ASTM F50-2012 Standard Practice for Continuous Sizing and Counting of Airborne Particles in Dust-Controlled Areas and Clean Rooms Using Instruments Capable of Detecting Single Sub-.pdf

1、Designation:F5007 Designation: F50 12Standard Practice forContinuous Sizing and Counting of Airborne Particles inDust-Controlled Areas and Clean Rooms Using InstrumentsCapable of Detecting Single Sub-Micrometre and LargerParticles1This standard is issued under the fixed designation F50; the number i

2、mmediately following the designation indicates the year of originaladoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscriptepsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 T

3、his practice covers the determination of the particle concentration, by number, and the size distribution of airborne particlesin dust-controlled areas and clean rooms, for particles in the size range of approximately 0.01 to 5.0 m. Particle concentrationsnot exceeding 3.5 3 106particles/m3(100 000/

4、ft3) are covered for all particles equal to and larger than the minimum sizemeasured.1.2 This practice uses an airborne single particle counting device (SPC) whose operation is based on measuring the signalproduced by an individual particle passing through the sensing zone. The signal must be direct

5、ly or indirectly related to particlesize.NOTE 1The SPC type is not specified here. The SPC can be a conventional optical particle counter (OPC), an aerodynamic particle sizer, acondensation nucleus counter (CNC) operating in conjunction with a diffusion battery or differential mobility analyzer, or

6、any other device capableofcounting and sizing single particles in the size range of concern and of sampling in a cleanroom environment.1.3 Individuals performing tests in accordance with this practice shall be trained in use of the SPC and shall understand itsoperation.1.4 Since the concentration an

7、d the particle size distribution of airborne particles are subject to continuous variations, the choiceof sampling probe configuration, locations and sampling times will affect sampling results. Further, the differences in the physicalmeasurement, electronic and sample handling systems between the v

8、arious SPCs and the differences in physical properties of thevarious particles being measured can contribute to variations in the test results. These differences should be recognized andminimized by using a standard method of primary calibration and by minimizing variability of sample acquisition pr

9、ocedures.1.5 Sample acquisition procedures and equipment may be selected for specific applications based on varying cleanroom classlevels. Firm requirements for these selections are beyond the scope of this practice; however, sampling practices shall be statedthat take into account potential spatial

10、 and statistical variations of suspended particles in clean rooms.NOTE 2General references to cleanroom classifications follow Federal Standard 209E, latest revision. Where airborne particles are to be characterizedin dust-controlled areas that do not meet these classifications, the latest revision

11、of the pertinent specification for these areas shall be used.1.61.6 The values stated in SI units are to be regarded as the standard. The values given in parentheses are provided for informationonly and are not considered standard.1.7 This standard does not purport to address all of the safety conce

12、rns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use. For specific hazards statements, see Section 8.2. Referenced Documents2.1 ASTM Standa

13、rds:2D1356 Terminology Relating to Sampling and Analysis of AtmospheresF328 Practice for Calibration of an Airborne Particle Counter Using Monodisperse Spherical Particles1This practice is under the jurisdiction of ASTM Committee E21 on Space Simulation and Applications of Space Technology and is th

14、e direct responsibility ofSubcommittee E21.05 on Contamination.Current edition approved Nov. 1, 2007. Published November 2007. Originally approved in 1965. Last previous edition approved in 2001 as F5092(2001)1DOI:10.1520/F0050-07.Current edition approved April 1, 2012. Published May 2012. Originall

15、y approved in 1965. Last previous edition approved in 2007 as F50 07. DOI: 10.1520/F0050-12.2For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document

16、Summary page on the ASTM website.1This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recom

17、mends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.F649 Practice

18、for Secondary Calibration of Airborne Particle Counter Using Comparison ProceduresF658 Practice for Calibration of a Liquid-Borne Particle Counter Using an Optical System Based Upon Light Extinction2.2 U.S. Federal Standard:Federal Standard No. 209E, Clean Room and Work Station Requirements, Control

19、led Environment3,42.3 Other Documents:5ISO 14644-1 Cleanrooms and Associated Controlled Environments, Classification of air cleanlinessISO 14644-2 Cleanrooms and Associated Controlled Environments, Specifications for testing and monitoring to provecontinued compliance with ISO 14644-13. Terminology3

20、.1 Definitions of Terms Specific to This Standard:3.1.1 dust-controlled areaa clean room or clean work space in which airborne and deposited particulate contamination levels,or both, are controlled on the basis of a documented standard such as Federal Standard 209E.3.1.2 dynamic rangethe particle si

21、ze range, expressed as a multiple of the minimum measured size, over which the SPC canmeasure particles with size resolution of 10 % or less.3.1.3 particle concentrationthe number of individual particles per unit volume of ambient temperature and pressure air,particles/m3or particles/ft3.3.1.4 parti

22、cle sizeequivalent diameter of a particle detected by an SPC.3.1.4.1 DiscussionThe equivalent diameter is the diameter of a reference sphere of known size and physical characteristics(for example, refractive index when using an OPC; density when using an aerodynamic particle sizer; etc) and generati

23、ng the sameresponse in the SPC sensing zone as the particle being measured. Spherical particles are used for calibration of the SPCs consideredhere. The SPC response is related to the size, shape, orientation and physical properties of the particle passing through the SPCsensing zone. If an optical

24、particle counter is used, the geometry of the optical system, as well as the spectral distribution of theilluminating light influences the reported particle size. If a condensation nucleus counter with a size-fractionation device is used,the SPC operating parameters and the particle properties that

25、affect the nucleation efficiency and, for example, the diffusioncoefficient, will influence reported data. The SPC instruction manual should make the user aware of the effects of such factors onthe indicated particle size data.3.1.5 primary calibrationcalibration with standard reference particles fo

26、r particle size and (optionally) concentration. Initiallycarried out by the SPC manufacturer.3.1.6 resolutionthe capability of the SPC to differentiate between particles with small difference in size.3.1.6.1 DiscussionIt can be quantified as the ratio of the square root of the difference between the

27、 measured and actualvariances of a monosized particle size distribution to the mean diameter of those monosize particles, using procedures as shownin Practice F658.3.1.7 standardizationsecondary calibration of electronic system voltage and signal response threshold levels using thereference system b

28、uilt into the SPC.3.1.7.1 DiscussionThe SPC should be capable of carrying out this procedure with a simple, rapid manual operation or byinternal timed or microprocessor controlled components.3.2 For definitions of other terms used in this practice, see Terminology D1356 and (Federal Standard 209E).4

29、. Summary of Practice4.1 Satisfactory primary calibration within the manufacturers recommended time period and routine standardization should beverified as a first step.4.2 A sample acquisition program is established on the basis of the cleanliness level that is to be verified or monitored. Thisprog

30、ram will include sample point identification, sample size definitions and sampling frequency, specification of the sampler inletand sample transport system, definition of the particle size ranges to be measured, and any other parameters of concern in thedust-controlled area or clean room.4.3 Air sam

31、ples are passed through the SPC and the particle content of each sample is defined by the SPC. Particles containedin the sampled air pass through the sensing zone of the SPC. Each particle produces a signal that can be related to particle size.An electronic system sorts and counts the pulses, regist

32、ering the number of particles of various sizes that have passed through thesensing zone during passage of a known gas volume. The concentration and particle size data can be displayed, printed or otherwiseprocessed, locally or remotely.3Available from U.S. General Services Administration, Federal Su

33、pply Service, Standardization Division, Washington, DC 20406, http:/www.gsa.gov.4Fed-Std-209E has been replaced by ISO/DIS 14644-1 and -2, but may continue to be used by mutual agreement.5Available from IEST, 940 E. Northwest Highway, Mt. Prospect, IL 60056 and the International Organization for Sta

34、ndardization (ISO), 1 rue de Varemb, Case postale56, CH-1211, Geneva 20, Switzerland, http:/www.iso.ch5Available from Institute of Environmental Sciences and Technology (IEST), Arlington Place One, 2340 S. Arlington Heights Rd., Suite 100, Arlington Heights, IL60005-4516, http:/www.iest.org, and fro

35、m International Organization for Standardization (ISO), 1, ch. de la Voie-Creuse, CP 56, CH-1211 Geneva 20, Switzerland,http:/www.iso.org.F501225. Significance and Use5.1 The primary purpose of this practice is to describe a procedure for collecting near real-time data on airborne particleconcentrat

36、ion and size distribution in clean areas as indicated by single particle counting techniques. Implementation of somegovernment and industry specifications requires acquisition of particle size and concentration data using an SPC.5.2 The processing requirements of many products manufactured in a clea

37、n room involves environmental cleanliness levels solow that a single particle counter with capability for detecting very small particles is required to characterize clean room air.Real-time information on concentration of airborne particles in size ranges from less than 0.1 m to 5 m and greater can

38、beobtained only with an SPC. Definition of particles larger than approximately 0.05 m may be carried out with direct measurementof light scattering from individual particles; other techniques may be required for smaller particles, such as preliminary growth bycondensation before particle measurement

39、.5.3 Particle size data are referenced to the particle system used to calibrate the SPC. Differences in detection, electronic andsample handling systems among the various SPCs may contribute to differences in particle characterization. Care must be exercisedin attempting to compare data from particl

40、es that vary significantly in composition or shape from the calibration base material.Variations may also occur between instruments using similar particle sensing systems with different operating parameters. Theseeffects should be recognized and minimized by using standard methods for SPC calibratio

41、n and operation.5.4 In applying this practice, the fundamental assumption is made that the particles in the sample passing through the SPC arerepresentative of the particles in the entire dust-controlled area being analyzed. Care is required that good sampling procedures areused and that no artifact

42、s are produced at any point in the sample handling and analysis process; these precautions are necessaryboth in verification and in operation of the SPC.6. Interferences6.1 Since the SPC is typically a high sensitivity device, its response may be affected by internally or externally generated noise.

43、The SPC should not be operated at a sensitivity level so high that internal noise produces more than 5 % of the data signals.6.2 Precautions should also be taken to ensure that the test area environment does not exceed the radio frequency orelectromagnetic interference capabilities of the SPC.6.3 Op

44、eration at acceptably low levels of internal noise can be verified by drawing a sample into the SPC through a filter orother gas cleaning device that will positively remove at least 99.97 % of all particles of size equal to and greater than that whichthe SPC will measure. After a short stabilization

45、 period, any signals reported by the SPC can be assumed to arise from internalor external noise sources.7. Apparatus7.1 SPCThe apparatus shall consist of a SPC, selected on the basis of its ability to count and size single particles in therequired size range. The SPC shall include a sample air flow

46、system, a particle characterization system, and a data processingsystem. The minimum measurable particle size shall be selected from the clean area definition stated in ISO 14644-1 (Table I ofFederal Standard 209E), or from a different specification of clean-area airborne particle concentration at a

47、 stated minimum particlesize. For classification levels based on measurement of particles larger than 0.05 m, an optical particle counter (OPC), anaerodynamic particle sizer or an equivalent SPC can be used. For classification levels based on particles less than 0.05 m, a CNCin combination with a di

48、ffusion battery, a differential mobility analyzer or an equivalent SPC can be used.7.1.1 Sample Air Flow System, consists of an intake tube, the particle sensing/measurement chamber, an air flow metering orcontrol system, and an exhaust system. No abrupt transitions in dimension should occur within

49、the air flow system. The inlet tubeshould consist of a sharp-edged inlet nozzle connected to a tube that will transport the sample air to the particle characterizationsystem. The sample inlet nozzle should have a cross-sectional area equivalent to that of a circle of diameter at least 2 mm. Thenozzle can be attached to a transit tube with dimensions so that residence time in the tube will not exceed 10 s. Sample tubes shouldbe configured so that the flow Reynolds number is maintained in the range 5 000 to 25 000. For particles in the size range 0.1 mto