The SF-421 has an SDI-12 digital output. The detector is a combination of two temperature sensors (precision thermistors) in a single housing. One sensor is designed to mimic a plant leaf the other a flower bud. The SF-421 provides close approximations to leaf and bud temperatures and has a temperature measurement range of -50 to 70 C. Typical 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.
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 Repeatability Less than 0.05 C
Non-stability (Long-term Drift) Less than 0.2 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
Response Time Fastest data transmission rate for SDI-12 circuitry is 1 s
Self-heating Less than 0.01
Operating Environment -50 to 70 C, 0 to 100% relative humidity
Input Voltage Requirement 5.5 to 24 V DC
Current Drain 0.6 mA (quiescent), 1.3 mA (active)
Dimensions 570 mm length, 21 mm pipe diameter, 70 mm disk diameter
Mass 400 g
Cable 5 m of two conductor, shielded, twisted-pair wire with santoprene rubber jacket (high water resistance, high UV stability, flexibility in cold conditions), additional cable available
Warranty 4 years against defects in materials and workmanship
