Apogee Instruments ST-150 Руководство пользователя - Страница 4
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Печатать страницуINTRODUCTION
Temperature is generally thought of as the relative degree of 'hotness' or 'coldness' of a specific object or material.
In actuality, temperature is a measure of the average thermal energy (internal kinetic energy) of an object.
Thermal energy is associated with the motion (kinetic energy) of the atoms and molecules making up the
object/material. Higher temperatures correspond to higher thermal energies (faster motion of atoms and
molecules), whereas colder temperatures correspond to lower thermal energies (slower motion of atoms and
molecules).
Properties of materials, and nearly all biological, chemical, and physical processes, are temperature dependent.
Temperature is also a fundamental weather variable. As a result, temperature is perhaps the most widely
measured environmental variable.
Thermometers are sensors that measure temperature. Thermometers are often electronic, with multiple options
available. The main advantages of thermistors over other electronic thermometers (thermocouples, platinum
resistance thermometers) are high signal-to-noise ratio, requirement of only a single-ended channel for
measurement, and low cost, while still maintaining comparable accuracy.
Apogee Instruments ST-100 temperature sensors consist of a precision thermistor enclosed in a waterproof rubber
covering, a precision bridge resistor, and lead wires to connect the sensor to a measurement device. ST-100
sensors are weatherproof and are designed for continuous temperature measurement in air, soil, or water.
ST-110 temperature sensors consist of a precision thermistor, a precision bridge resistor, and lead wires to connect
the sensor to a measurement device. ST-110 sensors are weatherproof, have excellent long-term stability, but do
not offer the same level of ingress protection as the ST-100. The ST-110 is designed for continuous air temperature
measurement when housed in the TS-100 aspirated radiation shield. Thermal conductivity to the precision
thermistor is minimized by using constantan wire, which has twenty-fold lower thermal conductivity than copper
wire.
ST-150 is a platinum resistive thermometer (PRT) enclosed in a stainless steel sheath, and lead wires to connect
the sensor to a measurement device. The sensor is weatherproof and is designed for continuous air temperature
measurement when housed in the TS-100 aspirated radiation shield. The ST-150 is designed to be used with
dataloggers that have resistors built in.
ST-200 temperature sensors have a fine-wire precision thermistor, precision bridge resistor, and lead wires, but
the thermistor is not packaged in a weatherproof housing. ST-200 sensors are weather resistant and are designed
for temperature measurement of delicate surfaces (e.g., leaves, fruits) and small samples (where a narrow field of
view infrared radiometer may not be suitable due to the integration over the conical field of view), or applications
where rapid response is required.
ST-300 is a 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 sensor are
weatherproof and is designed for continuous air temperature measurement when housed in the TS-100 aspirated
radiation shield.
All Apogee thermistor temperature sensors output an analog voltage (when supplied with an input voltage) that is
related to thermistor resistance. Resistance is directly related to temperature.