micron clean handbook

Garmentmanagementfor controlledenvironments: an introduction

getting started

test ing

typica l c leanroom laundry funct ion

garment management systems

c leanroom garments

contaminat ion contro l12

3

4

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the micronclean organisation

c o n t e n t

Micronclean International was established in the 1980’s to meet the growing need for professional cleanroomclothing management services. Now Micronclean is present throughout the world and has a portfolio of customers indiverse industrial and service organisations.

The organisation operates to the highest standards of professionalism, workingwithin the very latest international codes of practice. It is recognised as an innovator, having contributed significantly to modern cleanroom garmentdesign and management techniques.

All Micronclean centres operate from modern premises and witha workforce committed to a ‘right first time’ philosophy.

Objectives and philosophyWe aim to be the best! We are prepared to meet the

ever increasing technical demands on fabrics, clothing style production and the disciplines required within our processing plants.Only by being the best do we expect to command the respect andfuture business from our customers.

The International dimensionMicronclean has but one standard - the highest possible quality.

Our procedures are common to all processing plants and our policy ofclosed loop garment management is designed to ensure efficient tracking and optimised asset management irrespective of geographicallocation. One policy, one standard!

Communication with customersAll Micronclean companies have a commitment to communicate with their

customers. The results for garment performance and the processing are both communicated.We help you with the training of your personnel. We keep you informed on international standardsand developments and we help you to find any specific information you might need. Micronclean is putting a lot of effortinto the continuous improvement of our communications by using technology (e.g. the internet).

Global guaranteeWhen you are served by a Micronclean company, you have the assurance of dealing with a quality global cleanroom

solution partner.

Uninterrupted serviceEvery Micronclean company has a fully detailed contingency plan with another Micronclean plant to ensure your

cleanroom garment needs are always met.

Leading edge technologyMicronclean companies undergo a formal technology audit every six months. Then, against a peer group of advanced

cleanroom operations from around the globe, quality of output, equipment capabilities and quality systems are analysed,compared and refined.

Research and developmentMicronclean International has permanent R&D projects. These projects include all elements of the cleanroom services

we offer, be it specific decontamination processes for a certain industry, garment and fabric development. We have our owntesting facilities and co-operate with specialised research laboratories where needed. Most of the time we include some ofour customers in our R&D projects to combine our know-how with practical experience.

Cleanroom solution partnerAll twenty-plus Micronclean companies around the globe share informaton. They are truly partnering with customers

to find solutions for all their cleanroom needs. Micronclean International has unparalleled depth to call upon to help findthose optimal solutions. We have resources around the globe, with experience in every cleanroom application, classificationand service aspect. Micronclean companies lead the industry and can rapidly bring the experience and knowledge to helpsolve your toughest problem.


Garment management for controlled environments: an introduction 3

Low cost providerMicronclean companies benchmark all leading indicators of efficiency and performance on a continuous basis.

Copy exactlyMicronclean International understands international customer’s need for identical cleanroom processes across multiple

locations. We are uniquely positioned to accommodate “copy exactly” requirements. We speak a common languagearound the globe and have a support team charged with facilitating cross-site communication. We operateinternational working groups and an aggressive schedule of cross training and visitation programmes.

International standardsMicronclean International has representatives at the standards bodies which impact your business

and quality requirements.Micronclean International has the manpower and international reach to stay abreast ofdevelopments communicating them promptly around the globe. Micronclean companies meet all recognised standards.

Market coveragePrinciple areas of operation include: Microelectronics - Pharmaceuticals - Opticals - Biotechnology -

Telecommunications - Aerospace & Defence - Medical devices - Static Sensitive Areas - Hospital Pharmacies - Cosmetics - FoodProcessing - ...

With this brochure Micronclean International provides you a basic knowledge of contamination control and garmentmanagement for cleanrooms. We will be pleased to assist with any information you might request.



Headquarters:

Micronclean InternationalDiedenweg 946717 KV Edethe Netherlandsphone: +31 318 622 484fax: +31 318 630 [email protected]

Members Europe:

AUSTRIAMicronclean AustriaWozabal Sterilgut-SystemeAtterseestraße 974860 Lenzingphone: +43 7672 913 0fax: +43 7672 913 85www.wozabal.com

BELGIUMMicronclean BelgiumScaldis St.Martin36, rue de la Hurtrie7600 Peruwelzphone: +32 69 77 16 25fax: +32 69 77 57 70www.micronclean.com

DENMARKMicronclean DenmarkBerendsen Textil ServiceVølundsvej 124300 Holbækphone: +45 59 43 22 22fax: +45 59 43 53 72www.berendsen.com

FRANCEMicronclean FranceInitial Services TextilesParc d’activités de Villejust6, rue Lionel Terray91971 Courtaboeufphone: +33 1 69 31 76 80fax: +33 1 69 31 76 89www.initial-btb.fr

GERMANYMicronclean GermanyBilger-SchwenkStollweg 672760 Reutlingenphone: +49 7121 3121 57fax: +49 7121 3121 21www.micronclean.de

HOLLANDMicronclean HollandMicroncleanKoopman Heeresweg 108701 PR Bolswardphone: +31 515 578 990fax: +31 515 578 981www.micronclean.nl

IRELANDMicronclean IrelandMicron Clean (Ireland)Spiddal Industrial EstateSpiddal, Co. Galwayphone: +353 91 553 066fax: +353 91 553 068www.micronclean.ie

ITALYMicronclean – ICS ItalyLinen Supply ItalianaVia Cesare da Sesto 1520123 Milano MIphone: +39 02 89 40 05 23fax: +39 02 89 40 14 93www.intlcleanroom.com

SWEDENMicronclean SwedenBerendsen Textil ServiceRättarvägen 4611 35 Nyköpingphone: +46 155 20 96 00fax: +43 155 28 49 40www.berendsen.com

Micronclean SwedenBerendsen Textil ServiceAxel Danielssons väg 195215 92 Malmöphone: +46 40 36 80 00fax: +46 40 36 80 60www.berendsen.com

UNITED KINGDOMMicronclean NewburyMicroncleanC1 Faraday RoadNewbury, BerkshireRG14 2ADphone: +44 1635 37901fax: +44 1635 31528www.micronclean-newbury.co.uk

Micronclean SkegnessMicroncleanRoman BankSkegness, LincolnshirePE25 1SQphone: +44 1754 767377fax: +44 1754 610344www.micronclean.co.uk

Members America:

BRAZILMicronclean – ICS BrazilALSCO Toalheiro BrasilRua Conde de Itú, 87504741-001 São Paulophone: +55 11 5523 8722fax: +55 11 5523 6961www.intlcleanroom.com

USAMicronclean – ICS USAAmerican Cleanroom GarmentsP.O. Box 82269Portland, OR 97282-0269phone: +1 503 233 5445fax: +1 503 235 0509www.intlcleanroom.com

Micronclean – ICS USAAmerican Cleanroom Garments971 Northpoint BoulevardWaukegan, IL 60085-8214phone: +1 847 473 1200fax: +1 847 473 4595www.intlcleanroom.com

Micronclean – ICS USAAmerican Cleanroom GarmentsServitex Cleanroom Services3 Yadkin StreetDurham, NC 27703phone: +1 919 957 9800fax: +1 919 957 0403www.intlcleanroom.com

Members Australia:

Micronclean – ICS AustraliaClean Room Products1 Carlotta StreetArtamon NSW 2064Sydneyphone: +61 2 9439 3622fax: +61 2 9437 4351www.intcleanroom.com



Micronclean International

Contamination control is a key element in the concept of the zero defect philosophy employedby an increasing number of modern production and service organisations.

Few productive entities escape the need for close attention to contamination control. Gone arethe days when cleanroom concepts were confined to ‘leading edge’ space and biological developments. The cleanroom philosophy can now be found in production environments asdiverse as vehicle finishing and food processing where all important added value factors arereliant on quality and performance.

1.1. The nature of contamination

Contamination can be considered as anything which has an effect on the quality or performance of something beingcreated. Contaminates can take the form of particulate, biopollutants, chemical cross-contamination or electrical charges(ESD), which individually or collectively can have a deleterious effect on product or process performance.

That such contaminates can be of infinitesimally small or of surprisingly large proportion - as small as 0,1 micrometers in the caseof particulate or as high as 0,1 Amp in ESD terms - makes the task all the more challenging. Furthermore, nosingle element can be considered in isolation. The integrity of any process is only as strong as its weakest link, be that in theoperating environment, the logistics including style, composition and comfort of clothing or in the inherent disciplines whichmust be maintained throughout the cycle.

By working within a controlled area like a cleanroom, some pollutants can be filtered out, others eliminated byimprovements in the production environment. Airborne particles - skin, fibres, bacteria - pose the greatest challenge.

1.2. Different contaminants

Whilst there are many different potential contaminants, these four pose thegreatest threat:

1.2.1. Dust

In this context this can be considered as skin shed by operatives or particulate matter brought into the production area from outside either by

operatives or through poorly filtered purging air. (fig. 01)

1.2.2. Bacteria

In the broadest sense this embraces not only particulate andchemical pollutants likely to affect the quality of production but also thehealth of operators. Thus production chemicals and incoming air mustbe strictly controlled. This is mainly a problem for pharmaceutical andfood processing industries. (fig. 02)

1 contamination control


fig. 01

fig. 02

1.2.3. Chemicals

Potential cross-contamination from process-to-process or from bodies, garments or equipment entering the controlledenvironment.

1.2.4. Electrical charge

Static electricity is a contaminant causing possible problems in all areas of cleanroom activity. Polyester cleanroom garments produce static electrical charge as fabric is in contact with fabric or with garments worn under the cleanroom garments. Electrical charges of many thousands of volts may be present on the garments during use. The charge may bedischarged at any time to the cleanroom structure, articles or products in the cleanroom. Discharges of static electricity maycause problems in the following ways:

- Microelectronics: the discharge of static electricity may damage sensitive products such as microchips and disc drives. Discharges of static electricity occur so rapidly that current flow for a short duration may be highenough to damage products. Damage may weaken components causing premature failure.

- Pharmaceuticals: these cleanrooms are not normally associated with products that are damaged by electrostaticdischarge, however many pharmaceutical cleanrooms require protection:- Protection against explosion caused by spark discharges- Protection against damage to sensitive microelectronic measuring equipment- Protection against attraction or repulsion of micro-organisms by electrically charged cleanroom

garment fabrics.

1.3. Cleanrooms

The history of cleanrooms starts during World War II. Indeed during the assembly of the first atomic weapons, it wasfound that some of the problems were related to dust. The idea of the HEPA (High Efficiency Particulate Air Filter) wasintroduced in an air-conditioned environment.

A next step in the development of cleanroom techniques was the space race. Dust particles causedproblems in the liquid oxygen release valves in the rockets. This introduced a research

programme to develop precision component assembly methods. This programme led tothe laminar flow cleanroom.

Microelectronics and the pharmaceutical industries started using cleanrooms in the60’s and 70’s. Since the 80’s other industries became interested in the advantages of cleanrooms for their critical production processes. Now we findcleanrooms in such diverse industries as: opticals; biotechnology; tele-communications; aerospace & defence; medical devices; static sensitive areas;hospital pharmacies; cosmetics; food processing; ... Cleanroom concepts alsofound their way into the modern operating theatres.

A cleanroom is an enclosed space served by HEPA filtered air at positive pressure. In view of the major threat to the ‘clean’ environment posed by

humans, the area should preferably be unpopulated by operators - obviously notalways possible.

Modern cleanrooms are extremely efficient in reducing contamination but there areno standard solutions. Each industry and location has its own priorities. To a micro-

electronics specialist the problem of static electricity is probably as critical as particulate contamination; to a micro-biological company the attendant risk might well come from the danger

from toxins or explosion. Each project must be the subject of individual risk assessment.

Logically, the current trend is towards compact, localised cleanrooms or compartmentalised workstations for essential cleanworking rather than large volume coverage. This approach is most flexible, controllable and economical.

Whilst much has been achieved in the design of production benches and equipment, such elements now contribute abouthalf the pollution, the balance being from incoming air, gases, chemicals and people.



RA

RA

Turbulent

SA

Displacement

RA

RA

Turbulent

SA

Displacement

1.4. Basic cleanroom concepts

Modern cleanrooms fall into two principal categories:

- Unidirectional cleanrooms (fig. 03). The airflow in this type of cleanroom is often vertical. The air flows downwards through HEPA or ULPA (Ultra Low

Penetration Air) filters located in the ceiling and is extracted through perforated flooring or grilles mounted in the walls atfloor level. Airflow in unidirectional cleanrooms may also be horizontal when the air flows through a full wall of filters and isextracted through returns in the opposite wall. Horizontal airflow is used in applications where operations with stringentcleanliness requirements take place close to the wall of filters and operations with decreasing cleanliness requirements takeplace “downstream” (meaning further away from the filter wall).

- Non-unidirectional cleanrooms (fig. 04). In this type of cleanrooms the air flows from HEPA or ULPA filters located in various positions and is returned through

opposite locations. Filters may be distributed at equal intervals throughout the cleanroom or grouped over critical areas.Because of the distribution of the filters and returns, the airflow may be turbulent in nature.

In several cleanrooms a combination of both types can be found.



Horizontal

SA RA

Vertical

SA

RAHorizontal

SA RA

Vertical

SA

RA

fig. 04

fig. 03

The classification of the cleanroom environment is determined by the number of particles of a given size in a cube ofair at any moment. Fig. 05 illustrates the established standard classifications for controlled environments. These form partof internationally accepted working practices detailed elsewhere in this publication.

Class limits (particles/m3)

ISO 14644-1 Fed Std. 209E 0,1 µm 0,2 µm 0,3 µm 0,5 µm 1 µm 5 µm

ISO Class 1 101= 10 2

ISO Class 2 102= 100 24 10 4

ISO Class 3 Class 1 103= 1.000 237 102 35 8

ISO Class 4 Class 10 104= 10.000 2.370 1.020 352 83

ISO Class 5 Class 100 105= 100.000 23.700 10.200 3.520 832 29

ISO Class 6 Class 1.000 106=1.000.000 237.000 102.000 35.200 8.320 293

ISO Class 7 Class 10.000 352.000 83.200 2.930

ISO Class 8 Class 100.000 3.520.000 832.000 29.300

ISO Class 9 35.200.000 8.320.000 293.000

fig. 05: Airborne particulate cleanliness classes



1.5. Cleanroom standards

The construction and operation of cleanrooms is subject to a number of international standards and recommendedpractices.

The first standard on cleanrooms was the American Federal Standard 209, which has been revised several times. The role ofthis Federal Standard will be taken over by the international standard ISO 14644.

For the operation of cleanrooms several standards and recommended practices have been developed by standardisationbodies such as ISO and CEN or controlled environment organisations such as IEST, FDA, ... In most cases these organisationsare related to a specific industry, e.g. HACCP for the food processing industry, GMP for the pharmaceuticals, ...

1.6. The human element

Between 40 % and 80 % of contamination can be traced to human operatives working in cleanrooms.

The threat posed by human intrusion into cleanrooms is obvious - each of us sheds our outer layer of skin approximately everyweek in the form of loose particles (about 4/5 micrometers) or groups of cells typically 25/30 micrometers or larger. Abrasioncan grind these into a fine powder, using convection to issue these particles - some of which contain chemical or bio residues- into the atmosphere.

Fig. 06 shows the particulate shed by humans during a range of activities.

Sex, age, temperature differentials and patterns of activity all have a bearing on the rate of issue, as do contaminantsfrom clothing, cosmetics and personal hygiene.


100.000

500.000

1.000.000

2.500.000

5.000.000

10.000.000

15.000.00030.000.000

fig. 06


1.7. Use of specialist clothing

The human body creates its own micro-environment of potentially damaging particulate contamination (fig. 07). Sincehumans are essential to production situations, damage limitation through the use of purpose-designed cleanroomclothing has proved to be the most practical solution to the problem.

The use of specialist clothing is now commonplace. To be effective it must:- form a particulate barrier for the human micro-environment- allow freedom of movement and be comfortable- address any specialist requirement, e.g. static dissipation- avoid being a significant particulate contributor itself

Details of parameters for garments includingthose for the head, torso and feet are included insection 2 of this publication.



fig. 07

2.1. Garment materials

As mentioned in the previous section, people are one of the greatest contaminants in a controlled environment. Therefore we need specialised garments to protect the environment and the workplace from the human contaminant.

Cleanroom garments are unique as they must meet specific protection criteria. This involves special materials, particular construction and individual styling. They must be comfortable, easy to apply and practical in use.

Inevitably the result is a compromise between ‘wearability’ and optimum ‘barrier efficiency’. The overriding function is containment of particulate matter. The contaminant should be retained within the garment and not released into thesurrounding atmosphere. Of course the garment itself should not create any contaminants.

In some cases additional requirements for protection are needed depending on the actual use of the garments and thesituation in the cleanroom. These requirements can include ESD characteristics, protection against flames or chemicals, ...

The fabrics must:(a) be low shedding(b) permit the body to breathe whilst trapping particles within the garment(c) be flexible enough for comfortable wearing(d) withstand repeated cleaning / sterilisation cycles(e) meet any specific requirements like control of static(f) meet the opacity requirements (g) look and feel as good as possible(h) be cost-effective

There are 3 broad categories of fabric used in the construction of cleanroom garments. These include:- woven fabrics- laminated or membrane fabrics- disposable or limited life materials

2.1.1. Woven fabrics

First of all there is the choice of the fibre material. Since the garmentsshould not shed particles, it is obvious that the fibres need to be continuous.This excludes all natural fibres since all of these have a limited length (e.g. cotton fibres have an average length of 30 mm). Polyester still has thebest characteristics for use in cleanroom conditions (see further in this section).Fig. 08 shows a cotton fabric - fig. 09 is a polyester cleanroom fabric.

Woven or re-usable fabrics are the most commonly used fabrics in cleanroomenvironments. As the name implies, they are woven on sophisticated looms fromyarns of continuous filaments of polyester. The thickness of the yarn and filaments isimportant (the finer the yarn the tighter the weave can be made and the better the filtration), but also pattern and tightness of the weave isimportant to reduce the pore size to a minimum. The use ofcontinuous filament polyester means that there are few loose endsfrom which particles may be shed.


2 cleanroom garments

fig. 08

fig. 09

The weave is critical to the trade-off between desired filtration and comfort. The yarn must be closely and consistently woven to provide a consistentfabric pore size ... too small a pore size will cause wearer discomfort throughinability of the fabric to ‘breathe’ and emit vapour; too large and the garmentbecomes an ineffective filter.

Plain weave (fig.10) produces a tighter fabric and good results under test buttight bending of the yarns can lead eventually to damageand particulate flaking.

Twill weaves (fig.11) produce less stressing andshow superior results in ‘body box’ testingwhich simulates normal use.

Calendered woven fabrics are another optionin which the fabric surface is flattened afterweaving under (heated) rollers to produce ashiny finish. This can, however, affect thebreathing characteristics and is subject topore re-opening after prolonged use.

2.1.2. Laminated fabrics

Laminated fabrics, favoured for some high grade microelectronic environments, are produced by bonding together 2 or more layers (often a combination of woven and non-woven fabrics) (fig. 12). Particle retention andvapour permeability are achieved by incorporating a membrane that will givethe filtration required. The lamination is a critical process in the productionof these materials.

To work efficiently garments from these materials require optimum sealing atall openings, making production relatively expensive.

2.1.3. Disposable or limited use fabrics

The most common of these non-woven fabrics are from spun bonded olefin and polypropylene. Comprising a denselyinterlinked matt of fibres, these can provide good results for a limited period.

Garments from such materials need to be processed and decontaminated before use in the cleanroom.

Disposable or limited use garments are mainly used in those environments where protection of the wearer against potentially hazardous products are required. A typical example is an environment where toxic chemicals are used. Otherapplications for these garments are situations where the process would ruin re-usable garments, such as working with certaininks, or where the wearer is on a one-off visit to the cleanroom.

Widespread use is seldom cost-effective but in low frequency applications where a managed cleaning cycle is unwarranted orwhere there is a casual requirement for units off-the-shelf, the disposal concept may prove perfectly viable.


2 cleanroom garments

fig. 12

fig. 10

fig. 11


2 cleanroom garments2.1.4. Coping with Electro-Static Discharge

Almost all modern cleanroom fabrics have a “grid” of conductive yarns woven into the fabric. These yarnscontain carbon or other electrically conductive material so that the fabric becomes

electrically conductive. The conductive yarns may have the conductivematerial exposed, partially encapsulated or totally encapsulated in a non

conductive polyester (fig. 13).

It was thought that garments manufactured from suchfabric would discharge to “earth” if connected to a groundingpoint in the work area. The methods commonly used are by a wriststrap or by use of an electrically conductive floor and electrically

conductive soled footwear. Garments manufactured by traditionalmethods prove difficult to electrically connect to ground and this

approach, at best, reduces electrostatic charge from several thousandvolts to several hundred volts. In the past this degree of control was

adequate and still is in some applications, but as products have become sensitive to voltages as low as 25 volts, more effective control is required. In these cases the

design and construction of the garment will require special attention.

2.2. Garments

2.2.1. Design and construction

For the design and construction of the garments the same basic requirements as the fabrics apply. Indeed, a performing fabric does not necessarily mean that the garments made up in this fabric will meet the requirements for use incontrolled environments.

A garment produced purely for maximum protection would be made out of one piece of material, without seams and covering the whole body. Clearly this is impractical, if only because of personal size and shape differences. Normally thedesign will, nevertheless, feature the minimum of seams and closures, no pockets, belt pleats or tucks and be configured toreduce abrasion against skin and any under clothing.

Seams must be constructed in such a way that they do not allow air flow through them and thus keep the particles inside thegarment. They must also encapsulate the raw edges of the material. Raw edges should be prepared (e.g. heat sealed orencapsulated) to prevent fibres fraying.

Since the performance of the garment equals the performance of the weakest part, all materials used in the garment (sewingthread, zips, studs, knitted material for cuffs, ...) must meet the basic requirements individually. This means that e.g. thesewing thread must also be a polyester filament yarn or the zip must resist repeated sterilisation cycles.

The design of the garment system must be such that air currents generated by the natural movements of the wearer andtrapped by tightly woven fabrics do not pass readily through garment closures. This means that particular attention needs tobe paid to fitting around the face of hoods, garment closures and fitting at neck, wrists and ankles. The better fitting andmore flexible the garment, the less this 'pumping' action and air compression. This means careful selection of materials, careful styling and the availability of a suitable range of size options.

To combat static dissipation the garment construction may require adding conductive tapes to the seams, earthing studsand/or specific sole material and cuffing for full effectiveness.

Garment systems may include several layers of garments, depending on the extent of the control required. Generally morelayers mean more protection. Choosing the right inner layer can also improve the comfort of the wearer and thus lead toimproved working conditions.

Most cleanroom garments are unisex, produced in a wide range of sizes and with possible options to suit most male andfemale requirements off-the-shelf. This reflects the need for cost-effectiveness whilst offering the choice required to ensuresuitability for purpose.

fig. 13


2 cleanroom garments2.2.2. Areas of protection

Garments are designed to provide protection for the head, body, hands and feet.

2.2.2.1.Head

Options include open face hoods, pullover hoods, peaked hats, berets, face masks, hairnets, goggles, helmets and avariety of specialist protection items. In some environments full head covering with external supply of air is required.

In general the more you cover and the more layers you use, the higher the level of protection. Items which only partially coverhair give only limited protection and are apt to be misworn. (fig. 14, 15, 16)

2.2.2.2.Body

A wide variety of undergarments, secondary and tertiary layer garments are available to meet the infinite variety ofcleanroom applications.

Coveralls (anything up to ISO class 3 conditions - fig. 17) are the most popular top layer and are normally essential where ahigh degree of protection is required. These are normally front entry and sealed with a zip from crutch to neck. Other optionsinclude centre zip coats (fig. 18) and trouser/jacket combinations (ISO class 7 or less strict).

Undergarments can either be one-piece or a top and trouser set. (fig. 19)

fig. 14 fig. 15 fig. 16

fig. 19fig. 17 fig. 18


2 cleanroom garments2.2.2.3.Hands

The choice of gloves involves decisions about tactile sensitivity, nature of use and cost. The majority are disposable butseveral types of re-usable barrier gloves are available - used mainly in microelectronics production environments. (fig. 20, 21)

Inner gloves made of knitted re-usable materials may improve the comfort for the wearer.

Oversleeves, which cover the forearm and wrist, may also be worn to give added protection.

2.2.2.4.Legs and feet

Coveralls are used in combination with dedicated captive footwear to provide the protection required in highclassification cleanrooms.

Where the demands are more relaxed and outdoor clothing is worn in the cleanroom, shoes will normally be covered by overshoes which can be either disposable or re-usable. In such cases staff should be required to ensure that items of general clothing are clean and not liable to produce fibre contamination. Alternatively, an undergarment suit or disposablecleanroom socks can be worn to achieve adequate leg covering and protection.

Boots and overshoes are available with a variety of soles and fastenings to meet pharmaceutical, (micro-)electronic and otherspecial needs. Some examples are shown in fig. 22 and 23.

2.3. Garment selection

In establishing a system for garment selection one must consider the broader aspect of cleanroom use: suitability offabric, garment style, layers, the nature of the tasks involved, costs and any regulatory or specific customer requirement.

The classification of the cleanroom will inevitably be the major factor in determining the degree of personnel protectionrequired and thus the fundamental choice of garments. Factors which also need to be addressed include the provision ofchanging facilities, operating procedures and the garment management system. These are covered in Section 3 of this publication.

fig. 20 fig. 21

fig. 22 fig. 23


2 cleanroom garments2.3.1. Choosing a fabric

Technical specification is clearly important in fabric selection (see section 2.1.) but so are these practical factors:

- Continuity of supply for both initial and subsequent batches for garment replacement.- Repeatability: successive batches must conform to specification.- Wearer comfort - essential for optimum productivity. Not just theoretical performance but embracing the “feel right”

factor, opacity, air and vapour permeability, fit, style, ... factors which sometimes only wearer trials will confirm.- Special factors including the need for sterilisation (often gamma irradiation or steam sterilisation). Polyester is the

only fabric which will withstand repeated gamma irradiation and even this involves fibre breaks and loss of integrity under intense treatment.

- Cost of the material.

The aim must be to match a fabric to the combined needs of the end use, be they for unclassified or the highest gradecleanroom. Investing unnecessarily in a high specification material for a low grade project merely wastes money. On the otherhand to under-specify can have potentially disastrous consequences. Suppliers will readily assist with the selection.

2.3.2. Choosing a style

The wearer issue system - either disposable products or re-usable pool stock will influence the choice of garment.

Disposables equate to limited life items like gloves, masks and certain caps and overshoes. These are usually the subject ofbulk supplies in one or a limited range of sizes for distribution at the point of use.

When re-usable garments are provided the options are to issue each wearer with an individual and identified set or to provide a pooled range of sizes and for each wearer to select a set of garments as required.The latter policy has cost advantages since the number of items issued as part of an efficient garment management regime isless in a pool programme. It also provides a stock of garments for casual users, avoiding the need for disposable garmentsfor visitors.

The policy should allow for the need to isolate the garments or specify different fabrics for staff whose tasks create stainingcontaminants which could spread through the garment stock.

In any pool system care should be taken to relate choices of style and size to the existing and any intended balance ofmale/female wearers and to the range of tasks.

Fig. 24 gives some indications for the type of garments in function of the classification of the controlled environment.

ISO class body head feet hands3 coverall full hood + mask long overboots powder & lint free4 coverall full hood + mask long overboots powder & lint free5 coverall full hood long overboots powder & lint free

mask as required6 coverall or coat hood or snood overboots or powder & lint free

overshoes7 coverall or coat hat or cap overshoes as required8 coat hat or cap overshoes as required

fig. 24


3 garment management systemsThe principle aim of any garment management system must be to ensure that every person working in the controlled environment has access to appropriate clothing on a continuous basis,taking into account the three basic elements:

- In-use phase- In-transit phase (to and from laundry)- In-laundry phase

The cleanroom user's quality commitments are dependent on the consistent availability of suchsupplies. Thus the entire project team must essentially aim towards a zero tolerance quality programme. In practice professional suppliers work within the ISO 9002 standard or its equivalent.

3.1. Cost parameters

Whilst each set of cleanroom requirements is unique to individual sites there are certain basic elements which have tobe considered in any cost projection:

- the capital cost for garment purchase- capital cost of plant if opting for in-house laundry- capital cost of stockholding- projected duration of the programme- staff cost, including any management element- operating costs if opting for own laundry (including distribution, stock handling, maintenance and repair)- garment processing cost in case the laundry cycle is contracted out- rental cost in case the garments are rented from a service company

3.2. Supply options and quantities

Fig. 25 illustrates a typical service cycle. This assumes that cleaning will be undertaken by an outside specialist laundry.

Two fundamental decisions are to be made:

- to buy or to rent the garments- to dedicate garments to each person or install a pool stock

3.2.1. To buy or rent?

However you evaluate the two options the costs invariably come out much the same. Those who buy outright can claim control over the asset but take on the responsibility of the day-to-day management and running costs of the processing operation. They will also have to finance the stock of garments and make sure there are at all times new garments available. In return, they save on the profit element required by any external garment management facility.

Sufficient to say that there is a significant movement towards the use of external specialists handling the entire supply / handling / cleaning cycle. The investment in plant and manpower, the commitment required and the technology involved inachieving the ever higher demands of performance (focus on core business) has much to do with this trend!

Those opting for the renting service, where garment purchase cost, identification, replacement and refurbishing costs are covered by a periodical (mostly weekly) rental charge, will certainly benefit from greater all-round support, particularly in areasof programme development.

In a full garment management service, the supplier will undertake 100% of the garment life cycle, including programme development, supply, collection, cleaning and delivery. Under this programme the garments will effectively be leased to thecustomer under a contract spanning several years.

3.2.2. To dedicate or use a pool stock

The decision of whether to commit a set of garments to aspecified individual or have staff draw from a pool stock, has to be apragmatic one based on the circumstances. By far the majority ofthose who employ external contractors choose pool stock programmes with all the benefits of readily available replacement garments in the event of loss or damage and the significantly reducedgarment quantities.

Fig 26 illustrates how the volume of garments required to support aweekly service cycle (most programmes are based on a weekly projection) can amount to a significant investment. Enough garmentshave to be in circulation to allow the user company to have at least aweeks stock of clean garments on site.

The number of garments required will also depend on the frequencyof changes made by the wearers. Recommendations for usageaccording to cleanroom classification are covered by the IESTRecommended Practice CC003 (varies from one change a week forISO class 8 and 9 to a change at each entry in ISO class 3 or cleaner).

To this must be added a quantity in transit (influenced by the numberof deliveries per week) and a quantity equal to a week’s usage at anytime being processed in the laundry.

The implications of dedicating specific sets of garments to individual operatives are clear to see. The pool stock, by comparison, allows reductions based on experience of true usage and a much more flexible operating cycle, particularly at thepoint of distribution where handling and storage can be critical.


3 garment management systemsfig. 25

CHANGEFREQUENCYBASED ONWEEKLYCYCLE

1 x PER WEEK

STOCK = 3 SETS

2 x PER WEEK

STOCK = 5 SETS

DAILY =

5 x PER WEEK

STOCK = 11 SETS

4 x PER DAY =

20 x PER WEEK

STOCK = 44 SETS

IN-USE TRANSIT LAUNDRY

fig. 26


3 garment management systems3.2.3. Wearer measurement and supply programmes

Whether purchasing or hiring, dedicating or pooling, the supplier needs to know the size mix and the nature of the garments he is to issue.

The best way to obtain the size mix is by using sets of garments covering the full range of options, allowing wearers the chanceto try a complete set (under- and outer-garments where applicable). It is by no means certain that the wearer of a mediumhood will also require a medium coverall or medium overboot. It is important for the wearer not only to put on the set ofgarments, but also make the movements he is likely to make during his activities in the controlled environment to make surehe gets the best and most comfortable fit.

Normally suppliers will readily provide such fitting sets. The assessment of each wearer’s requirements should be agreed byboth parties at the end of the measurement session.

Supply quantities will be a function of:

- the number of staff to be equipped- the changing frequency- the process turnaround time- any required buffer stock for replacements or visitors

3.3. Garment issue

Traceability requirements dictate that, prior to the issue of any garment, each should be identified detailing size, style, issue date and any otherrelevant information. Increasingly this is being achieved by using a bar code or chip as illustrated in fig. 27.

In addition to providing proof of receipt and issue this coding will formthe basis of a stock management programme which will monitor the garment's history. Events such as repairs, replacementsand judgements about the continued suitability-for-purpose of eachgarment will take place within the agreement between supplier and customer.

Since a similar system makes it possible to know exactly which itemsare dedicated to a certain batch in the laundry production, all rela-tive information on the decontamination cycles (monitoring of thewash and dry process, cleanroom monitoring at the laundry, results ofbatch testing) can be traced for each individual garment. This will beessential in the quality management system of both the garment supplierand the customer.

The information obtained will be used to improve the garment managementfor the customer. Indeed accurate information on e.g. the actual changes,number of garments available at any given time, real life-time of the garments, over or under usage of garments for certain individuals or departments will lead to better understanding of the situation and thus to better management of the garment issuing.

Information technology makes it possible to have this information available inthe most convenient form for the customer. Even on-line access at any momentis possible through the internet.

fig. 27


3.4. On-site procedures

Whilst the design and layout of cleanroom preparation areas are site-specific, the principles of employing progressiveareas from the discarding of outdoor clothing, through robing to the air shower prior to entry into the cleanroom are well established.

Staff training in robing procedures is essential for the effectiveness of the garment system. These procedures may differ infunction of the class of the controlled area and the garments in use. In most cases the following steps will be included inthese procedures:

- remove all jewellery and store in lockers provided- remove all cosmetics- remove shoes, stow in lockers and apply any specialist cleanroom footwear- apply any specified initial hair covering (e.g. a hairnet)- clean face and hands using soap and water, thoroughly scrubbing to remove all soiling, paying particular attention to

fingernails- fit disposable robing gloves to avoid cross-contamination during robing- put the headwear on first, making sure hair is tucked in and out of sight. Smooth the shoulder cape and do up any

fastenings.- fit face mask- draw the garment from its store, remove any packing and fit the garment as directed, ensuring no contact with floor or walls- ensure any headwear elements are tucked well inside the garment and close fastenings (zip, neck studs, ankle and wrist

fixings).- collect and fit cleanroom overboots as directed, ensuring that items do not touch contaminated surfaces. Fix securely

without leaving any draping ties.- change from robing to cleanroom gloves as directed, then move to the production area

Exit from the cleanroom using the reverse procedure, employing receptacles provided specifically for clothing that will be wornagain or for garments to be decontaminated, depending on the change cycle.

3 garment management systems


4 typical cleanroom laundry functionThe basic functions of the laundry can be seen from fig. 25. Essentially there are four basic functions:

- stock control- handling of incoming and outgoing garments- cleaning and decontamination- quality control

4.1. Issue and identification of stock

One of the primary reasons for choosing to use a contract cleanroom laundry is the anticipated thoroughness of stock handling and control. In today's laundry, every garment is positively identified and the subject of closedloop control which enables full tracking and service history feedback.

There are no standard breakdowns of content but a coding system might include:

- company name of the customer- size- operative's code and name- departmental location- garment number and issue date- user cleanroom reference- garment type, fabric and colour- locker number

Information which might be recorded with each scan could include the following which gradually builds up a vital history foreach item:

- current location- current process date- condition of garment- repairs undertaken

Before the garments are issued, the laundry will organise the necessary fitting sessions to obtain the sizes required.

In some cases the application of logo's may be required by the customer. This logo may be a way to identify the wearer as avisitor or somebody with specific skills (e.g. training in first aid) or it may be used to enhance the corporate identity. In anycase, the material and the application method must be compatible with the controlled environment.

4.2. Pre- and post-processing operations

Cleanroom laundering remains a personal service. Each garment is manually inspected upon arrival and set aside, ifnecessary, for repair or special attention.

Repairs will be done according to standards set by the laundry and appropriate for cleanroom garments. In most cases thetype and number of repairs acceptable for the customer are part of the service contract. The specially trained laundry personnel uses original materials for the repairs, where possible.

Production batches are made based on the capacity of the washing machines, the type of garment and on the process needed to clean the garments. By linking the garments to the batch number, all relative process information is available bothduring and after the process.

In-process quality control also ensures each garment is manually inspected after cleaning and prior to despatch.

The garment identification makes it possible to check the number of garments received and despatched to the customer,ensuring the customer receives the same quantity sent in.

4.3. Cleaning and decontamination

4.3.1. General principles

A typical cleanroom laundry will have a controlled environment similar to the class where the garments to be cleanedare used (fig. 28). The barrier washing machines are built into the walls and are loaded outside the controlled room and unloaded inside the cleanroom. Also the dryers are built into the walls and are only accessible from within the cleanroom.Tables are put in the cleanroom for controlling and folding the garments. Once the garments are packed, they leave the cleanroom for further sorting and preparation for despatching (fig. 29).

Great care is given to the cleaning of the controlled room and the equipment. Every possible measure is taken to avoid cross-contamination. In certain cases it will be necessary to empty the cleanroom completely before starting the process forthe next customer.


4 typical cleanroom laundry function

DRYING

unloadload PASSOUTFOLDING PACKING

TESTEQUIPMENT

WASHINGMACHINE

AIR SHOWER

CHANGING ROOM

fig. 28

fig. 29


4 typical cleanroom laundry functionWashing

The soiled garments are subject to a wet wash providing a physical and chemical action to remove pollutants. The detergents involved are designed

to remove soil and retain it in suspension prior to being dumped to waste.

Different processes are possible depending on the type of garment, the useof the garments, the size of the machines etc. Some examples aredescribed further in this chapter. All parameters (e.g. temperature, pH,chemicals, ...) are available and will automatically control the washingprocess. Monitoring is essential for the quality control.

According to the type of article, the weight of the load and the machinethe dosage of the chemicals is fully automated and controlled. The latter

means when chemicals are dispensed, there is a check on the amounts dispensed and the same occurs when entering the washing machine.

Defects are registered by the machine and result in adjustments.

The water used for the cleaning cycle must of course be treated before use, in order to prevent contamination of thegarments. A flow diagram of a typical water treatment plant(fig. 31) in a laundry is shown in fig. 32.

fig. 31

Flow Diagram of Water Treatment Plant

MainsWater

CarbonFilter

WaterSoftener

UltraFiltration

U.F. StorageTanks

ReverseOsmosis

ElectronicDI Unit

U.V.Light

WashingMachines

Polisher

DI Tank

Point of Use -Washing Machines

fig. 32

- Ultra Filtration: Filters water down to sub micron level- Reverse Osmosis: Removes bacteria, salt, rust and fine suspended

matter and filters water down to 0,2 µm- Electronic DI Unit: Takes positive ions from water- U.V. Light: Kills bacteria- Polisher: Keeps water pure

fig. 30


4 typical cleanroom laundry functionFollowing this cleaning cycle great care must be taken to ensure the garments are not re-contaminated. The garments arerinsed several times to remove all detergents. The temperature of the rinsing water is gradually lowered to prevent thermalshock. Depending on the process, chemicals can be added in the last rinse cycle for specific finishes.

Decontamination

Particles are physically removed from the surface of the cleaned garment ina tumble drying sequence (fig. 33). The air used in the dryers is filteredaccording to the cleanliness desired (mostly HEPA filters are used).

After the garments have dried and cooled (the cooling must be gradual to avoid wrinkling or creasing of the fabric), particles are liberated into the tumbler plenum and removed in the exhaust air.

Packing

Once cleaning and decontamination have been completed each garment mustbe packed and heat sealed in clean non-particulating bags for issue tothe wearer (fig. 34). This activity must be undertaken underthe same cleanroom conditions as the previous processsteps.

If sterile garments are required a subsequentsterilisation must be undertaken once the garment has been packed. This may need specific packaging material.

4.3.2. Specific processes

Some examples of specific processes aredescribed in this part. In consultation with the laundry specialist a customer specific process can be developed.

4.3.2.1.The pharma process

The high demands of the pharmaceutical industry for sterile garments on the one hand and on the other hand theknowledge that repeated sterilisation cycles decreases the life-time of the garments drastically, have led to the developmentof the pharma process by the Micronclean organisation. With this process it is possible to produce disinfected garments thatcan be used in aseptic production environments without conventional sterilisation.

The pharma process involves aseptic cleanliness throughout the entire wash / decontaminate / dry / packing cycle using barrier techniques, optimum control of washing water and truly clean surfaces in all areas. Before the application of the pharma process the cleanroom and all equipment is cleaned and monitored. Only if the necessary level of aseptic cleanlinessis achieved can the process start. Monitoring of the environment requires constant microbiological checks. Staff training iseven more critical.

Choosing the suitable chemicals and their dosage was a crucial part in the development of the process. And even with yearsof experience with the process, research and development effort is made in research and development to improve the processand the monitoring of it. The rewards, however, justify the effort since results indicate that the life-time of such garments canbe doubled using the pharma process.

fig. 34

fig. 33


4 typical cleanroom laundry function4.3.2.2.E.S.D. process

Increasingly electronics based companies are demanding higher garment cleaning standards to combat E.S.D.behaviour. To maintain the performance of the garments produced for this industry the call is for ISO class 7 laundry facilities.

The process includes specialised finishes of the garments as well as specific equipment and training for the personnel. Onlythe most professional suppliers are able to meet such demands.

Garments designated for the microelectronics industry where ISO class 3 or 4 are common may be treated with the same specific finishes as mentioned above but adding the most demanding care for particle cleanliness.

4.3.2.3.Food process

The food industry is more and more aware of the necessity of particle clean garments. Looking clean is no longer acceptable. Working in controlled environment with the appropriate garments can lead to a significantly longer shelf life forthe food processed. This is essential for a growing industry.

Micronclean developed specific processes for garments designated to ISO class 7 or 8 environments. Since the concern of thefood industry is similar to the pharmaceutical industry, the pharma process is the basis for the treatment of the food garments.The levels of cleanliness both for particulate and microbiological contamination are adapted to the specific needs of the industry.

4.4. Garment delivery and collection

Most cleanroom laundries use their own transport to ensure the essential control over a facility which is more criticalthan it might at first appear. Efficiency in this area means that garments are issued accurately to the wearer and retrieved ingood time ready for processing. Any urgent amendments to schedules can be accommodated without undue cost and without unnecessary upheaval. It also provides a vital direct point of contact between customer and supplier.

An inadequate or inappropriate system will rapidly cause garment shortages and eventually disrupt customer production.

The system employed will depend on several factors:

- pool stock or identified wearer- change frequency- storage between use- distribution method- available space

If a wearer-identified system has been selected then it will be necessary to distribute each garment set to each individual (toallocated lockers or shelves, or by staff collecting their garments from a central distribution point).

Garments issued to a pool stock system require bins or shelves allocated by size for "picking" by staff.

Change on entry systems produce discarded items at a central soiled collection point. Any scheme involving re-use requiresa storage facility (as simple as named hanging pegs or more elaborate like laminar flow garment storage cabinets) and a moredisciplined system of handover.

Available space, number of wearers, size of the site and scattered production all make their contribution to programming andcosting. Suppliers will provide as much or as little help as you need to develop the best programme.


5 testingThe regime selected for each cleanroom will form an integral part of the whole contaminationcontrol and must, therefore, be incorporated into the QA and validation procedures.

This requirement extends not only to the area in which the garments are used, but also to the processing controls and environment of the cleanroom laundry.

These are the minimum checks and systems that will be required:- Registration to and effective operation of a recognised quality management system - normallyISO 9002.

- Particulate, airflow and pressure validation of the cleanroom by an independent organisation toshow conformance to specified and recognised standards e.g. ISO 14644-1.

- Routine environment monitoring of the cleanroom for microbiological contamination to showcompliance to a standard e.g. ISO 14698.

- Additional microbiological monitoring of the bioburden on cleaned garments, of critical water systems and other relevant areas.

- Maintenance of batch records to show that critical processing parameters have been met e.g.for thermal disinfection.

- Tests on processed garments to show that particle decontamination has been achieved to a stated standard e.g. ASTM F51-68.

- Tests on processed garments to show that static dissipation is functioning to a stated standard.

- Supply of accurate and traceable conformance paperwork e.g. for gamma irradiated garments.

5.1. Fabric testing

In order to assess the suitability of different fabrics for different applications, it is necessary to test a range of characteristics both of the fabric and the garments made from it. It is also important to do several tests on new fabrics andon washed materials to determine the evolution of the characteristics throughout the life-time of the garments. Most of thetests require specialised equipment and will therefore be used mainly for research and development purposes.

Tests on fabrics may include:

5.1.1. Pore size

Test principle: the fabric is wetted with a suitable fluid of known surface tension. Air pressure is applied across thefabric. By studying the fabric and measuring the air pressure required to overcome the surface tension of the fluid, the bubble-point may be ascertained. This air pressure measure is then used to determine the relative pore size of the fabric. Thetest is fully described in BS 3321.

The smaller the pore size, the greater the particle retention and therefore the better the filtration. The ability to transmit airand water is inversely proportional, so a balance has to be found. Ideal for filtration would be a fabric with pore size 0, butsuch fabrics will not allow the fabric to breathe and will thus be extremely uncomfortable.

For a highly effective woven monofilament polyester fabric the pore diameter will typically be 20 µm or less.


5 testing5.1.2. Comfort factors

Factors such as weight, pore size, weave will influence the wearer comfort of the fabrics used in controlled environments. Different textile laboratories are doing a lot of research on methods for measuring comfort in one single objective test. So far no single test has proven to be applicable. The following tests give a good indication:

Water vapour permeability: A test to determine the rate at which water vapour passes through the fabric, measured in grams per square meter per hour,gives an indication of the comfort level of the fabric. The lower the water vapour permeability, the lower the comfort. 25 g/m2/h is a typical result for a high grade barrier fabric.

Air permeability:This test establishes the litres of air per square meter per second at 0.98 mbar pressure differential. The higher the result, thebetter the comfort, but also the worse the filter efficiency. A typical result for a woven barrier fabric would be about 45 l/m2/sec.

5.1.3. Particle holdout efficiency

Test principle: The test fabric is challenged with an air stream containing a known contamination (number and size ofthe particles). By comparing this particle count with those of the air that passed through the fabric, the particle holdout efficiency is calculated in a percentage for a given particle size. The counts can be repeated at different given time intervals(e.g. after 5, 15, 30 and 60 minutes).

The higher the holdout percentage, the better the filtration efficiency of the fabric. A woven high grade barrier fabric shouldgive results higher than 80% for particles > 0,3 µm. The bigger the particles, the better the holdout efficiency should be.

5.1.4. Particle generation

This test examines the number of particles generated by the fabric whilst undergoing a standard flexing under mildabrasion. Results of this test give an indication of the linting of the material. The lower the figure, the better the fabric is suited for use in cleanrooms. For a monofilament polyester woven fabric the result would be typically less than 75 particles > 5 µm.

5.2. Garment system testing

As mentioned in section 2, the fabric is an important element in the garment, but other factors also influence the efficiency of the garment to be used in a controlled environment. Therefore test methods to evaluate the garment systemneed to be developed.

To test wearer comfort, so far the only way is to set up a real life trial to compare different possibilities. The selection of thetest persons and the way the evaluation by these persons is reported are essential to the success of the test, as are other factors that will influence the results. A good test programme will give an indication of the most comfortable garment system testedat the same time. Results from one test are not to be compared with results from another test, since too many variables are involved.

Body boxIn order to test the particle control efficiency of garment systems, a simulation test was developed, the body box. The full set of cleanroom garments under test is worn by a tester whostands in a cabinet which is fed from the top with filtered air (fig. 35). The tester moves in a stan-dard way in time to a metronome. Air is continuously drawn from the base of the box cabinet and the number of liberated particles counted. This is therefore the most realistic dynamicmeasure of the garment in actual use.

By using the same wearer and experimental conditions, it is possible to directly compare the filtration efficiency of different garment systems. Once again this test gives a comparison and notabsolute figures.

fig. 35


5 testing5.3. Particle counting (monitoring)

American Standards ASTM F51-68 and Fed. Std. 209 have provided the basis for analysis of the cleanliness of a controlled environment, but the recently introduced ISO 14644 part 1 and 2 have the benefits of being compiled against modern production procedures. The former standard specifies the procedures for verifying a given cleanroom classification,the latter the testing and monitoring required to prove continued compliance. In the same series a number of standards dealing with design, cleanroom operations and many more are in preparation (see fig. 06).

Monitoring the cleanroom in which the decontamination process takes place is essential for the quality control of the laundry.

But there is also a need to measure the efficiency of the decontamination process. ASTM F51-68 was the first test on decontaminated garments. The disadvantage of this test is that the particles are counted on a relatively small surface of the garment and visually by means of a microscope.

Over the past years the Helmke Drum test has become the most applied test method to batch check the decontaminationprocess (fig.37). Garments to be tested are placed in a rotating drum and tumbled to release particulate matter. The air fromthe drum passes an automatic particle counter to determine the amount of particles per size range. IEST developed a classification chart for Helmke results in its Recommended Practice IEST-RP-CC003 (see fig. 36). This is based on the averagesurface of the fabric in the tested garments (size M is used as reference). The numbers of particles are 0,5 µm or larger.

Different organisations over the world (including Micronclean) are working on the improvement of the test method (e.g. repeatability, number of tests to do per batch).

It has to be remarked that this method gives an indication of the number of particles released by the garments. A HelmkeDrum result gives no indication of the particle holdout efficiency of the garments tested. It could be possible to obtain goodHelmke results with a garment offering no filtration efficiency.

5.4. Microbiological controls

Many medical and pharmaceutical cleanrooms demand nothing short of sterile garments. Historically this has beenachieved by autoclaving, irradiation (gamma or beta) or ETO (ethylene oxide). Autoclaving and irradiation are destructive tomodern fabrics through thermal shock or fibre breakdown.

The pharma process developed by Micronclean offers a solution for most applications. By aseptic cleanliness throughout theentire process using barrier techniques, it is possible to deliver “sterile” garments.

In order to assure the quality it is necessary to monitor the bioburden in all steps of the process. Before, during and after theprocess all relevant surfaces (e.g. folding tables, fingertips of operators) are checked with dipslides. Since there are, at themoment, no internationally accepted standards to check the bioburden on garments, the test method and level of acceptance is part of the agreement between the laundry and the customer. Extensive research is actually being done byMicronclean to develop practical test methods to ensure the quality of its processes.

fig. 37fig. 36Category Garment tested Particles countedI 1 coat < 1.000

1 coverall < 1.2003 hoods < 450

II 1 coat 1.000 – 10.0001 coverall 1.200 – 12.0003 hoods 450 – 4.500

III 1 coat 10.000 – 100.0001 coverall 12.000 – 120.0003 hoods 4.500 – 45.000


5 testing5.5. Static electricity

Static electricity is a contaminant causing possible problems in all areas of cleanroom activity. Polyester garments produce static electrical charge as fabric makes contact with fabric or with garments worn under the cleanroom garments.Electrical charges of many thousands of volts may be present on the garments during use. The charge may be discharged atany time to the cleanroom structure or materials in the cleanroom.

Different tests are used in this field, all covering a part of the phenomenon. It is important to test not only new garments,but also garments after a number of washes.

Surface resistivity:

Measures the resistivity on the surface of the material. This test was initially developed for materials having the same composition at any place on the surface. This is not the case for cleanroom fabrics with a grid structure of conductive yarns.Another problem for this test is the use of encapsulated conductors in the conductive yarns, since in this type of fabric the conductivity is not at it strongest on the surface. Generally results between 7.5 x 10E5 and 1 x 10E12 ohm are accepted.

Static decay test:

The garment is charged to 1.000 volts. The time is measured to discharge the garment to 50 volts after connecting the garment to a grounding point. Less than 2 seconds is accepted in most cases.

For some applications, 50 volts is too much. Indeed some products have become sensitive to voltages as low as 25 volts. In reality the behaviour of the garment will be influenced by such factors as the method of grounding, the fabrics worn underthe cleanroom garment, the conductivity of the flooring, etc. These are not taken into account in this test method.

Testing electrostatic voltage on the body:

A person wears the test garment seated on a plastic covered chair. A probe connects an electrostatic voltmeter to the hand.The wearer then moves to create an electrostatic charge. The next step is for the wearer to stand. At the moment the chairand the garment separate, an electrostatic charge may be recorded.

With this principle you can test garments in different ways (garment connected to earth or not, feet on insulated plate or notand any combination). If the test person is grounded at the wrist, body voltages generated decay rapidly, however the residual charge on the garment is typically 50 to 300 volts for standard cleanroom garments. With specific designed garments the decay is faster (less than 0,2 seconds) and the residual charge is reduced to below measurable levels.


6 getting startedThis publication illustrates that a cleanroom garment management programme covers substantiallymore than garment cleaning and that any relationship is likely to involve a long term partnership(most contracts are based on a 3 year minimum period).

Since the involvement is significant, it makes sense to consider all aspects before committing toa specific supplier. The process must begin with an assessment of the needs of the user. Theseneeds have to be translated to specifications and become a part of the agreement with the supplier.

A number of matters to be considered are listed here:

6.1. Garments specifications

Materials to be used:- particle barrier required in function of classification of the controlled environment- need for sterilisation- ESD requirements- specific risks such as flame, chemicals, ...

Garment system:- styles involved, again in function of the classification (coverall, hood, boot, coat, ...)- multiple layers or not- compatibility of the garment system with other equipment (e.g. gloves, safety shoes, earthing straps, ...) - choice of colour for the garments (taking into account opacity)- need for differentiation of personnel (using different colours, logo’s, ...)- garments as part of the corporate identity programme

Issue programme:- number of changes (daily, weekly, ...)- estimate for garments for visitors- garments dedicated to a person or pool stock- dressing procedures- sizes available- possibility to obtain customised sizes from supplier- evolution of the number of wearers (stable number or variable)

6.2. Decontamination specifications

- type of contamination of the soiled garments- type of process: microelectronics, pharmaceutical, food, ESD, ...- need for a customer specific process- sterilisation and if yes what process (autoclave, irradiation, ETO)- number of changes per week- specific requirements for folding and packaging


6 getting started6.3. Service specifications

- number of deliveries per week- delivery schedule (e.g. 1 place at the customers plant or delivery in each department)- distribution system of the garments, taking into account the choice of pool stock or designated garments- buffer stock of new garments- identification of the garments including barcode or chip- training of the personnel (e.g. dressing procedures)- fitting of sizes- tests of new garments- garment repairs: who and what is acceptable- replacement of used garments- adjustments to garments (e.g. shortening of trousers)- information on the garment programme available from supplier- research and development possibilities- involvement in standardisation- contingency plan in case of break down

6.4. Monitoring specifications

- ISO 9000 or similar QA system- test methods applied by the supplier in function of the decontamination process- performance levels for the different tests- validation of the processes- traceability- effectiveness of the corrective action plan in case of a problem- reports on quality (at each delivery or only when requested)


appendix: bibliographyISO standards:ISO 14644: cleanrooms and associated controlled environmentsPart 1: classification of air cleanlinessPart 2: specification for the testing and monitoring to prove continued compliance with ISO 14611-1Part 3: metrology and test methodsPart 4: design, construction and start-upPart 5: cleanroom operationsPart 6: terms and definitionsPart 7: enhanced clean devicesPart 8: molecular contamination

ISO 14698: cleanrooms and associated controlled environments – biocontamination controlPart 1: general principlesPart 2: evaluation and interpretation of biocontamination dataPart 3: methodology for measuring the efficiency of processes of cleaning and (or) disinfection of inert surfaces bearing

biocontamination wet soiling or biofilms

The IEST (Institute of Environmental Sciences and Technology) publishes a number of recommended practices (RP) and reference documents (RD) for controlled environments. On the matter of garment management, the following are specificallyof interest:IEST-RP-CC003: garment system considerations for cleanrooms and other controlled environmentsIEST-RD-CC009: compendium of standards, practices, methods and similar documents relating to contamination controlIEST-RD-CC011: a glossary of terms and definitions relating to contamination controlIEST-RP-CC022: electrostatic charge in cleanrooms and other controlled environments

Information on ISO standards is available on: www.iso.ch. For more information on the IEST documents and other standards:www.iest.org

micron clean handbook

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