The Design And Development Of Ammonia Nitrogen Detector In Water Quality Testing

The ammonia nitrogen content is one of the regular project in water quality testing, the limit of ammonia nitrogen content in drinking water hygiene standards is 0.5 mg/L. As a result, the water quality of ammonia nitrogen detector is widely used in surface water, sewage outfalls, farms, and drinking water quality tests. To develop both can apply various water samples, and with high measurement precision ammonia nitrogen detector, has important practical value.The paper analyze the nessler’s reagent spectrophotometry, and realized the collection and sample concentration determination based on the theoretical law of lambert- bill. On this basis, the ammonia nitrogen detector hardware system and software system are designed. Circuit diagram is given based on AM335 X series processor; Use 420 nm cathode lamp to test for the light source, photoelectric diode as light intensity detection sensor. Aiming at the interference of other components substances in water quality, design the distillation pretreatment with constant temperature control device, make nessler’s reagent spectrophomtry test results more accurate, can detect all kinds of complicated samples. Shows the flow chart of software system, using the least squares fitting work curve, and the work curve and measuring results stored in the detector, through the LCD display. Human-computer interaction module using the touchscreen interface menu operation, and store the testing data of measurement results can query at any time.The paper analyzed the influence of the constant temperature system of test results. Through experimental analysis to detect ammonia nitrogen detector of repeatability, the function such as zero drift, span drift. Paper analyzes the error sources, especially the sampling process, temperature, the impact of work environment change on the test results and interference, and gives way to reduce the error. Using curve fitting method for data analysis and verification, it is concluded that the system resistance, wide adaptability, high precision of testing results. Detection limit of 0.05 mg/L.