Fluid Handling

Practical pumps and seals

Sheila Kennedy says innovations improve flow control.

By Sheila Kennedy

Assorted innovations in pumps and seals are improving how flow is controlled. Application-specific solutions and new designs and materials are delivering performance, safety, cost, and lifecycle benefits.

Specialty pumps

Transferring dangerous fluids, particularly in small amounts, requires a special type of pump. The B2 Vario electric drum and container pump from Lutz Pumps is designed for this purpose. It uses a sealless pump tube to prevent dry running and fluid leakage, protecting the end user and the environment. Other features include a variable-speed motor with safety cut-out and an integrated on/off switch. The delivery rate is regulated by the operator with a hand movement. Available with a 110 V or air motor in polypropylene or stainless steel, the Lutz B2 Vario is lube-free and easy to dismantle and service, and it has a long service life.

Trash pumps operating in potentially explosive or ignitable conditions require a unique design and construction. The Infinity (SF Series) line of explosion-proof submersible trash pumps from Gorman-Rupp has been awarded FM approval for models through 24 hp for use in Class I, Div. 1, Groups C & D Hazardous Locations. The line’s patent-pending finned motor housing enhances motor cooling, and its Class H insulation and moisture detection in both the seal and motor chambers are standard features. Designed for sewage and industrial wastewater handling, every SF Series pump passes a minimum 3-in. spherical solid.

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“The SF line features a combination of high-efficiency vortex impellers and premium high-efficiency motor components. This combination provides end users with lower operating costs than other submersible vortex pumps,” says Craig Redmond, director of engineering at Gorman-Rupp.

ITT Goulds Pumps recently introduced new innovations in its Vertical Industrial Double Suction line. “A patented casing design in our double suction pumps modifies the thrust loads to stabilize the rotor, reducing vibration, and a patented rubber bellows seal at the bottom of the enclosed oil tube prevents liquid from getting to the bearings,” says John Manna, vice president, global marketing and product development, ITT Goulds Pumps.

Distinctive seals

Sheila Kennedy is a professional freelance writer specializing in industrial and technical topics.Sheila Kennedy is a professional freelance writer specializing in industrial and technical topics. She established Additive Communications in 2003 to serve software, technology, and service providers in industries such as manufacturing and utilities, and became a contributing editor and Technology Toolbox columnist for Plant Services in 2004. Prior to Additive Communications, she had 11 years of experience implementing industrial information systems. Kennedy earned her B.S. at Purdue University and her MBA at the University of Phoenix. She can be reached at sheila@addcomm.com.

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For screw conveyor applications where barrier gas can’t be used, special seals are required. Meco Seals offers HB and HC model seals for CEMA standard and metric screw conveyors. The HB model has a seal cavity charged with low-pressure air or gas, acting as a barrier fluid to prevent pneumatic seal face loading, whereas the HC variation is an HB seal reconfigured to operate without a barrier fluid. It uses a hose clamp to energize the seal faces.

“The Meco HC rotating shaft seal provides a solution in applications where a lip seal, an air seal, or a packing seal don’t. It does not require compressed air, and it works against abrasive materials,” says Paul Wehrle, chief engineer at Meco Seals. The HB seal model or its HC variant are suitable for bulk process industry applications such as screw conveyors or scrolls, small blenders, bucket elevators, and similar rotating equipment.

Bonding the hardest known material to a seal face is an innovative way to improve its mechanical properties and performance. Flowserve signed a collaborative agreement with Advanced Diamond Technologies (ADT), a spinoff company from the U.S. Department of Energy's Argonne National Laboratory, to deliver such a solution. ADT will exclusively develop and supply diamond-coated hard faces for Flowserve’s mechanical seals.

ADT’s ultrananocrystalline-structured diamond coating, when applied to Flowserve base materials, is said to surpass the capabilities of carbon, silicon carbide, and tungsten mechanical seal face materials. Flowserve’s nanocrystalline diamond-coated silicon carbide seal faces produce an exceptionally hard surface with improved friction and resistance to wear, abrasion, and chemicals. Applications requiring protection from slurry, dry running conditions, or chemical corrosion are among the candidates for these seal faces.

"Flowserve needs a high-quality, technologically advanced, and dependable source for diamond-coated hard faces for its seals," says Ken Lavelle, president of seal operations at Flowserve. "We are proud of our long-term collaboration with ADT."

Read Sheila Kennedy's monthly column, Technology Toolbox.