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Enabling better global research outcomes in soil, plant & environmental monitoring.

Apogee ST-300-PRT Platinum Resistance Thermometer

The ST-300 is a 1/10 DIN platinum resistance thermometer (PRT) consisting of a platinum resistive element enclosed in a stainless steel sheath, and lead wires to connect the sensor to a measurement device.

ST-300 sensors are weatherproof and designed for continuous air temperature measurement when housed in an aspirated radiation shield, such as the TS-100 fan aspirated radiation shield.



Alternatively, see the ST-150: A 1/8 inch, Class A PRT (Platinum Resistance Thermometer) with an IP67 rating. White heat shrink is used on the cable behind the PRT to minimize heat transfer to the sensor. PRT sheath dimensions are 3 mm diameter and 65 mm length, miminzing thermal mass.

Apogee ST Series temperature sensors are designed to be mounded inside solar radiation shields, such as the model TS-100 fan aspirated radiation shield. ST-300 sensors can also be buried in soils/porous media, or submerged in water.

The temperature measurement returned by a temperature sensor is the temperature for the sensor itself and not that of the environment the sensor is in, unless the sensor is in thermal equilibrium with the environment. In order to get representative temperature measurements, ST series sensors must be in thermal contact with the medium of interest. Accurate air temperature measurement requires a radiation shield to minimise the effects of shortwave radiation absorption and longwave radiation emission by the sensor. Proper ventilation is also required to ensure coupling and thermal equilibrium with air. Condensation on air temperature sensors can pose a problem because it is a source of latent heat that can warm the sensor. When the condensed water evaporates, it cools the sensor via removal of latent heat (evaporational cooling).

Calibration Uncertainty: -50 to 70°C
Measurement Repeatability: < 0.01°C
Non-Stability (Long-term Drift): < 0.05°C per year (when used in non-condensing environments
Equilibration Time: 15 seconds
Self-Heating: < 0.01°C (Typical, assuming pulsed excitation of 2.1 V DC);
0.09°C at 5°C (maximum, assuming continuous input excitation of 2.1 V DC)
Operating Environment -50 to 70°C, 0 to 100% relative humidity
Input Voltage Requirement: 2.1 V DC
Output Voltage Range: 16 to 27 mV DC (assuming input excitation of 2.1 V DC)
Current Drain: 0.21 mA DC (maximum, assuming continuous input excitation of 2.1 V DC)
Dimensions: 65mm length, 3mm diameter
Mass: 95 g
Cable 5m of four conductor, shielded, twisted-pair wire. Additional cable available in multiples of 5m.
Santoprene rubber jacked (high water resistance, high UV stability, flexibility in cold conditions). Pigtail lead wires.