The single end face mechanical seal has only a pair of friction pairs, simple structure, easy to manufacture, disassemble and assemble, generally only need to set up flushing system, do not need external liquid sealing system.

• Pressurized double mechanical seal (formerly known as double end face mechanical seal) refers to two pairs of friction pairs, complex structure, need external sealing liquid system, pressurized double mechanical seal seal cavity with 0.5~1.5bar higher than medium pressure The isolation fluid plays the role of blocking and lubricating, and the isolation fluid plays a lubricating effect on the inner seal.

Application scenarios of pressurized double mechanical seals:

• The pressure of the pressured double mechanical seal isolation fluid is higher than the medium pressure, so the pumped medium will not enter the sealed cavity. The inner seal of the double-pressure mechanical seal prevents the isolation fluid from entering the pump cavity. Therefore, when transporting viscous, abrasive, and high-temperature media, the inner seal of the pressurized double mechanical seal is not exposed to the media, so it can be made without expensive alloys. The outer seal of the pressurized double mechanical seal only serves to prevent the isolation fluid from leaking into the atmosphere.

• Non-pressure double seal (formerly known as tandem seal) means that there are two pairs of friction pairs, the structure is complex, and an external liquid sealing system is required. The buffer in the non-pressure double seal seal cavity is not pressurized, and the process medium lubricates the inner seal. effect.

Application scenarios of non-pressure double mechanical seals:

• Pressureless double mechanical seals can be widely used in toxic, volatile and dangerous media such as vinyl chloride, carbon monoxide, and light hydrocarbons. The inner seal (the first seal) of the non-pressure double mechanical seal is the main seal, which is equivalent to a single-end internally mounted mechanical seal, and the single-end mechanical seal lubricant acts as the sealing medium. The sealed cavity is filled with liquid from the sealed liquid tank and is not pressurized. Once the inner seal of the non-pressure double mechanical seal fails, which causes the pressure in the sealed chamber to increase, it can be displayed, recorded or alarmed by the pressure gauge of the sealing liquid tank. At the same time, the outer seal of the non-pressure double mechanical seal can seal and contain the leaking liquid before maintenance.