IEST G-CC1001-1999 Counting Airborne Particles for Classification and Monitoring of Cleanrooms and Clean Zones.pdf

1、INSTITUTE OF ENVIRONMENTAL SCIENCES AND TECHNOLOGY Contamination Control Division Technical Guide 1001 IEST-G-CC1001 Counting Airborne Particles for Classification and Monitoring of Cleanrooms and Clean Zones INSTITUTE OF ENVIRONMENTAL SCIENCES AND TECHNOLOGY Arlington Place One 2340 S. Arlington He

2、ights Road, Suite 100 Arlington Heights, IL 60005-4516 Phone: (847) 981-0100 Fax: (847) 981-4130 E-mail: iestiest.org Web: www.iest.org 2 Copyrighted material INSTITUTE OF ENVIRONMENTAL SCIENCES AND TECHNOLOGY IEST-G-CC1001 IEST-G-CC1001 INSTITUTE OF ENVIRONMENTAL SCIENCES AND TECHNOLOGY Copyrighted

3、 material 3 This Guide is published by the INSTITUTE OF ENVIRONMENTAL SCIENCES AND TECHNOLOGY to advance contamination con-trol technology and the technical and engineering sciences. Its use is entirely voluntary, and determination of its applicability and suitability for any particular use is solel

4、y the responsibility of the user. Copyright 1999 by the INSTITUTE OF ENVIRONMENTAL SCIENCES AND TECHNOLOGY ISBN 978-1-877862-74-8 No part of this publication may be copied or reproduced in any form, or by any means, including electronic, mechanical, photocopying, or otherwise, without the prior writ

5、ten permission of the Institute of Environmental Sciences and Technol-ogy, 2340 S. Arlington Heights Road, Arlington Heights, IL 60005-4516. INSTITUTE OF ENVIRONMENTAL SCIENCES AND TECHNOLOGY Arlington Place One 2340 S. Arlington Heights Road, Suite 100 Arlington Heights, IL 60005-4516 Phone: (847)

6、981-0100 Fax: (847) 981-4130 E-mail: iestiest.org Web: www.iest.org 4 Copyrighted material IEST-G-CC1001 INSTITUTE OF ENVIRONMENTAL SCIENCES AND TECHNOLOGYIEST-G-CC1001 INSTITUTE OF ENVIRONMENTAL SCIENCES AND TECHNOLOGY Copyrighted material 5Counting Airborne Particles forClassification and Monitori

7、ng ofCleanrooms and Clean ZonesIEST-G-CC1001CONTENTSSECTION1 Application 72 Scope 73 Definitions . 74 Apparatus for counting airborne particles . 85 Measurement test procedures. 86 References 9APPENDIXAPPENDIX A; Data Report Example 106 Copyrighted material IEST-G-CC1001 INSTITUTE OF ENVIRONMENTAL S

8、CIENCES AND TECHNOLOGYIEST-G-CC1001 INSTITUTE OF ENVIRONMENTAL SCIENCES AND TECHNOLOGY Copyrighted material 7INSTITUTE OF ENVIRONMENTAL SCIENCES AND TECHNOLOGYContamination Control DivisionGuide 1001Counting Airborne Particles forClassification and Monitoring ofCleanrooms and Clean ZonesIEST-G-CC100

9、11 ApplicationThis guide describes standard protocols for mea-surement of concentrations of airborne particlesthat are characterized by distributions havingthreshold sizes (lower size limits) ranging from 0.1m to 5 m. Measurements are made in any of threeoccupancy states (as-built, at-rest, or opera

10、tional)as defined in ISO 14644-1. These measurements aremade to determine or verify the classification of theair in cleanrooms and clean zones in accordancewith ISO 14644-1, or for monitoring or testing forcontinuing compliance with ISO 14644-1, in accor-dance with ISO 14644-2.2 ScopeAir sampling pr

11、ocedures are provided for bothunidirectional and nonunidirectional airflow envi-ronments. The methods presented herein are refer-ence methods; other appropriate methods of equiva-lent accuracy may be used by agreement betweenthe customer and the supplier. If no alternativemethod has been agreed upon

12、, or in case of dispute,the reference method shall be used.3 Definitions3.1 cleanroomA room in which the concentration of airborneparticles is controlled and which contains one ormore clean zones.3.1.1 cleanroom, as-builtA cleanroom that is complete and ready for opera-tion, with all services connec

13、ted and functional, butwithout production equipment or personnel withinthe room.3.1.2 cleanroom, at-restA cleanroom that is complete and has the produc-tion equipment installed and operating, but with-out personnel within the room.3.1.3 cleanroom, operationalA cleanroom in normal operation with all

14、servicesfunctioning and with production equipment andpersonnel, if applicable, present and performingtheir normal work functions in the room.3.2 clean zoneA defined space in which the concentration ofairborne particles is controlled to specified limits.3.3 discrete-particle counter (DPC)An instrumen

15、t, such as an optical particle counter,that is capable of resolving responses from indi-vidual particles. The optical particle counter re-ports particle size as the equivalent diameter of aknown reference sphere.3.4 isoaxialA condition of sampling in which the direction ofthe airflow into the sampli

16、ng probe inlet is the sameas that of the unidirectional airflow being sampled.3.5 isokinetic samplingThe condition of isoaxial sampling in which themean velocity of the air entering the samplingprobe inlet is the same as the mean velocity of theunidirectional airflow at that location.3.6 nonunidirec

17、tional airflowAirflow that does not qualify as unidirectionalbecause it has a multiplicity of flow directions ormultiple-pass circulation (eddies), or both.8 Copyrighted material IEST-G-CC1001 INSTITUTE OF ENVIRONMENTAL SCIENCES AND TECHNOLOGY3.7 unidirectional airflowAir that flows in a single pass

18、 in a single directionthrough a cleanroom or clean zone with generallyparallel streamlines.3.8 zero count rateThe maximum count indicated by a discrete-par-ticle counter (DPC) within a specified period oftime, while sampling air that is free of particleslarger than the lower sizing limit of the DPC.

19、 Alsoreferred to as false count rate or background noise level.NOTE: For further definitions and explanations ofterms in this document, see IEST-RD-CC011.4 Apparatus for counting airborneparticlesMeasurement of airborne particles is accomplishedby using a discrete-particle counter (DPC), as de-scrib

20、ed in ASTM F 50 (reference 6a). The DPC shallpossess the following features and characteristics:a) Capability to count and size airborne particles.b) Size discrimination capability to measure par-ticles in the size range(s) pertinent to the air clean-liness class under consideration.c) Capability of

21、 displaying or recording the par-ticle count in the pertinent size range(s).d) Valid certificate of primary calibration; the cali-bration shall have been performed using standardreference particles as described in ASTM F 328(reference 6b) or ASTM F 649 (reference 6c), asagreed upon by the customer a

22、nd the supplier.e) When used in multiples of two or more and datacorrelation is of concern, secondary calibration shallhave been performed in accordance with ASTMF 649 (reference 6c).5 Measurement test proceduresThe protocol for the determination of air cleanli-ness consists of two phases: measureme

23、nt proce-dures and reporting procedures.NOTE: For details concerning the number of sam-pling point locations, selection of the locations,and data requirements for air cleanliness clas-sification, consult ISO 14644-1 (reference 6d).For details concerning the testing protocol as-sociated with surveill

24、ance monitoring tests,consult ISO 14644-2 (reference 6e).5.1 Preparation for countingPrior to collecting particle count data, the proce-dure to be used for sample acquisition must beestablished and documented. The procedure shouldbe based on the airborne particulate cleanlinesslevel of the cleanroom

25、 or clean zone for whichclassification or monitoring is to be performed.Preparation for counting involves establishing thefollowing equipment configuration and operatingcriteria:a) Description of the DPC to be used; theb) Sample transit system; thec) Sample inlet probe; thed) Range of particle sizes

26、 to be measured; thee) Location(s) for sample acquisition; and thef) Frequency of sampling.5.2 Procedure for counting airborneparticles5.2.1 Setup procedure for the discrete-particle countera) Install the DPC at the specified sampling loca-tion.b) Adjust the sample flow to the specified rate.c) Sele

27、ct the specified particle size threshold(s) onthe basis of ISO 14644-1.d) Select a sampling probe with inlet dimensionssuitable for isokinetic sampling in unidirectionalflow at the prevailing airflow velocity, and orientthe probe inlet isoaxially (i.e., directly into theprevailing airflow). If the a

28、irflow is nonunidirec-tional, orient the sampling probe inlet so that itfaces upward.e) Configure the sampling system so that the tran-sit tube between the sampling probe inlet and theDPC sensor is as short as possible and withoutsharp (small radius) curvature. When collectingdata for particles in t

29、he size range 5 m, the transittube should be no longer than 2 m.f) Select a transit tube with an inner diameter thatwill ensure a Reynolds number for airflow insidethe tube in the range of 5,000 to 25,000. Under theseconditions, errors resulting in loss of small particlesby diffusion and larger part

30、icles by sedimentationand impaction will be no more than 5%. If the errorexceeds 5%, the measured particle count data shouldbe corrected by appropriate means or a shortertransit tube should be used.5.2.2 Counting particles for aircleanliness classificationa) Sample the required single sample volume

31、atIEST-G-CC1001 INSTITUTE OF ENVIRONMENTAL SCIENCES AND TECHNOLOGY Copyrighted material 9each specified sampling location. Follow with rep-licate measurements as required, in accordancewith ISO 14644-1.NOTE: When information on stability of particleconcentration is required, make three or moremeasur

32、ements at selected locations over se-lected time intervals, as agreed upon by thecustomer and the supplier.NOTE: When the cleanliness of air is to be measuredas the air comes from a potential contaminatingsource, or as contaminated air approaches apotential target, an appropriate procedure shouldbe

33、selected from ASTM F 50-00, reported, andfollowed.b) Calculate the airborne particle concentrations inthe specified particle size ranges, as agreed upon bythe customer and the supplier.c) Report the concentration data and other relatedinformation, as specified, using the formats pro-vided in section

34、 5.3 and Appendix A as a guide.5.2.3 Counting particles for monitoringor continuing compliance testinga) Establish a plan for testing based on the airborneparticulate cleanliness level and the degree of pro-tection required for products being produced orprocesses being carried out in the cleanroom o

35、rclean zone. The plan shall include specifications forfrequency of data collection and the number ofreplicate measurements for each sample, in accor-dance with ISO 14644-2.b) Specify the number and locations of samplingpoints.c) Specify the method to be used for interpretationof the particle count m

36、easurement data.d) Report the specified count or concentration dataand other related information, as specified, usingappropriate portions of the formats provided insection 5.3 and Appendix A as a guide.5.3 Data reportingRecord the following information, as specified, foreach cleanroom or clean zone:

37、a) Identification and location of the cleanroom orclean zone.b) Identification of the DPC and its calibrationstatus.c) Zero count rate for the DPC.d) Date and time when the DPC count data werecollected.e) Cleanroom or clean zone status: as-built, at-rest,or operational.f) Type of testing: classifica

38、tion; characterizationof air flowing from potential source(s) of contami-nation or air flowing toward specified target areasof concern; or monitoring.g) Cleanroom or clean zone classification level (an-ticipated, if initial measurement).h) Particle size threshold(s) for which data werecollected.i) D

39、PC inlet sample flow and sensing volumesample flow rate.j) Locations of sampling points.k) Sampling schedule for classification or sam-pling protocol for testing.l) Raw data for each measurement, if required.6 Referencesa) ASTM F 50, Continuous Sizing and Counting ofAirborne Particles in Dust Contro

40、lled Areas andCleanrooms Using Instruments Capable of Detect-ing Single Sub-micrometer and Larger Particles.West Conshohocken, Pennsylvania: AmericanSociety for Testing and Materials.b) ASTM F 328, Standard Practice for Calibration ofan Airborne Particle Counter Using MonodisperseSpherical Particles

41、. West Conshohocken, Penn-sylvania: American Society for Testing andMaterialsc) ASTM F 649, Practice for Secondary Calibration ofAirborne Particle Counter Using Comparison Pro-cedures. West Conshohocken, Pennsylvania:American Society for Testing and Materials.d) ISO 14644-1, Cleanrooms and associate

42、d controlledenvironments Part 1: Classification of air cleanli-ness. Geneva, Switzerland: ISO, InternationalOrganization for Standardization.e) ISO 14644-2, Cleanrooms and associated controlledenvironments Part 2: Specifications for testing andmonitoring cleanrooms and clean zones to provecontinued

43、compliance with ISO 14644-1. Geneva,Switzerland: ISO, International Organizationfor Standardization.f) IEST-RD-CC011, A Glossary of Terms and Defini-tions Relating to Contamination Control. MountProspect, Illinois: Institute of EnvironmentalSciences and Technology.10 Copyrighted material IEST-G-CC10

44、01 INSTITUTE OF ENVIRONMENTAL SCIENCES AND TECHNOLOGYAPPENDIX AData Report ExampleParticle Count Data ReportCleanroom identification Company _Dept. _ Room _DPC identification Mfr. _ Model _ SN _Zero count rate _ counts/minData collection information Date _ /_ /_ Time _ Operator _Area status As-built

45、 a73 At-rest a73 Operational a73Type of testing Classification a73 Measurement of airborne contaminantfrom source a73, or toward target a73 Monitoring a73Area air cleanliness classification ISO Class _Particle size threshold(s) a) _ m b) _ m c) _ mCounter sample flow rate Inlet _ m3/sec; Sensor _ m3

46、/secSampling point (probe) location Equipment or grid designation _Sampling schedule, as specified Operation or equipment step _Sampling frequency _Raw data count results Concentration(s) at threshold size(s):a) _ particles/m3b) _ particles/m3c)_ particles/m3IEST-G-CC1001 INSTITUTE OF ENVIRONMENTAL SCIENCES AND TECHNOLOGY Copyrighted material 11INSTITUTE OF ENVIRONMENTAL SCIENCES AND TECHNOLOGY Arlington Place One 2340 S. Arlington Heights Road, Suite 10 Arlington Heights, IL 6005-4516 Phone: (847) 981-010 Fax: (847) 981-4130 E-mail: iestiest.org Web: ww.iest.org