Operating Principles

The Solinst Model 107 TLC measures temperature, level and conductivity. Temperature and conductivity readings are displayed on the LCD screen and water level is read from the tape as with a conventional Water Level Meter. When the probe is immersed in a conductive fluid, a circuit is completed and the water level is indicated by a tone and light.

Conductivity measurements are read from 0-80,000 µS/cm with readings giving accuracy of 2% of reading or 30 µS (which ever is greater). The ‘smart probe’ displays conductivity which has been standardized to 25°C, i.e. Specific Conductance (Temperature Coefficient is 2.0%). Temperature measurements are read from -15°C to +50°C. The TLC will not operate outside this temperature range and displays “^^^^^^^^” to indicate that temperature is outside the operational range.

Note:

If this device is used in a manner not specified by Solinst, the protection provided by the equipment may be impaired.

Conductivity Sensor Operation

The TLC was specifically designed to be an economical temperature and electrical conductivity profiler and water level meter. As a conductivity profiling instrument it is quite precise when used to determine conductivity change or difference. Its measurement of relative conductivity change over the range is more accurate than its absolute reading of conductivity. Whereas its absolute reading accuracy may fall within +/-2% of actual, the accuracy of relative conductivity change approaches 1% or better.

The Solinst TLC conductivity sensor uses calibration markers and complex, integer polynomial equations to determine the Specific Conductance of a fluid. Readings have an overall accuracy of +/-2%, including calibration readings. When calibrating for Specific Conductance, the cleaning and calibration procedure described in the Instructions sheet should be followed. The TLC Meter should then calibrate to within +/-2% of the Calibration Solution Value. Subsequent TLC readings will fall within the stated accuracy of +/-2%.

Note:

It is not necessary to achieve a perfect match between the Displayed Calibration Reading on the TLC Meter and the Calibration Solution Value.

If after 3 repetitions of the calibration procedure, an accuracy of +/-2% difference between Displayed Calibration Reading and Calibration Solution Value cannot be achieved (which may occur in very cold or very hot environments) then manual compensation of subsequent readings can be achieved as follows:

Record the TLC Calibration Solution Value and the corresponding Displayed Calibration Reading.

Calculate the Compensation Multiplier (CM = Calibration Solution Value/Displayed Calibration Reading). For example when calibrating to 1413 µS/cm, if the Displayed Calibration Reading is 1455 the compensation multiplier will be 1413/1455 = 0.9711.

Multiply all subsequent TLC readings by the Compensation Multiplier. For example if the dispayed TLC reading is 1650 µS/cm the actual conductivity reading will be 0.9711 x 1650 = 1602 µS/cm.

Notes:

The zero measurement point of the TLC Meter is the tip of the shorter sensor pin visible within the shroud at the bottom of the probe. If the display indicates ‘LOW BATT’ there is still some life left in the battery, but it is recommended that you change the batteries as soon as possible.