1. ECG-1903 series of microcomputer-based industrial control instruments are precision meters for measurement of conductivity or resistivity of solution. With complete functions, stable performance, simple operation and other advantages, they are optimal instruments for industrial measurement and control. 2. The advantages of this instrument include: LCD display with back light and display of errors; automatic temperature compensation; isolated 4-20mA current output; dual relay control; adjustable delay; alarming with upper and lower thresholds; power-down memory and over ten years of data storage without backup battery. 3. According to the range of resistivity of the water sample measured, the electrode with a constant k=0.01, 0.1, 1.0 or 10 can be used by means of flow-through, immerged, flanged or pipe-based installation.