1. Introduction Industrial PH Meter PHG-1800 is the intelligent upgrade product of industrial pH testing instrument. It could measure and control pH value of wastewater continuously, the pH meter is applicable for municipal wastewater treatment, chemistry, printing and dyeing, paper, medicine, plating and environmental production etc. In accordance with the environment and characteristics of water industry, as well as the international power supply standard, considering the electricity design in special environment, the pH meter could be supplied with power 220V AC, and safe low voltage 24V AC,24V DC for selection. Main Characteristics: Chinese and English language display Measure pH/ORP, high/low limit control, current output, digital communication It could be set automatic or manual temperature compensation pH high limit alarm, low limit alarm, double relay, alarm delay could be adjust Instrument mode isolated transmitting port, max circle resistance bigger than 300Ω Sound alarm function could be set; Backlight of LCD could select power saving mode, timing automatic off High performance CPU, good electromagnetic compatibility Password management avoid non-professional person operation 2. Main Technical Index Measure range: pH(0 - 14 pH) ; ORP( -1900 - +1900 mV) Accuracy: + 0.02 pH; + 1 mV Resolution: 0.01pH; 1mV Stability:≤ 0.02 pH/24hr ; ≤ 3 mV/24hr pH standard solution: 4.01/6.86/9.18 Display: 128 * 64 dot matrix LCD Temperature compensation: 0-100 ºC manual / automatic(NTC10K) Signal output: Isolated 4-20mA signal output ;max circle resistance 300Ω Alarm output: high and low limit alarm contact each group(3A/250 V AC),normal open contact relay Power supply: AC 220V±10% 50Hz Power consumption: ≤3W Working environment:(1)temperature 0~ 60 ºC (2)humidity≤85%RH Outline dimention: 96×96×110mm(high×width×depth) Hole size: 92×92mm(height×width)