If you’ve got product, you’ve got to move it along. Particularly as shear-sensitive liquid biopharmaceutical products have proliferated, the industry has paid more attention to pump technology, from filtration and fluid transfer, to formulation, dispensing and fill/finish. While traditional pumps — of the centrifugal or piston variety, for example — have all shown steady improvement in design, materials and finishes, more sensitive and easy-to-clean peristaltic, lobe and diaphragm pumps have captured significant market share as well.
With 316L stainless steel, electopolishing and USP Class 6 elastomers standard on most hygienic pumps, anything labeled “pharma-grade” today is usually the real deal, says Mike Matton, technical sales engineer for process equipment supplier New England Sales, Inc. (Pembroke, Mass.). This might not have been true five years ago, he says.
The problem is choosing the right pump for the right application. “There are probably 50 pump technologies that overlap to some degree,” he says. Got a process with a high flow rate and volume? A good centrifugal pump is probably best, Matton says. High viscosity, like a cream or lotion? Try a lobe pump. High pressure, low flow? Mechanically activated diaphragm pumps. Low-shear, low-pressure? Probably a peristaltic tube or hose pump.
Still, those are merely rules of thumb. In each case, “There’s probably a few different right answers,” Matton says. And a lot of manufacturers get pump selection wrong and end up with excessive maintenance or downtime. Matton urges manufacturers to do their due diligence up front to understand their own needs and processes, and to provide pump suppliers with as much information as possible regarding: flow rate and pressure; fluid pH, viscosity, specific gravity and shear sensitivity; line size, pumping distance and inlet/outlet conditions.
And it takes more than just one person to find the right fit. “You need a team,” says Matton, including process engineers, maintenance personnel and line operators, all of whom are likely to have differing views on what pump is best for a given application.
Several trends are shaping pump technology, says Wallace Wittkoff, global hygienics director for the Pump Solutions Group (Grand Terrace, Calif.), which markets Wilden, Mouvex and Almatec brands for life sciences. These include the increase in continuous processing, the trend towards higher containment, control and cleanability, the gradual separation of equipment mechanics from the process and the increase in disposable technologies relying upon Teflon PTFE.
For Wittkoff, these trends point towards products such as the Almatec Biocor UB series, what he calls a “fully contained” diaphragm pump designed for pharma, in which the liquid chamber is made of machined stainless components and features no mechanical seals, greatly reducing the risk of leakage or contamination.
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What about shear? There’s a misconception that the diaphragm significantly compresses the product, Wittkoff says. Rather, like the human heart, he says, the pump gently massages product through production tubing.
Biocor also has the UA series pump, which is machined from PTFE, used primarily for batch processes and (though not cheap) can be discarded at any time and can thus be considered "disposable". In addition, Wilden’s Saniflo and BioPharm air-operated double-diaphragm pumps are made with passivated stainless steel components and come in various sizes and finishes.
Lewa, Inc. (Leonberg, Germany) offers a different design of process diaphragm pumps for high pressure processes, which can handle critical or toxic fluids, as well as those with extremely low viscosity or abrasive suspensions. The diaphragms come in durable metal or PTFE with their own monitoring systems.
Peristaltic pumps are broadening their applications, says Peter Lambert, national sales manager for the biopharmaceutical division of Watson-Marlow, Inc. (Wilmington, Mass.), which markets Flexicon peristaltics. “The benefit of the peristaltic pump is that it doesn’t have seals or mechanical parts, so product is only in contact with the tubing,” Lambert says. The industry trends toward risk-mitigation and single-use technologies have encouraged a shift toward peristaltic pumps, he says.
The knock on these pumps has been that they’re not suitable for high-volume applications such as dispensing. Lambert says that Flexicon has been improving its pump head and tubing technologies to allow for accurate, high-volume dispensing or filling down to .1 mL fill volumes. An example is the PD12 peristaltic dispenser.
“An engineer will say, ‘You can’t beat the piston for reliability,’ “ says Lambert. “Yes, but things are changing.”