by Richard A. Matthews
Perhaps the most exciting and original activity of the ISO Technical Committee ISO/TC209 “Cleanrooms and associated controlled environments” has been the creation of an original standard. It is ISO 14644-7 “Separative Enclosures (clean air hoods, glove boxes, isolators and minienvironments).” This standard defines and explores entirely new ground and it fills a specific need in the cleanroom community.
TITLE: Cleanrooms and associated controlled environmentsPart 7: Separative enclosures (clean air hoods, glove boxes, isolators and minienvironments).
SCOPE: Specifies the minimum requirements for the design, construction, installation, testing and approval of separative enclosures in those respects where they differ from cleanrooms.
STATUS: Currently awaiting ISO issuance of a 5-month ISO DIS (Draft International Standard) vote by all the nations of ISO.
A “separative enclosure” is a cleanroom without any people inside. It is usually relatively small in size, but not necessarily so. Examples are clean air hoods, glove boxes, isolators and minienvironmentsterms that, in many cases, are industry specific. For example, what the healthcare industry refers to as an isolator, the microelectronics industry refers to as a minienvironment. However, the healthcare user quite often has to sterilize his enclosure, whereas the microelectronic user does not. This leads to significant design and construction differences.
By way of clarification, prior to May 2000, ISO 14644-7 was referred to as “Enhanced clean devices.” [See “Enhanced clean devices,” CleanRooms, Dec. 1999, page 42.] The writers of this ISO document were not satisfied with its title, and it was changed to the current term “Separative enclosures” because this term is more descriptive and definitive of these types of clean environments. Also, translation into other languages is more accurate.
The term “Separative enclosures” is generic as is the subject matter covered in ISO 14644-7. Separative enclosures encompass a wide range of configurations from open unrestricted air over-spill to totally contained hardwall containers. They provide the appropriate level of protection from unwanted particle, microbiological, gaseous and liquid contamination, as well as worker safety and comfort.
They provide for special atmospheres and bio-decontamination, as well as remote manipulation of enclosed manufacturing processes.
In writing this ISO-14644-7 standard, all factors of a clean environment had to be considered in miniature. Such issues of material ingress and egress, personnel interface, installation and maintenance, support services, testing and certification had to be considered for a very different style of clean enclosure than what is required for a typical cleanroom.
ISO 14644-7 is a comprehensive 48-page tome highly recommended for anyone who manufactures or uses clean air hoods, glove boxes, isolators, minienvironments or like-minded enclosures. Such enclosures may be no-wall, softwall or hardwall, but they all share a unifying conceptthat a continuum of separation exists between the operator and the operation.
The details can be found in this new ISO standard. Briefly stated, they cover such issues as design and construction, risk analysis, contamination control concept, assessment of external influences, access devices, transfer devices, installation, and testing and approval procedures, including glove breech test, leak test, pressure differential test and routine alarm requirements.
There are many other aspects of these separative enclosures for which guidance is provided in the detailed annexes.
Probably the most valuable is Annex A, which spells out the newly created “Separation continuum concept.” This is the key basis for defining a particular separative enclosure. It weighs the separation means (from aerodynamic to physical) against the assurance of maintaining separation (from low to high). In simple terms, anything from an airflow curtain to a stainless steel wall can be used, recognizing that the more physical the barrier, the higher the assurance of separation.
It is important to recognize that the manufacturing process to be enclosed and the specific requirements for contamination control will dictate where on this separation continuum is the best enclosure design. Some processes will require only a simple air curtain for effectiveness. Other processes will require softwall curtained enclosures, and still others will require leak-tight stainless steel containers. The process will dictate the choice.
However, no matter what the choice is, all aspects of ISO-14644-7 will apply. Additional annexes address such issues as air handling and gas systems, access device options in detail, transfer device options in detail, leak detection and testing methods, pressure integrity of enclosures and support devices, as well as design and construction parameters.
It is impossible on this one page to convey the true value of this document. You need to read it yourself. ISO-14644-7 will be available shortly for a nominal charge from the Institute of Environmental Sciences and Technology (IEST), 940 East Northwest Highway, Mt. Prospect, IL 60056. Ph: (847) 255-1561; Fax: (847) 255-1699, or at iest.org. The IEST is currently accepting orders for fulfillment as soon as the ISO releases 14644-7 for its DIS vote, which is expected shortly.
Whether your interest is “isolators only” because you are in the healthcare field or “minienvironments only” because you are in the microelectronics field or “glove boxes only” because you are in the nuclear field, or even just plain “clean air hoods,” you need to be very familiar with ISO-14644-7. It will affect your business, for it is the newly created international standard covering all separative enclosures requiring a contamination controlled environment.
It provides a common ground for all the disciplines noted above.
Richard A. Matthews is founder of Filtration Technology Inc. (Greensboro, NC) and president of Micron Video International. He is chairman of the International Organization for Standardization Technical Committee ISO/TC209 “Cleanrooms and associated clean environments,” and past president of the Institute of Environmental Sciences and Technology. He is on the CleanRooms Editorial Advisory Board.