential of frost damage to crops. Sensor includes IP68 marine-grade stainless-steel cable connector 30 cm from head to simplify sensor removal and replacement for maintenance and recalibration. While most users choose to mount the SF-411-SS to a branch or stick using zip ties, the AM-260 mounting fixture can be used as a more permanent mounting option.

Drawing of SF-421-SS detector:

Specifications of SF-421-SS detector:

Measurement Range	-50 to 70 ℃
Measurement Uncertainty	0.1 ℃ (from 0 to 70 ℃), 0.2 ℃ (from -25 to 0 ℃), 0.4 ℃ (from -50 to -25 ℃)
Measurement Repeatability	Less than 0.05 ℃
Non-stability (Long-term Drift)	Less than 0.2 ℃ per year (when used in non-condensing environments where the annual average temperature is less than 30 ℃; continuously high temperatures or continuously humid environments increase drift rate)
Equilibration Time	10 s
Response Time	Fastest data transmission rate for SDI-12 circuitry is 1 s
Self-Heating	Less than 0.01 ℃
Operating Environment	-50 to 70 ℃, 0 to 100 % relative humidity
Input Voltage Requirement	5.5 to 24 V DC
Current Drain	1.56 mA (quiescent), 1.93 mA (active)
Dimensions	17.5 cm length, 2.2 cm pipe diameter, 6.0 cm disk diameter
Mass	75 g
Cable	5 m of three conductor, shielded, twisted-pair wire; additional cable available in multiples of 5 m; TPR jacket (high water resistance, high UV stability, flexibility in cold conditions)
Warranty	4 years against defects in materials and workmanship
Manufactured	Made in the USA