Thermometers and Temperature Strings
Temperature is a very important parameter to control for evaluating the influence of the thermal effects on the measurements and on the structure which is monitored.
Thermometers are available with platinum RTD (Resistance Thermal Detector) thermistor or vibrating wire probes. All models are housed in a shock resistant stainless steel body to be embedded in concrete.
Temperature string probe is available for multiple thermal measurements in boreholes, treches or to be embedded into concrete.
Vibrating wire transducer is essentially composed by a taut wire clamped at its ends and tensioned so that it is free to vibrate at its natural frequency. The frequency of vibration varies with the wire tension and thus small relative movements between the two end clamps.
With VW transducers frequencies rather than voltage levels are measured, so a dedicated readout/datalogger must be used to measure the resonant frequency. These ones excites the VW transducer, measures the response, performs some calculations on the response, and returns the result.
SISGEO VW transducer uses ‘pluck and read’ method and not ‘auto resonant’ method; when the readout/datalogger plucks the wire a magnetic attraction is created to the coil and the wire start to vibrate and it causes an alternating voltage of the same frequency of the natural frequency of the wire; the voltage signal is transmitted on the cable and read from the readout/datalogger.
VW transducers have a reputation for long expected life and long-term stability.