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Conductivity Meter Widely Used In Industry, Agriculture
Jul 01, 2017

Conductivity Meter is mainly used to measure the conductivity of liquid medium, widely used in industry, agriculture, scientific research, environmental protection and other fields. In order to ensure the accuracy of the test results, need to be maintained, the common note is as follows:

1, temperature (5 ~ 40 ℃), relative humidity (≤ 85%) in line with the provisions of the instrument.

2, to prevent moisture, corrosive gases into the machine, the electrode socket should be kept dry.

3, in full bloom containing the solution of the container must be clean, no other ion pollution.

4, after the use of electrodes should be cleaned, wipe clean with clean paper.

5, the potentiometer on the chassis, switch to keep dry, regularly wipe with a lubricant.

Conductivity Meter is two parallel plates, into the measured solution, at both ends of the plate with a certain potential (usually voltage), and then measured between the plate flow. According to the ohm, the conductivity (G) - the reciprocal of the resistance (R) is determined by the conductor itself.

The basic unit of conductivity is Siemens (S), originally known as ohm. Because the geometrical shape of the conductivity cell affects the conductivity value, the standard measurement is expressed in unit conductivity S / cm to compensate for the differences in the various electrode sizes. The unit conductivity (C) is simply the product of the measured conductivity (G) and the conductivity cell constant (L / A). Where L is the length of the liquid column between the two plates, and A is the area of the plate.

The conductivity of the aqueous solution is directly proportional to the concentration of dissolved solids, and the higher the concentration of solids, the greater the conductivity. The relationship between the conductivity and the dissolved solids concentration is approximately 1.4 μS / cm = 1 ppm or 2 μS / cm = 1 ppm (per million units of CaCO3).

The total hardness value of water can be indirectly obtained by using a Conductivity Meter or a total solid dissolution amount. As described above, 1 μs / cm conductivity = 0.5 ppm hardness for approximate conversion. Conductivity is the material transfer current, relative to the resistance value, in units of Siemens / cm (S / cm), expressed in units of 10-6 in μS / cm, expressed at mS / cm at 10-3.

But need to pay attention to:

(1) to indirectly measure the hardness of water, the theoretical error of about 20-30ppm

(2) the conductivity of the solution determines the size of the movement of molecules, the temperature affect the movement of molecules, in order to compare the measurement results, the test temperature is generally set at 20 ℃ or 25 ℃

(3) the use of reagent testing can obtain more accurate water hardness value.