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July 8, 1999

5 Min Read
Waterlines clogged? Descale without disassembly

Lime scale. Say the words and injection molders cringe. To molders, scale, caused by calcium in hard water, is a devil that forms as water flows through pipes, contaminating and clogging lines throughout a plant. When scale builds up in the pipes and heat exchangers on a molding machine’s hydraulic system, it causes poor heat transfer, which prevents molders from running their machines at full capacity. Similarly, when scale clogs mold cooling water passages (Figure 1), it creates a thermal barrier that hinders the cooling and heating of the mold. All of this adds up to wasted machine time and money.

Such was the case with Sussex Plastics (Sussex, WI), which molds cosmetics products for companies such as Mary Kay, Avon, and Revlon on machines ranging from 55 to 725 tons. Phil Salzman, Sussex’s director of manufacturing, oversees the company’s 52 molding machines. He says heat exchangers were plugging up more times than employees cared to open them up and clean them.

“We do maintenance on heat exchangers on a scheduled basis,” says Salzman, who has been with Sussex since the company’s inception 22 years ago. “We take the end caps off, clean [the scale] out, and make sure everything is fine. But we found we were overheating oil more often than we should.”

Too Good to Be True

Like many companies, Sussex battled the scale problem by injecting the lines with chemicals. This method slowed down the accumulation of scale, but did not eliminate it. Other companies use salt water softeners, or ion exchange units, which put two atoms of sodium into the water for every one of calcium removed in order to eliminate water hardness. These systems, which are also popular in residential use, reduce calcium buildup, but do not remove it. Then, nearly three years ago, Salzman was presented with a product called ScaleBan from EcoSoft Engineering (Waukesha, WI), and he hasn’t had to worry about scale buildup in the heat exchangers since (Figure 2).

At first, ScaleBan—a maintenance-free solution—seemed too good to be true. In fact, being more than a little skeptical, Salzman first tested it on one molding machine heat exchanger for several months. The results persuaded him to take the plunge, and soon he installed a big 4-inch-pipe unit for the plant’s entire machine hydraulic oil cooling water circuit.

ScaleBan, which was first commercially introduced in 1991, is comprised of a main signal generator unit (no bigger than a shoe box), a power transformer, and 14-gauge wire. The user simply wraps the wire around an incoming water pipe forming a 25-turn solenoid coil, plugs the transformer into the signal generator, and then into a 115V outlet. It immediately starts the descaling treatment to the point where pipes become “virtually scale-free,” reports Salzman. The unit runs continuously, maintenance-free, at a cost of about $3/year thanks to its efficient circuit design.

Making Bad Calcium Good Calcium

The ScaleBan unit uses a frequency-modulated a-c electromagnetic field to convert calcium from a form that promotes scale to a form that does not (see Figures 3 and 4). Specifically, it converts calcium carbonate-calcite, a sticky crystal form that promotes scaling tendencies, into calcium carbonate-aragonite. Calcite (lime scale) and aragonite are two of the three (vaterite is the third) physical crystal forms of CaCO3, or calcium carbonate. They are all chemically identical, but have different physical structures and therefore behave differently. ScaleBan simply converts the calcite into nonsticky aragonite, and in addition, promotes the redissolving of existing scale buildups.

EcoSoft Engineering owner/president Ed Ebert says the ScaleBan process will convert at least 90 percent of carbonate to aragonite. In lab tests, this number has been as high as 100 percent. Other nonchemical processes have reportedly only shown 30 to 40 percent conversion in lab tests, he adds.

Injection molding machines are typically run at about 65 to 75 percent of their fastest cycle times because of poor heat transfer. It takes just a 1/16-inch-thick buildup of scale to cause a 15 percent slowdown in a machine’s cycle because it takes longer to extract the heat. A solution like ScaleBan keeps machines running clean, which allows them to run at 100 percent, he emphasizes.

Building on an Accident

The ScaleBan technology was discovered accidentally by a Scotsman in 1894, when a maintenance worker stored a large permanent magnet near a water pipe in a physics lab, says Mike Gagnon, owner of Milwaukee, WI-based MPG Inc.—a ScaleBan sales distributor. When the day came for some plumbing work, he noticed the pipes were calcium filled, except for the area where the magnet had been and from there on downstream.

Permanent magnets, tried for more than 100 years, ultimately proved to be a poor method for removing scale. EcoSoft Engineering determined that a multiple-frequency phase-modulation a-c signal, now patented, is what would be required for reliable descaling.

EcoSoft Engineering offers systems that range from the basic ScaleBan 2000, designed for 11/2-inch ID pipes ($599.95), up to units designed for 24-inch pipes ($38,400).

The system for Sussex’s 4-inch pipes cost about $8000, a cost that has since been recovered by the company, reports Salzman. “From our standpoint, it’s been very good,” he adds. “It’s maintenance-free—we haven’t had to do anything to the unit; we hooked it up and it’s just been there. It’s not the answer to everything, but it takes care of the scale.” Salzman is now considering installing a second system on his mold cooling water lines.

Contact information
Sussex Plastic Inc.
Sussex, WI
Phil Salzman
Phone: (414) 246-8022
Fax: (414) 246-8423

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