YSI ProDSS [626902] Conductivity & Temperature Sensor. he YSI ProDSS conductivity & temperature sensor is a digital smart sensor featuring welded titanium construction for use with the ProDIGITAL family of instruments. Compatible instruments include the ProDSS Meter, ProSwap Meter, and ProSwap Logger. The sensor provides accurate and fast temperature data. It is also used to calculate salinity, specific conductance, and total dissolved solids. The temperature sensor uses a highly stable and aged thermistor with low-drift characteristics. The thermistor’s resistance changes with temperature. The measured resistance is then converted to temperature using an algorithm. The temperature sensor receives a multi-point NIST traceable wet calibration, and the accuracy specification of 0.01˚C is valid for the expected life of the probe. No calibration or maintenance of the temperature sensor is required, but accuracy checks can be conducted. The conductivity sensor uses four internal, pure-nickel electrodes to measure solution conductance. Two of the electrodes are current-driven, and two are used to measure the voltage drop. The measured voltage drop is then converted into a conductance value in milliSiemens (millimhos). To convert this value to a conductivity value in milliSiemens per cm (mS/cm), the conductance is multiplied by the cell constant that has units of reciprocal cm (cm-1). The cell constant for the conductivity cell is approximately 5.5/cm ±10%. For most applications, the cell constant is automatically determined (or confirmed) with each deployment of the system when the calibration procedure is followed. ProDSS sensors have internal thermistors for quality assurance purposes. Turbidity uses the internal thermistor for temperature compensation, while all other ProDSS sensors reference the C/T probe for temperature compensation. To display and log temperature, a C/T probe must be installed on a ProDIGITAL meter.