Development Of Water Turbidity Measuring Instrument Based On Light Scattering

Water plays an important role in our lives.It is the source of life and one of the most important material resources indispensable for human survival and development.Because the water contains suspended particles and colloidal particulate matter,a cloudy visual phenomenon occurs,and the turbidity is called turbidity.Turbidity is one of the quality indicators that characterize water.According to the requirements of the latest 《Sanitary Standards for Drinking Water 》(GB5749-2006),the turbidity of drinking water generally does not exceed 1 NTU.At present,the foreign turbidity meters dominated by Hach Company are the mainstream in the market,and the domestic turbidity meters are not far behind foreign brands in terms of product reliability,stability and measurement accuracy.With the development of electronic technology,new processes and new materials are constantly updated,and the detection requirements of turbidity meters are getting higher and higher.The turbidity measuring instrument developed in this paper uses LED with a specific peak wavelength as the emission light source to avoid the influence of water chromaticity;The unique internal cavity design of the sensor minimizes the influence of stray light;the sensor has an automatic cleaning system to effectively cope with the challenges of high turbidity environments;the special sealing structure design can still be used under 1Mpa high pressure environment.The main work of the thesis is as follows:(1)The whole turbidity measuring instrument was designed and developed.The whole machine contains two parts: controller and sensor.The whole system mainly includes hardware design,structural design and software design.Hardware design is divided into hardware circuit design and hardware structure design.The hardware circuit design mainly includes the light source drive and the receiver circuit design,the minimum system and data acquisition based on STM32 Single chip microcomputer.The hardware structure design is mainly to analyze the layout of the optical path of the sensor,including the selection and placement of the light source and detector,and the design of sealing to prevent water leakage.Software design is mainly software algorithm analysis and basic hardware drivers,to achieve data collection,processing and real-time signal output functions;(2)The turbidity sensor adopts a special double sealing structure,which can still maintain good sealing performance in high pressure,high temperature,oil resistance,acid and alkali,chemical corrosion and other environments.The actual test shows that it can be used in high pressure applications;(3)The performance evaluation test of the whole machine was designed and carried out.The test results show that the turbidity meter designed in this paper is within the range of 0-100 NTU low turbidity range,and the measurement results are accurate and reliable.