ASTM_F_312_-_08.pdf

Designation:F31208Standard Test Methods forMicroscopical Sizing and Counting Particles fromAerospace Fluids on Membrane Filters1This standard is issued under the fixed designation F312;the number immediately following the designation indicates the year of originaladoption or,in the case of revision,the year of last revision.Anumber in parentheses indicates the year of last reapproval.Asuperscriptepsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 These test methods cover the determination of the sizedistribution and quantity of particulate matter contaminationfrom aerospace fluids isolated on a membrane filter.Themicroscopical techniques described may also be applied toother properly prepared samples of small particles.Two testmethods are described for sizing particles as follows:1.1.1 Test Method AParticle sizes are measured as thediameter of a circle whose area is equal to the projected area ofthe particle.1.1.2 Test Method BParticle sizes are measured by theirlongest dimension.1.2 The test methods are intended for application to particlecontamination determination of aerospace fluids,gases,surfaces,and environments.1.3 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.4 These test methods do not provide for sizing particlessmaller than 5 m.NOTE1Results of these methods are subject to variables inherent inany statistical method.The use of these methods as a standard for initiallyestablishing limits should be avoided unless ample tolerances are permis-sible.1.5 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2F302 Practice for Field Sampling of Aerospace Fluids inContainersF303 Practices for Sampling for Particles in AerospaceFluids and ComponentsF311 Practice for Processing Aerospace Liquid Samples forParticulate Contamination Analysis Using Membrane Fil-tersF314 Methods of Test for Identification of Metallic andFibrous Contaminants in Aerospace Fluids(Withdrawn1990)3F318 Practice for Sampling Airborne Particulate Contami-nation in Cleanrooms for Handling Aerospace Fluids3.Terminology3.1 Definitions:3.1.1 unit areathe area selected for counting particles.This may be the area of a reticle grid or some subdivisionthereof,the area of one imprinted membrane grid,or any otheraccurately calibrated area.3.1.2 effective filter areathe area of the membrane whichentraps the particles to be counted.3.1.3 particle sizethe size of a particle as defined by areacomparison or by its longest dimension.4.Summary of Test Methods4.1 The membrane is examined through a microscope andthe particles counted according to size or size categories usinga calibrated reticle.The total number of particles present isestimated by statistical methods from the actual number ofparticles counted.Either sizing Test Method A or B may beselected according to the preference and results expected.5.Significance and Use5.1 Reported particle size measurement is a function of boththe actual particle dimension and shape factor as well as theparticular physical or chemical properties of the particle beingmeasured.Caution is required when comparing data frominstruments operating on different physical or chemical param-eters or with different particle size measurement ranges.1These test methods are under the jurisdiction of ASTM Committee E21 onSpace Simulation and Applications of Space Technology and are the directresponsibility of Subcommittee E21.05 on ContaminationCurrent edition approved Nov.1,2008.Published December 2008.Originallyapproved in 1969.Last previous edition approved in 2003 as F312 97(2003).DOI:10.1520/F0312-08.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.3The last approved version of this historical standard is referenced onwww.astm.org.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 Sample acquisition,handling and preparation can also affectthe reported particle size results.6.Apparatus6.1 Microscope,capable of resolving the smallest particlesto be counted and producing a flat field of view.6.1.1 The following optic combinations are recommended:MagnificationOcularObjectiveMinimumNumericalAperture501050.1510010100.2520010200.50Similar ocular-objective combinations resulting in magnifi-cations of 50 6 10,100 6 10,and 200 6 20 may be used.The optimum equipment is a compound binocular microscope.Conventional stereo microscopes will not meet these require-ments.6.2 Mechanical Stage,capable of traversing the entireeffective