Balancing performance, value
“Laboratories typically use pure or ultrapure water, but more pure isn’t always better,” says Frank Firicano, division manager at Aries Filter Works (West Berlin, NJ). Aries, a division of filtration media manufacturer ResinTech, turns ion exchange and activated carbon media into point-of-use products.
Because of operating costs and maintenance, operating with ultrapure water may sometimes be overkill. Firicano cautions customers who want their water systems to serve every conceivable situation, “You pay for that.”
Monitoring water for very high purity also entails costs. The most common in-line techniques are resistivity and conductivity, which quantify ions. Other tests include total organic carbon and bacterial load. Checking for bacteria is time-consuming and involves culturing the organisms, which takes days. For the most part, lab water quality is built in through the use of filtration and ion exchange technologies that are known to remove contaminants to specified levels.
The other knock on ultrapure water, according to Firicano, is its aggressiveness in removing ions from surfaces they encounter. “Ultrapure water can damage equipment, when all you might need is water that will not scale or interfere with your process.”
For situations where ultrapure water is required—HPLC, for example—Firicano cautions on water transfers, a source of contamination from atmosphere, containers, and tubing. Ultrapure water is usually generated at the point of use to avoid these issues.
But not always.
Julie Foster, global product manager at Thermo Fisher Scientific (Asheville, NC) notes a strong preference for remote dispensing, an approach that purifies water some distance from the point of use. The principal drivers for remote dispensing are space savings and a desire to create a distributed water generation network within a lab.
Last year Thermo launched a water purification upgrade, Genpure X-CAD+, which with a remote dispenser provides flexible water delivery within about a ten-foot radius of the purification system. All key purity parameters are displayed on both the main and remote units.
“Our customers hang the remote dispensers on walls or under benches, out of sight,” Foster tells Lab Manager.
Transportation is known to degrade type 1 water. For remote dispensing systems, any quality falloff is tightly controlled. Materials of construction for remote units and hoses are identical to those in the water generator.
Moreover, distance from the mother unit is restricted in the Thermo system to three meters. “There’s a set length that we think is safe,” Foster says. “Tubing and electrical components are cut to that length, and we don’t supply anything longer.”
Type 1 systems also incorporate a recirculation loop to maintain quality. Type 2 and reverse osmosis systems, for less critical applications, do not employ recirculation. Users can expect a resistivity of 18.2 MΩ-cm from remote dispensing systems—as good as it gets.
Remote dispensing changes how water is generated, distributed, and used within a lab. Since one generator can serve multiple dispensing units, the nine-meter reach covers an area of roughly 80 square feet. That, and the potential for installing multiple central units, means that workers are rarely more than a few steps away from high-quality water.
Avoiding cartridge issues
At one time manufacturers of pure water systems kept tight control over maintenance and cartridge replacement. Some would not allow labs to swap out their disposables, for example. That has changed. Vendors still prefer labs use their replacement cartridges (the razor blade business model, if you will), but they now encourage lab workers to do it themselves.
Foster discourages labs from acquiring thirdparty cartridges, however, because of quality and consistency issues. “There’s IP around cartridges, but that doesn’t mean there aren’t copies out there,” she says. Knockoff cartridges may work, but their use hinders troubleshooting if problems arise. “And in some instances, they may void the original warranty.”
For additional resources on water purification systems, including useful articles and a list of manufacturers, visit www.labmanager.com/water-purification
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