Shanghai Bilang conductivity meter electrode constant K relationship.
The principle that the conductivity meter measures the conductivity: the electric field that causes ions to move in the solution being measured is generated by the two electrodes that are in direct contact with the solution. The measurement of conductivity needs to clarify two aspects: 1. The conductivity of the solution, 2. The geometric relationship of 1 / A in the solution. The conductivity can be obtained by the measurement of current and voltage.
The measuring electrode (conductivity electrode) of the conductivity meter must be made of materials resistant to chemical corrosion. The materials often used in practice are stainless steel. The measuring electrode composed of two electrodes is called Kohlrausch electrode. The electrode constant K = L / A, this measurement principle has been applied in today's direct display measuring instruments.
K = L / A; A—the effective plate of the measuring electrode; L—the distance between the two plates; the value of K is called the electrode constant. In the case of a uniform electric field between the electrodes, the cell constant can be calculated from the geometric dimensions. When two square plates with an area of ​​1cm2 are separated by 1cm to form an electrode, the constant K = 1cm-1 of this electrode. If the conductivity value measured by this pair of electrodes is G = 1000μS, then the conductivity of the tested solution K = 1000μS / cm.
In general, the electrodes of the conductivity meter often form a partially non-uniform electric field. At this time, the cell constant must be determined with a standard solution. The standard solution generally uses KCl solution. This is because the conductivity of KCl is very stable and accurate at different temperatures and concentrations. The conductivity of 0.1mol / l KCl solution at 25 ℃ is 12.88mS / CM. Non-uniform electric fields, also known as stray fields and leakage fields, have no constants, but are related to the type and concentration of ions. Therefore, a pure stray field electrode is the worst electrode, it can not meet the needs of a wide measurement range through one calibration.
BILON brand, dedicated service
China Xuchang Wig Co., Ltd , https://www.hairxuchang.com