Studying And Designing The Device For Measuring The Concentration Of Hydrazine In Water By Spectrophotometry

In view of the sewage examination at rocket and satellite launch site, the paper develops the pocket, portable and appropriative metrical instrument for measuring the concentration of hydrazine in water.First contrasting the aspects of developer type, response condition, examination wave on the existing photoelectric examination methods, the p-dimethylaminobenzaldehyde spectrophotometric method for measuring the concentration of hydrazine in water is put forward. The feasibility of the examination method is proved by U4100 spectrophotometer in the laboratory, and find out the influencing factors of the detecting precision by theoretical analysis and experiments. The experimental results indicate that the detection limit is 2μg/L for hydrazine and 40μg/L for monomethyl hydrazine in water. Based on the results, the whole design scheme of the instrument is proposed.According to the whole design scheme of the instrument, the paper designs the metrical instrument in detail. Analyzing influences of the wave length, the optical power and the stability of spectral line on instrument, the selecting principle of the light source is given. The beam collimating system, the fixed device to colorimetric ware, the drive circuit of LED and control circuit of MCU are designed, and the detecting circuits of the instrument are analyzed and designed. Based on these, the lab instrument is created. The testing results of the instrument performance show that the lab instrument is stable, sensitive, and the detection limit is 2μg/L for hydrazine and 20μg/L for monomethyl hydrazine in water.Finally, focusing on the requirements of engineering prototype, testing method of multi-light-source for measuring the concentration of hydrazine and monomethyl hydrazine in water at the same time is realized at the fist time. The power module is designed for supplying power to the engineering prototype. The testing results are displayed on OCM12864-5 LCD, and serial communication is achieved, while the corresponding software of receiving and processing data is programmed. The result shows that the lab instrument is superior to the same kind instrument abroad, comparing the lab instrument and the product of HANNA.