Brief introduction: The online conductivity/resistivity detector EC-420 is a product of SUNTET Taiwan, with an external size of 144 * 144. It has dual screen single screen switching, two or one sets of conductivity/resistivity monitoring can be selected freely, and it is equipped with LED light indication warning for operation status and electrode diagnosis. The cleaning action status has automatic and manual range switching, and accepts dual pole and four pole electrode input. It has automatic desalination rate display and alarm setting function combination keys to enter the setting and calibration mode design, to prevent erroneous changes and provide an electrode automatic cleaning device