Increase efficiency. Improve product handling characteristics. Meter ingredients or cleaning chemicals more accurately. Cut maintenance time and downtime. Decrease energy usage. All of these actions can decrease costs and improve your bottom line. And, you’d probably like to do all of them with the selection of the right pump.
Tech Update - Pumps
Look before you leap into pump selection
While there may be more than one pump solution for a specific application, it pays to do some homework first to find the most efficient solution.
April 9, 2013
While no one pump can be the panacea to every problem, chances are it might be worth taking another look at an existing application if the current pump’s lifecycle is about over, or it’s costing too much to maintain the pump. Maybe another type of pump would serve the application better. If it’s a brand-new application, there may be several options and factors to consider.
Finding the right pump for your application doesn’t have to be a difficult chore. Plenty of help is available from several sources—from pump suppliers to distributors and system integrators (SIs) and online consulting services and software.1 In addition, many pump suppliers have online/software selection tools. One look at a typical pump-specialty SI’s website2 may reveal it carries a dozen, two dozen or more pump brands, so the SI is well armed to solve most pump problems that arise.
Viscosity plays an important role in the selection of a pump, as do the total solids and type of solids present in the liquid, says Jim LeClair, SPX Flow Technology global product manager-pumps. The lower the viscosity of a product, the better adapted a centrifugal pump is for the application. However, as solids are added, or if the product is shear sensitive, other pumping technologies are more suited to the application, such as a rotary positive displacement (PD) pump, adds LeClair.
While centrifugal pumps are typically used for water and other low-viscosity products (e.g., sodas, beer, thin juices) where shear is not an issue, PD pumps are used to move more viscous products that could be damaged from the shear created in centrifugal pumps. These products include yogurt, meats, soups and any other food or beverage product where maintaining the original state of the product is important. In this case, a PD pump may be the only option.
“The pump can’t change the product,” says Mike Dillon seepex, Inc. president. “The size of particulates, texture, homogeneity, color and all those visceral attributes designed by the food scientists, the lab or the marketing people are critical.” seepex progressive cavity pumps are used in dairy, fruit and vegetable processing, brewing and distilleries and poultry and meat processing, and provide nearly pulsation-free output with low shear.
Another PD pump with low shear is the diaphragm pump. For example, the Marlen twin-piston PD pump provides a solution to moving food or beverages with particulates where product integrity needs to be maintained. “With the PD design, there are no areas where product can bypass the internal components, causing damage to the product,” says Doug Vogelsmeier, Marlen product line manager.
Sizing a pump is important, and planning ahead can save time and money in the future. “The pump [should] be sized on the required flow rates, total discharge pressures, product viscosity and temperature,” says Bob Wells, Fristam Pumps USA OEM manager. “Process design changes, like increasing or reducing the size of discharge piping, could have an effect on the proper pump selection, as it would either increase or decrease the total discharge pressure, based on the designed flow rates.”
“There are many examples of pumps that are used to pump multiple products with varying consistencies,” says LeClair. The most important detail that is often overlooked is providing that information to the supplier at the beginning of the project so all styles of pumps can be considered during the selection process. Knowing a pump is going to see multiple duties allows the applications engineering staff to consider how to fit the pump to stay as close to the best-efficiency point (BEP) as possible for a centrifugal pump—or to properly apply the various options within a PD pump, adds LeClair.
“Anyone responsible for specifying the best pump for any application must go beyond tradition,” asserts David Kirk, hygienic market manager at Pump Solutions Group. “There was a time when air-operated, double-diaphragm [AODD] pumps, for example, were thought of as simply ‘tote emptiers.’” Today, many major processors use EHEDG (European Hygienic Engineering & Design Group)-approved AODD pumps, such as Wilden’s HS (Hygienic Series) in their processes, according to Kirk. “Take orange juice processing as an example. Companies have moved away from traditionally used pump technologies [e.g., centrifugal] to AODD because of AODD’s low-shear capability, which protects their products from having damaged pulp.”
Soup manufacturers are increasingly adopting AODD pumps as well—but not just because of their low shear and ability to handle large solids, says Kirk. AODD pumps can deadhead (continue running safely when pumping directly into a closed valve or plugged line) and run dry, eliminating downtime and alleviating pump-monitoring stress for food operators, according to Kirk.
The design of rotary PD pumps can help save energy and work in products with multiple viscosities on the same line. “The ECP [external circumferential piston] pump is a great example of a technology that provides multi-duty capability within a process line,” says LeClair. The Universal Pump with the ECP construction allows for duties that can range from very thin liquids to products that are viscous or have large particulates, adds LeClair.
Today’s PD pumps are being called upon to handle several types of food and beverage products on the same line. For instance, Kerry Ingredients (Altona, Victoria, Australia) needed to move materials that ranged from water (CIP) to high-viscosity products up to 50,000 cP. Kerry’s Project Engineer Geoff Walker chose a Grundfos NOVAlobe pump to handle various products. “It pumps a variety of liquids from mayonnaise through to chocolate and strawberry sauces and, of course, hot cleaning water. It transfers our products to portable tanks and fillers—or whatever else is required to move the product around the factory.
“The pump sits on a frame beneath a homogenizer, which in turn, is directly below an 1,800-liter SS tank, operates up to half a dozen times per shift and has been working faultlessly since its installation,” adds Walker. “The pump operates at temperatures ranging from 59°F to 194°F, and has tremendous flexibility because of its CIP attributes.” While this was not a new installation, the new lobe pump replaced an existing pump and is doing a great job, according to Walker.
Another PD pump with low shear is the eccentric disc pump, such as the one supplied by Mouvex. “Eccentric disc pump technology offers strong suction and allows dry running, effectively clearing a line after each batch,” says Kirk. “This ultimately leads to tremendous product recovery savings, which can be significant, given the cost of certain edible oils and flavorings.”
With another twist on PD design, the MasoSine pump has a single shaft and sinusoidal rotor. With the shaft and rotor, there is no need for the complex timing gears and multiple seals often associated with conventional rotary lobe pumps. A large poultry processor recently switched to this pump for transferring its marinated boneless breast meat. Vacuum and air pumps were previously used to transfer the product into a drop hopper, which attempted to meter the product onto the conveyor. Neither the vacuum nor air pump was efficient since both provided only slugs to the line. Rates were inconsistent, and product had to be spread manually onto the conveyor.
The processor installed two MasoSine MR 160, six-in. PD pumps that move marinated chicken and turkey breast without damaging the product beyond use. The pumps were set up to meter boneless products through spreader horns supplied by the processor. Two pumps and two horns were arranged to feed two 16-in. wide, half-inch thick sheets of boneless breast meat onto the conveyor. The final outcome was an almost labor-free roasting line with continuous meat being delivered to the oven. The line no longer needs a full-time person, and there are nearly zero marinade losses.
A PD pump that maintains separation between the pump mechanism and the product is the peristaltic pump, which makes use of a quickly replaceable tube or hose (depending on flow volume) that handles the product to be pumped. Watson-Marlow recently released the Model 520, which can be used to meter dyes, flavors or vitamins into a product. The LoadSure elements are easily changed in one minute for product changes; the pump does not need to be flushed out when the element (tube) is changed.
Peristaltic pumps can also move large quantities of product. A winery installed a VerderFlex Model VF 25 peristaltic hose pump to transfer a yeast mixture to a filter press, according to Shawna Andrews, Verder Northeast regional sales manager. Plus, the hose pump provides benefits similar to those of a tubing pump but also offers greater flow and discharge pressures. This pump was installed to transfer a slurry mixture of fermented wine and diatomaceous earth at 176 gallons per hour via a 32mm suction line to the filter press. This process yields the wine ready for bottling.
To achieve the proper flow of the fermented wine mixture to the press, a dome—also known as a pulsation dampener—was incorporated into the flow path on the discharge side. The pulsation dampener also serves to reduce pulsations that are caused by the backflow of liquid on the discharge side. To control flow, the dome is pressurized at 145psi. When the flow drops through the filter, the pressure also drops in the dampener, triggering a pressure switch on the top of the dome and turning off the pump. The pump comes back on when the pressure lowers to 101psi. This process occurs over and over until the filter is completely filled with the fermented wine mixture.
Because a food processing environment has to be clean, a lot is asked of pumps. “Principles of sanitation design practices need to be followed along with materials of high-enough stainless [quality] to resist corrosion and rust, preventing bacteria harbor points or contamination,” says Vogelsmeier. In addition, surface finish has to be fine enough to aid in complete and thorough cleaning. The number of parts removed for sanitation and the ease of disassembly/reassembly are also vital factors to consider when making a pump selection, he adds.
“It’s important to consider a well-designed and built pump,” says Sandra Molinaro, Alfa Laval technical sales support specialist, pump applications. “Close tolerances and optimized internal design are the keys to maximizing performance, and that requires a robust construction. The pump should be CIP-able as standard, thus reducing the need for manual cleaning.”
The pump’s materials must always be compatible with both product and CIP cleaning solutions. “For most food processes, 316L SS will suffice, but keep in mind that every CIP system can differ in duration, temperature and strength of caustic,” says Kirk. Therefore, it’s a good idea to discuss cleaning options with specialists from cleaning companies.
Fristam pumps are made of 316L SS. A variety of seal materials is available depending on the characteristics of the product. “For more abrasive products, we would typically use silicon carbide seal faces,” says Wells. “All Fristam pumps are designed to be cleaned in place, including our PD pumps. Therefore, no disassembly is required.”
“Any pump is at its most vulnerable when it is disassembled,” says Kirk. “Components can get dropped and seals compromised with dirt. Some pumps—and even seals—have so many parts that just keeping track of them can be a challenge. Eliminating or decreasing disassembly means eliminating downtime.” Both Wilden’s HS AODD pumps and Mouvex eccentric disc pumps have no seals that can be prone to leaking or contamination, adds Kirk.
“Any pump in the system should be EHEDG accredited [see www.ehedg.org], which verifies the pump is cleanable,” says Kirk. “In addition to EHEDG, look for easy-to-clean components such as an integral piston diaphragm technology offered by Wilden HS pumps.”
When it comes to acceptable materials that may come in contact with food, EHEDG has been working with 3-A in the US to develop similar, compatible standards, according to Dillon. Therefore, 3-A is becoming more restrictive in its standards. Dillon points out that elastomers must meet REACH standards. REACH is a regulation of the European Union, adopted to improve the protection of human health and the environment from the risks that can be posed by chemicals, while enhancing the competitiveness of the EU chemicals industry.
While most processors would like to see energy savings when they make process changes, finding the best pump for an application typically means finding an efficient pump that will increase productivity. “The efficiency of the pump is the basis of all energy considerations in the process line,” says LeClair. “The pump must meet the basic requirements of the process at the best-efficiency point [BEP] to provide the best return on energy savings.”
“If there is a fixed duty point, review multiple pumps to check which size is most efficient,” adds Molinaro. “Look for a broad product offering plus the availability of a computer-aided selection tool to help you get closer to optimum pump performance.” Centrifugal pumps are used extensively and perform best in the transfer of low-viscosity water-like liquids. On thicker liquids (greater than 500 cP), the centrifugal pump becomes less efficient, as a disproportionate amount of energy is required to move the same volume of liquid. PD pumps perform best at the higher viscosities and are capable of handling high discharge heads without significant loss of performance, according to Molinaro.
“Volumetric efficiency is critical, but perhaps more important is selecting a pump that is best for that specific application,” says Kirk. “Don’t select a pump for an application simply because it worked elsewhere. That can be a recipe for disaster.”
Using throttling valves to control flow by artificially increasing head pressure is a costly solution. Operating a pump away from its BEP creates inefficiencies and leads to higher power consumption, says Molinaro. Conversely, reducing speeds using variable-frequency drives (VFDs) can significantly reduce wasted energy. As speed is reduced, the power consumption drops with the cube of the speed change.
Morris National, Azusa, CA-based manufacturer of Nutffles (whole roasted nut truffles with a crisped rice inclusion in Belgian chocolate coating), found itself trying to redesign its process and packaging line because its existing PD pump couldn’t handle recirculating the chocolate with crisped rice without reducing the size of the rice pieces by as much as 50 percent, according to Luigi Girotto, general manager of engineering and maintenance.3
Rather than redesign the process and packaging lines, Girotto thought it easier to change out the old pump with a PD pump that could handle the product. He tested a Waukesha Cherry-Burrell Universal Series I PD pump and found the size of the crisped rice pieces was maintained throughout the entire 35-minute cycle. With the old pump, maintenance crews had to replace the scraper-gate shuttles sometimes as often as twice a week to avoid concerns about product contamination. After switching to the SPX Waukesha PD pump, downtime disappeared, and maintenance returned to being straightforward and manageable. When the pump was not in production, Girotto opened it, inspected it for wear and found none. He reports a major improvement in productivity over the old pump.
The Universal Series pump with the ECP architecture has a very low slip ratio that allows the pump to become “fully positive” at lower viscosities, says LeClair. Once a pump is fully positive, the energy efficiency is maximized and can be over 90 percent of the input power from the motor, he adds.
Time is money, and reducing tanker truck offloading times by half through a pump change-out made it possible to save money for Bulmers, a large European cider company. The processor was experiencing problems at its Hereford, UK cider mill when an existing pump was not only failing to deliver at very low temperatures, but was also proving slow in warm conditions due to pressure in the pipe-work. The existing pump took four hours to unload concentrate from the tanker, and it created waste because it couldn’t completely empty the tank.
To fix the problem, John Williams, cider production manager, installed a Mono Helios progressive cavity pump to offload the concentrate at a capacity of 12 cu.-meters/hr. (3,170 gal./hr.) and a pressure of 9.5 bar (138psi), which provides an improved, faster flow rate. The pump is self-priming, has excellent suction capabilities, handles high viscosities and solids in suspension and is unaffected by system pressure changes.
“The Helios pump has more than met our performance criteria and is able to offload the tanker in less than two hours, avoiding any demurrage charges,” says Williams. “It handles the cold, high-viscosity apple juice very well and is quiet in operation with very little vibration.”
Progressive cavity pumps handle a number of food and beverage items, including sausage, chicken and other prepared meats. Moyno sanitary pumps are available in 150 standard models and meet 3-A sanitary requirements with no modifications. These pumps feature quick disassembly for easy cleaning, no valves and the ability to handle thin liquids like soups and juices or viscous slurries like peanut butter, candies and jam. Plus, they can handle fluid temperatures up to 400°F and solids up to one in. in diameter.
Spend a little more on energy to get a lot more output? That’s what Arla Foods did at its mozzarella production facility in Rødkærsbro, Denmark. The facility operates nearly continuously, producing more than 60,000 tons of mozzarella, pizza topping and shredded cheese per year. According to the facility’s Engineering Manager Per Hansen, mozzarella production was on track in 2011 to reach 63,000 tons, 25 percent more than was produced two years previously. “At the same time, we have used just 2 percent more energy.”
Much of the improvement came from installing nearly 300 Alfa Laval pumps and reducing CIP time. “When we started, we were performing CIP seven times a week,” says Hansen. “Today, we perform CIP just five times a week. This has meant 10 more hours of available production time per week.
“Alfa Laval pumps and processing technologies have played an important part in us being able to increase our production and energy performance,” adds Hansen. Tetra Pak, an Alfa Laval alliance partner, was heavily involved with process optimization at the facility, ensuring low energy consumption from processing equipment like pumps and maintaining high operational reliability.
According to Torben Bertelsen, Tetra Pak key account manager, “The reduction in CIP at the 24/7 facility has meant meeting specific demands related both to the process and its components, like ensuring low energy consumption from units like pumps, maintaining extremely high operational reliability and having a responsive approach to maintenance and service planning.” Bertelsen says pumps and valves are kept in stock. “So when there is a planned stop for CIP, we can quickly exchange pumps and valves without risking a standstill in operations.”
“Considering the purchase price of a pump is less than 10 percent of its lifetime cost, a high-quality pump will outlast an inferior pump, saving you money in the long run,” says Wells. But changing out a pump is not like changing a light bulb. Installation costs (re-piping and mounting changes), maintenance and repair, energy consumption, downtime and end-product quality are all important considerations. Run pumps within their ratings and use the OEM seals designed for the equipment, and they’ll provide lasting performance.
“Many SPX pumps have been installed for years and have proven a pump that lasts for an extended period of time lowers the total cost of ownership,” says LeClair. A pump’s longevity provides the end-user with a sustainable solution with minimal unplanned production downtime. For users with several pumps, LeClair recommends considering the commonality of spare parts, ease of maintenance, durability of the pumps and the availability of product pre- and post-installation.
1 - Example of an online selection tool for centrifugal pumps: www.pump-flo.com.
2 - ALEDco Inc., Allentown, PA, www.aledco.com.
3 - “Pumping up productivity,” Candy Industry, September 2011, BNP Media.
For more information:
Bob Wells, Fristam Pumps USA, 800-841-5001, firstname.lastname@example.org
Doug Vogelsmeier, Marlen International, 913-888-3333, email@example.com
Shawna Andrews, Verder Inc., 478-283-6994, firstname.lastname@example.org
David Kirk, Pump Solutions Group, 707-484-9023, email@example.com
Mike Dillon, seepex, Inc., 937-864-7150, firstname.lastname@example.org
Jim LeClair, SPX Flow Technology, 262-728-4912, email@example.com
Sandra Molinaro, Alfa Laval, 262-605-2600, firstname.lastname@example.org