Metering device, water sample diluting device and ammonia nitrogen online analyzer

The utility model provides a metering device, a water sample diluting device and an ammonia nitrogen online analyzer. The utility model provides a metering device which is used for metering a solution to be detected of an ammonia nitrogen online analyzer and comprises a metering tube, a first detection device, a second detection device and a third detection device, the metering tube is used for accommodating the to-be-detected solution, and the to-be-detected solution comprises a water sample, a detection reagent and distilled water; the first detection device, the second detection device and the third detection device are respectively used for detecting the quantitation of any solution to be detected, and the quantitation detected by the first detection device, the second detection device and the third detection device is sequentially increased. The ammonia nitrogen content deviation of the finally diluted water sample can be prevented from exceeding 5%, and the standard requirement is met. 本实用新型提供一种计量装置、水样稀