Sensors help humans explore the ocean world

“Discovery One”scientific research ship“deep sea warrior”The number of manned submersibles docked in Sanya, and successfully completed my country's TS10 deep-dive scientific expedition voyage covering the southwestern Indian Ocean and the central Indian Ocean.“deep sea warrior”In the hydrothermal areas of the Southwest Indian Ocean and the Central Indian Ocean with high sea conditions and complex seabed geological environment, the No. 1 has created a series of new records for China's manned deep diving operations. People's exploration of the ocean continues to deepen, and the help of instruments is indispensable. With these instruments for ocean exploration, we can more accurately understand the unfamiliar ocean world. The measurement method of seawater salinity and its sensor When the temperature and pressure are constant, the properties of seawater always depend on its composition, because there is a certain relationship between the concentration and salinity of seawater both in theory and in practice, Therefore, the salinity can be determined by determining a certain physical and chemical parameter of seawater. A number of methods have been proposed to measure salinity: hydrogravimetry - based on the density of seawater; freezing point depression - based on the relationship between the freezing point of water and the amount of salt dissolved in water; refractometer - based on the refractive index of light ; Magnetic induction method - according to the principle of magnetic induction; impedance method - according to the capacitance between two conductive layers; electrical measurement method - according to conductivity; Some of these methods are quite accurate, for example, in theory, the error of the impedance method can reach±0.0001%, but most (with the exception of electromechanical methods) do not work well because some methods are too complicated to implement and some measurements are too inefficient. However, the development of modern science and technology has given people the opportunity to re-examine the evaluation of the above-mentioned methods. For example, the invention of optical quantum generators has prompted intensive research into new refractometric methods, which have an error of about 10-4% under experimental conditions. Among the various salt measurement methods listed above, two commonly used methods are chloride titration and electrical measurement. Automatic potentiometric titrator measurement method The automatic potentiometric titrator measurement method is one of the basic methods for measuring salt. Because of its high reliability, this method will be used in the reproduction and inspection of measurement results in the near future. will remain irreplaceable. By titrating seawater with silver nitrate solution and potassium dichromate, the concentration of chloride ions can be determined, and the chloride ion can be accurately calculated in the correction number, and then the salinity can be calculated according to the formula. Issues related to the determination of chlorine degree are described in more detail in the special manual. According to the phenomenon that the physical parameters of the solution change rapidly at the end of the reaction, an automatic potentiometric titrator can be developed. The changed parameters can make the solution's transparency, color, conductivity or acidity. After indicating the critical point at which the titration ends, the instrument automatically records the consumption of the titration solution. The time for one analysis of the commonly used intermittent working titrator is generally not more than 6 minutes. It is also important that the output of such a titrator is directly expressed in salinity units and can be recorded automatically.