Pump Suppliers Boost Performance, Not Prices
By reviewing traditional engineering and design practices and investigating alternative materials, manufacturers of flow control components discover cost-effective solutions for the device industry.
Facing unprecedented pressure to contain costs in recent years, medical device manufacturers have avidly searched for ways to generate savings without compromising the efficacy of their products or research and development efforts. The burden of meeting this challenge has also trickled down to OEM suppliers of products and services.
Cost is always a driver, that goes without saying," says Adam Meyers, president of Bio-Chem Valve Inc. (Boonton, NJ, USA). "Yes, price is always an issue," agrees Herbert Hansel, marketing manager at ASF Thomas (Puchheim, Germany), but he adds that oil-free operation, low noise, low vibration, and flexibility along with package size can be of equal concern. Size comes in a close second, after price, for Mark Jernigan, director of operations at Smart Products Inc. (San Jose, CA, USA). "Our customers always seem to be asking, 'can you make it smaller?'" says Jernigan. "Small and battery operated . . . that seems to be a real trend right now." Pushing the limits of technology while keeping a tight rein on the bottom line will continue to drive the device industry for the foreseeable future. Suppliers have few options but to go along for the ride. Here are examples of how some manufacturers of pumps have managed to contain costs while enhancing performance.
At Verder LabTec GmbH & Co. KG (Karlstein, Germany), engineers have developed a pocket-sized pump that delivers pulse-free operation. According to the company, the project was initiated when the firm became aware of a study predicting growing demand for compact peristaltic pumps with flow rates in the 250-ml/min range. The pulse-free peristaltic pump, which is small enough to fit into rinsing and suction units and miniature laboratory equipment, is supplied ready for use in laboratories and cleanrooms. A low-pulse OEM version is also available.
Leak prevention was of primary concern at GRI Europe a/s (Soeborg, Denmark) during the development of its magnetic-drive centrifugal pumps. According to marketing manager Greg Schoenman, the magnetic-drive design obviated the need for a shaft in the housing, thereby eliminating a potential leakage site.
Regulator-Free Pump: Less Is More
Sometimes, a product's appeal to OEMs resides in its intrinsic simplicity. That is one of the features of a line of solenoid-operated micropumps developed by Bio-Chem Valve. The low-cost pumps, which combine a small footprint and high repeatability, operate without a pressure regulator, enabling a reduction in cost and greater freedom in product design.
"The industry standard today is to take a pressurized reservoir that leads to a valve, open the valve for a specific period of time, and, based on empirical testing, determine the amount of volume that will be produced," says company president Adam Meyers. "A very tight pressure regulator is required, because any change in pressure is going to give you a change in output." Likewise, he continues, the valve needs to have a highly controlled transit stage—the on and off time—to ensure that the dispensing volume does not vary from valve to valve and machine to machine. "The micropumps we have developed use a technology similar to a valve but they don't require a pressure source," says Meyers. "It's not what you would call leading-edge technology," he adds, "it's just the right application of technology."
Simplicity in design and concomitant cost reductions also informed the development of liquid diaphragm pumps at Smart Products. The pumps, according to Jernigan, cost two to three times less than other models with comparable performance specifications. The company achieved dramatic savings in production costs by methodically examining the pump's constituent parts, says Jernigan. "We spent a great deal of time looking at the parts involved, finding a motor that was inexpensive yet performed to specs," he says. "Because we do all of our moulding in-house, we were able to exercise a great deal of control over that process, as well."
Material selection was another opportunity to trim costs. "We can manufacture the pump in a fairly amazing new material called Carilon," he says. Formulated by Shell Chemical Co. (London), Carilon combines the chemical resistance of Kynar and the heat resistance of nylon while costing about as much as polypropylene, according to Jernigan. Shell, he adds, hopes to obtain FDA approval for the material by early 1999. "We can make the pump out of polypropylene, which is the most common for medical applications, or practically any other material for that matter," explains Jernigan, but he readily admits to being a Carilon booster. "Few people know about this material yet, and we hope to help educate them so that they will start using it. It's really a great inexpensive material."
Suppliers Focus on Long-Life Designs
In addition to the initial purchase price, OEMs should not neglect taking into consideration a product's longevity, stresses Hansel of ASF Thomas. The company's twin-piston air compressors and vacuum pumps feature a "more reliable, longer-life design than previous models," he points out, which is an important feature of these components that are typically used in oxygen concentrators. ASF Thomas backs its pumps with a 25,000-hour guarantee, he adds. Another German supplier, KNF Neuberger GmbH (Freiburg, Germany) has reduced the overall size and enhanced the working life of its miniature diaphragm pumps by incorporating a structured diaphragm.
One area that holds great promise, according to Bio-Chem Valve's Meyers, involves components that facilitate reduced process costs. "There's a lot of talk about nanolitre dispensing right now," he says. "Any time you can minimize the amount of reagent that is used to create the chemistry you want, you're reducing your customer's end cost," says Meyers. Pumping technology is critical to research that is currently being conducted to develop systems of this sort, he adds. "I would say that this is one of the most significant issues at the moment in terms of future trends."
The suppliers mentioned above as well as others devoting their expertise to the development of more-reliable and cost-effective pumping solutions for device manufacturers are profiled on the following pages. As always, be sure to circle the appropriate reader service number on the product information card and drop it in the mail to request more information on a particular product or company.
Bio-Chem Valve Inc.
Inert solenoid-operated microdispensing and micrometering pumps are available in fully chemically inert as well as self-priming versions. The self-priming 120SP can be factory set for discrete outputs between 25 and 60 µl per actuation with ±2% repeatability. Up to 400 actuation cycles per minute and 24-ml/min flow rates can be achieved. The 110TP pump, composed of chemically inert Teflon, Tefzel, and ruby, offers discrete outputs between 20 and 40 µl per actuation. Repeatability for this model attains ±5% per actuation.
These pumps are not designed to perform a variety of tasks, and that is one of their advantages over other products, notes Adam Meyers, president of Bio-Chem Valve Inc. (Boonton, NJ, USA). "They are specifically geared to automated diagnostic systems where the required dispense volume of a reagent or sample is known," says Meyers. "The pumps combine a small package size, a highly repeatable dispense, and a low-cost reliable configuration," he says, noting that, above all, customers are taken with the simplicity and directness of the components. The micropumps do not require a pressure source to operate; consequently, the design of products incorporating the component can be streamlined. "It fits in the same space as a valve, but it doesn't require a pressure source on the reservoir," says Meyers. "You're doing away with that whole part of the machine." The absence of a pressure source also eliminates concerns about variations in output caused by a change in pressure. "Because it is set for a specific volume, the pump provides an accurate dispense each and every time, regardless of internal variations or machine-to-machine changes."
Diener Precision Pumps Ltd.
A company that supplies various types of positive displacement metering pumps to medical device OEMs has more than 30 years' experience in fluid-handling applications. In addition to a broad range of reciprocating piston pumps and magnetically driven gear pumps, Diener Precision Pumps Ltd. (Zug, Switzerland) routinely collaborates with manufacturers to design and develop custom pumps to their specifications. "Medical device manufacturers demand high quality and performance at reasonable prices," says sales manager Rick Anderson, "and Diener tailors its products to optimize design and performance at competitive prices."
Featuring flow ranges from less than 1 ml/min to more than 15 L/min, the company's pumps are suited for use in dialysis, water filtration, chemical analysis, x-ray cooling, laser cooling, and chemical dosing and dispensing applications. Materials typically used in pump construction include 316 stainless steel, alloy C, PEEK, PVDF, polypropylene, ceramic, PTFE, PPS, and titanium, along with other engineered plastics and metals. The company is currently investigating new technologies that may further reduce costs, according to Anderson, while maintaining the quality and performance that device manufacturers demand. The company also plans to expand its European and North American operations in the near future.
ASF Thomas Industries GmbH
Twin-piston air compressors and vacuum pumps used in oxygen concentrators, among other applications, feature a more reliable, longer-life design than previous models, according to Herbert Hansel, marketing manager of ASF Thomas Industries GmbH (Puchheim, Germany). The oilless 2650 series has a 2.80–5.60 cu-ft/min open flow rate, maximum intermittent pressure up to 50 psig, and maximum continuous pressure up to 40 psig. All models in the series are fitted with permanently lubricated bearings; oilless pistons and cylinders that require no lubrication; lightweight die-cast aluminium components; and a long-life, high-performance piston seal. Durability, according to Hansel, is one of the pumps' prime selling points. "As you can well imagine, long life is a very important feature of these pumps, particularly when they are being used in oxygen concentrators," says Hansel. "That's why the pumps come with a 25,000-hour guarantee."
ASF Thomas designs and manufactures a wide range of OEM compressors and pumps, including a microdiaphragm pump that delivers the same flow volume regardless of how it is fitted and linear pumps with a performance range that extends from 45 to 300 L/min.
Smart Products Inc.
A liquid diaphragm pump with very few moving parts has been developed by Smart Products Inc. (San Jose, CA, USA). "It has a moving diaphragm, of course, and an input and output valve, and that's about it," says director of operations Mark Jernigan. Keeping the internal mechanism simple not only increases dependability, says Jernigan, but it also significantly reduces the cost of the overall product. The self-priming pump is suited for the transfer of fluids attaining a viscosity of 90-weight gear oil. Maximum output pressure is 1.38 bar and the pump attains a maximum flow rate of 1.31 L/min.
The company, which performs its own moulding, offers the pump in a variety of materials. "Polypropylene is the most commonly requested material for medical applications, but we can make the pumps from almost anything," says Jernigan. He is especially excited about Carilon, a new polymer from Shell Chemical Co., which combines the chemical resistance of Kynar and the heat resistance of nylon at a cost equivalent to polypropylene, according to Jernigan. "It's a great, inexpensive material that few people know about yet," he says.
GRI Europe a/s
Compact magnetically driven centrifugal pumps are designed to handle a variety of chemicals without developing leaks. "The principle of the magnetic-drive pump is basically the same as a centrifugal pump," says marketing manager Greg Schoenman of GRI Europe a/s (Soeborg, Denmark), "but because no seal is used, there is no leakage. The impeller is driven by a magnet, so there is no need to run a shaft through the housing that would need to be sealed."
Three different models are available with flow rates up to 10 L/min, and their hydraulic design ensures optimal performance in relation to pump size. The magnetic-drive pumps are but one example of how GRI Europe can meet the needs of OEMs worldwide. "Device manufacturers are looking for low-voltage dc motors, products with a long life span, and no leaks," says Schoenman. GRI Europe, he adds, is well equipped to fulfill those demands.
Fluid Metering Inc.
Designed for precise fixed-displacement, low-pressure OEM applications, "living hinge" metering pumps are moulded versions of the Model RH pumps, also manufactured by Fluid Metering Inc. (Syosset, NY, USA). The STH pumps feature the same valveless positive displacement operation as the RH models; in addition, they have been designed to accommodate directly mounted stepper motors and optical encoders for pump-stroke verification. The two standard models provide displacement ranges of 0–50 and 0–100 µl/stroke. They are fitted with a matched ceramic piston and liner housed in a fluorocarbon cylinder case to ensure chemical resistance. Optical encoding and ¼-28 female threaded suction and discharge ports are standard; factory-adjusted volume-per-stroke settings are available. Despite their small size—the pumps require only 2 3/8 in. panel space—the components are 99.9% accurate. In addition to the two standard models, the STH pumps can be configured for custom OEM use.
KNF Neuberger GmbH
Microprocessor-controlled pumps combine the advantages of diaphragm technology with a smooth, almost continuous flow. Like diaphragm pumps, they are self-priming, can safely run dry, require no maintenance, and resist chemicals, says Martin Becker, chief executive vice president of KNF Neuberger GmbH (Freiburg, Germany). But, he adds, the FEM 1.08 series pumps also achieve a steady flow because the stepper motor executes the suction stroke at its maximum speed and then slows down to a selected speed for the delivery stroke.
Featuring a delivery rate that ranges from 0.08 to 80 ml/min, the pumps are suited for use in medical and analytical equipment. The simplest version of the pump is fitted with a potentiometer for manual adjustment of the flow rate. A module that supports analogue or digital control of a number of parameters is available.
The company also supplies miniature diaphragm vacuum pumps to medical device OEMs for applications that involve the transfer and evacuation of gasses and vapours. A proprietary diaphragm design has led to improvements in the overall package, according to Becker. The development of a structure for the underside of the diaphragm has enabled the company to combine the advantages of flat and moulded diaphragms while eliminating the drawbacks of the respective designs. In particular, "the structured diaphragm has enabled us to reduce the size of the pump compared to previous models and to increase its working life," says Becker.
The pumps feature flow rates attaining 34 L/min, vacuums down to 100 mbar absolute, and maximum pressures of 0.5 bar gauge.
Verder LabTec GmbH & Co. KG
An eight-channel dosing pump capable of dispensing up to 50 ml per dose has been developed by Verder LabTec GmbH & Co. KG (Karlstein, Germany). The application involves the simultaneous pulse-free filling of eight containers with varying media to a precision of ±0.5%. The company was able to achieve a further reduction in pulsation, down to 50 mbar, which was required for a related process.
The company has also developed a pulse-free peristaltic pump that provides flow rates up to 250 ml/min yet is compact enough to fit into rinsing and suction units and other small medical devices. The ready-to-use pump can be configured for use in the field; a low-pulse version is available for OEMs.
Pumps developed by the company also play a role in the harvesting of bone marrow cells. This procedure requires a high degree of repeatability and pulse-free operation to ensure that cells are not damaged. The company's Pericor CD and SR pumps, which are used in that delicate process, have also proved advantageous in other centrifugal applications, such as the preparation of plasma proteins in the pharmaceutical industry.
