Russell Hallman
Controlling Moisture
April / May 2010
Volume 8 Number 2
Russell Hallman is a problem solver at the Y-12 National Security Complex in Oak Ridge, Tenn. His innovative solutions have earned him four patents since 1984, and another five are pending with the U.S. Patent and Trademark Office. The patent currently garnering the most interest is perhaps most elegant in its simplicity: a more accurate and inexpensive moisture blending system.
The system was developed to support Y-12’s precision machining for the Department of Energy’s nuclear security missions. Researchers needed to know how quickly materials corrode under a range of conditions, and gathering data required creating various mixtures of gas and water vapor. The problem was the water vapor.
“It was difficult to blend moisture with gas because water is sticky,” said Hallman, an engineer. “It doesn’t like to mix with things. If you mix water with a dry gas, you would have to use it immediately. You couldn’t store it. It wouldn’t even stay mixed long enough to run it through a pipe.”
So Hallman invented a device that combines water vapor with gas in precise ratios and releases the result in a steady stream. Because the mixture is continuously created and delivered, the water vapor doesn’t have a chance to settle out.
“My first attempt was a recreation of an old, crude machine that gave consistent results, but it didn’t look like much. We called it the train wreck. It wasn’t perfect, but it was the only game in town,” said Hallman.
The train wreck, more precisely known as a successive dilution process, stayed in constant use at Y-12 for a couple of years. “It provided low, precise amounts of moisture for testing parts, but it was finicky and made large amounts of gas,” said Hallman. “We then developed a new, more precise machine called the Moisture Blending System.”
The prototype instrument was sold to Los Alamos National Laboratory, where it’s been in constant use ever since. LANL’s Jonathan Phillips said, “It’s marvelous because it’s simple, and it works.”
“I use a tiny plastic tube, with a hole the size of a human hair, that’s submerged in water,” said Hallman. “By controlling the water temperature and the pressure in the tube, I can control the amount of moisture in a gas pushed through that tube.”
At Y-12 the device has been just as popular. Over the years Hallman built five models that are routinely used for calibrating the hygrometers that monitor the processing of moisture-sensitive reactive materials. The system holds Nationally Recognized Testing Laboratory certification.
In the original moisture blending system, the user can select moisture ranges and flow rates, and the device can be equipped with either an electric or mechanical flow controller. The system is portable, cost-efficient, and easy to program and operate. A subsequent “intrinsically safe” model requires no electricity, which is an ideal safety feature when instruments need to be calibrated in potentially explosive areas, such as where solvents or fuels are used. The unit offers predefined moisture ranges and a unique, intrinsically safe gas-flow controller, which provides a continuous flow of gas to accommodate changing process conditions. Both systems can be custom designed for large- or small-scale applications.
The high-resolution blending system works with gases, vapors, and volatile (readily vaporizable) liquids in addition to moisture. In the manufacture of silicon chips, for instance, the system would be ideal for moisture control during the wafer-masking process. The system also could produce moisture levels to control static during the assembly of integrated circuits. In the pharmaceutical industry the system could be vital in establishing and maintaining process control parameters when drugs are synthesized. Other potential applications include biostudies (determinations of threshold limit values), electronics (the blending of corrosive gases), and environmental synthesis (green chemistry). These applications of the technology are available through patent licensing.
Among its materials-testing uses, a modified version of the system can conduct film permeation measurements to quantify how effectively the film blocks unwanted gases. Gas transports, liquid migrations, and salt intrusions across films are just some of the phenomena that can be measured. The resulting data can aid in the search for the best coating, barriers, paints, and films for seals, protective surfaces and related products.
The system is also key to the Ph.D. Hallman is pursuing in polymer engineering. “I can make a polymer with specific barrier properties,” he said. “I am investigating how to produce a film that will allow a specific amount of gas to move across the film. For example, in the moisture blending system we want a polymer that lets through a specific amount of moisture, consistently and reproducibly, every time.”
Hallman credits his inventiveness to family genes—his grandparents were machinists and craftspersons—and to encouragement from his mother. She first suspected he had mechanical talent when, as a first grader, he disassembled her vacuum cleaner. When he reassembled it, he also repaired the long-broken retractable cord. “She made sure I always had the tools and materials I needed for tinkering,” said Hallman.
A lifetime of innovations later, it’s clear that her money was well spent.
Tammy Graham is at the Y-12 Office of Technology Transfer.
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