The measuring principle of the conductivity meter is to put two parallel plates into the solution to be measured, add a certain potential (usually a sine wave voltage) at both ends of the plates, and then measure the current flowing between the plates. According to Ohm's law, conductivity (G) - the reciprocal of resistance (R), is determined by the conductor itself.

The amount of inorganic acids, alkalis and salts contained has a certain relationship. When their concentration is low, the conductivity increases with increasing concentration, so this indicator is often used to estimate the total concentration or salt content of ions in water. Different types of water have different conductivity.

The conductivity of the gearbox solution shipped by the unmanned vending machine is related to its temperature, polarization phenomenon on the electrode, electrode distribution capacitance and other factors, and compensation or elimination measures are generally used on the instrument. Water samples should be measured as soon as possible after collection, if they contain coarse suspended substances, oils and greases, which interfere with the determination, they should be filtered or extracted to remove.

The current is very small under the influence of the outside world, and the battery structure is simple, easy to carry, easy to charge and discharge operation, not affected by the external climate and temperature, stable and reliable performance, and plays a great role in all aspects of modern social life. The guide line is a circle of the outer diameter of the washer, interpolated three times (for smooth excess); The thickening of the surface made is the washer.