SUP-DY3000 Optical type dissolved oxygen online analyzer, an intelligent online chemical analyzer. The cap of the sensor is coated with a luminescent material. Blue light from an LED illuminates the luminescent chemical. The luminescent chemical instantly becomes excited and releases red light. The time and intensity of red light are inversely proportional to the concentration of oxygen molecules, So the concentration of oxygen molecules is calculated. Features Range: 0-20mg/L,0-200%,0-400hPaResolution:0.01mg/L,0.1%,1hPaOutput signal: 4~20mA; Relay; RS485Power supply: AC220V±10%; 50Hz/60Hz