How to choose between single-end face and double-end face mechanical seals? What are the differences in the core of the shaft seal of a centrifugal pump?

The mechanical seals of ATACH industrial pumps are mainly divided into single-end face mechanical seals, double-end face mechanical seals and cartridge mechanical seals. 

Now we mainly explain how to choose between single-end face and double-end face mechanical seals?

The differences between single-end face seals and double-end face seals of mechanical seals are as follows:

A) Structural aspect

1- Single-end face seal: Composed of a pair of sealing end faces, it has a simple structure and is easy to manufacture and install. 

2- Double-end face seal: Composed of two pairs of sealing end faces, it has a complex structure. 

Double-end face seals include axial double-end face seals and radial double-end face seals. 

Axial double-end face seals have structures arranged face-to-face or back-to-back.

B) in terms of working principle

1- Single-end face seal: Relying on the end faces perpendicular to the rotation axis, under the action of fluid pressure and the elastic force of the compensation structure, the auxiliary seal is used to ensure a constant contact state, generating a relative sliding effect to prevent fluid leakage. 2- Double-end face seal: Its working principle is largely the same as that of single-end face seal. However, the fluid pressure and the elastic element jointly generate a resultant force, creating another significant pressure ratio on the end face of the double-end face seal device. This promotes the contact end faces to adhere to each other and forms a narrow liquid film between the two end faces, thereby achieving a sealing effect.

C)In terms of sealing performance

1- Single-end face seal: Slight leakage is allowed, generally 5 mL/h, but the sealing performance is relatively poor. 

2- Double-end face seal: It has relatively good anti-leakage performance. Generally, sealing fluid needs to be injected into the sealing cavity from an external sealing fluid system to achieve sealing, and at the same time, it can achieve lubrication and cooling effects. Introducing sealing fluid with a pressure 0.05 to 0.15MPa higher than the medium pressure between the two pairs of end faces can achieve "zero leakage" of the medium.

D)In terms of applicable scenarios

1- Single-end face seal: Suitable for general liquid applications, such as oil products, etc. Single-end face seals can be used when the medium itself has good lubricity and allows for slight leakage. 

2- Double-end face seal: It is suitable for corrosive, high-temperature, liquefied gas containing solid particles and fibers, media with poor lubrication performance, as well as toxic, flammable, explosive, volatile, crystallizable and valuable media. 

It is also applicable to highly corrosive, high-temperature, valuable or toxic media.

E)In terms of system requirements

1- Single-end face seal: Generally, only a flushing system needs to be set up, and an external sealing liquid supply system is not required. 

2- Double-end face seal: An external sealing liquid supply system is required.