This standard applies to the calibration of multiparameter water quality testers and similar equipment, including the specification of the calibration conditions, items, methods, result processing and calibration cycle of multiparameter water quality testers. Prepare work before calibration, strictly implement the operating procedures to ensure the integrity of the calibration results, and comply with the relevant national standards. Multiparameter water quality testers are mainly used to measure parameters such as temperature, conductivity, dissolved oxygen, ph value, turbidity in water. Standard equipment and accessories include host, handheld display/recorder, cable, electrodes for corresponding parameters, calibrating cup and standard liquid, etc. Appearance, functional display, assembly, insulation performance and working performance have specific technical requirements.