IEST RP-CC003 4-2011 Garment System Considerations for Cleanrooms and Other Controlled Environments (Includes Supplement 11 2011).pdf

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1、IEST-RP-CC003.4 intended to cover the arms and torso, and meet the knees of the wearer; generally used in cleanrooms of less critical air clean-liness classifications. garment set A complete assemblage of body coverings specified for a particular cleanroom application. garments, cleanroom Specially

2、designed items of clothing that are worn to prevent or reduce the dispersion of contaminants that may be shed or released by cleanroom personnel. 8 IEST 2011 All rights reserved Institute of Environmental Sciences and Technology IEST-RP-CC003.4 Examples: coveralls, footwear, shoe covers, gloves, and

3、 head covers gowning system (also known as garment system) A set of specified articles of apparel and accessories, together with specifications governing their donning, use, doffing (removal), reprocessing or replacement, and storage, as well as specifications related to the way in which they intera

4、ct with equipment, fixtures, and facilities. Gram-positive bacteria Bacteria that retain the purple color of the crystal violet dye when treated with Grams staining tech-nique. knit fabric A fabric made by interlacing threads in a series of interconnected loops. laminated fabric A fabric manufacture

5、d from two or more layers of different materials, bonded together to create a single multilayer structure exhibiting a beneficial blend of the properties of the individual layers. legging (also known as upper) The upper fabric area of a cleanroom boot, which extends over the pant leg or over the ank

6、le and calf of the coverall. Material Safety Data Sheet (MSDS) A document prepared by a chemical or material man-ufacturer, describing the composition, reactivity, properties, and hazards of a chemical or material along with recommended safeguards for handling, storage, and use. non-aseptic cleanroo

7、m A cleanroom having no requirements regarding the presence of microorganisms. nonwoven fabric A flat, flexible, porous sheet structure produced by interlocking layers or networks of fibers or filaments (bonded together thermally, mechanically, or chemi-cally) or by perforating films. opacity The ca

8、pacity of a fabric to inhibit the passage of light and prevent visual recognition of images, as related to personal modesty. particle A minute portion of matter with defined physical boundaries, usually between 1 nm and 1mm in size. pass-through washer A washing machine with two doors, which provide

9、s for the loading of soiled garments outside of the cleanroom and removal of cleaned garments inside of the cleanroom. permeability The quantitative measure of the ability of a material to transfer mass (solid, liquid, or gaseous) through its pores under the influence of a pressure gradient. placket

10、 (also known as zipper placket) A strip of material that completely covers the outside surface of a closed zipper. porosity The ratio of the combined volume of all of the pores in a material to the overall volume of the material. processing The cleaning and packaging of cleanroom garments to meet re

11、quired cleanliness specifications. raglan sleeve A sleeve attached to a modified armhole with slanted seams extending from underarm to neck (see Figure 5). serge The process of overcasting the raw edges of a piece of fabric with long, slanting widely spaced stitches meant to prevent raveling. set-in

12、 sleeve A sleeve attached to an armhole of a garment with a vertical seam (see Figure 5). snood cap (also known as snood) A net or fabric bag worn to hold the hair at the back of the head, and tied behind the head. tumble dryer A drying system that tumbles a bulk quantity of damp garments in a rotat

13、ing drum that is fed by filtered, heated air. tunnel dryer A drying system in which garments are hung sepa-rately on a continuous conveyor that moves them through a tunnel supplied with heated, filtered air moving at a speed sufficient to dry the garments be-fore they emerge into the cleanroom. warp

14、 A series of yarn filaments that extend lengthwise in woven fabric. weft (also known as woof or filling) A series of yarn filaments that are woven crosswise through the warp in woven fabric. woven fabric A cloth made on a loom by interlacing warp (vertical) and weft (horizontal) yarn filaments. IEST

15、-RP-CC003.4 Institute of Environmental Sciences and Technology IEST 2011 All rights reserved 9 4 BACKGROUND AND PURPOSE The design phase of any contamination control program should consider the effects of contamination from all sources. Personnel and their activities are one of the major sources of

16、contamination. Therefore, specification and use of an appropriate gowning system is essential in limiting the elements of human-generated contamination from reaching and affecting product or processes in the cleanroom. This RP is intended to assist the end user, system designer, supplier, and proces

17、sor in defining required performance criteria, test methods, and procedures for gowning system use and maintenance, as well as in developing a quality control plan for the apparel and accessories that may be included in the system. The RP identifies garment-related factors that may influence the per

18、formance of cleanrooms. This RP covers selection, construction, material characteristics, performance, laundering, maintenance, validation, and documentation, as well as test methods that can be used in evaluating relevant properties for cleanroom applications. 5 PRODUCT CONSIDERATIONS This section

19、describes types of fabrics and relevant properties and methods of testing of the materials used in cleanroom garments, as well as the design and construction of appropriate configurations and special features of such garments. 5.1 Fabrics Various types of fabrics are used in the construction of garm

20、ents and accessories to be worn in cleanrooms and other controlled environment areas. Fabric selection is based on the specific degree of contamination control required in the area, as well as other factors, including cost, comfort, and durability. Characteristics of fabrics, threads (continuous fil

21、ament polyester fibers), and other materials used in apparel and accessories may affect the performance of the gowning system. Fabric types can be divided into three main categories: woven, knit, nonwoven. Each type of fabric has specific advantages and disadvantages and is available in a variety of

22、 forms. Fabrics chosen for evaluation should be cleanable by available methods and should be compatible with chosen sterilization technology. Fabrics containing natural fibers, such as cotton, linen, and wool are non-compatible cleanroom fabrics. They will shed particles and fibers and should not be

23、 used. 5.1.1 Woven fabrics a) General Woven fabrics are typically used in the construction of garment systems, including body coverings, head coverings, and footwear, for use in all classifications of controlled environments. In addition, some woven fabrics are used in facial coverings. The yarns us

24、ed in the manufacture of woven fabrics intended for use in cleanroom garment systems are typically made of continuous, multifilament polyester. The number, size, shape, and texture (bulk) of these yarns can be varied in order to impart different properties to the fabric. Woven fabrics are produced o

25、n looms and are formed by the intersecting and interlacing of perpendicular sets of yarns, one of which runs the length of the fabric and the other of which crosses the fabric from edge (or selvage) to edge. These sets of yarns are called: warp (long, or length, direction of the fabric), filling or

26、weft (short, or cross, direction of the fabric). The float of a fabric is determined during weaving. This characteristic is the result of crossing a given number of consecutive vertical strands of yarn with another number of consecutive horizontal strands of yarn (e.g., 1 1, 2 1, 2 2, 3 2, etc.). Th

27、e float can produce a visual pattern known as the weave design. The weave design not only affects the way a fabric looks, but it also affects the physical properties of the fabric. Weave design, yarn density, and filament selection play a critical role in determining the following properties of a fa

28、bric: thickness, weight, flexibility and drape, hand (feel to the touch), filtering and barrier properties, comfort, strength and durability. b) Types of weave designs and fabrics 1) Plain weave fabric or taffetaThe most basic of weave designs, in which yarns pass over and under adjacent yarns in a

29、1 1 float pattern. A plain weave is capable of being the tightest, lightest, and thinnest of the fabric weaves. Even tighter weaves may be attained through calendaring (see section 5.1.1b3). 10 IEST 2011 All rights reserved Institute of Environmental Sciences and Technology IEST-RP-CC003.4 2) Twill

30、weave fabricIn a twill weave, the warp yarns pass over, under, or over and under two or more adjacent weft yarns. The fabric surface usually exhibits a diagonal pattern. Common twill floats are 2 1, 2 2, and 3 2. Longer floats typically allow fabric to be more flexible and therefore softer to the to

31、uch, but usually also cause the fabric to be thicker and have greater permeability. A herringbone weave is a twill variation. Twills and other loosely constructed woven fabrics are recommended for less critical environments. 3) Calendered fabricA woven fabric may be calendered by being pressed under

32、 high heat and pressure in order to soften and flatten the filaments. The calendering process reduces the space between the filaments, thereby reducing pore size, increasing filtration efficiency, and decreasing permeability. The resultant reduction in permeability, i.e., moisture vapor transmission

33、 rate (MVTR), should be assessed, since it may cause discomfort to those wearing the garments. NOTE: Although calendering reduces air permeability, experience has shown a small decrease in MVTR due to calendering when comparing MVTR of the same fabric before and after calendering. 4) Laminated fabri

34、cA woven fabric may also be laminated to a film or membrane in order to further reduce its permeability and to control shedding of fibers and particles. NOTE: Calendered fabric and laminated fabric are typically used in more critical environments. c) Special treatments In controlled environments whe

35、re electrostatic discharge (ESD) is a concern, woven fabrics may contain conductive or static-dissipative monofilament or multifilament yarns in a stripe or grid pattern. In some instances, woven fabrics may also contain durable, topical, chemical finishes designed to provide splash protection, impr

36、ove soil release, reduce static, control microbial growth. It is important that the end user thoroughly evaluate the relative advantages and potential disadvantages of the various treatments or fabric modifications in order to ensure a selected treatment or modification will not adversely affect the

37、 users product or process. d) Effects of processing Garments made of woven polyester fabrics can be laundered and reused many times and, when required, can usually be sterilized by a variety of techniques, including steam and ionizing radiation (gamma-ray cobalt 60 or high-energy, electron-beam E-be

38、am). Ethylene oxide (EtO) is not recommended as a sterilization technology for polyester because outgassing (or offgassing) of residual EtO after sterilization is difficult to control. Repeated launderings may have an effect on some chemical and mechanical fabric finishes and treatments. Care should

39、 be taken to follow the manufacturers recommended fabric care practices in order to maximize the useful life of a garment set. 5.1.2 Knit fabrics a) General Knit fabrics are generally characterized by their stretch, flexibility, and lightness. Multifilament polyester yarns similar to those used in m

40、aking woven fabrics are the primary yarn of choice in making knit fabrics. While it is possible to produce a fairly tight and rigid knit fabric, the innate characteristics of knit fabrics do not provide a stable filtration medium for body-covering garments. Accordingly, knit fabrics are not recommen

41、ded for use in cleanrooms. Knit fabrics are produced on knitting machines and are formed by the interlacing of a series of yarn loops known as wales (column of loops lying lengthwise in the fabric), courses (rows of loops running across the fabric). b) Types of knit configurations and uses 1) Warp k

42、nitsOne basic variety in which the yarns generally run lengthwise with one or more yarns per needle. 2) Weft knitsAnother variety in which a continuous yarn runs crosswise in the fabric, forming all of the loops in a course. Weft knits are an effective method for terminating collars and cuffs of cle

43、anroom garments. Weft knits are also used in T-shirt-type applications. 3) Laminated knitsA laminated knit is a barrier fabric produced by laminating a synthetic film or membrane to one side of a knit fabric. c) Special treatments Knit fabrics may be treated with many of the same finishes as woven f

44、abrics. Knit fabrics may also be specified to contain conductive or static-dissipative IEST-RP-CC003.4 Institute of Environmental Sciences and Technology IEST 2011 All rights reserved 11 monofilament or multifilament yarns for use in ESD-sensitive areas. In warp knits, the static-dissipative pattern

45、 created by the conductive or static-dissipative yarns is typically diamond- or hexagon-shaped. d) Effects of processing Garments made from polyester knits may be processed and sterilized as discussed in section 5.1.1d. Consideration should be given to heat and sterilizing effects on the garments or

46、 knitted features as they pertain to the users requirements. 5.1.3 Nonwoven fabrics a) General A third fabric type used in the construction of cleanroom garment systems is nonwoven fabric. Produced directly from synthetic fibers or filaments by a variety of processes, nonwoven fabrics are commonly r

47、eferred to by the type of process used to create them. Nonwoven fabrics may be used alone or as substrates with nonporous or microporous films in laminate structures. Nonwoven fabrics run the gamut from loosely organized bonded strands to tightly arranged films and membranes. Many cleanroom garments

48、 made from nonwoven fabrics are thought of as single-use or limited-reuse products. The fibers or filaments typically used in nonwoven fabrics for cleanroom environments are polypropylene (a polyolefin), polyethylene (a polyolefin), polyester. NOTE: A polyolefin is any long-chain synthetic polymer c

49、omposed of at least 85% (by weight) of ethylene, propylene, or other olefin units. b) Types of nonwoven fabrics and their uses 1) Spunbonded or thermal bondA commonly available nonwoven fabric typically made from polypropylene in a relatively open structure and used in bouffant caps, shoe covers, etc. Due to the structure of spunbonded or thermal bond fabrics, this type of nonwoven fabric does not demonstrate high barrier performance, i.e., high filtration efficiency and splash resistance. Spunbonded and thermal