Gas separation – Combined or convertible – In environmental air enclosure
Reexamination Certificate
2001-10-26
2003-10-14
Smith, Duane (Department: 1724)
Gas separation
Combined or convertible
In environmental air enclosure
C055SDIG001, C055SDIG002, C055SDIG007, C454S049000, C454S056000, C454S059000, C454S184000, C454S187000, C454S188000, C454S189000
Reexamination Certificate
active
06632260
ABSTRACT:
TECHNICAL FIELD
Generally, the invention relates to enclosures having adjustable clean gas flow environments and methods of enclosed pressure differential distribution technology. Specifically, clean gas flow enclosures, which provide for isolation of materials from airborne micro-particulate contamination.
BACKGROUND
Clean (or filtered) gas flow material handling systems are used in manufacturing to isolate clean materials from contamination by airborne macro-particulates or micro-particulates. There are three major categories of smaller filtered gas flow material handling systems, which are categorized based on the type of air flow: 1) Vertical Laminar Flow, 2) Horizontal Laminar Flow, and 3) Exhaust or Fume hoods. Each of the three types of devices have advantages depending on the various types of material handling application requirements. A focus of some of the embodiments of this invention are on the vertical laminar flow and the horizontal laminar flow categories. Particular embodiments of the invention encompass small, modular, reconfigurable, filtered gas flow environments for isolating materials from airborne particulate contamination. Smaller filtered gas flow environments are desirable because they eliminate many problems with larger clean room environments.
A significant problem with large clean room environments may be that gas must be filtered and moved long distances, while passing by people, machines, and open space. It is difficult to maintain such a gas flow and keep it within the Federal Standard 209 guidelines for particulate contamination. Federal Standard 209E,
Airborne Particulate Cleanliness Classes in Cleanrooms and Clean Zones
, 1992 hereby incorporated by reference. It can be even more difficult to stay within these guidelines at the work surface or within the work zone. Smaller clean air environments that move gas a shorter distance, and remove people and machines out of the airflow path are generally less costly and provide cleaner air within the work zone (or filtered gas flow space). In addition, it is much easier to direct and maintain the desired gas flow when moving air a shorter distance because the gas flow has fewer opportunities to encounter the gas currents and eddies that are produced by people moving inside a larger clean environment.
Another significant problem with clean room environments may be that it is more costly to maintain clean room environments, than a smaller, more modular clean environments. Clean rooms typically require people and machines to be totally immersed in the filtered gas flow. This requires additional space or cost for facilities and supplies. The people in clean rooms are required to wear clean room suits, shoes, gloves, masks, hair-covers, and other specialized equipment while inside the clean room environment. This also requires a changing room for people to enter and exit through and the changing room is usually accompanied by an gas-shower to blow off contamination being carried on clothing. In addition, this means that there must be aisle ways, standing or sitting areas, or the like that are part of the clean environment further adding to possible sources of contamination or adding additional cost to the clean room solution. By comparison, smaller clean environments that do not require the person to be totally immersed in the filtered gas flow can greatly reduce the need for these non-value added costs while providing a more human friendly environment to work in. See also, Adjustable Clean Air Flow Material Handling Environment, U.S. patent application 60/131,461 herein by incorporated by reference.
Even though small clean environments are desirable and generally used in manufacturing processes which require filtered gas environments, there are major problems which remain unresolved in the small clean environment industry.
A first problem can be the incompatibility of different clean environment enclosures which can be different shapes and sizes and may not be designed for being coupled or linked together. Interior and exterior dimensions vary considerably from manufacturer to manufacturer, and even between clean environment enclosures from the same manufacturer. These variations impose numerous problems with respect to material handling since even working surface heights may differ by inches, or the overall depth from one clean environment enclosure to the next may differ by several inches. In addition, even where the overall dimensions are compatible there may not be compatible side access panels on certain units which may prohibit linking units together in a side-by-side arrangement. Accommodating these variations may lead to wasted factory floor space which may not be reclaimed.
A second problem can be that existing clean enclosures do not distribute filtered gas to the entire surface of the gas flow delivery panel (or perforated plenum panel) adjoined to the clean work zone (or filtered gas flow space). In many existing arrangements the filtered gas is distributed within a static regain space of a plenum. The plenum has a perforated surface to deliver the filtered gas as a flow to the filtered gas flow space. Often the configuration of the static regain space prevents the flow of the filtered gas to distribute to the entire surface of the perforated plenum adjoined to the static regain space. As such, the filtered gas may not enter the filtered gas flow space from the entire surface area of the perforated plenum panel. This may result in only a portion of the surface of the perforated plenum panel delivering filtered gas to the filtered gas flow space. As shown for example in U.S. Pat. No. 4,927,438, the gas flow is directed substantially horizontally within a top plenum space which then delivers the gas flow substantially vertically into the filtered gas flow space. A rectangular plenum space with a dead end as shown often does not allow distribution of gas flow over the entire surface of the filter (
28
) or to the entire surface of the perforated plenum panel adjoining the plenum space.
A third problem can be that existing clean environment enclosures do not adjoin the perforated surface of the plenum to the entire flow path defined by the filtered gas flow space. As shown by U.S. Pat. Nos. 4,927,438; 5,326,316; and 5,487,768, the surface of the perforated plenum panels adjoined to the filtered gas flow space do not adjoin to either the entire height and width of the horizontal flow path defined by the filtered gas flow space (as disclosed by U.S. Pat. Nos. 5, 487,768 and 4,927,438), or to the entire depth and width of the vertical flow path defined by the clean work zone (as disclosed by U.S. Pat. Nos. 5,326,316 and 4,927,438).
A fourth problem can be that existing clean environment enclosures do not allow selectable gas flow within the filtered gas flow space of the clean environment enclosures. Presently, a single clean environment enclosures may not exist which allows for routine adjustment between horizontal gas flow, vertical gas flow, or a combination of both horizontal and vertical gas flow within the same filtered gas flow space. As shown by U.S. Pat. Nos. 4,557,184 and 3,895,570, the clean environment enclosures only allow for gas flow in the vertical flow path of the clean work zone.
A fifth problem can be that existing clean environment enclosures do not provide filtered gas flow having a substantially uniform velocity from the entire surface of the perforated plenum panel adjoined to the filtered gas flow space. This may be particularly true when the or filtered gas flow has a first direction of flow from the gas flow generator and a second direction of flow at the surface of the perforated plenum panel adjoined to the filtered gas flow space.
A sixth problem can be that existing clean environment enclosures do not position the area of minimum velocity in the filtered gas flow space at a location most distal from the access to the filtered gas flow space. As disclosed by U.S. Pat. No. 4,557,184, as an example, the area of lowest velocity within the clean work zone may be at the bott
Hamor Gary D.
Siemers Warren G.
Miles Craig R.
Pham Minh-Chau T.
Santangelo Luke
Santangelo Law Offices P.C.
Smith Duane
LandOfFree
Adjustable clean-air flow environment does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Adjustable clean-air flow environment, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Adjustable clean-air flow environment will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3123445