ASTM_F_649_-_01.pdf

Designation:F 649 01Standard Practice forSecondary Calibration of Airborne Particle Counter UsingComparison Procedures1This standard is issued under the fixed designation F 649;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon(e)indicates an editorial change since the last revision or reapproval.1.Scope1.1 This practice covers procedures for adjusting the sizeranges of an airborne discrete particle counter(DPC)to matchsize/concentration data from a reference DPC that has beencalibrated for counting and sizing accuracy in accordance withPractice F 328 and is kept in good working order.The practiceis applied in situations where time,capabilities,or both,required for carrying out procedures in Practice F 328 are notavailable.It is particularly useful where more than one DPCmay be required to observe an environment where the particu-late material being counted and sized is different in composi-tion from the precision spherical particulate materials used forcalibration in Practice F 328 and/or all of the DPCs in use arenot similar in optical or electronic design.1.2 Procedures covered here include those to measuresampled and observed air volume or flow rate,zero count level,particle sizing and counting accuracy,particle sizing resolu-tion,particle counting efficiency,and particle concentrationlimit.2.Referenced Documents2.1 ASTM Standards:F 328 Practice for Calibration of an Airborne ParticleCounter Using Monodisperse Spherical Particles2E 20 Practice for Particle Size Analysis of Particulate Sub-stances in the Range of 0.2m to 75 m by OpticalMicroscopy32.2IEST Standard:IEST RP-CC001.3 HEPA and ULPA Filters43.Summary of Practice3.1 The DPC under test is used to sample from an environ-ment containing polydisperse aerosol whose nature is thatanticipated where the DPC will be used.At the same time,thereference DPC that has been calibrated in accordance withPractice F 328,and maintained in good working order,is usedto sample from the same environment.The size range settingsof the DPC(s)under test are adjusted so that the reportedconcentration data are in good agreement with the dataproduced by the reference DPC.4.Significance4.1 In some measurements,two or more DPCs must beused.Operators have noted that differing results may beobtained by two DPCs sampling the same air parcel,evenwhen the DPCs have been recently been placed in goodoperating order and are operating within their design specifi-cations.4.2 Identical or closely similar data are not developed by theDPCs as a result of several possible causes.The most importantis the difference between the ambient aerosol and the calibra-tion aerosol in terms of both composition and particle sizedistribution.Another cause is variation in design and perfor-mance between the two DPCs.Still another cause is normalsample variance and the effects of possible difference in samplesize.Thus,even with good sample handling procedure,thesecauses may result in differences of up to an order of magnitudein concentrations reported by two or more DPCs.NOTE1A more detailed discussion of these factors is given inAppendix X1.5.Interferences5.1 Since the DPC is typically a high-sensitivity device,radio frequency or electromagnetic interference may affect it.Precautions should be taken to ensure that the test areaenvironment does not exceed the RFE-EMI capabilities of theDPC.Electronic or operational verification can be made,suchas indication of acceptable background level data reported.1This practice is under the jurisdiction ofASTM Committee E29 on Particle andSpray Characterizationand is the direct responsibility of Subcommittee E29.02onNon-Sieving Methods.Current edition approved May 10,2001.Published June 2001.Originallypublished as F 649-80.Last previous edition F 649-80(1999)2Annual Book of ASTM Standards,Vol 14.02.3Discontinued;see 1993 Annual Book of ASTM Standards,Vol 14.02.4Available from Institute of Environmental Sciences and Technology,940 E.Northwest Hwy.,Mt.Prospect,IL 600563444.1Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959,United States.6.Apparatus6.1 Reference DPCThis DPC should have been calibratedwithin the last 6-month period in accordance with PracticeF 328 and maintained in good operating order.It is recom-mended that the reference DPC be retained in a standardizationor calibration laboratory and used only as a standard referenceinstrument.6.2 Gas FlowmeterA flow meter with low pressure dropcharacteristics is required to measure sample flow into theDPC.Use a variable area flowmeter with DPC rated flow nearthe top of the flowmeter scale.The flowmeter should becalibrated and operated for low pressure drop across theflowmeter.6.3 TubingSmooth-walled tubing with inside diametersized in accordance with the DPC(s)inlet section should beused.The tubing shou