Diamond-coated seals extend pump life

Although problem-free pump operation is the primary goal of all pump operators, achieving that goal is not a simple matter. The key components of a pump - mechanical seals, impellers, couplings, roller bearings and housings – are all subject to wear. Keeping a pump in good working condition is essential for cost-effective and reliable operation of plants and systems. Unplanned downtime can ruin production schedules and adversely affect a facility’s bottom line.

“Any system can only be as functional as the lifespan of its weakest component” – this statement applies to many types of products – but is especially true of mechanical seals. While mechanical seals are one of the key components of a pump, they also have one of the shortest average service lives. Mechanical seals are recognized to be responsible for most pump failures and consequently  represent the highest cost for pump repairs. Therefore, reducing the mean time between failure (MTBF) or the mean time between repair (MTBR) can significantly improve pump operations and save money.

When working properly, mechanical seals are generally safe and reliable components that operate virtually wear-free. Problems occur when the sliding faces of a mechanical seal are not adequately lubricated, resulting in a dry-running condition that ultimately causes the destruction and breakdown of the seal. Industry surveys  have shown that dry running or inadequate lubrication are responsible for more than 50% of all mechanical seal damages; consequently, it is safe to state that approximately 20% of all pump failures are due to poor lubrication or dry running of the mechanical seal faces.

To combat the problem of dry-running, EagleBurgmann has developed an innovative seal face coating based in diamond.  Diamond is the hardest natural mineral known and offers excellent chemical and thermal resistance. EagleBurgmann’s new technology is a synthetically manufactured, ultrapure diamond with the same outstanding characteristics as the natural stone. It has a microcrystalline coating of 8-µm thickness on a silicon carbide seal face extends the life of the seal, reducing maintenance costs and minimizing lifecycle costs for pump users.

While SiC/SiC material pairings have become popular for seal faces during the last 10 to15 years, they perform worry-free only if adequate lubrication is maintained in the sealing gap. Any form of insufficient lubrication results in rapid and massive temperature increases which damages the sliding faces and secondary seals (O-rings). In extreme cases, the time to total failure of the sliding faces can be just a few seconds. Combining SiC seal faces with EagleBurgmann’s diamond-based coating allows dry-running periods up to several hours without any excessive heat build-up.  

In an analysis of the service life of pump components, it was found that mechanical seals, with an average service life of only 1.2-years, are the weakest link in terms of pump components, compared to the next weakest component, bearings, with an average service life of 3-years. To minimize pump repairs and downtime, it would be advantageous to pump operators if the average service life of the mechanical seals increased to match the service life of the bearings.

By using mechanical seals coated with diamond, the average service life of mechanical seals substantially increases. This allows pump operators to schedule preventive inspections of mechanical seals and eliminate or reduce the costs of unplanned process interruptions. By increasing the service life of mechanical seals, approximately every second pump repair, along with associated downtime and production disruption, can be avoided.

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