Tech Update: Pumps

October 7, 2007
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Mechanical seals with a nanoscale diamond coating promise longer run times in select food-pumping applications.

The growth of CIP systems puts increased demands on pumps, requiring new materials of construction to withstand pH and temperature extremes in processing and cleaning. Source: Central States Industrial.

Seal failure is synonymous with pump failure, and until operating abuse is eliminated or much tougher components are created, that’s likely to remain the case.

Romeoville, IL-based Advanced Diamond Technologies Inc. (ADT) can’t help with the operator who lets a feed kettle run dry, but the firm is touting a big advancement in mechanical seals: an ultrananocrystalline diamond (UNCD) film that coats the face of a seal. Extreme durability is only part of the benefit. The smooth finish means very low friction and cooler operating temperatures, notes Charles West, ADT’s vice president-engineering. “You can pump products that are more temperature-sensitive without damaging them,” says West, “and the seal’s ability to withstand occasionally abusive conditions is much higher than with conventional mechanical seals.”

Diamond thin-films have progressed by fits and starts over the past 20 years, but their potential to save energy by reducing friction and improving machine performance has kept the funding spigot open from the US Department of Energy and other technology investors. A fundamentally different way of creating diamonds in the 3-5 nanometer range from gas was developed in the mid-1990s at Argonne National Laboratories in suburban Chicago, and a series of related advances culminated in UNCD seals. Field testing in a variety of process industries, including food, are underway in cooperation with John Crane Inc.

Extensive testing at the seal manufacturer’s Morton Grove, IL, headquarters was very encouraging, according to Doug Volden, director-end user marketing. Testing was done on centrifugal pumps with shafts ranging from 1-4 inches in applications involving abrasive materials, high operating pressures and extreme temperatures that lower seal life and reliability. Field tests involving a major corn processor were expected to begin in September. Food-grade seals should be available commercially in 2008.

“Uptime is a big issue in the process industries,” Volden points out, “and extending mean time to failure is very important. If we can see 10-20% improvement in how cool a seal runs because of reduced coefficient of friction, that’s pretty significant.”

UNCD creates a mirror-smooth finish on silicon carbide or a similar substrate. ADT fabricates the film in its Romeoville, IL, facility, using a chemical vapor deposition process to mix acetylene, hydrogen and an inert gas in a vacuum at very precise temperatures, explains West. Less than 8% of the resulting diamonds are more than 10 nm, or one-hundredths of a micron. One inch equals 25,400 microns.

ADT was created four years ago to commercialize UNCD technology. ADT manages 17 patents related to the technology, which also delivers high electric conductivity. The ability to precisely control the diamond’s shape, geometry and placement holds tremendous potential in micro-electrical mechanical systems and medical devices, but mechanical seals will be the first commercial application. And while UNCD will not supplant existing seal technology in most applications, Volden believes there will be enough incremental benefits to carve a niche in select processes, including low-margin food products.

A mirror-smooth diamond finish on mechanical seals for large pumps as well as smaller units promises reduced friction and lower operating temperatures, along with greatly enhanced durability. Source: Diamond Technologies Inc.

Certified sanitary

A less dramatic but potentially more impactful change in pump technology is the development of 3A certification of replacement parts. Though pump OEMs would seem to be the primary beneficiaries of stricter parts standards, the impetus for the program came from dairy processors and other end-users, according to Lou Beaudette, a member of 3-A Sanitary Standards Inc.’s board of directors.

“End-users can save money by going to parts resellers in the aftermarket, but there is concern that there is no standard for those replacement parts,” says Beaudette, who also is president of Admix Inc., Manchester, NH. “Pumps are probably the most widely used piece of equipment in food manufacturing, and seal design is a very important component of sanitary design.”

Last month, the 3-A board announced application procedures for its new Replacement Part Qualification Certificate Program. Replacement parts that conform to the fabrication, design and materials of construction required by 3-A will be allowed to display the 3-A symbol once independent auditors have documented their procedures.

If materials of construction weren’t a concern before, this spring’s pet-food poisonings involving wheat gluten laced with melamine and cyanuric acid was a wake-up call to raw-material vulnerabilities. In the global economy, end-users are at the mercy of quality standards in place where a part or ingredient is fabricated, and in the case of the contaminated wheat gluten, Chinese standards clearly were deficient.

Ingredient traceability is mandated under the Bioterrorism Act of 2002, and the drug industry extends that to materials traceability. A certificate of performance often accompanies seal kits, drive shafts, impellers and other pump components shipped to pharmaceutical clients of Fristam Pumps USA. The documentation carries a surcharge, but those end-users demand a paper trail. “We can trace materials all the way back to the foundry and the heat numbers for all the springs,” says Randy Verges, senior applications engineer at Middleton, WI-based Fristam.

The firm purchased an X-ray fluorescence gun to verify the stainless steel it buys is the correct grade. In some cases, 316 stainless alloys turn out to be lesser grades. The difference might not be great, but it underscores the gap between what manufacturers pay for and what they sometimes get. Verges estimates 50-60% of the seal failures he encounters in Fristam pumps involve inferior knock-offs. “We can tell just by looking at it that the seal isn’t ours,” he says.

Low friction and wear plus unsurpassed durability are delivered in mechanical pump seals coated with ultrananocrystalline diamond film. The layer of 3-5 nanometer diamonds on this substrate cross-section have a combined thickness of about 2 microns, or 1/12,700th of an inch. Source: John Crane Inc.

Similar problems are reported by Frank Hinlopen, business development manager at Alfa Laval, Pleasant Prairie, WI. Even if a Niton analyzer yields positive material identification of an alloy, how a part is fabricated can have an impact. A sintering process is used for Alfa Laval’s silicon carbide seal faces, for example, while some knock-offs use reaction binding that can result in corrosion when pH changes dramatically between product processing and CIP cycles. “A lot of times our customers don’t realize they’re buying knock-offs made with elastomers that are not FDA-approved,” Hinlopen says.

Certified materials of construction justify the premium prices of Wright Pump Co.’s “Ultra Pure” TRA 400 centrifugal and circumferential piston pumps, explains inventor Tom Holdorf, Wright’s vice president-engineering. Pharmaceutical manufacturers are the primary buyers, he says, though major dairies are beginning trials on the 2-year-old units.

An alumnus of Fristam, Holdorf founded Softwave Pumps five years ago. The company was purchased by Idex Corp. and rolled into Wright, a Milwaukee area manufacturer founded in 1996 by ex-Waukesha Cherry Burrell engineers who originally targeted the parts business. They started their own foundry, with certified and documented stainless steel, elastomers and other materials. Peace of mind is part of what Wright sells, and Holdorf applauds 3-A’s parts certification effort. “We thought we could make a high-purity pump with material traceability, but we had to prove it with bacterial testing at University of Wisconsin,” he says. “We work very hard to achieve and maintain 3-A certification,” and extending validation to the aftermarket will help maintain Wright pumps’ sanitary integrity.

Validating materials of identity is a small part of activities at pump OEMs, of course. Both Fristam and Alfa Laval incorporated removable front plates on centrifugal pumps in recent years to make seals more accessible. With plants extending their production runs and coping with maintenance manpower shortages, the pump makers wanted to cut the time needed to remove back plates to access components. Fristam dubbed those units PR series pumps, while Alfa Laval incorporated the change in its Solid-C pumps, introduced in 2003. Cast steel replaced sheet metal in forming the C series’ parts. As with Fristam’s FPR units, the pumps are designed to handle the heavier hydraulic shock loads in today’s processing environments.

Properly designed CIP systems can boost production and reduce labor requirements, but many processors are not realizing those advantages because of pump issues. “Three-quarters of the pumps are being handled manually for cleaning,” maintains Steve Cook, food engineering manager for Central States Industrial, a Springfield, MO, engineering firm. Even seals in CIP pumps are undergoing hand cleaning, resulting in rotor damage and possible recontamination of the line. The solution is in bypass piping and relief valves that leverage the advantages of newer pumps (see related story on page 89).

Development of the even-wall stator was among the technological advances that earned seepex Inc. a technology innovation award from Frost & Sullivan. Source: seepex Inc.

Technology kudos

ADT is garnering technology innovation awards for its UNCD seals from a variety of organizations, including the research consultancy Frost & Sullivan. Another pump-related recipient of a Frost & Sullivan innovation award is Enon, OH-based seepex Inc., which was cited for advances in its progressive cavity PD pumps.

Research analyst Dushyant Mehra cites the development of new applications in food & beverage, meat processing and wastewater treatment and the introduction of energy-efficient, highly reliable and low-maintenance units by seepex. He credits product innovation with driving 15% annual growth at the firm, compared to 3.5% in the overall industrial pump business. Longevity and efficiency are enhanced with the inclusion of variable speed controls, Mehra notes.

“That’s old news,” scoffs seepex president Mike Dillon. “Almost every pump we sell has a VFD.” More significant is a new universal joint that can handle extremely high processing temperature and pressures in excess of 700 psi through a heat exchanger. One such pump is 20-ft. long and is driven by 70 hp, “and is providing even pressure, no shear and zero slip” after 14,000 hours of continuous operation, Dillon says. Another refinement he touts is an even-wall design developed to tolerate “very aggressive chemicals in flavors” and new CIP solvents at 200º F-plus temperatures without destroying the elastomers.

 Progressive cavity pumps were invented in France, and French dairy processor Danone was almost alone in using them in the US when the firm set up shop here a quarter of a century ago. Now other dairy processors are beginning to use them, and the pumps’ ability to deliver both high performance and gentle handling of particulate has led to other food applications. The units’ ability to handle very viscous, fibrous materials also helps end-users convert byproducts into value-added materials. Simplot integrates progressive cavity pumps in a process that converts potato peels to ethanol, and the technology is helping convert corncobs and stalks into ethanol, as well, according to Dillon.

He credits the 20 applications engineers in the company’s US office with driving most of seepex’s innovation. “It is a huge investment,” he allows, “but you have to stay heavily involved with customers if you want to be responsive and innovative.” Helping food companies move from batch to continuous processes is a key focus of current technology development, Dillon adds.

The seepex example is more reflective of pump advances than UNCD film. Breakthrough technology can occur, but the real work is in incremental improvements and superior process controls. A pump may still be a pump, but its performance in a manufacturing plant is steadily improving and expanding.  u

For more information:

Lou Beaudette, Admix Inc./3-A Sanitary Standards Inc., 603-627-2340,

lou@admix.com

Charles West, Advanced Diamond Technologies Inc., 815-293-0900, cfwest@thindiamond.com

Frank Hinlopen, Alfa Laval, 262-605-2621, frank.hinlopen@alfalaval.com

Doug Volden, John Crane Inc., 847-967-2412, djvolden@johncrane.com

Steve Cook, Central States Industrial, 417-831-1411, stevec@csidesigns.com

Randy Verges, Fristam, 608-831-5001, rverges@fristampumps.com

Mike Dillon, seepex Inc., 937-864-7150, ext. 121, mdillon@seepex.net

Tom Holdorf, Wright Pump Co., 262-679-4814

CIP pump technology and pipe solutions

The advent of universal pumps for CIP systems often don’t deliver the promised efficiencies because many processors, particularly of viscous foods, continue to open pump faces to remove rotors and manually clean the seal area. But a properly engineered piping system with a pressure relief valve can eliminate that redundancy and provide a safe, sanitary processing environment, maintains Steve Cook, food engineering manager with Central States Industrial.

A manually installed jumper across the pump is a down-and-dirty solution in some processing industries, “but I’ve only seen that once or twice in food,” says Cook. “It’s just not sanitary.” A permanent jumper pipe with a manual bypass valve meets threshold needs, “but it’s not a very good solution,” he adds.

The most common solution is bypass piping with an air-operated tee-body valve. The problem is that product fills up in the dead leg behind the valve. An operator can open the valve periodically to minimize product stagnation, but that’s counterproductive in an automated system.

The best solution would be an air-operated cross body valve seated on top of the piping immediately downstream of the pump. Product never stagnates in a dead leg, and cleaning and sanitizing fluids can be pulsed through the pump during CIP cycles.

“The piping is a little squirrelly, and the downstream pipe has to slope down to come around and under the pipe feeding into the pump, but if you can afford the room, it’s the best solution,” Cook argues. However, few food clients have accepted this design, opting instead for a U-pipe with an air-operated valve.

The preferred solution requires a CIPable pump, he adds, and valve position would change only periodically to clean the pump; most of the time, solvents flowing at 101 gpm through a 3-inch pipe hit a bottleneck in a pump that moves perhaps 60 gpm. But dismantling pumps for cleaning would be a thing of the past, optimizing the benefits of CIP.

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