Saturday, August 18, 2012

Customized Cleanroom Applications Meet Today’s Environmental Challenges

Customized environmental solutions can resolve unique cleanroom requirements.
For many critical cleanroom environments like those in the aerospace, pharmaceutical, semiconductor, and metrology industries, an off-the-shelf solution may not provide optimal results. Specialized manufacturing and research facilities demand technically challenging environmental process control systems and the expertise to create customized solutions.
The key word is customized. Unusual applications with exacting specifications often require specialized engineering solutions that fit components, controls, and ductwork into small spaces; limit exposure to corrosive elements; or handle stringent drop testing. An environmental control solutions provider can help a facility meet these challenges.
For example, a major U.S. government laboratory that develops and operates unmanned scientific spacecraft for Earth observation, astronomy, and space physics missions initially used in-house personnel to design its environmental control systems. The systems needed to account for factors like particulate counts, room pressurization, floor plan changes, and regulatory guidelines. The on-staff engineers were responsible for the performance of the equipment, while also managing the installation, start up, and maintenance.
Air Innovations, North Syracuse, N.Y., a specialist in environmental process control of temperature, humidity, filtration, and pressure, created customized environmental control solutions for the laboratory’s unique applications.
Six different installations were completed for the laboratory. The desired location of the environmental control equipment included a mezzanine, rooms with height restrictions, and inside a process cleanroom. Equipment was custom-designed for every space, using modules measuring 34 by 34 in, 26 by 30 in, and a range of other sizes and shapes. The operation and performance of the company’s equipment helped the laboratory achieve its technical objectives.
The laboratory conducts humidity-sensitive projects. If the air is too dry, there is a risk of creating static electricity. If the air is too humid, excessive bacteria may grow. In one case, the general requirement was for cleanroom-quality air at 45% relative humidity (±5%) and a temperature of 68°F (± 2 degrees). The solution included ultrasonic humidification for energy savings.
The air in the cleanroom needed to be maintained to 0.1 in of positive pressure.
For two other projects, equipment using various cooling media was designed and built, including a 15-ton direct expansion cooling unit and a 3.5-ton chilled water system, according to the type of conditions the laboratory wanted to maintain. Direct expansion, for example, provided good humidity control because of its ability to reach the room’s required dew point. Chilled water was mostly used for sensible cooling in the space to keep the lab’s personnel comfortable.
Another project involved replacing a large existing air handling system with a 15-ton horizontal unit in a mezzanine area. In order to transport the new unit up to the mezzanine, it had to be built in separate pieces that could be fit into a small freight elevator and then assembled in place.
For another application, a vertical, three-cube system was designed to be located inside of a closet. Because the unit was backed up to power a cleanroom and only a few inches were left to spare in the closet, service panels on both the front and back of the unit solved the problem of maintenance access.
Other features of the laboratory’s environmental control systems included: high static pressure fans to provide airflow through long runs of ductwork, proportional- integral-derivative (PID) controllers to precisely adjust process control set points; and reheaters for tighter temperature control. All the equipment was non-outgassing, using a special insulation and caulk that would not interfere with lenses and other apparatus being built in the laboratory.
Customized engineering can be applied to other critical environments that require systems that feature close tolerance control of temperature to ± 0.01°C; humidity control tolerances to ± 0.%; direct expansion, chilled water or thermoelectric capabilities; broad filtration capabilities (HEPA, ULPA, and molecular); and pressure control.
Of course, customization means projects are neither quick nor inexpensive. The cost of systems for the government lab, for example, ranged between $40,000 to more than $100,000, with lead times of at least 12 to 14 weeks after the order was received. From the initial conversation to a particular installation, a job takes anywhere from six months to two years.
The process begins by providing three-dimensional, computer-aided drawings in computer assisted design software such as SolidWorks to validate designs, simulate fluid flows and thermal analyses, expedite concept development, and determine which concepts and virtual prototypes function properly—well in advance of the manufacturing process. Often, the scope of work includes creating a full sized prototype that can be tested and inspected under simulated contract load conditions in an environmental chamber. Other projects require capabilities such as enclosure engineering, regulatory submissions, or international distribution.
Today’s solutions providers must build and control a wide range of exacting environmental conditions for just about any industry, custom fit in spaces that range from desktop to the size of a two-car garage, and perform in harsh ambient conditions that range from -32°C to 52°C (-25°F to 125°F) for both small-scale production and full-run manufacturing. By building upon prior experiences and pushing the envelope of environmental process control, a solutions provider can help its clients achieve their most challenging technical objectives.

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