1、Designation: D 3249 95 (Reapproved 2005)Standard Practice forGeneral Ambient Air Analyzer Procedures1This standard is issued under the fixed designation D 3249; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revis
2、ion. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1. Scope1.1 This practice is a general guide for ambient a
3、ir analyzersused in determining air quality.1.2 The actual method, or analyzer chosen, depends on theultimate aim of the user: whether it is for regulatory compli-ance, process monitoring, or to alert the user of adverse trends.If the method or analyzer is to be used for federal or localcompliance,
4、it is recommended that the method published orreferenced in the regulations be used in conjunction with thisand other ASTM methods.1.3 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 establi
5、sh appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. For specific hazardstatements, see Section 6.2. Referenced Documents2.1 ASTM Standards:2D 1356 Terminology Relating to Sampling and Analysis ofAtmospheresD 1357 Practice for Planning
6、the Sampling of the AmbientAtmosphereD 3609 Practice for Calibration Techniques Using Perme-ation TubesD 3670 Guide for Determination of Precision and Bias ofMethods of Committee D22E 177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE 200 Practice for Preparation, Standardizat
7、ion, and Stor-age of Standard and Reagent Solutions for Chemical Analy-sis3. Terminology3.1 Definitions:3.1.1 For definitions of terms used in this practice other thanthose following, refer to Terminology D 1356.3.1.2 analyzerthe instrumental equipment necessary toperform automatic analysis of ambie
8、nt air through the use ofphysical and chemical properties and giving either cyclic orcontinuous output signal.3.1.2.1 analyzer systemall sampling, analyzing, and read-out instrumentation required to perform ambient air qualityanalysis automatically.3.1.2.2 sample systemequipment necessary to provide
9、 theanalyzer with a continuous representative sample.3.1.2.3 readout instrumentationoutput meters, recorder,or data acquisition system for monitoring analytical results.3.1.3 full scalethe maximum measuring limit for a givenrange of an analyzer.3.1.4 interferencean undesired output caused by a sub-s
10、tance or substances other than the one being measured. Theeffect of interfering substance(s), on the measurement ofinterest, shall be expressed as: (6) percentage change ofmeasurement compared with the molar amount of the interfer-ent. If the interference is nonlinear, an algebraic expressionshould
11、be developed (or curve plotted) to show this varyingeffect.3.1.5 lag timethe time interval from a step change in theinput concentration at the analyzer inlet to the first correspond-ing change in analyzer signal readout.3.1.6 linearitythe maximum deviation between an actualanalyzer reading and the r
12、eading predicted by a straight linedrawn between upper and lower calibration points. Thisdeviation is expressed as a percentage of full scale.3.1.7 minimum detection limitthe smallest input concen-tration that can be determined as the concentration approacheszero.1This practice is under the jurisdic
13、tion ofASTM Committee D22 onAir Qualityand is the direct responsibility of Subcommittee D22.03 on Ambient Atmospheresand Source Emissions.Current edition approved Oct. 1, 2005. Published January 2006. Originallyapproved in 1973. Last previous edition approved in 2000 as D 3249 - 95(2000).2For refere
14、nced 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.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West
15、Conshohocken, PA 19428-2959, United States.3.1.8 noiserandom deviations from a mean output notcaused by sample concentration changes.3.1.9 operating humidity range of analyzerthe range ofambient relative humidity of air surrounding the analyzer, overwhich the analyzer will meet all performance speci
16、fications.3.1.9.1 operating humidity range of samplethe range ofambient relative humidity of air which passes through theanalyzers sensing system, over which the monitor will meetall performance specifications.3.1.10 operational periodthe period of time over whichthe analyzer can be expected to oper
17、ate unattended withinspecifications.3.1.11 operating temperature range of analyzerthe rangeof ambient temperatures of air surrounding the analyzer, overwhich the monitor will meet all performance specifications.3.1.11.1 operating temperature range of samplethe rangeof ambient temperatures of air, wh
18、ich passes through theanalyzers sensing system, over which the analyzer will meetall performance specifications.3.1.12 outputa signal that is related to the measurement,and intended for connection to a readout or data acquisitiondevice. Usually this is an electrical signal expressed as milli-volts o
19、r milliamperes full scale at a given impedance.3.1.13 precisionsee Practice D 3670.3.1.13.1 repeatabilitya measure of the precision of theanalyzer to repeat its results on independent introductions ofthe same sample at different time intervals. This is thatdifference between two such single instrume
20、nt results, obtainedduring a stated time interval, that would be exceeded in thelong run in only one case in twenty when the analyzer isoperating normally.3.1.13.2 reproducibilitya measure of the precision ofdifferent analyzers to repeat results on the same sample.3.1.14 rangethe concentration regio
21、n between the mini-mum and maximum measurable limits.3.1.15 response timethe time interval from a step changein the input concentration at the analyzer inlet to an outputreading of 90 % of the ultimate reading.3.1.16 rise timeresponse time minus lag time.3.1.17 span driftthe change in analyzer outpu
22、t over astated time period, usually 24 h of unadjusted continuousoperation, when the input concentration is at a constant, statedupscale value. Span drift is usually expressed as a percentagechange of full scale over a 24-h operational period.3.1.18 zero driftthe change in analyzer output over astat
23、ed time period of unadjusted continuous operation when theinput concentration is zero; usually expressed as a percentagechange of full scale over a 24-h operational period.4. Summary of Practice4.1 A procedure for ambient air analyzer practices has beenoutlined. It presents definitions and terms, sa
24、mpling informa-tion, calibration techniques, methods for validating results, andgeneral comments related to ambient air analyzer methods ofanalysis. This is intended to be a common reference methodwhich can be applied to all automatic analyzers in thiscategory.5. Significance and Use5.1 The signific
25、ance of this practice is adequately covered inSection 1.6. Hazards6.1 Each analyzer installation should be given a thoroughsafety engineering study.36.2 Electrically the analyzer system as well as the individualcomponents shall meet all code requirements for the particulararea classification.6.2.1 A
26、ll analyzers using 120-V, a-c, 60-Hz, 3-wire systemsshould observe proper polarity and should not use mechanicaladapters for 2-wire outlets.6.2.2 The neutral side of the power supply at the analyzershould be checked to see that it is at ground potential.6.2.3 The analyzers ground connection should b
27、e checkedto earth ground for proper continuity.6.2.4 Any analyzer containing electrically heated sectionsshould have a temperature-limit device.6.2.5 The analyzer, and any related electrical equipment (thesystem), should have a power cut-off switch, and a fuse orbreaker, on the “hot” side of the lin
28、e(s) of each device.6.3 Full consideration must be given to safe disposal of theanalyzers spent samples and reagents.6.4 Pressure relief valves, if applicable, shall be provided toprotect both the analyzer and analyzer system.6.5 Precautions should be taken when using cylinders con-taining gases or
29、liquids under pressure. Helpful guidance maybe obtained from Ref (1), (2), (3), (4), and (5).46.5.1 Gas cylinders must be fastened to a rigid structure andnot exposed to direct sun light or heat.6.5.2 Special safety precautions should be taken when usingor storing combustible or toxic gases to ensur
30、e that the systemis safe and free from leaks.7. Installation of Analyzer System7.1 Assure that information required for installation andoperation of the analyzer system is supplied by the manufac-turer.7.2 Study operational data and design parameters furnishedby the supplier before installation.7.3
31、Review all sample requirements with the equipmentsupplier. The supplier must completely understand the appli-cation and work closely with the user and installer. It isabsolutely necessary to define carefully all conditions ofintended operation, components in the atmosphere to beanalyzed, and expecte
32、d variations in sample composition.3The user, equipment supplier, and installer should be familiar with require-ments of the National Electrical Code, any local applicable electrical code, U.L.Safety Codes, and the Occupational Safety ” ISA RP12.1, “Electrical Instruments in Hazardous Atmospheres;”
33、ISARP12.2, “Intrinsically Safe and Nonincendive Electrical Instruments;” ISA RP12.4,“Instrument Purging for Reduction of Hazardous Area Classification;” and APRP550, “Installation of Refinery Instruments and Control Systems, Part II.”4The boldface numbers in parentheses may be found in the Reference
34、 section atthe end of this method.D 3249 95 (2005)27.4 Choose materials of construction in contact with theambient air sample to be analyzed to prevent reaction ofmaterials with the sample, sorption of components from thesample, and entrance of contaminants through infusion ordiffusion (6), (7), (8)
35、, (9).7.4.1 Choose materials of construction and components ofthe analyzer system to withstand the environment in which it isinstalled.7.4.2 Avoid the use of pipe-thread compounds in favor ofpolytetrafluorethylene tape.7.5 Select the sampling point so as to provide a representa-tive and measurable s
36、ample as close as possible to the samplesystem and analyzer (see Practice D 1357).7.5.1 Provide a convenient access to the entire analyzersystem.7.5.2 Provide a necessary connection for introducing stan-dard samples or withdrawing laboratory check samples imme-diately upstream of the analyzer sampli
37、ng system.7.6 Sample lines should be as short as practical.7.6.1 Install the analyzers exhaust so that no liquid or gaspressure buildup will occur. Provide proper venting, as far aspossible from the sampling point.7.7 After the installation has been completed, allow theanalyzer to stabilize before t
38、esting performance specifications.8. Calibration8.1 One of the most important steps in analyzer operation isproper calibration of the instrument. Various calibration tech-niques may be used depending on the samples physical orchemical property requiring measurement. Frequency of cali-bration depends
39、 largely on the application, degree of accuracy,and reliability expected. Perform calibration using spotsamples (ambient) or a standard reference sample and utilizethe analyzer adjustments as recommended by the manufacturer.Consult the supplier to determine the calibration procedurenecessary for the
40、 particular analysis involved as preliminaryinstrument adjustments using zero and upscale standards maybe necessary. Charts and calibration curves are essential andshould be routinely verified.8.1.1 In all cases, standard used for calibration purposesmust be as representative as possible of the atmo
41、sphere to beanalyzed, but cannot always contain all potential interferingsubstances.8.2 Spot Sample Calibration MethodAsample is removedfrom the sampling line close to the analyzer inlet during aperiod when the sample flowing through the line is of uniformcomposition and the analyzer readout has rea
42、ched an equilib-rium value.8.2.1 When this condition is reached, withdraw a samplefrom the inlet stream for analysis using the appropriate ASTMtest method for the component of interest.8.2.2 For most applications, a minimum of nine samples arerequired, and these shall be withdrawn each cycle for int
43、ermit-tent analyzers or for continuous analyzers after a stableresponse is achieved.8.2.3 After each spot sample has been removed, record it asto time, sample number, date and corresponding analyzerreadout. This equivalent readout is used in establishing a singlecalibration point.8.2.4 Each spot sam
44、ple must be analyzed in duplicate usingthe corresponding ASTM test method and the two resultsaveraged. The standard deviation for the spot sample iscalculated as the difference (larger value minus the smallervalue) divided by=2 . If this standard deviation exceeds thetest method repeatability limit,
45、 r, (see Practice E 177) then thattest average must be discarded. (This assumes that a repeat-ability limit has been determined for the test method and thelaboratory conducting the test. This rejection criterion willdiscard 5 % of the spot sample results even if the test methodis operating properly.
46、)8.2.5 Determine the amount of calibration offset by averag-ing the deviations, as shown in Table 1, and correct theanalyzer readout accordingly. It may be necessary to review themanufacturers recommended procedure for making calibra-tion offset adjustments.8.3 Standard Sample Calibration Method Use
47、 a standardreference sample in accordance with the ASTM test methodchosen, or by generating a known sample concentration, usingNIST calibrated permeation tubes (see Practice D 3609).8.3.1 A standard sample benchmark analysis is made byaveraging the results of at least nine determinations using theco
48、rresponding ASTM test method. This average value isacceptable for benchmark analysis only if the correspondingstandard deviation is lower in magnitude than the test methodsrepeatability limit, r, (see Practice E 177).8.3.2 Check all operating parameters of the system inaccordance with the instrument
49、 specifications and data forspecific analysis.Allow sufficient time for the analyzer to reachequilibrium as indicated by a stable output.8.3.3 Introduce the standard reference sample into theanalyzer using the recommended instrument operational pro-cedure. Activate the readout equipment.8.3.4 After sufficient standard has been allowed to flowthrough the analyzer, adjust the readout to conform with thebenchmark value. This establishes a single calibration point.8.3.5 Continue introducing standard sample and recordanalysis after a stable response is achi
