Reliable sealing of valve rod: the valve rod adopts a bottom mounted structure with reverse seal, and the sealing force of the reverse seal increases with the increase of the medium pressure, so it can ensure the reliable sealing of the valve rod. In addition, when the valve rod rises abnormally, the valve rod will not eject.

The conductivity of industrial water and its aqueous solution is greater than 10-4S/cm, the conductivity of acid, alkali and salt solution is between 10-4 and 10-1S/cm, so there is no problem in use, and the conductivity of low distilled water is 10-5S/cm. Electromagnetic flowmeter cannot measure liquid with very low conductivity, such as petroleum products and organic solvents. Gas, steam and liquid containing many large bubbles cannot be measured. It is found from the data that some pure solutions or aqueous solutions have low conductivity, which is considered to be unusable. However, in actual work, there will be instances that can be used because of impurities, which are beneficial to increase conductivity. For aqueous solution, the conductivity in the data is measured in the laboratory with pure water ratio. The actual aqueous solution may be proportioned with industrial water, and the conductivity will be higher than that found, which is also conducive to flow measurement.