Conductivity analyzer(Conductivity Meter, conductivity monitor) is a wide temperature range online water quality analysis instrument developed for medical multi-effect distilled water system, boiler bottom water, condensate, heat exchange system, industrial heat cleaning of mechanical parts, industrial circulating water and other high-end water quality management and automation control in higher temperature environments.
Online conductivity meter is a new generation of high-grade instruments with English micro-models, with the characteristics of all English display, English menu operation, full intelligence, multi-function, high measurement performance, strong environmental adaptability and so on. The secondary meter is equipped with an electrode with a constant of 1.0 or 10 to measure the conductivity of the general liquid; Equipped with 0.1 or 0.01 electrodes, it can accurately measure the conductivity of pure water or ultrapure water, especially suitable for online continuous monitoring of high-purity hydropower conductivity such as boiler feed water and steam condensate in power plants.
Conductivity controllers are widely used in industrial, electric power, agriculture, medicine, food, scientific research and environmental protection and other fields. The instrument is also a necessary inspection equipment in food factories and drinking water plants in QS and HACCP certification.
The Conductivity Tester is a multi-range instrument that meets the inspection requirements of applications ranging from deionized water to seawater. The instrument provides automatic temperature compensation and the ability to set the temperature coefficient, so it can be used to measure liquid samples with a different temperature coefficient than water. It is capable of three ranges and has an automatic range selection function to automatically select the most appropriate range during inspection.
Conductivity is a numerical representation of the ability of a solution to conduct current. The conductivity of water has a certain relationship with the amount of inorganic acids, alkalis and salts it contains, and when their concentration is low, the conductivity increases with the increase of concentration, so this indicator is often used to speculate on the total concentration or salt content of ions in water.
1. Conductivity and hardness of water
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 conductivity and concentration of
dissolved solids is approximately expressed as: 1.4 μS/cm = 1 ppm or 2 μS/cm = 1 ppm (CaCO3per million units). The total hardness value of water can be obtained indirectly by using a conductivity meter or a total solids solubility meter,
as mentioned above, for the convenience of approximate conversion, 1μs/cm conductivity = 0.5ppm hardness.
However, it is important to note that:
(1) The hardness of water is indirectly measured by electrical conductivity, and the theoretical error is about 20-30ppm;
(2) The size of the conductivity of the solution determines the
movement of the molecules, the temperature affects the movement of the molecules, in order to compare the measurement results, the test temperature is generally set at 20 ° C or 25 ° C;
(3) Reagent detection can obtain a more accurate
hardness value of water.
2. Soft water and hard water
Water is divided into soft water, hard water, where does not contain or contain a small amount of calcium, magnesium ions of water is called soft water, vice versa is called hard water. The hardness of the water, if caused by sodium bicarbonate or magnesium bicarbonate, is temporary hard water (boiling temporary hard water, decomposing sodium bicarbonate, insoluble carbonate generated and precipitated, water from hard water to soft water); If it is caused by sulfates or chlorides containing calcium and Why use conductivity meter to test TDS copymagnesium, it is permanent hard water. According to the total hardness value of water, the total hardness of 0-30ppm is called soft water, the total hardness of more than 60ppm is called hard water, high-quality drinking water is not more than 25ppm, and the total hardness of high-quality soft water is 10ppm Hereinafter. In natural water, rainwater and snow water that are far away from the city are soft water; Spring water, stream water, river water, reservoir water, mostly temporary hard water, some groundwater belongs to high hardness water.
3. The conversion of common units for water quality hardness conversion is :
1mmol/L(1/2Ca2+ , 1/2Mg2+)=50 ppm( in CaCO3)
1mmol/L (1/2Ca2+ , 1/2Mg2+) = 2.92grain/gallon.
1 grain/gallon =17.lppm (in CaCO3).
1m3=264gallon (US) =22O gallon(UK).
lkg = 2.2pounds ( British pounds ).
1ppm=1mg/L.
TDS (Total Dissolved Solids) is used to measure the total content of all ions in water, usually expressed in ppm.
In pure water who manufactures, conductivity can also be used indirectly to express it as TDS.
The conductivity of the solution is equal to the sum of the conductivities of the various ions in the solution.
The empirical formula is that the conductivity in micro-Siemens is about half equal to TDS (ppm).
Sometimes TDS is also expressed in terms of other salts, such as CaCO3 (coefficient 0.66).
The conversion coefficient of TDS to conductivity can be adjusted between 0.4-1.0 to correspond to different types of electrolyte solutions.
4. Conductivity
Conductivity is the ability of a substance to transmit current, as opposed to the value of resistance, in Siemens/cm .
5. The hardness of the water
The hardness of water refers to the concentration of calcium and magnesium ions in water, the hardness unit is ppm, and 1ppm represents the content of calcium carbonate in water 1 mg/l (mg/L).
Conductance (G) is the reciprocal of the resistance (R). Therefore, when two electrodes (usually platinum electrodes or platinum black electrodes) are inserted into the solution, the resistance R between the two electrodes can be measured. According to Ohm's law, when the temperature is fixed, this resistance value is proportional to the electrode spacing L(cm) and inversely proportional to the cross-sectional area of the electrode A(cm2), that is, R = ρ× ( L/A）； where ρ is the resistivity, which is 1 cm long and has a cross-sectional area of 1 cm2 conductors, the size of which depends on the nature of the substance.
According to the above formula, the conductivity (G) of the conductor can be expressed as the following formula: G = 1 / R = (1 / ρ) × (A / L) = K× (1 / J ） ； where K=1/ρ is called conductivity, and J=L/A is called the electrode constant; Electrolyte solution conductivity refers to the conductivity of two parallel electrodes 1 cm apart when a 1 cm3 solution is charged. As can be seen from the above equation, when the electrode constant (J) is known and the solution resistance (R) or conductivity (G) is measured, the conductivity can be obtained.
1. The lead of the electrode must not be wet, otherwise it will not be accurate.
2. High-purity water should be measured quickly after being put into the container, otherwise the conductivity will rise quickly, because the CO2 in the air dissolves into the water and becomes carbonate ions.
3. The container containing the solution to be measured must be clean and free of ion contamination.
● Power plant - water treatment;
● Water plants and sewage plants - wastewater treatment;
● Papermaking - production process / wastewater treatment;
● Chemical refining - production process / wastewater treatment;
● Metallurgy and mining - production process/ wastewater treatment;
● Food and beverage - production process / wastewater treatment;
● Pharmaceutical industry - biological reaction and fermentation/wastewater treatment;
● Semiconductor - production process / wastewater treatment / high purity water production.
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