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Diamond-coated mechanical seals promise pump energy savings

November 01, 2013
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Even as controversies still clog media airwaves with strident opinions about how “real” various impending resource crises actually are, our engineers are finding the increasingly needed solutions. Further, it’s common knowledge that industrial pumps and motors as a category are amongst the really great global energy expenders.

Because diamonds are extremely hard and strong, with low-friction properties, their use as a mechanical-seal coating for pumps moving caustics, solvents or acids is seen as a way to increase productivity and save energy.  

To further use of diamond-coated hard faces for its mechanical seals, Flowserve Corp., provider of flow-control solutions for global infrastructure, signed an agreement with Advanced Diamond Technologies, Inc. (ADT) announced at the 42nd annual Turbomachinery and 29th annual pump symposia in October.

Flowserve becomes exclusive supplier of diamond-coated hard faces based on ADT’s ultrananocrystalline-structured diamond (UNCD) coating. Applied to base materials, the coating is an exceptionally hard surface with improved wear characteristics, the companies say. This is beneficial in pumping services needing protection from slurry; subject to dry running conditions; or requiring resistance to chemical corrosion.

It’s also suitable for many common pumping applications, says Jack Vasko, a Flowserve product manager. “Pumps so often aren’t operated as originally intended. When that’s the case, it’s the seal face where the greatest danger lies. Running dry can kill a mechanical seal in seconds.”

The traditional way to combat seal stress, or that caused by hot water, for example, is to water-cool or use dual mechanical seals. Instead, Vasko says, “Using single seals in lieu of dual seals means less horsepower is needed. Requirements for cooling water and barrier fluid are gone.”

While “diamond-like” coatings have been around for many years, John Yerger, ADT’s CEO and president says, “UNCD is unique, with small grain size and tremendous smoothness.”

The diamond coating “is the next step in the evolution for us,” Vasko says. “It consumes less power. It is a thin coating that has good adhesion to the seal face and runs against a variety of materials. It is unique in its range of applications and seal types with which it can be used.”

Flowserve and ADT, a spinoff from the Argonne National Laboratory, have worked together since the 1980s. By turning natural gas into diamond in a highly reproducible process, ADT supplies films for electronic, mechanical, industrial and biomedical uses.

Vasko concludes, “To operate in dirty and low-lubricity fluids without using cooling water or dual mechanical seals, change to UNCD-coated faces running directly on product fluid without external support. You’ll save energy.”

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