109

The 109 is a rugged, accurate probe that measures air, soil, and water temperature for a variety of applications. It consists of a thermistor encapsulated in an epoxy-filled aluminum housing. The housing protects the thermistor, allowing you to bury the 109 in soil or submerge it in water. The 109 measures from -50° to +70°C, and it outputs a 0 to 2.2 V signal when using 2500 mV excitation.

Air Temperature

When exposed to sunlight, the 109 should be housed in a 41303-5A, 41303-5B, or RAD06 6-plate radiation shield. The louvered construction of these radiation shields allows air to pass freely through the shield, thereby keeping the sensor at or near ambient temperature. The shields’ white color reflects solar radiation

The RAD06 uses a double-louvered design that offers improved sensor protection from driving rain, snow, and insect intrusion, and it has lower self-heating in bright sunlight combined with higher temperatures (> 24°C [~75°F]) and low wind speeds (< 2 m s^-1 [~4.5 mph]), giving a better measurement.

The 41303-5A and RAD06 attach to a crossarm, mast, or user-supplied pipe with a 2.5 to 5.3 cm (1.0 in to 2.1 in) outer diameter.

The 41303-5B attaches to a CM500-series pole or a user-supplied pole with a 5.1 cm (2.4 in) outer diameter.

Water Temperature

The sensor can be submerged to 15 m (50 ft) or 21 psi. The 109 is not weighted, and therefore the installer should either add a weighting system or secure the sensor to a fixed, submerged object, such as a piling.

Soil Temperature

The 109 is suitable for shallow burial only. Placement of the sensor’s cable inside a rugged conduit may be advisable for long cable runs—especially in locations subject to digging, mowing, traffic, use of power tools, or lightning strikes.