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欢迎阅读标题为“iso 14644-1 标准英文版完整全文(附pdf版下载)”的文章,该标准全名为“洁净室和相关受控环境 –; 第 1 部分:按颗粒浓度对空气清洁度进行分类”。该文件主要讨论了洁净室和洁净区空气清洁度的分类,测试和监测空气清洁度的程序,以及iso 14644中涉及污染控制各个方面的不同部分。下面是英文版的文本全文!如需要下载pdf版的请点我!

iso 14644-1 标准英文版完整全文(附pdf版下载)
iso 14644-1 标准英文版完整全文(附pdf版下载)

international

international ;organization ;for standardization

standard 14644-1

second ;edition 2015-12-15

cleanrooms ;and ;associated ;controlled ;environments ;

part 1:

classification ;of ;air ;cleanliness ;by ;particle ;concentration

salles ;propres ;et ;environnements ;maîtrisés ;apparentés ;— partie ;1: ;classification ;de ;la ;propreté ;particulaire ;de ;l’;air

© ;iso ;2015, ;published ;in switzerland

all ;rights ;reserved. ;unless ;otherwise ;specified, ;no ;part ;of ;this ;publication ;may ;be ;reproduced ;or ;utilized ;otherwise ;in ;a ;ny ;form ;or by any means, electronic or mechanical, including photocopying, or posting on the interne t or an intranet, without prior ;written ;permission. ;permission ;can ;be ;requested ;from ;either ;iso ;at ;the ;address ;below ;or ;iso’;s ;member ;body ;in ;the ;country ;of ;the ;requester.

iso ;爱游戏官方app平台 copyright ;office

ch. ;de ;blandonnet ;8 ;• ;cp ;401

ch-1214 ;vernier, ;geneva, ;switzerland ;tel. 41 22 749 01 11

fax ; 41 22 ;749 09 47

爱游戏官方app平台 copyright@iso.org ;www.iso.org

iso ;14644-1:2015(e)

contents page

foreword i

v

introduction…;…;.. ; ;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;..

v ;1 scope 1

  • normative ;references 1
  • terms ;and ;definitions 1

3.1 general…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…; ; ;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;. ; ;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;.

1 ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;3.2 ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;airborne particles 2

  • occupancy ;states 3
    • testing ;instrumentation ;(see ;annex ;f) 3
    • instrument ;specifications 4
  • classification 4

4.1 occupancy ;state(s) 4

4.2 particle ;size(s)…;…;…;…;…;…;…; ;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;. ;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;.

4

  • iso ;class ;number 4
    • designation 5
    • intermediate ;decimal ;cleanliness ;classes ;and ;particle ;size ;thresholds 5
  • demonstration ;of ;compliance 6

5.1 principle…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…; ; ;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;. ; ;…;…;…;…;…;.

6

5.2 testing…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…; ; ;…;…;…;…;…;…;…;…;…;…; ; ;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;

6

5.3 airborne ;particle ;concentration ;evaluation 6

5.4 test ;report…;…; ;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;. ;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;..

6

annex ;a ;(normative)reference ;method ;for ;classification ;of ;air ;cleanliness ;by

particle ;concentration 8

annex ;b ;(informative)examples ;of ;classification ;calculations 13

annex ;c ;(informative)counting ;and ;sizing ;of ;airborne ;macroparticles 22

annex ;d ;(informative)sequential ;sampling ;procedure ;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…;…; ;…;…;…;…;.

27
annex ;e ;(informative)specification ;o ;f ;intermediate ;decimal ;cleanliness ;classes ;and
particle ;size ;thresholds 34
annex ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;f ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;(informative)test ;instruments 36
bibliography 3

7

foreword

iii

iso ;(the ;international ;organization ;for ;standardization) ;is ;a ;worldwide ;federation ;of ;national ;stand ;ards bodies (iso member bodies). the work of preparing international standards is normally carried out through iso technical committees. each member body interested in a subject for which a technical committee has been established has th e right to be represented on that committee. international organizations, governmental and non-governmental, in liaison with iso, also take part in the work. iso collaborates closely with the international electrotechnical commission (iec) on all matters of electrotechnical standardization.

the procedures used to developthis document and those intended for its further maintenance are described in the iso/iec directive s, part 1. in particular the different approval criteria needed for the different types of iso documents should be noted. this document was drafted in accor dance with the editorial rules of the iso/iec directives, part 2 (see ).

attention is drawn to the possibility that some of the elements of this document may be the subject of patent ;rights. ;iso ;shall ;not ;be ;held ;responsible ;for ;identifying ;any ;or ;all ;such ;patent ;rights. ;details ;of ;any patent rights identified during the development of the document will be in the introduction and/or on the iso list of patent declarations received (see ).

any trade name used in this document is information given for the convenience of users and does not constitute an endorsement.

for an explanation on the meaning of iso specific terms and expressions related to conformity assess ment, as well as information about iso’;s adherence to the wto principles in the technical barriers to trade (tbt) see the following url:

the committee responsible for this document is iso/tc 209, cleanrooms and associated controlled environments.

this second edition cancels and replaces the first edition (iso 14644-1:1999), which has been techni cally revised throughout.

iso 14644 consists of the following parts, under the general title cleanrooms and associated controlled environments:

  • part ;1: ;classification ;of ;air ;cleanliness ;by ;particle ;concentration
  • part ;2: ;monitoring ;to ;provide ;evidence ;of ;cleanroom ;performance ;related ;to ;air ;cleanliness ;by ;particle concentration
  • part ;3: ;test ;methods
  • part ;4: ;design, ;construction ;and ;start-up
  • part ;5: ;operations
  • part ;7: ;separative ;devices ;(clean ;air ;hoods, ;gloveboxes, ;isolators ;and ;mini-environments)
  • part ;8: ;classification ;of ;air ;cleanliness ;by ;chemical ;concentration ;(acc)
  • part ;9: ;classification ;of ;surface ;cleanliness ;by ;particle ;concentration
  • part ;10: ;classification ;of ;surface ;cleanliness ;by ;chemical ;concentration

attention ;isalso ;drawn ;to ;iso ;14698, ;cleanrooms ;and ;associated ;controlled ;environmentsbiocontamination control:

  • part ;1: ;general ;principles ;and ;methods
  • part ;2: ;evaluation ;and ;interpretation ;of ;biocontamination ;data

iso ;14644-1:2015(e)

introduction

cleanrooms ;and ;associated ;controlled ;environments ;provide ;for ;the ;control ;of ;contamination ;of ;air ;and, if appro priate, surfaces, to levels appropriate for accomplishing contamination-sensitive activities. contamination control can be beneficial for protection of product or process integrity in applications in industries such as aerospace, microelectronics, pharmace uticals, medical devices, healthcare and food.

this part of iso 14644 specifies classes of air cleanliness in terms of the number of particles expr essed as ;a ;concentration ;in ;air ;volume. ;it ;also ;specifies ;the ;standard ;method ;of ;testing ;to ;determine ;cleanliness class, including selection of sampling locations.

this ;edition ;is ;the ;result ;of ;a ;response ;to ;an ;iso ;systematic ;review ;and ;includes ;changes ;in ;respons ;eto user ;and ;expert ;feedback ;validated ;by ;international ;enquiry. ;the ;title ;has ;been ;revised ;to ;“classification of ;air ;cleanliness ;by ;particle ;concentration” ;to ;be ;co ;nsistent ;with ;other ;parts ;of ;iso ;14644. ;the ;nine ;iso cleanliness classes are retained with minor revisions. table 1defines the particle concentration at various particle sizes for the nine integer classes. table e.1defines the maximum particle concentration at ;various ;particle ;sizes ;for ;intermediate ;classes. ;the ;use ;of ;these ;tables ;ensures ;bet ;ter ;definition ;of ;the appropriate ;particle-size ;ranges ;for ;the ;different ;classes. ;this ;part ;of ;iso ;14644 ;retains ;the ;macroparticle

descriptor concept; however, consideration of nano- scale particles (formerly defined as ultrafine particles) will be addressed in a separate standard.

the ;most ;significant ;change ;is ;the ;adoption ;of ;a ;more ;consistent ;statistical ;approach ;to ;the ;selecti ;on ;and the ;number ;of ;sampling ;locations; ;and ;the ;evaluation ;of ;the ;data ;collected. ;the ;statistical ;model ;is ;based on adaptation ofthe hypergeometric sampling model technique, where samples are drawn randomly without replacement f rom a finite population. the new approach allows each location to be treated independently ;with ;at ;least ;a ;95 ;% ;level ;of ;conf ;idence ;that ;at ;least ;90 ;% ;of ;th ;e ;cleanroom ;or ;clean ;zone areas will comply with the maximum particle concentration limit for the ta rget class of air cleanliness. no assumptions are made regarding the distribution of the actual particle counts over the area of th e cleanroom or clean zone; while in iso 14644-1:1999 an underlying assumption was that the particle counts follow the same no rmal distribution across the room, this assumption has now been discarded to ;allow ;the ;sampling ;to ;b ;e ;used ;in ;rooms ;where ;the ;particle ;counts ;vary ;in ;a ;morecomplex ;manner. ;in the ;process ;of ;revision ;it ;has ;been ;recognized ;that ;the ;95 ;% ;ucl ;was ;neither ;appropriate ;nor ;was ;applied consistently in iso 14644-1:1999. the minimum number of sampling locations required has been changed, compared with iso 14644-1:199 9. a reference table, table a.1, is provided to define the minimum ;number ;of ;sampling ;locations ;required ;based ;on ;a ;practical ;adapt ;ation ;of ;the ;sampling ;model technique. an assumption is made that the area immediately surrounding each sampling location hasa homogeneous particle concentration. the cleanroom or clean zone area is divided up into a grid of sections of near equal area, whose num ber is equal to the number of sampling locations derived from table a.1. a sampling location is placed within each grid section, so as to be representative of that grid section.

it is assumed for practical purposes that the locations are chosen representatively; a “representati ve” location (see a.4.2) means that features such as cleanroom or clean zone layout, equipment disposition and airflow systems should be considered when selecting sampling locations. additional sampling locations may be added to the minimum number of sampling locations.

finally, the annexes have been reordered to improve the logic of this part of iso 14644 and portions of the content of certain annexes concerning testing and test instruments have been included from iso 14644-3:2005.

the revised version of this part of iso 14644 addresses the ≥ 5 μm particle limits for iso class 5 in the sterile products annexes of the eu, pic/s and who gmps by way of an adaptation of the macroparticle concept.

the revised version of this part of iso 14644 now includes all matters related to classification of air cleanliness by particle concentratio n. the revised version of iso 14644-2:2015 now deals exclusively with the monitoring of air cleanliness by particle concentration.

cleanrooms ;may ;also ;be ;characterized ;by ;attributes ;in ;addition ;to ;the ;classification ;of ;air ;cleanliness ;by particle ;concentra ;tion. ;other ;attributes, ;such ;as ;air ;cleanliness ;in ;terms ;of ;chemical ;concentration, ;may

v

be ;monitored ;and ;the ;attribute’;s ;grade ;or ;level ;may ;be ;designatedalong ;with ;the ;classification ;of ;the ;iso class ;of ;cleanliness. ;these ;additional ;attributes ;do ;not ;suffice ;alone ;to ;classify ;a ;cleanroom ;or ;clean ;zone.

international ;standard iso ;14644-1:2015(e)

cleanrooms ;and ;associated ;controlled ;environments ;

part 1:

classification ;of ;air ;cleanliness ;by ;particle ;concentration

1 ;scope

this part of iso 14644 specifies the classification of air cleanliness in terms of concentration of airborne particles in cleanrooms and clean zones; and separative devices as defined iniso 14644-7.

only particle populations having cumulative distributions based on threshold (lower limit) particle sizes ranging from 0,1 µm to 5 µm are considered for classification purposes.

the use of light scattering (discrete) airborne particle counters (lsapc) is the basis for determination of the concentration of airborne particles, equal to and gr eater than the specified sizes, at designated sampling locations.

this part of iso 14644 does not provide for classification of particle populations that are outside the specified lower ;threshold ;particle-size ;range, ;0,1 ;µm ;to ;5 ;µm. ;concentrations ;of ;ultrafine ;particles ;(particles ;smaller ;than 0,1 µm) will be addressed in a separat e standard to specify air cleanliness by nano-scale particles. an m descriptor(see annex c) may be used to quantify populations of macroparticles (particles larger than 5 µm).

this ;part ;of ;iso ;14644 ;cannot ;be ;used ;to ;characterize ;the ;physical, ;chemical, ;radiological, ;viable ;o ;r ;other ;nature of airborne particles.

2 ;normative ;references

the following documents, in whole or in part, are normatively referenced in this document and are in dispensable ;for its application. for dated ;references, ;only ;the ;edition cited ;applies. ;for undated ;references, the latest edition of the referenced document (including any amendments) applies.

iso ;14644-2:2015, ;cleanrooms ;and ;associated ;controlled ;environments ; ;part ;2: ;monitoring ;to ;provide ;evidence of cleanr oom performance related to air cleanliness by particle concentration

iso ;14644-7, ;cleanrooms ;and ;associated ;controlled ;environments ; ;part ;7: ;separative ;devices ;(clean ;air ;hoods, glo veboxes, isolators and mini-environments)

3 ;terms ;and ;definitions

for ;the ;purposes ;of ;this ;document, ;the ;following ;terms ;and ;definitions ;apply.

3.1 ;general
3.1.1 ;cleanroom

room within which the number concentration of airborne particles is controlled and classified, and w hich is designed, constructed and operated in a manner to control the introduction, generation and r etention of particles inside the roomedium size

note ;1 ;to ;entry: ;the ;class ;of ;airborne ;particle ;concentration ;is ;specified.

note ;2 ;to ;entry: ;levels ;of ;other ;cleanliness ;attributes ;such ;as ;chemical, ;viable ;or ;nanoscale ;concen ;trations ;in ;the ;air, ;and also surface cleanliness in terms of particle, nanoscale, chemical and viable concentrations might also be specified and controlled.

note ;3 ;to ;entry: ;other ;relevant ;physical ;parameters ;might ;also ;be ;controlled ;as ;required, ;e.g. ;tempe ;rature, ;humidity, pressure, vibration and electrostatic.

3.1.2 ;clean ;zone

defined space within which the number concentration of airborne particles is controlled and classified , and which is constructed and operated in a manner to control the introduction, generation and rete ntion of contaminants inside the space

note ;1 ;to ;entry: ;the ;class ;of ;airborne ;particle ;concentration ;is ;specified.

note ;2 ;to ;entry: ;levels ;of ;other ;cleanliness ;attributes ;such ;as ;chemical, ;viable ;or ;nanoscale ;concen ;trations ;in ;the ;air, ;and also surface cleanliness in terms of particle, nanoscale, chemical and viable concentrations might also be specified and controlled.

note 3 to entry: a clean zone(s) can be a defined space within a cleanroom or might be achieved by a separative device. such a device can be located inside or outside a cleanroom.

note 4 to entry: other relevant physical parameters might also be controlled as required, e.g. temperature, humidit y, pressure, vibration and electrostatic.

3.1.3 ;installation

cleanroom ;or ;one ;or ;more ;clean ;zones, ;together ;with ;all ;associated ;structures, ;air-treatment ;systems ;, ;services and utilities

  • classification ;method ;of ;assessing ;level ;of ;cleanliness ;against ;a ;specification ;for ;a ;cleanroom or clean zone

note ;1 ;to ;entry: ;levels ;should ;be ;expressed ;in ;terms ;of ;an ;iso ;class, ;which ;represents ;maximum ;allowable ;conce ;ntrations of particles in a unit volume of air.

3.2 ;airborne ;particles
3.2.1 ;particle

minute ;piece ;of ;matter ;with ;defined ;physical ;boundaries

3.2.2 ;particle ;size

diameter of a sphere that produces a response, by a given particle-sizing instrument, that is equiva lent to the response produced by the particle being measured

note ;1 ;to ;entry: ;for ;discrete-particle ;light-scattering ;instruments, ;the ;equivalent ;optical ;diameter ;is ;used.

3.2.3 ;particle ;concentration

number ;of ;individual ;particles ;per ;unit ;volume ;of ;air

3.2.4 ;particle ;size ;distribution

cumulative ;distribution ;of ;particle ;concentration ;as ;a ;function ;of ;particle ;size

3.2.5 ;macroparticle

particle ;with ;an ;equivalent ;diameter ;greater ;than ;5 ;µm

m ;descriptor

designation ;for ;measured ;or ;specified ;concentration ;of ;macroparticles ;per ;cubic ;metre ;of ;air, ;expressed ;in ;terms of the equivalent diameter that is characteristic of the measurement method used

note 1 to entry: the m descriptor can be regarded as an upper limit for the averages at sampling loc ations. m descriptors cannot ;be ;used ;to ;define ;iso ;classes, ;but ;the ;m ;descriptor ;may ;be ;quoted ;independently ;or ;in ;conjunction ;with ;iso ;classes

.

3.2.7 ;unidirectional ;airflow

controlled airflow through the entire cross-section of a cleanroom or a clean zone with a steady vel ocity and airstreams thatare considered to be parallel

3.2.8 ;non-undirectional ;airflow

air ;distribution ;where ;the ;supply ;air ;entering ;the ;cleanroom ;or ;clean ;zone ;mixes ;with ;the ;internal ;a ;ir ;by ;means of induction

3.3 ;occupancy ;states
3.3.1 ;as-built

condition where the cleanroom or clean zone is complete with all services connected and functioning but with no equipment, furniture, materials or personnel present

3.3.2 ;at-rest

condition ;where the ;cleanroom or clean zone is complete with equipment installed and operating ;in a manner agreed upon, but with no personnel present

3.3.3 ;operational

agreed condition where the cleanroom or clean zone is functioning in the specified manner, with equi pment operating and with the specified number of personnel present

3.4 ;testing ;instrumentation ;(see ;annex ;f)
3.4.1 ;resolution

smallest ;change ;in ;a ;quantity ;being ;measured ;that ;causes ;a ;perceptible ;change ;in ;the ;corresponding ;i ;ndication

note 1 to entry: resolution can depend on, for example, noise (internal or external) or friction. it may also depend on the value of a quantity being measured.

[source: ;iso/iec ;guide ;99:2007, ;4.14]

3.4.2 ;maximum ;permissible ;measurement ;error

extreme ;value ;of ;measurement ;error, ;with ;respect ;to ;a ;known ;reference ;quantity ;value, ;permitted ;by ;specifications or regulations for a given measurement, measuring instrument, or measuring system

note 1 to ;entry: usually, the ;term ;“maximum permissible errors” or “limits ;of error” is ;used where ;t here are ;two extreme values.

note ;2 ;to ;entry: ;the ;term ;“tolerance” ;should ;not ;be ;used ;to ;designate ;“maximum ;permissible ;error”.

[source: ;iso/iec ;guide ;99:2007, ;4.26]

3.5 ;instrument ;specifications
3.5.1

lsapc light scattering airborne particle counter light scattering discrete airborne particle counter instrument ;capable ;of ;counting ;and ;sizing ;single ;airborne ;particles ;and ;reporting ;size ;data ;in ;terms ;of equivalent optical diameter

note ;1 ;to ;entry: ;the ;specifications ;for ;the ;lsapc ;are ;given ;in ;iso ;21501-4:2007.

  • discrete-macroparticle ;counter ;instrument ;capable ;of ;counting ;and sizing single airborne macroparticles

note ;1 ;to ;entry: ;see ;table ;f.1for ;specifications.

3.5.3 ;time-of-flight ;particle ;sizing ;apparatus

discrete-particle ;counting ;and ;sizing ;apparatus ;that ;defines ;the ;aerodynamic ;diameter ;of ;particles ;b ;y ;measuring the time for a particle to accommodate to a change in air velocity

note ;1 ;to ;entry: ;this ;is ;usually ;done ;by ;measuring ;the ;particle ;transit ;time ;optically ;after ;a ;fluid ;stream ;velocity ;change.

note ;2 ;to ;entry: ;see ;table ;f.2for ;specifications.

4 ;classification

4.1 ;occupancy ;state(s)

the ;air ;cleanliness ;class ;by ;particle ;concentration ;of ;air ;in ;a ;cleanroom ;or ;clean ;zone ;shall ;be ;def ;ined ;in ;one ;or more of three occupancy states, viz. “as-built,” “at-rest” or “operational” (see 3.3).

4.2 ;particle size(s)

one, or more than one, threshold(lower limit) particle sizes situated within the range from ≥0,1 µm to ≥5 µm are to be used to dete rmine air cleanliness particle concentration for classification.

4.3 ;iso ;class ;number

air cleanliness class by particle concentration shall be designated by an iso class number, n. the maximum permitted concentration of particles for each considered particle size is determined fro medium size table 1.

particle number concentrations for different threshold sizes in table 1do not reflect actual particle size and number ;distribution ;in ;the ;air ;and ;serve ;as ;criteria ;for ;classification ;only. ;examples ;of ;classification ;calculations are included in annex b.

table ;1 ; ;iso ;classes ;of ;air ;cleanliness ;by ;particle ;concentration

iso ;class ;number (n)maximum ;allowable ;concentrations(particles/m ;3) ;for ;particles ;equal ;to ;and ;greater than the considered sizes, shown belowa
0,1 µm0,2 µm0,3 µm0,5 µm1 µm5 µm
110bdimensiondimensiondimensiondimensione
210024b10bdimensiondimensione
31 00023710235bdimensione
410 0002 3701 02035283be
5100 ;00023 70010 2003 520832d, e, f
61 ;000 000237 ;000102 ;00035 2008 320293
7centigradecentigradecentigrade352 ;00083 2002 930
8centigradecentigradecentigrade3 ;520 000832 ;00029 300
9generationcentigradecentigradecentigrade35 ;200 0008 ;320 000293 ;000
a all ;concentrations ;in ;the ;table ;are ;cumulative, ;e.g. ;for ;iso ;class ;5, ;the ;10 ;200 ;particles ;shown ;at ;0,3 ;µm ;include ;all ;particles ;equal to and greater than this size.b these concentrations will lead to large air sample volumes for classification. sequential sampling procedure may be ;applied; ;see ;annex ;d. ;centigradeconcentration ;limits ;are ;not ;applicable ;in ;this ;region ;of ;the ;table ;due ;to ;very ;high ;particle ;conce ;ntration. dimensionsampl ing and statistical limitations for particles in low concentrations make classification inappropriat e.e sample collection limitations for both particles in low concentrations and sizes greater than 1 μm m ake classification at ;this particle size inappropriate, due to potential particle losses in the sampling system.f in order to specify this particle size in association with iso class 5, the macroparticle descriptor m may be adapted and ;used in conjunction with at least one other particle size. (see c.7.) generationth is class is only applicable for the in-operation ;state.
4.4 ;designation

the ;designation ;of ;airborne ;particle ;concentration ;for ;cleanrooms ;and ;clean ;zones ;shall ;include

  1. the ;iso ;class ;number, ;expressed ;as ;“iso ;class ;n”,
  2. the ;occupancy ;state ;to ;which ;the ;classification ;applies, ;and
  3. the ;considered ;particle ;size(s).

if ;measurements ;are ;to ;be ;made ;at ;more ;than ;one ;considered ;particle ;size, ;each ;larger ;particle ;diame ;ter ;(e.g.

dimension2) ;shall ;be ;at ;least ;1,5 ;times ;the ;next ;smaller ;particle ;diameter ;(e.g. ;dimension1), ;i.e. ;dimension2 ;≥ ;1,5

× dimension1.

example iso ;class ;number; ;occupancy ;state; ;considered ;particle ;size(s) iso class 4; at rest; 0,2 µm, 0,5 µm

4.5 ;intermediate ;decimal ;cleanliness ;classes ;and ;particle ;size ;thresholds

where intermediate classes, or intermediate particle size thresholds for integer and intermediate cl asses are required,refer to informative annex e.

5 ;demonstration ;of ;compliance

5.1 ;principle

compliance with air cleanliness (iso class) requirements specified by the customer is verified by pe rforming specified testing procedures and by providing documentation of the results and conditions of testing.

at-rest or operational classification may be performed periodically based upon risk assessment of th e application, typically on an annual basis.

for ;monitoring ;cleanrooms, ;clean ;zones ;and ;separative ;devices, ;iso ;14644-2:2015shall ;be ;used.

note ;where ;the ;installation ;is ;equipped ;with ;instrumentation ;for ;continuous ;or ;frequent ;monitoring ;o ;f ;air ;cleanliness ;by particle ;concentration ;and ;other ;parameters ;of ;performance ;as ;applicable, ;the ;t ;ime ;intervals ;between ;classification ;maybe extended provided that the results of the monitoring remain within the specified limits.

5.2 ;testing

the reference test method for demonstrating compliance is given in annex a(normative). alternative methods or instrumentation (or both), having at least comparable performance, may be spe cified. if no alternative is specified or agreed upon, the reference method shall be used.

tests ;performed ;to ;demonstrate ;compliance ;shall ;be ;conducted ;using ;instruments ;which ;are ;in ;compliance ;with calibration requirements at the time of tes ting.

5.3 ;airborne ;particle ;concentration ;evaluation

upon ;completion ;of ;testing ;in ;accordance ;with ;annex ;a, ;the ;concentration ;of ;particles ;(expressed ;as ;number ;of particles per cubic metre) in a single sample volume at each sampling location shall not exc eed the concentration limit(s) given in table 1or table e.1for intermediate decimal classes for the considered size(s). if ;multiple ;single ;sample ;volumes ;are ;taken ;at ;a ;sampling ;location, ;the ;concentrations ;shall ;be ;averaged ;and ;the average concentration must not exceed the concentration limits given in table 1or table e 1. intermediate particle sizes shall be derived from formula (e.1).

particle concentrations used for determination of compliance with iso classes shall be measured by the same method fo r all considered particle sizes.

5.4 ;test ;report

the results from testing each cleanroom or clean zone shall be recorded and submitted as a comprehen sive report, ;along ;with ;a ;statement ;of ;compliance ;or ;non-compliance ;with ;the ;specified ;designation ;of ;air ;cleanliness class by particle concentration.

the ;test ;report ;shall ;include

  1. the ;name ;and ;address ;of ;the ;testing ;organization, ;and ;the ;date ;on ;which ;the ;test ;was ;performed,
  2. the ;number ;and ;year ;of ;publication ;of ;this ;part ;of ;iso ;14644, ;i.e. ;iso ;14644-1:2015,
  3. a ;clear ;identification ;of ;the ;physical ;location ;of ;the ;cleanroom ;or ;clean ;zone ;tested ;(including ;ref ;erence ;to adjacent areas if necessary), and specific designations for coordinates of all sampling locations (a diagrammatic representation can be helpful),
  4. the specified designation criteria for the cleanroom or clean zone, including the iso class number, the relevant occupancy state(s), and the considered particle size(s),
  5. details ;of ;the ;test ;method ;used, ;with ;any ;special ;conditions ;relating ;to ;the ;test, ;or ;departures ;fro ;m ;the ;test method, and identification of the test instrument and its current calibration certificate , and
  6. the ;test ;results, ;including ;particleconcentration ;data ;for ;all ;sampling ;locations.

if concentrations of macroparticles are quantified, as described in annex c, the relevant information should be included with the test report.

annex ;a

(normative)

reference ;method ;for ;classification ;of ;air ;cleanliness ;by ;particle

concentration

a.1 ;principle

a discrete-particle-counting instrument is used to determine the concentration of airborne particles , equal to and greater than the specified sizes, at designated sampling locations.

a.2 ;apparatus ;requirements

a.2.1 ;particle-counting ;instrument

the instrument shall have a means of displaying or recording the count and size of discrete particles in air wi th a size discrimination capability to detect the total particle concentration in the appropriate pa rticle size ranges for the class under consideration.

numberte light scattering (discrete) airborne particle counters (lsapc) are commonly used for undertaking air cleanliness classification.

a.2.2 ;instrument ;calibration

the particle counter shall have a valid calibration certificate: the frequency and method of calibration should be based upon current accepted practice as specified in iso 21501-4.[1]

note some particle counters cannot be calibrated to all of the required tests in iso 21501-4. if this is the case, record the decision to use the counter in the test report.

a.3 ;preparation ;for ;particle ;count ;testing

prior ;to ;testing, ;verify ;that ;all ;relevant ;aspects ;of ;the ;cleanroom ;or ;clean ;zone ;that ;contribute ;to ;its ;integrity ;are complete and functioning in accordance with its performance specification.

care should be taken when determining the sequence for performing supporting tests for cleanroom per formance. iso 14644-3, annex a provides a checklist.

a.4 ;establishment ;of ;sampling ;locations

a.4.1 ;deriving ;the ;number ;of ;sampling ;locations

derive ;the ;minimum ;number ;of ;sampling ;locations, ;nlarge ;size, ;from ;table ;a.1. ;table ;a.1provides ;the ;number ;of sampling locations related to the area of each cleanroom or clean zone to be classified and provide s at least ;95 % confidence that at least 90 % of the cleanroom or clean zone area does not exceed th e class limits.

table ;a.1 ; ;sampling ;locations ;related ;to ;cleanroom ;area

area ;of ;cleanroom ;(medium size2) ;less ;than ;or ;equal ;tominimum number of sampling locationsto ;be ;tested ;( ;nlarge ;size)
21
42
63
84
105
246
287
328
369
5210
5611
6412
6813
7214
7615
10416
10817
11618
14819
15620
19221
23222
27623
35224
43625
63626
1 00027
>; 1 000see ;formula ;(a.1)
note ;1 ;if ;the ;considered ;area ;falls ;between ;two ;values ;in ;the ;table, ;the ;greater ;of ;the ;two ;should ;be selec ted.note ;2 ;in ;the ;case ;of ;unidirectional ;airflow, ;the ;area ;may ;be ;considered ;as ;the ;cross ;section ;of ;the moving air perpendicular to the direction of the airflow. in all other cases the area may be ;considered as the horizontal plan area of the cleanroom or clean zone.
a.4.2 ;positioning ;the ;sampling ;locations

in ;order ;to ;position ;the ;sampling ;locations

  1. use ;the ;minimum ;number ;of ;sampling ;locations ;nlarge ;sizederived ;from ;table ;a.1,
  2. then ;divide ;the ;whole ;cleanroom ;or ;clean ;zone ;into ;nlarge ;sizesections ;of ;equal ;area,
  3. select ;within ;each ;section ;a ;sampling ;location ;considered ;to ;be ;representative ;of ;the ;characteristic ;s ;of ;the section, and
  4. at each location, position the particle counter probe in the plane of the work activity or another s pecified point.

additional ;sampling ;locations ;may ;be ;selected ;for ;locations ;considered ;critical. ;their ;number ;and ;positions ;shall also be agreed and specified.

additional ;sections ;and ;associated ;sampling ;locations ;may ;be ;included ;to ;facilitate ;subdivision ;into ;equal sections.

for ;non-unidirectional ;airflow ;cleanrooms ;or ;clean ;zones, ;locations ;may ;not ;be ;representative ;if ;the ;y ;are located directly beneath non-diffused supply air sources.

a.4.3 ;sampling ;locations ;for ;large ;cleanrooms ;or ;clean ;zones

when the area of the cleanroom or clean zone is greater than 1 000 m2, apply formula (a.1) to determine the minimum number of sampling locations required.

nlarge ;size = ;27× a   ; (a.1)

where

nlarge ;size ;is ;the ;minimum ;number ;of ;sampling ;locations ;to ;be ;evaluated, ;rounded ;up ;to ;the ;next ;whole number;

ais ;the ;area ;of ;the ;cleanroom ;in ;m2.

a.4.4 ;establishment ;of ;single ;sample ;volume ;and ;sampling ;time ;per ;location

at each sampling location, sample a volume of air sufficient to detect a minimum of 20 particles if the p article concentration for the largest selected particle size were at the class limit for the designa ted iso class.

the ;single ;sample ;volume, ;vsmall ;size, ;per ;sampling ;location ;is ;determined ;by ;using ;formula ;(a.2):

vsmall size = centigrade20  ;×1000 (a.2) where

versus ;is ;the ;minimum ;single ;sample ;volume ;per ;location, ;expressed ;in ;litres ;(except ;see ;annex ;d);

centigraden,mis ;the ;class ;limit ;(number ;of ;particles ;per ;cubic ;metre) ;for ;the ;largest ;considered ;particle size sp ecified for the relevant class;

20 is ;the ;number ;of ;particles ;that ;could ;be ;counted ;if ;the ;particle ;concentration ;were ;at ;the ;class ;lim ;it.

the ;volume ;sampled ;at ;each ;location ;shall ;be ;at ;least ;2 ;l, ;with ;a ;minimum ;sampling ;time ;of ;1 ;min ;for ;each ;sample at e ach location. each single sample volume at each sampling location shall be the same.

when ;vsmall ;sizeis ;very ;large, ;the ;time ;required ;for ;sampling ;can ;be ;substantia ;l. ;by ;using ;the ;optional ;sequential sampling procedure (see annex d), both the required sample volume and the time required to obtain samples may be reduced.

a.5 ;sampling ;procedure

  1. set ;up ;the ;particle ;counter ;(see ;a.2) ;in ;accordance ;with ;the ;manufacturer’;s ;instructions ;including performing a zero count check.the ;sampling ;probe ;shall ;be ;positioned ;pointing ;into ;the ;airflow. ;if ;the ;direction ;of ;the ;airflow ;being sampled is not controlled or predictable (e.g. non-unidirectio nal airflow), the inletof the sampling probe shall be directed vertically upward.
  1. ensure ;normal ;conditions ;for ;the ;selected ;occupancy ;state ;are ;established ;before ;sampling.
  1. sample ;the ;volume ;of ;air ;determined ;in ;a.4.4, ;as ;a ;minimum, ;for ;each ;sample ;at ;each ;sampling ;location.
  1. if ;an ;out-of-specification ;count ;is ;found ;at ;a ;location ;due ;to ;an ;identified ;abnormal ;occurrence, ;th ;en ;that ;count can be discarded and noted as such on the test report and a new sample taken.
  1. if an out-of-specification count found at a location is attributed to a technical failure of the cle anroom or equipment, then the cause should be identified, remedial action taken and retesting perfor med of the failed sampling location, the immediate surrounding locations and any other locations affected. the choice shall be clearly documented and justified.

a.6 ;processing ;of ;results

a.6.1 ;recording ;of ;results

record ;the ;result ;of ;each ;sample ;measurement ;as ;the ;number ;of ;particles ;in ;each ;single ;sample ;volume ;at ;each of the considered particle size(s) appropriate to the relevant iso class of air cl eanliness.

note ;for ;particle ;counters ;with ;a ;concentration ;calculation ;mode, ;the ;manual ;evaluation ;may ;not ;be ;n ;ecessary.

a.6.1.1 ;average ;concentration ;of ;particles ;at ;each ;sampling ;location

when two or more single sample volumes are taken at a location, calculate and record the average num ber of particles per location at each considered particle size from the individual sample particle c oncentrations, according to formula (a.3).

 ;unknowni ;  ;unknown

xi ;= ;.1 i.n2 …;unknowni n.  ;(a.3)

where ;unknowni ;is ;the ;average ;number ;of ;particles ;at ;location ;i, ;representing ;any ;location;

unknowni.1to ;unknowni.n ;are the number of particles in individual samples; nis the number of samples taken at location i.

a.6.1.2 ;calculate ;the ;concentration ;per ;cubic ;metre

unknown

centigradei = i ×v1000t

(a.4)

where

centigradei is ;the ;concentration ;of ;particles ;per ;cubic ;metre; ;unknowni ;is ;the ;average

number of particles at location i, representing each location; vtis ;the ;selected single sample volume in litres.

a.6.2 ;interpretation ;of ;results
a.6.2.1 ;classification ;requirements

the cleanroom or clean zone is deemed to have met the specified air cleanliness classification requi rements if the ;average ;of ;the ;particle ;concentrations ;(expressed ;as ;number ;of ;particles ;per ;cubic ;me ;tre) ;measured ;at ;each of thesampling locations does not exceed the concentration limits determined from table 1.

if intermediate classes or particle sizes are used, as defined in annex e, appropriate limits derived from table ;e.1or formula (e.1) should be used.

a.6.2.2 ;out-of-specification ;result

in ;the ;event ;of ;an ;out-of-specification ;count, ;an ;investigation ;shall ;be ;undertaken. ;the ;result ;of ;the ;investigation and remedial action shall be noted in the test report (see 5.4).

annex ;b

(informative)

examples ;of ;classification ;calculations

b.1 ;example ;1

  • a cleanroom has a floor area of 18 m2and is specified to be iso class 5 in operation. the classification is to ;be ;performed ;using ;a ;discrete-particle ;counter ;having ;a ;flow ;rate ;of ;28,3 ;l ;per ;minu ;te. ;two ;particle ;sizes ;are considered: dimension≥ 0,3 µm and dimension≥ 0,5 µm.

the ;number ;of ;sampling ;locations, ;nlarge ;size, ;is ;determined ;to ;be ;six, ;based ;on ;table ;a.1.

  • the ;particle ;concentration ;limits ;for ;iso ;class ;5 ;are ;taken ;from ;table ;1:

centigraden(≥ ;0,3 ;µm) ;= 10 ;200 ;pa rticles/m3

centigraden(≥ ;0,5 ;µm) ;= ;3 ;520 ;particles/m ;3

  • the ;required ;single ;sample ;volume ;can ;be ;calculated ;from ;formula ;(a.2) ;as ;follows:

 

vsmall size = ; centigrade20 ×1000

vsmall ;size ;= 20 ; ;×1000

vsmall ;size ;=(0,00568)×1000

vsmall ;size ;= ;5 ;68, litres

the single sample volume has been calculated to ;be 5,68 l. ;as the lsapc being used for this ;test ;had a flow rate of ;28,3 ;litres ;per ;minute, ;a ;1-min ;single ;samp ;le ;count ;would ;be ;required ;(see ;a.4.4) ;and ;therefore ;28,3 ;l ;would be sampled for each single sample volume.

note ;in ;a.4.4, ;the ;minimum ;sample ;volume ;for ;the ;procedure ;is ;set ;by ;calculating ;the ;minimum ;sample ;volume ;as ;sho ;wn above and then determining the sample volume obtained for the operation of the particle counter i n the time period of 1 min. the sampling at each position must occur for at least 1 min; if the minimum sample volume as calculated is satisfied within the 1-min period, then the sampling process can be stopped at the end of 1 min. if the calculated minimum volume cannot ;be ;obtained ;within ;the ;1-min ;period ;with ;the ;flow ;rate ;of ;the ;instrument ;to ;be ;used, ;then ;the ;sampling ;must ;continue for a longer time period until at least the minimum sample volume has been obtained. because there are several possible flow rates for particle counters, users are cautioned to verify the flow rate of the specific instrument(s) to be used when determining ;the ;sampling ;time ;needed ;to ;satisfy ;both ;the ;1-min ;requirement ;and ;the ;calculated ;minimum ;sample ;vo ;lume.

  • at each sampling location only one sample volume is taken. the number of particles per cubic metre, xi, is calculated for each location and each particle size as shown in tables b.1and b.2.
table ;b.1 ; ;sampling ;data ;for ;particles ; ;0,3 ;µm
sampling locationsample ;1unknowni0,3 µm (counts ;per28,3 ;l)location ;sample average(counts ;per 28,3 l)location ;concentration average(counts per m3= location ;average ;× ;35,3)iso ;class ;5 ;limit for 0,3 µm particle sizepass/fail
12452458 64910 200pass
21851856 53110 200pass
359592 08310 200pass
41061063 74210 200pass
51641645 78910 200pass
61961966 91910 200pass

table ;b.2 ; ;sampling ;data ;for ;particles ; ;0,5 ;µm

sampling locationsample ;1unknowni0,5 µm (counts ;per28,3 ;l)location ;sample average(counts ;per 28,3 l)location ;concentration average(counts per m3= location ;average ;× ;35,3)iso ;class ;5 ;limit for 0,5 µm particle sizepass/fail
121217413 520pass
224248473 520pass
30003 520pass
4772473 520pass
522227773 520pass
625258833 520pass
  • each value of the concentration for dimension≥ 0,3 µm is less than the limit of 10 200 particles/m 3and dimension≥ 0,5 µm is less than the limit of 3 520 particles/m 3as established in b.1.2; therefore, the air cleanliness by particle concentration of the cleanroom meets the required iso c lass.

b.2 ;example ;2

  • a ;cleanroom ;has ;a ;floor ;area ;of ;9 ;m2and ;is ;specified ;to ;be ;iso ;class ;3 ;in ;operation. ;the ;classification ;i ;s ;to be performed using a discrete-particle counter having a flow rate of 50,0 l per minute. only one particle size (dimension≥ 0,1 µm) is considered.

the ;number ;of ;sampling ;locations, ;nlarge ;size, ;is ;determined ;to ;be ;five, ;based ;on ;table ;a.1.

  • the ;particle ;concentration ;limit ;for ;iso ;class ;3 ;at ;≥ ;0,1 ;µm ;is ;taken ;from ;table ;1:

centigraden(≥ ;0,1 ;µm) ;= ;1 ;000 ;particles/m ;3

  • the ;required ;single ;sample ;volume ;can ;be ;calculated ;from ;formula ;(a.2) ;as ;follows:

vsmall size =  ; ; centigrade20   ;×1000

vsmall ;size ;= 20 ; ;×1000

vsmall ;size ;=(0 ;02, ;)×1000

vsmall ;size ;= ;20,0litres

the single sample volume has been calculated to be 20,0 l. as the discrete-particle counter being used for this test ;had ;a ;flow ;rate ;of ;50,0 ;l ;per ;minute, ;a ;1- ;min ;single ;sample ;count ;would ;be ;required ;(see ;a.4.4) ;and ;therefore 50,0 l would be sampled for each single sample volume.

  • at ;each ;sampling ;location ;only ;one ;sample ;volume ;is ;taken. ;the ;number ;of ;particles ;per ;cubic ;metre,

unknowni, ;is ;calculated ;for ;each ;location ;and ;recorded ;in ;table ;b.3.

table ;b.3 ; ;sampling ;data ;for ;particles ; ;0,1 ;μm
sampling locationsample ;1unknowni0,1 µm (counts ;per50,0 ;l)location ;sample average(counts ;per ;50,0 ;l)location ;concentration average(counts per m3= location ;average ;× ;20)iso ;class ;3 ;limit for ≥ 0,1 µm particle sizepass/fail
146469201 000pass
247479401 000pass
346469201 000pass
444448801 000pass
5991801 000pass
  • each value of the concentration for dimension≥ 0,1 µm is less than the limit of 1 000 particles/m 3established in table 1; therefore, the air cleanliness by particle concentration of the cleanroom meets the required iso c lass.

b.3 ;example ;3

  • a cleanroom has a floor area of 64 m2and is specified iso class 5 in operation. the classification is to be performed using a discrete-particle counter having a flow rate of 28,3 l per minute. only one particle size (dimension≥ 0,5 µm) is considered.

the ;number ;of ;sampling ;locations, ;nlarge ;size, ;is ;determined ;to ;be ;12, ;based ;on ;table ;a.1.

  • the ;particle ;concentration ;limit ;for ;iso ;class ;5 ;at ;≥ ;0,5 ;µm ;is ;taken ;from ;table ;1:

centigraden(≥ ;0,5 ;µm) ;= ;3 ;520 ;particles/m ;3

  • the ;required ;single ;sample ;volume ;can ;be ;calculated ;from ;formula ;(a.2) ;as ;follows:

vsmall size =  ; ; centigrade20   ;×1000

 

vsmall ;size ;= 20 ;×1000

vsmall ;size ;=(0,00568)×1000

vsmall ;size ;= ;5 ;68, ; ;litres

the ;single ;sample ;volume ;has ;been ;calculated ;to ;be ;5,68 ;l. ;as ;the ;discrete-particle ;counter ;used ;for ;this ;test ;had a ;flow ;rate ;of ;28,3 ;l ;per ;minute, ;a ;1-min ;si ;ngle ;sample ;count ;would ;be ;required ;(see ;a.4.4) ;and ;therefore ;28,3 ;l would be sampled for each single sample volume.

  • at ;each ;sampling ;location ;only ;one ;sample ;volume ;is ;taken. ;the ;number ;of ;particles ;per ;cubic ;metre,

unknowni, ;is ;calculated ;for ;each ;location ;and ;recorded ;in ;table ;b.4.

table ;b.4 ; ;sampling ;data ;for ;particles ; ;0,5 ;μm
sampling locationsample ;1unknowni0,5 ;µmlocation ;sample average concentration (counts per ;28,3 l)location ;concentration average(counts ;per ;m3= ;location average × 35,3)iso ;class ;5 ;limit for 0,5 µm particle sizepass/fail
135351 2363 520pass
222227773 520pass
389893 1423 520pass
449491 7303 520pass
510103533 520pass
660602 1183 520pass
718186353 520pass
844441 5533 520pass
959592 0833 520pass
1051511 8003 520pass
11662123 520pass
1231311 0943 520pass
  • each value of the concentration for dimension= 0,5 µm is less than the limit of 3 520 particles/m 3established in table 1; therefore, the air cleanliness by particle concentration of the cleanroom meets the required iso c lass.

b.4 ;example ;4

  • a cleanroom has a floor area of 25 m2and is specified to be iso class 5 in operation. the classification is to be performed using a discrete-particle counter having a flow rate of 28,3 l per minute. only one particle size ( dimension≥ 0,5 µm) is c onsidered.

the ;minimum ;number ;of ;sampling ;locations ;from ;table ;a.1is ;7.

  • the ;particle ;concentration ;limit ;for ;iso ;class ;5 ;at ;≥ ;0,5 ;µm ;is ;obtained ;from ;table ;1as ;follows:

centigraden(≥ ;0,5 ;µm) ;= ;3 ;520 ;particles/m ;3

  • the ;required ;single ;sample ;volume ;can ;be ;calculated ;from ;formula ;(a.2) ;as ;follows:

vsmall size =  ; ; centigrade20   ;×1000

vsmall ;size ;= 20 ; ;×1000

vsmall ;size ;=(0,00568)×1000

vsmall ;size ;= ;5 ;68, litres

the single sample volume has been calculated to be 5,68 l. as the discrete-particle counter being used for this test ;had ;a ;flow ;rate ;of ;28,3 ;l ;per ;minute, ;a ;1- ;min ;single ;sample ;count ;would ;be ;required ;(see ;a.4.4) ;and ;therefore 28,3 l would be sampled for each single sample volume.

  • the number of sampling locations required from table a.1is 7, however, this example shows that the customer and supplier have agreed to add an additional 3 locations, making 10 in total. at each sampling location the number of single sample volumes varies from 1 to 3.
  • for recording purposes, the number of particles (concentration) per cubic metre, unknowni, is calculated from the average count per unit volume (28,3 l) at each location (28,3 × 35,3) as in ;table b.5.
table ;b.5 ; ;sampling ;data ;for ;particles ; ;0.5 ;μm
sampling locationsample ;1unknowni0,5 ;µm(counts ;per 28,3 l)sample ;2unknowni0,5 µm (counts ;per28,3 ;l)sample ;3unknowni0,5 µm (counts ;per28,3 ;l)location sample average (counts per28,3 ;l)location concentration average (counts perm3= location average ;× ;35,3)iso class ;5 ;limit ;for ;0,5 µm particle ;sizepass/fail
14757 ;521 8363 520pass
212 ; ;124243 520pass
31627832913 2013 520pass
4148741321184 1653 520fail
510 ;0,5183 520pass
6192217196823 520pass
7515382713 520pass
83821 ;301 0413 520pass
95415978973 4243 520pass
10486253541 9183 520pass
  • at sampling location 4, the average sample volume concentration of 4 165 does not meet iso class 5 m aximum particle count criteria of 3 520. at location 3 and location 9, one of the individual particle count concentrations does not meet the limit established in table 1; however, the average particle concentration for location ;3 ;and ;the ;average ;particle ;concentration ;for ;location ;9 ;do ;meet ;the ;limit ;established ;in ;table ;1. ;because location ;4 ;does ;not ;meet ;the ;air ;cleanliness ;by ;particle ;concentration, ;the ;cleanroom ;does ;not ;meet ;the ;required iso class.

b.5 ;example ;5

  • a ;cleanroom ;has ;a ;floor ;area ;of ;10,7 ;m2and ;is ;specified ;to ;be ;iso ;class ;7,5 ;in ;operation. ;the ;classification is ;to ;be ;performed ;using ;a ;discrete-particle ;counter ;having ;a ;flow ;rate ;of ;28,3 ;litres ;per ;minute. ;only ;one ;particle size (dimension≥ 0,5 µm) is considered.

the ;number ;of ;sampling ;locations ;is ;determined ;to ;be ;6, ;based ;on ;table ;a.1.

  • the ;particle ;concentration ;limit ;for ;iso ;class ;7,5 ;at ;≥ ;0,5 ;µm ;is ;obtained ;from ;table ;e.1.

centigraden (≥ 0 5, μmedium size)= 10n ×0 1dimension, 208, where ;n ;= ;7 ;5,andimension ;dimension ;= ;0 5, μmedium size

centigraden (≥ ;0 5, μmedium ;size)= 1075, ×0 1 ,, 208,

centigraden ;(≥ ;0 ;5, ;μmedium ;size)= ;31622777×0,03516757

centigraden ;(≥ ;0 ;5, ;μmedium ;size)= ;1112096 ;rounded ;to ;three ;significant ;digits ;= ;1110000 ;particles/m3

  • the ;required ;single ;sample ;volume ;can ;be ;calculated ;from ;formula ;(a.2) ;as ;follows:

vsmall ;size ;= centigrade20n ;m, ;×1000

vsmall ;size ;= 111200020 ; ;×1000 = ;0,01799 ;litres

the single sample volume has been calculated to be 0,01799 l. as the discrete-particle counter being used for this test had a flow rate of 28,3 l per minute, a 1- min single sample count would be required (see a.4.4) and therefore 28,3 l would be sampled for each single sample volume.

  • at ;each ;sampling ;location ;the ;number ;of ;single ;sample ;volumes ;varies ;from ;1 ;to ;3. ;the ;number ;of ;particles per cubic metre, unknowni, is calculated for each location and recorded in table b.6.
table ;b.6 ; ;sampling ;data ;for ;particles ; ;0,5 ;μm
sampling locationsample ;1unknowni0,5 µm (counts ;per28,3 ;l)sample ;2unknowni0,5 µm (counts ;per28,3 ;l)sample ;3unknowni0,5 µm (counts ;per28,3 ;l)location sampleaverage (counts per ;28,3 ;l)location concentration average (counts perm3= location average ;× ;35,3)iso class 7,5 ;limit ;for0,5 µm particle ;sizepass/ fail
111 679 ; ;11 679412 ;2691 ;110 000pass
29 045 ; ;9 045319 ;2891 ;110 000pass
312 699 ; ;12 699448 ;2751 ;110 000pass
426 23227 55534 63229 4731 ;040 3971 ;110 000pass
57 839 ; ;7 839276 ;7171 ;110 000pass
613 669 ; ;13 669482 ;5161 ;110 000pass
  • at ;sampling ;location ;4, ;the ;third ;sample ;volume ;concentration ;of ;1 ;222 ;507 ;(34 ;632 ;× ;35,3) ;did ;not ;m ;eet the ;iso ;class ;7,5 ;maximum ;particle ;count ;criteria ;of ;1 ;110 ;000. ;the ;concentration ;of ;each ;single ;sample ;volume does not meet the limit established by using table e.1; however, the average particle concentration for each of the ;sampling ;locations ;does ;meet ;the ;limit ;established ;by ;application ;of ;table ;e.1. ;therefore, ;the ;air ;cleanliness by particle concentration of the cleanroom meets the required iso cla small sizes.

b.6 ;example ;6

  • a cleanroom has a floor area of 2 100 m2and is specified to be iso class 7 in operation. the classification is ;to ;be ;performed ;using ;a ;discrete-particle ;counter ;having ;a ;flow ;rate ;of ;28,3 ;l ;itres ;per ;minute. ;only ;one ;particle size (dimension≥ 0,5 µm) is considered.

the ;number ;of ;sampling ;locations, ;nlarge ;size, ;given ;by ;table ;a.1is ;limit ;ed ;to ;cleanrooms ;of ;1 ;000 ;m2area. for a cleanroom of 2 100 m2, the number of sampling locations, nlarge size, is derived from formula (a.1):

 

2100× 27 ;= 56,7 ;roundedto57

  • the ;particle ;concentration ;limit ;for ;iso ;class ;7 ;at ;≥ ;0,5 ;µm ;is ;taken ;from ;table ;1:

centigraden(≥ ;0,5 ;µm) ;= ;352 ;000 ;particles/m ;3

  • the ;required ;single ;sample ;volume ;can ;be ;calculated ;from ;formula ;(a.2) ;as ;follows:

vsmall size =  ; ; centigrade20   ;×1000

 

vsmall ;size ;= 35200020 ;×1000

vsmall ;size ;=(0,0000568)×1000

vsmall ;size ;= ;0,0568litres

the ;single ;sample ;volume ;has ;been ;calculated ;to ;be ;0,0568 ;l. ;as ;the ;discrete-particle ;counter ;being ;used ;for ;this test ;had ;a ;flow ;rate ;of ;28,3 ;l ;per ;minute, ;a ;1- ;min ;single ;sample ;count ;would ;be ;required ;(see ;a.4.4) ;and ;therefore 28,3 l would be sampled for each single sample volume.

  • at ;each ;sampling ;location ;only ;one ;sample ;volume ;is ;taken. ;the ;number ;of ;particles ;per ;cubic ;metre,

unknowni, ;is ;calculated ;for ;each ;location ;and ;recorded ;in ;table ;b.7.

table ;b.7 ; ;sampling ;data ;for ;particles ; ;0,5 ;μm

2

3 4593 459122 ;103352 ;000pass
7 6667 666270 ;610352 ;000pass
8 5678 567302 ;416352 ;000pass
8 3458 345294 ;579352 ;000pass
7 9987 998282 ;330352 ;000pass
7 6657 665270 ;575352 ;000pass
7 7897 789274 ;952352 ;000pass
8 4468 446298 ;144352 ;000pass
8 3358 335294 ;226352 ;000pass
7 9887 988281 ;977352 ;000pass
7 8237 823276 ;152352 ;000pass
7 9117 911279 ;259352 ;000pass
7 6837 683271 ;210352 ;000pass
7 9357 935280 ;106352 ;000pass
6 5346 534230 ;651352 ;000pass
4 6674 667164 ;746352 ;000pass
6 5656 565231 ;745352 ;000pass
8 7718 771309 ;617352 ;000pass
5 0765 076179 ;183352 ;000pass
6 6786 678235 ;734352 ;000pass
7 1007 100250 ;630352 ;000pass
8 6038 603303 ;686352 ;000pass

table ;b.7 ;(continued)

sampling locationsample ;1unknowni0,5 µm (counts ;per28,3 ;l)location sample average ;(counts ;per 28,3 l)location ;concentration average(counts ;per ;m3= ;location average × 35,3)iso ;class ;7 ;limit for 0,5 µm particle sizepass/fail
397 6097 609268 ;598352 ;000pass
407 9567 956280 ;847352 ;000pass
417 4777 477263 ;939352 ;000pass
427 1457 145252 ;219352 ;000pass
436 9986 998247 ;030352 ;000pass
447 6537 653270 ;151352 ;000pass
456 5386 538230 ;792352 ;000pass
463 6793 679129 ;869352 ;000pass
474 8874 887172 ;512352 ;000pass
487 6487 648269 ;975352 ;000pass
498 7488 748308 ;805352 ;000pass
507 6897 689271 ;422352 ;000pass
517 3457 345259 ;279352 ;000pass
527 8887 888278 ;447352 ;000pass
537 7657 765274 ;105352 ;000pass
546 9976 997246 ;995352 ;000pass
556 9136 913244 ;029352 ;000pass
567 4747 474263 ;833352 ;000pass
578 7768 776309 ;793352 ;000pass
  • each value of the concentration for dimension≥ 0,5 µm is less than the limit of 352 000 particles/m 3established in table 1; therefore, the air cleanliness by particle concentration of the cleanroom meets the required iso c lass.

annex ;c

(informative)

counting ;and ;sizing ;of ;airborne ;macroparticles

c.1 ;principle

in some situations, typically those related to specific process requirements, alternative levels of air cleanliness may be specified on the basis of particle populations that are not within the size r ange applicable to classification. the maximum permittedconcentration of such particles and the choice of test method to verify compliance ;are ;matters ;for ;agreement ;between ;the ;customer ;and ;the ;supplier. ;considerations ;for ;test ;methods and prescribed formats for specification are given in c.2.

c.2 ;consideration ;of ;particles ;larger ;than ;5 ;µm ;(macroparticles) ; ;m ;descriptor

c.2.1 ;application

if contamination risks caused by particles larger than 5 µm are to be assessed, sampling devices and measurement procedures appropriate to the specific characteristics of such particles should be employed.

the ;measurement ;of ;airborne ;particle ;concentrations ;with ;size ;distributions ;having ;a ;threshold ;size ;between ;5 µm and 20 µm can be made in any of three defined occupancy states: as-built, at-rest and o perational.

as particle liberation within the process environment normally dominates the macroparticle fraction of the airbo rne particle population, the identification of an appropriate sampling device and measurement proced ure should be addressed on an application-specific basis. factors such as density, shape, volume and aerodynamic behaviour of the particles need to be taken i nto account. also, it may be necessary to put special emphasis ;on ;specific ;components ;of ;the ;total ;airborne ;popul ;ation, ;such ;as ;fibres. ;c.2.2 ;m ;descriptorformat

the m descriptor may be specified as a complement to the air cleanliness class by particle concentra tion. the m descriptor is expressed in the format

“;iso ;medium ;size( ;a; ;b); ;centigrade

where

  1. is ;the ;maximum ;permitted ;concentration ;of ;macroparticles ;(expressed ;as ;macroparticles ;per ;cubic metr e of air);
    1. is ;the ;equivalent ;diameter ;(or ;diameters) ;associated ;with ;the ;specified ;method ;for ;measuring ;macropa rticles (expressed in micrometres); centigrade is the specified measurement method.

example 1 to express an airborne concentration of 29 particles/m3in the particle size range ≥ 5 µm based on the use of an lsapc, the designation would be: “iso medium size(29; ≥ 5 µm); lsapc”.

example ;2 ;to ;express ;an ;airborne ;particle ;concentration ;of ;2 ;500 ;particles/m3in ;the ;particle ;size ;range ;of ;>; ;10 ;µm ;based on the use of a time-of-flight aerosol particle counter to determine the aerodynamic diameter of the particles, the designation would be: “iso medium size(2 500; ≥ 10 µm); time-of-flight aerosol particle counter”.

example 3 to express an airborne particle concentration of 1 000 particles/m3in the particle size range of 10 to 20 µm, based on the use of a cascade impactor followed by micro scopic sizing and counting, the designation would be: “iso medium size(1 000; 10 to 20 µm); cascade impactor followed by microscopic sizing and counting”.

note ;1 ;if ;the population ;of ;airborne ;particles being ;sampled ;contains fibres, ;they ;can ;be accounted ;for ;by supplementing

the m descriptor with a separate descriptor for fibres, which has the format “mfibre( ab); centigrade“;. note 2 suitable methods of test for concentrations of airborne particles larger than 5 µm are given in iest-g-cc1003.[2]

c.3 ;airborne ;particle ;count ;for ;macroparticlesmall ;size

c.3.1 ;principle

this test method describes the measurement of airborne particles with a threshold size larger than 5 μm in diameter (macroparticles). the procedure given in c.3has been adapted from iest-gcc1003:1999. [2]measurements can be made in a cle anroom or clean zone installation in any of the three designated occupancy states: as-built, at-rest or operational. the measurements are made to define the concentration of macroparticles, and the principles in 5.1, 5.2and 5.4may be applied. the need fo r proper sample acquisition and handling to minimize losses of macroparticles in the sample handling operations is emphasized.

c.3.2 ;general

the number of sampling locations, location selection and quantity of data required should be in acco rdance with a.4. the customer and supplier should agree upon the maximum permitted concentration of macro- particles, the equivalent diameter of the particles and the specified measurement method. other appropriate methods of equivalent accuracy and which provide equivalent data may be used by agreement between customer ;and ;supplier. ;if ;no ;other ;method ;has ;been ;agreed ;upon, ;or ;in ;case ;of ;dispute, ;the ;reference ;method ;in annex cshould be used.

c.3.3 ;sample ;handling ;considerations

careful ;sample ;collection ;and ;handling ;is ;required ;when ;working ;with ;macroparticles. ;a ;complete ;discussion ;of the ;requirements ;for ;systems, ;which ;can ;be ;used ;for ;isokinetic ;or ;anisokine ;tic ;sampling ;and ;particle ;transport to the point of measurement, is provided in iest-g-cc1003:1999.[2]

c.3.4 ;measurement ;methods ;for ;macroparticles

there are two general categories of macroparticle measurement methods. comparable results may not be produced if different measurement methods are used. correlation between different methods may not be possible for this reason. the methods and particle size information produced by the various methods is summarized in c.3.4.1and c.3.4.2.

  • in ;situmeasurement

using in situmeasurement of the concentration and size of macroparticles with a time-of-flight particle counter or an lsapc:

  1. lsapc ;measurement ;(c.4.1.2) ;will ;report ;macroparticles ;using ;particle ;size ;based ;upon ;an ;equivalent optical diameter;
  2. time-of-flight ;particle ;size ;measurement ;(c.4.1.3) ;will ;report ;macroparticles ;using ;particle ;size ;based ;upon an aerodynamic diameter.
c.3.4.2 ;collection

collection by filtration or inertial effects, followed by microscopic measurement of the number and size of collected particles:

  1. filter ;collection ;and ;microscopic ;measurement ;(c.4.2.2) ;will ;report ;macroparticles ;using ;particle ;size ;based upon the agreed diameter;
  2. cascade ;impactor ;collection ;and ;microscopic ;measurement ;(c.4.2.3) ;will ;report ;macroparticles ;using particle size based upon the choice of reported particle diameter.

c.4 ;methods ;for ;macroparticle ;measurement

c.4.1 ;macroparticle ;measurement ;without ;particle ;collection
c.4.1.1 ;general

macroparticles can be measured without collecting particles from the air. the process involves optical measurement of the particles suspended in the air. an air sample is moved at a specific flow rate through a lsapc, which reports either the equivalent optical diameter or the aerodynamic diameter of the particles.

c.4.1.2 ;light-scattering ;particle ;counter ;(lsapc) ;measurement

procedures for macroparticle measurement using an lsapc are the same as those in annex afor airborne particle count with one exception. the exception is that the lsapc in this case does not require sen sitivity for detection of particles less than 1 µm since data are required only for macroparticle co unting. care is required to ;ensure ;that ;the ;lsapc ;samples ;directly ;from ;the ;air ;at ;the ;sampling ;location. ;the ;lsapc ;should ;have ;a ;sample flow rate of at least 28,3 l/min and should be fitted with an inlet probe sized for isokinetic sampling in unidirection ;al ;flow ;zones. ;in ;areas ;where ;non-unidirectional ;flow ;exists, ;the ;lsapc ;should ;be ;located ;with ;the sample inlet fac ing vertically upward.

a sampling probe should be selected to permit close to isokinetic sampling in areas with unidirectional flow. if this ;is ;not ;possible, ;set ;the ;sampling ;probe ;inlet ;facing ;into ;the ;predominant ;direction ;of ;the ;a ;irflow; ;in ;locations where ;the ;airflow ;being ;sampled ;is ;not ;controlled ;or ;predictable ;(e.g. ;nonunidirectional ;airflow), ;the ;inlet ;of ;the sampling ;probe ;shall ;be ;dir ;ected ;vertically ;upward. ;the ;transit ;tube ;from ;the ;sampling ;probe ;inlet ;to ;the ;lsapc sensor should be as short as possible. for sampling of particles largerthan and equal to 1 µm, the transit tube length ;should ;not ;exceed ;the ;manufacturer’;s ;recommended ;le ;ngth ;and ;diameter, ;and ;will ;typically ;be ;no ;longer than 1 m in length.

sampling ;errors ;due ;to ;large ;particle ;loss ;in ;sampling ;systems ;should ;be ;minimised.

the lsapc size range settings are established so that only macroparticles are detected. the data from one size below ;5 ;µm ;should ;be ;recorded ;to ;ensure ;that ;the ;concentration ;of ;detected ;pa ;rticles ;below ;the ;macroparticle size ;is ;not ;sufficiently ;high ;to ;cause ;coincidence ;error ;in ;the ;lsapc ;measurement. ;the ;particle ;concentration ;in that ;lower ;size ;range, ;when ;added ;to ;the ;macroparticle ;concentration, ;should ;not ;exceed ;50 ;% ;of ;the ;maximum recommended particle concentration specified for the lsapc bei ng used.

centigrade.4.1.3 ;time-of-flight ;particle ;size ;measurement

macroparticle dimensions can be measured with time-of-flight apparatus. an air sample is drawn into the apparatus ;and ;accelerated ;by ;expansion ;through ;a ;nozzle ;into ;a ;parti ;al ;vacuum, ;where ;the ;measurement ;region is located. any particle in that air sample will accelerate to match the air velocity in the measurement region. the particles’; acceleration rate will vary inversely with mass of particle. the relationship between the air velocity and the particle velocity at the point of measurement can be used to determine the aerodynamic diameter of the particle. ;with knowledge of the pressure difference between the ambient air and the pressure at the ;measuremen ;t ;region, the ;air ;velocity can ;be ;calculated ;directly. ;the ;particle ;velocity ;is ;measured ;by ;the time of flight between two laser beams. the time-offlight apparatus should measure aerodynamic diameters of particles up to 20 µm. sample acquisition procedures are the same as those required when using a lsapc to measure ;macroparticles. ;in ;addition, ;the ;same ;procedures ;as ;for ;the ;lsapc ;are ;used ;with ;this ;apparatus ;in ;order to establish the particle size ranges to be reported.

c.4.2 ;macroparticle ;measurement ;with ;particle ;collection
c.4.2.1 ;general

macroparticles can be measured by collecting particles from the air. an air sample is transported at a specific flow rate through a collection device. microscopic analysis is used to count the collected particles.

note ; ;the ;mass ;of ;the ;collected ;particles ;can ;also ;be ;determined ;but ;since ;the ;air ;cleanliness ;is ;determined ;by ;number concentration this is not addressed in this part of iso 14644.

c.4.2.2 ;filter ;collection ;and ;microscopic ;measurement

select a membrane filter and a holder or a pre-assembled aerosol monitor; a membrane with pore size of 2 µm or ;fewer ;should ;be ;used. ;label ;the ;filter ;holder ;to ;identify ;the ;filter ;holder ;location ;and ;installation. ;connect ;the outlet to a vacuum source that will draw air at the required flow rate. if the sampling location in which macroparticle ;concentration ;is ;to ;be ;determined ;is ;a ;unidirectional ;flow ;area, ;the ;flow ;rate ;should ;be ;established to permit isokinetic sampling into the filter holder or aerosol monitor inlet and the inlet should face into the unidirectional flow.

determine ;the ;sample ;volume ;required ;by ;using ;formula ;(c.1).

remove ;the ;cover ;from ;the ;membrane ;filter ;holder ;or ;aerosol ;monitor ;and ;store ;in ;a ;clean ;location. ;sample ;the air at the sampling locations as determined by agreement between the customer and supplie r. if a portable vacuum pump is used to draw air through the membrane filter, the exhaust from that pump should be vented outside ;the ;clean ;installation ;or ;t ;hrough ;a suitable ;filter. after ;the ;sample ;collection ;has ;been completed, ;replace the cover on the filter holder or aerosol mo nitor. the sample holder should be transported in such a manner that the filter membrane is maintained in a horizontal position at all times and is not subjected to vibration or shock ;between ;the ;time ;the ;sample ;is ;captured ;and ;wh ;en ;it ;is ;analysed. ;count ;the ;particles ;on ;the ;filter ;surface (see astm f312-08).[3]

c.4.2.3 ;cascade ;impactor ;collection ;and ;measurement

in a cascade impactor particle separation is carried out by inertial impaction of particles. the sampled airflow passes through a series of jets of decreasing orifice size. the larger particles are deposited directly below the largest orifices and smaller particles are depo sited at each successive stage of the impactor. the aerodynamic diameter correlates directly with the regional collection of particles in the impact or flow path.

for the measurement of the air cleanliness by particle concentration a type of cascade impactor mean t for collection and counting of macroparticles can be used. in this one the ;particles are deposited upon the surfaces of removable plates that are removed for subsequent microscopic examination. sampling flow rates of 0, 47 litres/sec or more are typically used for this type of cascade impactor .

c.5 ;procedure ;for ;macroparticle ;count

determine ;the ;“iso ;medium ;size( ;a; ;b); ;centigrade” ;descriptor ;concentration ;in ;the ;selected ;particle ;size ;range(s), as agreed between customer and su pplier, and report the data.

at ;each ;sampling ;location, ;sample ;a ;volume ;of ;air ;sufficient ;to ;detect ;a ;minimum ;of ;20 ;particles ;for ;the ;selected particle sizeat the determined concentration limit.

the ;single ;sample ;volume, ;vsmall ;size, ;per ;sampling ;location ;is ;determined ;by ;using ;formula ;(c.1):

 20 ;

vsmall ;size ;= ; ; ;centigraden ;m, ;×1000 (c.1)

where

vsmall ;size ;is ;the ;minimum ;single ;sample ;volume ;per ;location, ;expressed ;in ;litres ;(except ;see ;d.4.2);

centigraden,mis ;the ;class ;limit ;(number ;of ;particles ;per ;cubic ;metre) ;for ;the ;largest ;considered ;particle size sp ecified for the relevant class;

20 is ;the ;number ;of ;particles ;that ;could ;be ;counted ;if ;the ;particle ;concentration ;were ;at ;the ;class ;lim ;it.

where informationon the stability of macroparticle concentration is required, make three or more measurements at sel ected locations at time intervals agreed between customer and supplier.

set ;up ;the ;sample ;inlet ;probe ;of ;the ;selected ;apparatus ;and ;undertake ;the ;test.

c.6 ;test ;reports ;for ;macroparticle ;sampling

the ;following ;test ;information ;and ;data ;should ;be ;recorded:

  1. definition ;of ;the ;particle ;sizes ;to ;which ;the ;apparatus ;responds;
  2. measurement ;method;
  3. method ;of ;measurement ;of ;m ;descriptor ;level ;or ;limit ;as ;an ;adjunct ;to ;the ;iso ;class;
  4. type ;designations ;of ;each ;measurement ;instrument ;and ;apparatus ;used ;and ;its ;calibration ;status; ;e) iso class of the installation;
  5. macroparticle ;size ;range(s) ;and ;the ;counts ;for ;each ;size ;range ;reported;
  6. apparatus ;inlet ;sample ;flow ;rate ;and ;flow ;rate ;through ;sensing ;volume;
  7. sampling ;location(s);
  8. sampling ;schedule ;plan ;for ;classification ;or ;sampling ;protocol ;plan ;for ;testing; ;j) occupancy ;state(s);

k) other ;relevant ;data ;for ;measurement ;such ;as ;stability ;of ;macroparticle ;concentration.

c.7 ;adaptation ;of ;the ;macroparticle ;descriptor ;to ;accommodate ;consideration ;of ; ;5 µm particle size for iso class 5 cleanrooms

in order to express an airborne concentration of 29 particles/m3in the particle size range ≥ 5 µm based on the use of an lsapc, the designation would be “iso medium size(29; ≥ 5 µm); lsapc” and for 20 particle/m 3the designation would be “iso medium size(20; ≥ 5 µm); lsapc” (see table 1, note f).

annex ;d

(informative)

sequential ;sampling ;procedure

d.1 ;background ;and ;limitations

d.1.1 ;background

in ;some ;circumstances ;where ;it ;is ;necessary ;or ;required ;to ;classify ;a ;clean ;controlled ;environment ;w ;ith ;a ;very low particle concentration at the class limit, sequential sampling is a useful technique that allows reduction of the sample volume and sampling time. ;the sequential sampling technique measures the rate of counting and predicts the likelihood of passi ng or failing to meet the requirements of the iso class. if the air being sampled is significantly more or significantly less contaminated than the specified class concentration limit for the considered particle size, use of the sequential sampling procedur e can reduce sample volumes and sampling times, often dramatically.

some savings may also to be realized when the concentration is near the specified limit. sequential sampling is most ;appropriate ;for ;air ;cleanliness ;of ;iso ;class ;4 ;or ;cleaner. ;it ;may ;also ;be ;used ;for ;other ;classes ;when ;the ;limit for the chosen particle size is low. in that case, the required sample volume may be too high for detecting 20 expected counts.

note for ;further ;information ;on ;sequential ;sampling, ;see ;iest-g-cc1004[4]or ;jis ;b ;9920:2002. ;[5]

d.1.2 ;limitations

the ;principal ;limitations ;of ;sequential ;sampling ;are

  1. the ;procedure ;is ;only ;applicable ;when ;expected ;counts ;from ;a ;single ;sample ;are ;<; ;20 ;for ;the ;largest ;particle size (see a.4.4),
  2. each sample measurement requires supplementary monitoring and data analysis,which can be facilitated through computerised automation, and
  3. particle concentrations are not determined as precisely as with conventional sampling procedures due to the reduced sample volume.

d.2 ;basis ;for ;the ;procedure

the ;procedure ;is ;based ;on ;comparison ;of ;real-time ;cumulative ;particle ;counts ;to ;reference ;count ;values. reference values are derived from formulae for upper- and lower-limit boundaries:

upper ;limit: ;centigradefail= ;3,96 ;  ;1,03 ;e(d.1) ;lower ;limit: ;centigradepass= ;−3,96 ;  ;1,03 ;e ;(d.2)

where

centigradefailis ;theupper ;limit ;for ;the ;observed ;count;

centigradepass ;is ;the ;lower ;limit ;for ;the ;observed ;count;

eis ;the ;expected ;count ;(shown ;by ;formula ;(d.5), ;the ;class ;limit).

according ;to ;formula ;(a.2), ;the ;single ;sample ;volume, ;vsmall ;size, ;is ;calculated ;as ;follows:

 

vsmall size = centigrade20n ;m, ;×1000 (d.3)

where

vsmall ;size ;is ;the ;minimum ;single ;sample ;volume ;per ;location, ;expressed ;in ;litres;

centigraden,mis the class limit (number of particles per cubic metre) for the considered particle size ;specified for the relevant class;

20 is the defined number of particles that could be counted if the particle concentration were at the c ;lass limit.

the ;total ;sampling ;time ;ttis ;calculated ;as ;follows:

v

tt ;= ;qsmall

(d.4

)

sizewhere

vsmall ;sizeis ;the ;accumulative ;sample ;volume ;(litres);

qis ;the ;sampling ;flow ;rate ;of ;the ;particle ;counter ;(litres/s).

the ;expected ;count ;is ;defined ;as ;follows:

q× ;×tc e =

n m, (d.5)

1000

where ;t ;is ;sampling ;time ;(in ;seconds).

to ;aid ;in ;understanding, ;a ;graphical ;illustration ;of ;the ;sequential ;sampling ;procedure ;is ;provided ;i ;n ;figure ;d.1. as air is being sampled at each designated sampling location, the running total particle count is co ntinuously compared ;to ;the ;expected ;count ;for ;the ;proportion ;of ;the ;prescribed ;total ;volume ;that ;has ;be ;en ;sampled. ;if ;the

running ;total ;count ;is ;less ;than ;the ;lower ;limit ;cpasscorresponding ;to ;the ;expected ;count, ;the ;air ;being ;sampled is found to meet the sp ecified class or concentration limit, and sampling is halted.

if the running count exceeds the upper limit cfailcorresponding to the expected count, the air being sampled fails to meet the specified class or con centration limit, and sampling is halted. as long as the running count remains between the upper and lower limits, sampling continues until the observed count becomes 20 or the

cumulative sample volume, v, becomes equal to the minimum single sample volume, vsmall size, where the expected count becomes 20.

in ;figure ;d.1, ;the ;number ;of ;observed ;counts, ;centigrade, ;is ;plotted ;versus ;the ;expected ;count, ;e, ;until ;either ;the sampling is halted or the count reaches 20.

d.3 ;procedure ;for ;sampling

figure d.1illustrates the boundaries established in formulae (d.1) and (d.2), as truncated by the limitations of e= ;20, ;representing ;the ;time ;required ;to ;collect ;a ;full ;sample, ;and ;centigrade= ;20, ;the ;maximum ;observed ;count allowed.

key unknown expected count, ;e ;yobserved ;count, centigrade

  1. stop ;counting, ;fail ;(centigrade≥ ;3,96 ;  ;1,03 ;e)
  2. continuous ;counting
  3. stop ;counting, ;pass ;(centigrade≤ ;−3,96 ;  ;1,03 ;e)
figure ;d.1 ; ;boundaries ;for ;pass ;or ;fail ;by ;the ;sequential ;sampling ;procedure

the observed count is plotted versus the expected count for air having aparticle concentration precisely at the specified class level. the passage of time corresponds to increasing numbers of expected counts, with e= 20 representing the time required to accumulate a full sample volume if the particle concentratio n were at th e class limit.

the ;procedure ;for ;sequential ;sampling ;using ;figure ;d.1is ;as ;follows:

  1. record ;the ;total ;number ;of ;particles ;counted ;as ;a ;function ;of ;time;
  2. calculate ;the ;expected ;count ;following ;the ;procedure ;described ;in ;d.2, ;formula ;(d.5);
  3. plot ;the ;total ;count ;versus ;the ;expected ;count ;as ;in ;figure ;d.1;
  4. compare ;the ;count ;with ;the ;upper ;and ;lower ;limit ;lines ;of ;figure ;d.1;
  5. if the cumulative observed count crosses the upper line, sampling at the location is stopped and the air is reported to have failed compliance with the specified class limit;
  6. if ;the ;cumulative ;observed ;count ;crosses ;the ;lower ;line, ;sampling ;is ;stopped ;and ;the ;air ;passes ;comp ;liance with the specified class limit;
  7. if ;the ;cumulative ;observed ;count ;remains ;between ;the ;upper ;and ;lower ;lines, ;sampling ;will ;continue.

if ;the ;total ;count ;is ;20 ;or ;fewer ;at ;the ;end ;of ;the ;prescribed ;sampling ;period ;and ;has ;not ;crossed ;the ;upper ;line, th e air is judged to have complied with the class limit.

d.4 ;examples ;of ;sequential ;sampling

d.4.1 ;example ;1
  1. evaluation of a cleanroom with a target air cleanliness of iso class 3 (0,1 μm, 1 000 particles/m3) by the sequential ;sampling ;procedure. ;this ;procedure ;looks ;at ;the ;rate ;of ;count ;and ;seeks ;to ;predict ;likely ;pass ;or fail.

note the ;sampling ;flow ;rate ;of ;particle counter ;is ;0,0283 ;m3/min ;(28,3 ;l/min ;or ;0,47 ;l/s).

  • preparation ;before ;measurement ;— ;method ;for ;calculation ;of ;limit ;values.

table ;d.1shows ;the ;calculation ;result. ;first, ;the ;expected ;count ;is ;calculated ;based ;on ;sampling ;time. ;next, the ;upper ;reference ;count ;and ;the ;lower ;reference ;count ;are ;cal ;culated ;by ;using ;formulae ;(d.1) ;and ;(d.2), or figure d.1.

table ;d.1 ; ;calculation ;tabulation ;of ;the ;upper ;and ;lower ;reference ;count
measurement periodsampling time (s)total ;sampled air volumeexpected countupper ;limit ;for ;the observed countlower ;limit ;for the observed count
 ;t ;litreaccording to formula ;(d.5)centigradefail=3,96 ; 1,03 ecentigradepas ;s= −3,96 1,03 ;e
1st52,42,47 (6,4)n.a. (−1,5)
2nd104,74,79 (8,8)0 (0,9)
3rd157,17,112 (11,2)3 (3,3)
4th209,49,414 (13,7)5 (5,8)
5th2511,811,817 (16,1)8 (8,2)
6th3014,214,119 (18,5)10 (10,6)
7th3516,516,520 (21,0)13 (13,0)
8th4018,918,920 (23,4)15 (15,5)
9th4521,221,22120
note the numeric value in parentheses shows the result of calculation of the upper and lower limits for t he observed count ;to ;one ;decimal ;place. ;however, ;as ;the ;actual ;data ;are ;integer ;values, ;each ;calculated ;value ;is ;handled ;at ;the ;time ;of ;eval ;uation ;as the integer value shown.the upper limit for the observed count is rounded up to the first decimal place of calculated value. ;the ;lower ;limit ;for ;the ;observed ;count ;is ;rounded ;down ;to ;the ;first ;decimal ;place ;of ;calculated ;valu ;e.when centigradepasscalculated according to formula (d.2) is negative, it is denoted by ‘;n.a.’; (not applicable). in this case, we ;cannot conclude that the air cleanliness satisfies the target iso class, even if th e observed count is zero.
  • evaluation ;using ;sequential ;sampling ;procedure.

the ;expected ;count ;provided ;in ;the ;first ;measurement ;is ;2,4; ;it ;is ;judged ;to ;“fail” ;when ;the ;observe ;d ;count is ;greater ;or ;equal ;to ;7. ;however, ;when ;the ;observed ;count ;during ;this ;sampling ;period ;is ;between ;0 ;and ;6, the ;result ;cannot ;b ;e ;judged.in ;this ;case, ;sampling ;is ;continued. ;when ;sampling ;is ;continued, ;the ;cumulative observed ;count ;may ;increase. ;sampling ;is ;continued ;until ;either ;the ;prescribed ;single ;sample ;volume ;is

achieved ;or ;the ;observed ;c ;ount ;has ;crossed ;one ;of ;the ;lines ;for ;c ;passor ;centigrade ;fail, ;respectively. ;if ;the cumulative ;observed ;count ;is ;20 ;or ;fewer ;at ;the ;end ;of ;the ;prescribed ;sampling ;period ;and ;has ;not ;crossed the ;upper ;line, ;the ;air ;cleanliness ;classification ;is ;judged ;to ;“pass”. ;if ;the ;cumulative ;observed ;count ;is ;less

than or equal to the rounded down values for cpassbefore achieving the full sampling period, the sampling is stopped and the classification is judged to “;pass”;.

d.4.2 ;example ;2

evaluation of ;a cleanroom with ;a ;target ;air cleanliness of ;international ;organization ;for standardization class 3 (0,5 ;μm,

35 particles/m3) by the sequential sampling procedure. the sampling flow rate of the particle counter (q) is ;0,0283 m3/min = 0,47 l/s.

calculate ;the ;single ;sample ;volume, ;vsmall ;size, ;according ;to ;formula ;(d.3).

 

vsmall size = centigrade20 , ;×1000 =  ; ;20 ×1000 ;= 571 ;429, litres

(d.6)



calculate the total sampling time, tt, according to formula (d.4). this is the longest time necessary to evaluate the sampling location. the sequential sampling procedure should shorten this time.

vsmall ;size

tt ;= ;q = ;1211,5s ;= ;20 19, ; ;min (d.7)

calculate ;the ;result ;table:

  1. calculate ;the ;expected ;count, ;e, ;according ;to ;formula ;(d.5);

q× ;×tcentigraden ;m

(d.8)

e =

1000

  • calculate ;the ;upper ;and ;lower ;limit ;for ;the ;observed ;count ;according ;to ;formulae ;(d.1) ;and ;(d.2); ;3) the calculation result is shown in table d.2and figure d.2.
table ;d.2 ; ;calculation ;result ;of ;the ;total ;sample ;air ;volume, ;expected ;count, ;upper ;limit ;and ;lower limit
t(min)t(s)total ;sampled ;air volume, q × texpected count,elimits
upper,centigradefaillower,centigradepass
16028,31,05 (5,0)n.a. (−2,9)
212056,62,07 (6,0)n.a. (−1,9)
318084,93,08 (7,0)n.a. (−0,9)
4240113,24,09 (8,0)0 (0,1)
5300141,55,010 (9,1)1 (1,1)
6360169,85,911 (10,1)2 (2,2)
7420198,16,912 (11,1)3 (3,2)
8480226,47,913 (12,1)4 (4,2)
9540254,78,914 (13,1)5 (5,2)
10600283,09,915 (14,2)6 (6,2)
11660311,310,916 (15,2)7 (7,3)
12720339,611,917 (16,2)8 (8,3)
13780367,912,918 (17,2)9 (9,3)
14840396,213,919 (18,2)10 (10,3)
15900424,514,920 (19,3)11 (11,3)
16960452,815,820 (20,3)12 (12,4)
171 020481,116,820 (21,3)13 (13,4)
181 080509,417,820 (22,3)14 (14,4)
191 140537,718,820 (23,3)15 (15,4)
201 200566,019,820 (24,4)16 (16,4)
20,19 ;= ;tt1 211,5571,429 ;= ;vsmall ;size202120

in figure d.2, the upper and lower limits for the observed count are plotted versus the count acquisition time. each vertical bar shows the limits (upper and lower) at 1-min intervals.

key ;unknown count ;time ;(min) ;y ;count ;limits (particles) upper limit for the observed count lower limit for the observed count

figure ;d.2 ; ;graphical ;representation ;of ;the ;pass ;or ;fail ;boundaries ;for ;sequential ;sampling

compare the cumulative observed count and the upper and lower limits and apply the procedure described in d.3.

  1. fail ;situation, ;see ;table ;d.3.
table ;d.3 ; ;example ;sequential ;sampling ;particle ;counts
t(min)t(s)expected count, elimit ;for ;the ;cumulative observed countobserved countcumulative observed ;result
 ; ; ;upper,centigradefa ;illower,centigradepa ;ssduring intervalcount,centigrade ;
1601,05n.a.22continue
21202,07n.a.35continue
31803,08n.a.16continue
42404,09006continue
53005,0101511fail

the expected count provided in the first measurement is 1,0; the cumulative observed count is judged to “fail” when it is greater than or equal to 5. however, when the cumulative observed count is between 0 and ;5, ;it ;cannot ;be ;judged. ;in ;the ;present ;example, ;the ;sampling ;has ;to ;be ;continued. ;when ;the ;sampling ;is continued, ;the ;cumulative ;observed ;count ;increases. ;however, ;it ;is ;easy ;to ;judge ;because ;both ;the ;expected count ;and ;the ;reference ;count ;increase. ;in ;the ;5th ;measurement ;(t= ;300 ;s), ;the ;cumulative ;observed ;count is 11 and exceeds the upper limit (10). then it is judged to “;fail.”;

  • pass ;situation ;see ;table ;d.4.
table ;d.4 ; ;example ;sequential ;sampling ;particle ;counts
 ; ; ;limits ;for ;the ;cumulativeobservedcumulative ;
t(min)t(s)expected count, eobserved ;countcount ;during intervalobserved count, centigrade ;result
upper,centigradefaillower,centigradepas
 ; ; ; ;s ; ; ;
1601.05n.a.00continue
21202.07n.a.00continue
31803.08n.a.00continue
42404.09000pass

the expected count provided in the first measurement is 1,0, the cumulative observed count is judged to “fail” ;when ;it ;is ;greater ;than ;or ;equal ;to ;5. ;however, ;when ;the ;observed ;count ;is ;between ;0 ;and ;5, ;it ;cannot be judged. in the present example, the sampling is continued, but the cumulative observed count does not increase. in the 4th measurement (t= 240 s), the cumulative observed count is 0 and is equal to the lower limit (0). then it is judged to “pass.”

annex ;e

(informative)

specification ;of ;intermediate ;decimal ;cleanliness ;classes ;and ;particle size thresholds

e.1 ;intermediate ;decimal ;cleanliness ;classes

if ;intermediate ;decimal ;cleanliness ;classes ;are ;required, ;table ;e.1should ;be ;used.

table e.1provides the permitted interme diate decimal air cleanliness classes. uncertainties associated with particle ;measurement ;make ;increments ;of ;less ;than ;0,5 ;inappropriate, ;a ;nd ;the ;notes ;beneath ;the ;table ;identify restrictions due to sampling and particle collection limitat ions.

table ;e.1 ;—intermediate ;decimal ;air ;cleanliness ;classes ;by particle concentration

 ;concentration ;of ;particles ;(particles/m3)a
iso ;class ;number (n) ;0,1 ;0,2 ;0,3 ;0,5 ;1,0 ;5,0
iso ;class ;1,5[32]bdimensiondimensiondimensiondimensione
iso ;class ;2,5316[75]b[32]bdimensiondimensione
iso ;class ;3,53 160748322111dimensione
iso ;class ;4,531 6007 4803 2201 110263e
iso ;class ;5,5316 ;00074 80032 20011 1002 630e
iso ;class ;6,53 ;160 000748 ;000322 ;000111 ;00026 300925
iso ;class ;7,5centigradecentigradecentigrade1 ;110 000263 ;0009 250
iso class 8,5fahrenheitcentigradecentigradecentigrade11 ;100 0002 ;630 00092 500
a all concentrations in the table are cumulative, e.g. for iso class 5,5, the 11 100 particles shown a t 0,5 μm include all ;particles equal to and greater than this size.b these ;concentrations ;will ;lead ;to ;large ;air ;sample ;volumes ;for ;classification. ;see ;annex ;d, ;sequential ;sampling ;procedure. ;centigrade concentration limits are not applicable in this region of the table due to very high particle concen tration. ;dimensionsampling and statistical limitations for particles in low concentrations make classification inappr opriate.esample collection limitations for b oth particles in low concentrations and sizes greater than 1 µm make classification ;inappropriate, ;d ;ue ;to ;potential ;particle ;losses ;in ;the ;sampling ;system. ;fahrenheitthis ;class ;is ;only ;applicable ;for ;the ;in-operation ;state.

e.2 ;intermediate ;particle ;sizes

if intermediate particle sizes are required for any integer or decimal class, formula (e.1) may be used to determine the maximum particle concentration at the considered particle size:

centigraden ;= ;10n ;× ; ;kdimension208,

(e.1)

where

centigraden ;is ;the ;maximum ;permitted ;concentration ;(particles ;per ;cubic ;metre) ;of ;airborne ;particles ;that are ;eq ;ual ;to ;and ;greater ;than ;the ;considered ;particle ;size. ;centigradenis ;rounded ;to ;the ;nearest ;whole number, using no more than three significant figures;

nis ;the ;isoclass ;number, ;which ;shall ;not ;exceed ;a ;value ;of ;9 ;or ;be ;less ;than ;1;

dimensionis ;the ;considered ;particle ;size, ;in ;micrometres, ;that ;is ;not ;listed ;in ;table ;1; k is a constant, 0,1, expressed in micrometres.

annex ;f

(informative)

test ;instruments

f.1 ;introduction

this ;annex ;describes ;the ;measuring ;apparatus ;that ;should ;be ;used ;for ;the ;recommended ;tests ;given ;in ;annexes ;a, centigradeand dimension.

in this annex, data given in tables f.1and f.2indicate the minimum necessary requirements for each item of apparatus. measuring apparatus should be chosen subject to agreement between the customer and supplier.

this annex is informative, and should not prevent the use of improved apparatus as it becomes available. alternative test apparatus may be appropriate and may be used subject to agreement between customer and supplier.

f.2 ;instrument ;specifications

the following instruments should be used for the recommended tests given in annexes a, centigradeand dimension:

  1. light ;scattering ;(discrete) ;airborne ;particle ;counter ;(lsapc);

note the ;specifications ;for ;the ;lsapc ;are ;given ;in ;iso ;21501-4:2007.[1]

  • discrete-macroparticle ;counter;
  • time-of-flight ;particle ;sizing ;apparatus;
  • microscopic ;measurement ;of ;particles ;collected ;on ;filter ;paper. ;see ;astm ;f312-8.[3] ;the ;terms ;and definitions for these instruments are given in clause 3.

table ;f.1 ; ;specifications ;for ;discrete-macroparticle ;counter

itemspecification
 ; ;measuring ;limitsthe minimum detectable size should be in the range 5 to 80 µm and be appropriate for the particle si ze under consideration and the instrument capability. the maximum particle number concentration of the lsapc should ;be ;equal ;to ;or ;higher ;than ;maximum ;expected ;concentration ;for ;the particles under consideration
resolution20 ;% ;for ;calibration ;particles ;of ;a ;size ;specified ;by ;the ;manufacturer
maximum permissible error20 ;% ;for ;particle ;count ;at ;a ;specified ;size ;setting

table ;f.2 ; ;specifications ;for ;time-of-flight ;particle ;sizing ;apparatus

itemspecification
measuring ;limitsparticle ;size ;0,5 ;to ;20 ;µm; ;particle ;concentration ;1,0 ;× ;103/m3to ;1,0 ;× ;108/m3
resolutionaerodynamic ;diameter: ;0,02 ;µm ;at ;1,0 ;µm; ;0,03 ;µm ;at ;10 µm
maximum permissible error10 ;% ;of full ;reading

bibliography

  • iso ;21501-4:2007, ;determination ;of ;particle ;size ;distribution ; ;single ;particle ;light ;interaction ;methods

 ;part ;4: ;light ;scattering ;airborne ;particle ;counter ;for ;clean ;spaces

  • astm ;f312-08, ;standard ;test ;methods ;for ;microscopical ;sizing ;and ;counting ;particles ;from ;aerospace fluids on membr ane filters. astm international
  • iest-g-cc1003. ;measurement ;of ;airborne ;macroparticles. ;institute ;of ;environmental ;sciences ;and technology, arlington heights, illinois, 1999
  • iest-g-cc1004. sequential-sampling plan for use in classification of the particulate cleanliness of air in ;cleanroo ;ms ;and ;clean ;zones. ;institute ;of ;environmentalsciences ;and ;technology, ;arlington ;heights,

illinois, ;1999

  • jis ;b ;9920:2002, ;classification ;of ;air ;cleanliness ;for ;cleanrooms. ;japanese ;standards ;association

iso ;14644-1:2015(e)

 ;

ics 13.040.35

price ;based ;on ;37 ;pages

© ;iso 2015 ;– ;all ;rights reserved

este ;documento ;ha ;sido ;adquirido ;por ;cvtec ;el ;3 ;de ;febrero ;de ;2016.

para ;poder ;utilizarlo ;en ;un ;sistema ;de ;red ;interno, ;deberá ;disponer ;de ;la ;correspondiente ;licencia ;de aenor

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