Mechanical shaft seal types

 Mechanical shaft seal types

1). Unbalanced O-ring seal with rigid torque transmission system:

• Robust O-ring seal featuring a rigid torque transmission design required for hard material pairings (WC/WC or SiC/SiC), even where lubrication is poor. The dynamic secondary seal is an O-ring. This involves a risk of wear on the shaft under the O-ring and of seal hang-up (blocking of axial movement of the rotating seal ring)

2). Rubber bellows seal:

• Bellows seal with torque transmission across the spring and around the bellows. Therefore it is not designed for hard material pairings in applications with poor lubrication.Due to the bellows, the seal does not wear the shaft, and the axial movement is not prevented by deposits or seizure on the shaft.

3). Unbalanced O-ring seal with spring as  torque transmission element

• Low-pressure, simple O-ring seal with the spring acting as torque transmission element. Therefore the seal is dependent on the direction of shaft rotation. The shown seal is for a counter-clockwise shaft rotation.The seal type is excellent for low-temperature, clean-water applications with a ceramic/carbon seal face pairing.

4). Balanced O-ring seal with spring on the atmospheric side

• Due to the balancing, this O-ring seal type is suitable for high-pressure applications. The seal is excellent for high-viscosity, dirt- and fibre-containing liquids because the spring is located on the atmospheric side. The seal features rigid torque transmission design.

5). Rubber bellows seal with reduced seal face

• Rubber bellows seal like type B but with a narrow seal face. Due to the narrow seal face, the seal performs well in high-viscosity and anti-freeze liquids.

6). Balanced, cartridge O-ring seal unit with rigid torque transmission system

• This seal type is assembled in a cartridge unit which makes replacement safe and easy. Similar to the type D seal, the balancing makes this O-ring seal type suitable for high-pressure applications.

7). Balanced, rolled-metal bellows cartridge seal unit

• The metal bellows acts both as spring and torque transmission element. This seal type has only static rubber parts, with reduced risk of hang-up similar to type B.

8). Unbalanced O-ring seal, type A, with reduced seal face

• O-ring seal like type A but with a narrow seal face. Due to the narrow seal face of the unbalanced design, the balancing ratio exceeds that of seal type A. This reduces the pressure and temperature operating limits of the seal. Similar to type G, the seal performs well in high-viscosity and anti-freeze liquids.

9). Two seals mounted in a “back-to-back” arrangement

• This seal arrangement incorporates a clean barrier fluid with a higher pressure than the pumped medium.This totally prevents leakage from the pumped medium to the environment and the clean barrier fluid secures a good lubrication of the seal faces of both seals

10). Two seals mounted in a “tandem” arrangement

• This seal arrangement incorporates a clean flushing fluid with a lower pressure than the pumped medium. This cools the seal rings of the seal in the pumped medium and prevents precipitation from leakage.