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Toolmaker finds answers in degreasing process.

The early 1990s was a time of unprecedented change for companies that practiced vapor degreasing. Environmental and health regulations governing the use of chlorinated solvents had become very stringent. Although new, environmentally responsible technology was beginning to enter the market, most companies still operated open top degreasers that did not comply with proposed standards.

Eyelet Toolmakers, Watertown, CT, a manufacturer of metal products for the cosmetics industry was one such company affected by the changes. Fortunately, Eyelet did not have to face them alone. The company received technical assistance from The Dow Chemical Co, Midland, MI, the leading producer of chlorinated solvents, and Serec Corp, Providence, RI, a developer of Airless brand vapor degreasers. With their help, Eyelet was able to make a smooth transition from an open top degreaser to an Airless system, and to conduct what is now one of the most environmentally responsible vapor degreasing operations in Connecticut.

Recognizing the issue

Eyelet purchased its first vapor open top degreaser in 1980. For its solvent, Eyelet chose a vapor degreasing grade of perchloroethylene (perc). This degreaser-solvent combination met the company's cleaning needs, and since regulations governing the degreasing process were relatively lenient at that time, Eyelet kept it that way for 17 years.

During the 1990s, however, EPA regulations and Connecticut restrictions on vapor degreasing and the use of chlorinated solvents led Eyelet to reevaluate its degreasing process. In 1989, the Occupational Safety and Health Administration (OSHA) set the permissible exposure limit (PEL) for perc at 25 ppm. Although the limit was overturned, it remains the exposure limit recommended for the industry

Eyelet had important concerns regarding vapor emissions from its open top degreaser. Al Rickevicius, president of Eyelet, wanted to provide a clean, vapor-free plant atmosphere for his employees. Throughout the 1980s and '90s, Eyelet had been making improvements in employee benefits, and Mr Rickevicius believed that good employee relations also demanded a completely safe workplace.

Eyelet had its degreaser retrofitted with chillers and a higher freeboard in 1995. The result was reduced vapor emissions, but still not low enough to meet the 25 ppm limit. So Eyelet turned elsewhere for a solution.

Zig Konans was hired in 1997 to direct Eyelet's sales and marketing, and Mr Rickevicius specifically wanted his input on what to do about the degreaser situation.

Joining the two in seeking a solution was plant manager Bob Greatorex.

Choosing the best solvent

The company's first step was to choose a solvent that met all environmental and health regulations.

Dow provided Mr Konans with information on its chlorinated solvents, all of which provided optimum performance for the type of work Eyelet did.

The most widely-used of these solvents, trichioroethylene (TCE), has a mid-range boiling point (189 F) that requires less energy than perc to turn into vapor. However, since its boiling point is low, it would require more mechanical cooling for efficient vapor control and recovery. Perc has a much higher boiling point than TCE (250 F). While perc does not require extensive cooling for efficient operation, it requires more energy to heat and create vapor. And because the company already had a boiler and. steam available on the premises, the cost of heating perc turned out to be much less than the cost of cooling TCE.

Eyelet decided to use Perchloroethylene SVG Double Stabilized solvent, a specially inhibited grade of perc produced by Dow. "The solvent we chose is very stable in the presence of water and other contaminants, and because of that it required less maintenance," Mr Konans says. "Since we were considering a fully enclosed degreaser for our operation, a stable solvent was a top concern."

Engineering a new degreaser

Mr Konans knew Serec Corp as a company that engineered fully closed-loop degreasing systems meeting the most stringent regulatory standards. Serec began designing degreasers for the aerospace industry in 1992 with only ten employees, but eventually grew to a staff of 40 with customers in the metal stamping and finishing industries as well.

In February 1998, Serec engineers provided Mr Konans with the specifications and statistics for one of the company's Airless degreasing systems.

The degreasers met and surpassed federal and state regulations for vapor emissions in the workplace. Even though they were designed to contain less than 25 ppm solvent vapor in the degreasing chamber at the cycle conclusion and prior to opening the chamber door, testing consistently measured less than 15 ppm in the chamber. That exceeded the requirements for Maximum Achievable Control Technology (MACT).

Serec's engineers had several goals to meet in designing Eyelet's degreaser. The first was to decrease vapor emissions. Open top vapor degreasers rely on the density of solvent vapor to prevent it from escaping. Since it is heavier than air, solvent vapor usually stays below a layer of chilled air during the cleaning cycle, but some vapor can still escape into the plant atmosphere. While using the open top degreaser, Eyelet reported emissions of 43,283 and 40,671 lb of perc in 1997 and 1998, respectively--normal numbers for open top degreasers.

"Since Serec's degreaser is a closed-loop system," says Peter Gebhard III, president of Serec, "very little vapor escapes into the workplace." He adds that Serec's controlled atmosphere vacuum technology removes virtually all solvent vapor from the chamber after each cleaning cycle. A release of only 200 lb of perc was the goal in 1999. That would be a phenomenal decrease from 1998.

Another goal that Serec met was to create a cleaning system that worked for Eyelet's metal products. Eyelet's lipstick case covers sometimes collected liquid solvent in their deep cavities. To prevent this, Serec incorporated a motor into the degreaser to rotate the pieces. At the beginning of each cycle, the lipstick cases are rotated inside liquid soak, which only fills about two-thirds of the chamber so that the pieces are not totally submerged. Any solvent that collects in the pieces is poured out during the rotation. After the cycle is completed, a deep vacuum is created to boil off any remaining solvent trapped in the pieces, leaving them clean and dry.

Serec also met Eyelet's goals for employee safety. Serec's degreaser came equipped with safety and hazard-detection systems. A fourth goal Serec met was preventing air and solvent from mixing inside the degreaser.

The final goal Serec met was designing a system that could handle the capacity Eyelet required. Eyelet's lipstick cases are made from pure aluminum, a very durable material, and are covered with large amounts of oil prior to stamping. According to Mr Konans, 10 gal of oil are used every day on average, and most of it ends up as contaminant in the solvent.

To prevent this oil and other contaminants from breaking down during distillation, Serec engineered a deep vacuum, low temperature distillation. Pure solvent vapor, Mr Gebhard says, free from contaminants, condenses quickly in a vacuum, as the absence of air causes a faster heat exchange. The condensed pure solvent rejoins the rest of the solvent in the storage tank, and the remaining contaminated solvent is distilled again until all the solvent is recovered.

Mr Gebhard says that this new process is so effective that the recovered oil is close to being reusable. For oil to be reusable, it must contain less than 3% solvent, while Eyelet still currently recovers the oil with exactly 3% solvent content.

"When you consider that the average degreaser still leaves 70% solvent in the oil," Mr Gebhard says, "our system exceeds expectations and produces an extremely condensed waste product."

Mr Konans says that even with Serec's improved distillation process, Eyelet uses so much oil that it could eventually cause the solvent to break down. Chlorinated solvents are stabilized with inhibitors which prevent them from reacting with water and oxygen to form acid, but the contaminants in a degreasing process can deplete these inhibitors. In an open top degreaser, fresh solvent is constantly being added to replace solvent losses, and this replaces lost inhibitors, but in a fully enclosed degreaser, solvent losses are so low that fresh stabilizer is needed to keep the solvent from turning to acid.

Eyelet turned to Dow for advice, and Dow was able to provide Eyelet with MAXISTAB stabilizers to replenish the stabilizer system. These stabilizers are specially formulated to work with Perchloroethylene SVG Double Stabilized solvent.

Mr Konans notes that while most stabilizers need to be added once a month to maintain the solvent in an enclosed degreaser, he has gone up to four months before adding MAXISTAB stabilizers in Serec's Airless system.

"The more effective the stabilizer," he says, "the more solvent you save, because the solvent lasts longer."
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Comment:Toolmaker finds answers in degreasing process.
Author:Mertens, James A
Publication:Tooling & Production
Article Type:Brief Article
Geographic Code:1USA
Date:Feb 1, 2000
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