Mechanical Seals for Pumps

“Most people know KSB Pumps and Valves as a pump manufacturer and are surprised to learn that we also design, manufacture and support our own range of mechanical seals for nearly every pump type and that we are continually introducing solutions for competitor products too,” says KSB SupremeServ sales engineer for mechanical seals, Phumelela Ngcobo,

The company is already producing a large portion of the seals used in its new pumps and has recently begun marketing and raising awareness of its sealing solutions. “The roles of mechanical seals are important for the reliable operation of many types of pumps as their primary purpose is to prevent the pumped material from leaking along the rotating shaft in order to ensure that the fluid remains safely contained within the pump and doesn’t leak into the surrounding environment.”

Detailed understanding

Phumelela explains that it was during the development of one of KSB’s pump ranges that company engineers encountered recurring seal failures that could not simply be resolved by changing operating practices.

“Because we know and understand pump designs we have a detailed understanding of hydraulic performance, shaft behaviour, bearing arrangements and the operating conditions inside the seal chamber. This allowed our engineers to identify the root causes of the failures and develop sealing solutions specifically designed to overcome those challenges.

Vast majority

“Today our range includes sealing solutions for the vast majority of KSB pumps together with universal mechanical seals suitable for many competitor brands. Where a standard solution is unavailable, our engineering team will even develop custom sealing systems based on pump dimensions and detailed process information supplied by the customer,” Phumelela adds.

The range includes component and cartridge mechanical seals available in both single and dual arrangements. It also comprises pump-specific sealing solutions, seals manufactured in accordance with DIN EN 12756, API 682-compliant sealing systems for applicable process pumps, slurry application seals, boiler feed pump seals, high-pressure mechanical seals, and ATEX-certified sealing solutions for use in hazardous environments.

Integrated package

A considerable advantage of manufacturing mechanical seals is the ability to offer customers complete sealing solutions from a single source. In addition to mechanical seals, the portfolio includes API 682-compliant seal support systems, piping plans, seal pots, heat exchangers, flow meters, and associated instrumentation.

Supplying these components as an integrated package ensures compatibility between the sealing equipment and support system simplifying procurement, installation, commissioning and ongoing maintenance while enhancing overall system reliability.

Reliable performance

It is important to note that every application is unique and the materials selected for a mechanical seal are chosen to maximise reliability under the specific operating conditions. For general industrial duties, Reaction Bonded Silicon Carbide (RBSiC) is often the preferred choice offering excellent wear resistance and reliable performance across a wide range of applications.

For more demanding services involving aggressive chemicals, elevated temperatures or higher operating pressures Sintered Silicon Carbide (SSiC) is typically specified due to its corrosion resistance, higher mechanical strength and excellent performance under severe operating conditions.

Demanding conditions

“Carbon is widely used as a seal face material due to its excellent self-lubricating properties and low coefficient of friction making it ideal for clean fluid applications across a range of industries including food and beverage processing.

“For more demanding operating conditions involving higher temperatures and pressures, antimony-impregnated carbon is often specified because of its improved mechanical strength, wear resistance and enhanced thermal conductivity,” Phumelela explains.