GT1000-CODCr equipment uses a high-temperature, corrosion-resistant multi-channel sampling valve to collect water sample and reagent. After precise optical quantification by a piston pump, a quantitative sample of water and reagent is sent to the reaction pool by a digestion valve for heating up to 175°C in a high-temperature digestion process. After the digestion, the CODCr value of test water sample is converted through photoelectric colorimetry. At the same time, the equipment will cool down rapidly. After cooling, the reaction waste fluid is discharged from the multi-channel injection valve module by the digestion valve to complete the entire measurement.