Mechanical seals from KSB for a large range of applications

Benefits of KSB mechanical seals

• Extended service life of the pump/system means reduced costs for maintenance and spare parts.
• One contact person for the entire system: service, pump, mechanical seal
• Numerous KSB mechanical seals can be used in KSB pumps as well as in pumps from other manufacturers.
• High-quality engineering at reasonable prices
• Special materials available
• Professional installation and repair service
• Wear parts and repair kits for all mechanical seals from KSB
• Maximum system availability and reliability

Mechanical seals in a nutshell

Top-quality seals increase operating reliability.

The seal faces of the sealing rings are pressed to each other by hydraulic and mechanical forces. One of them is connected with the rotating pump shaft, the other with the pump casing. The flexibility of the spring-loaded seal also compensates for axial or radial movement of the drive shaft to some extent.

A lubricating film in the sealing clearance of the mechanical seal – between the two seal faces – influences the mechanical seal function considerably. The distance between the two faces, also referred to as the clearance gap width, depends on several factors. For example, the surface quality of the seal faces, the pressure to be sealed off and the sliding velocity. By reducing friction between the seal faces as much as possible, the liquid film between the seal faces prevents wear.

Leakage: Small droplets or vapour escaping

As a matter of design, a very small amount of the fluid handled always escapes at a mechanical seal: Experts call it leakage. In the case of well-functioning mechanical seals, this leakage of the fluid handled is usually invisible to the naked eye or evaporates shortly before leaving the sealing gap, escaping to atmosphere. If a pump visibly loses some of the fluid handled, this is often a sign of advanced wear or of the seal already being defective.

Mechanical seals wear out faster in pumps that handle fluids containing solids, such as waste water. The reason: abrasive, grinding substances attack the material. There is a danger of particles entering the sealing clearance and causing premature wear of the seal faces. Over time, the solid particles deposit and block the springs as well as the moveability of the seal unit. This shortens the service life: The mechanical seal will start leaking earlier with large amounts of the fluid handled escaping from inside the pump.

To prevent damage caused by wear, pump operators often supply the mechanical seal area with a clean flushing fluid or barrier fluid. The barrier fluid stops abrasive solid particles from reaching the seal faces. It is also called the supply fluid. Depending on the application, the fluid fulfils different tasks. It may serve to cool, heat or lubricate the mechanical seal, for example, or to prevent deposits.

A mechanical seal? Or better a different seal type?

Pumps come in different designs. Selecting the right seal type depends on the sliding velocity, the pressure inside the pump and the temperature of the fluid to be transported. Mechanical seals cover a large range of applications and fluids handled. However, some pumps are still fitted with different seal types even today, e.g. with a gland packing. If suitable for the place of installation and if the required service staff know-how can be provided, this seal type is still an option even though it is no longer state of the art.

Mechanical seals have proven to be well-suited for low pressure and high pressure as well as for different circumferential speeds. The sealing clearance of the mechanical seal is at a right angle to the shaft axis. Major advantages the mechanical seal has got over other seals are its compact design, low friction loss, ease of service and low leakage. Unlike other sealing systems, mechanical seals are also suitable for variable speed pumps – a benefit that is not to be underestimated considering environmental protection, costs and energy efficiency.

Matching the pump and seal to each other

The ideal seal is often closely linked with the application of the corresponding pump. A perfect design and the use of optimum materials for seal, casing and shaft are just as important as many years of experience in the field of pumps. KSB mechanical seals are characterised by their design being optimised for the corresponding KSB pump.

KSB offers its customers a sealing concept tailored to the geometric and hydraulic properties of the pump. A KSB mechanical seal unites the following core characteristics:

• Easy to install
• Service-friendly
• Robust design and low wear

Most pump failures are caused by a defective mechanical seal. This is why an optimum mechanical seal should be chosen early on, together with the pump. As a full-range supplier, KSB provides the know-how and service required for the entire pump system.

With mechanical seals for standard applications and API applications, KSB offers its customers highly advanced seals and supply systems optimised for use in KSB pumps. In addition to technical advantages, a mechanical seal from KSB also has economic advantages, for example:

• Robust and precise design
• Minimal wear due to the use of resistant high-quality materials
• Long service life of the mechanical seal even under adverse conditions
• Minimum friction losses due to optimisation of the hydraulic forces acting on the seal faces
• Straightforward installation and removal