The isolation liquid is introduced between the pressed double-end mechanical seal (i. e. Face-to-Face double-end mechanical seal) and is used to completely separate the flow fluid in the pump from the environment.The pressure of this separator is always higher than the process medium pressure in the sealed pump. For the double end surface seal with pressure, the fluid used in the outer seal is collectively referred to as the isolation liquid (gas), and the pressure is higher than the pressure of the main sealing cavity medium inside. The isolation fluid (gas) isolates the sealing cavity medium from the atmosphere to achieve zero leakage. The flushing and cooling of both sealing surfaces are provided by the isolation solution.

　　Buffer solutionis introduced between non-pressure double-ended mechanical seals (i. e. Face-to-back series mechanical seals) and used as a lubricant or buffer.Non-pressure double end seal, the fluid used in the outer secondary protection seal is collectively known as buffer (gas), the pressure is lower than the pressure of the inner main sealing cavity medium, the buffer used for the contact film wet seal is usually connected to the safe discharge zone (e. g. flare), for contact dry running seal and non-contact dry gas seal, the injection pressure is 3-5 psia. The pressure of the buffer is usually always lower than the pressure of the process medium in the sealed pump.

　　The flushing fluid is introduced from the pump outlet or outside between the seal and the pressure relief liner, and is used to separate the flow fluid in the pump from the seal. The pressure of this rinse is always higher than the pump flow fluid pressure that is sealed.

　　The urgent cold liquid is introduced into the sealing end cover to cool the mechanical seal and shaft. Such as steam, clean water and other media.