Mechanical face seal
is a kind of main shaft sealing form, which makes use of spring or other elastic material to form a thin layer of liquid film between the end face of the main shaft seal. The mechanical end seal of the water turbine is usually composed of the original and elastic components of the moving ring, static ring and rubber material.
According to the installation position of the static ring, the mechanical seal
can be divided into the inner and outer parts, and the inner mounted static ring is mounted on the inside side. The outer mounted static ring is mounted on the outer side of the sealing end cover, and the end faces is back to the main working chamber. The built-in mechanical face seal has better mechanical state, less leakage and good lubricity. But the spring is easily corroded in the medium. The external mechanical face seal is less corrosive to the sealing elements and is easy to observe, install and maintain. However, when the medium pressure is low, the sealing is unstable and the leakage is large.
According to the quantity of seal face, mechanical face seal can also be divided into single mechanical end face seal and multi mechanical end face seal. The single mechanical end face seal is made up of a pair of sealing ends. It is easy to assemble and disassemble and has simple structure. The multi-end mechanical seal consists of two pairs or more sealing ends, which usually require sealing, lubrication, flushing and cooling. The sealing liquid pressure should be 0.05-0.15mpa higher than the medium pressure. Because of the axial displacement of the water turbine in the work, it is impossible to guarantee the normal work of the elastic element, so the mechanical end sealing is seldom used in the structure design of the water turbine.