1、Designation: D5110 98 (Reapproved 2017)Standard Practice forCalibration of Ozone Monitors and Certification of OzoneTransfer Standards Using Ultraviolet Photometry1This standard is issued under the fixed designation D5110; the number immediately following the designation indicates the year oforigina
2、l adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice covers a means for calibrating ambient,workplace, or
3、 indoor ozone monitors, and for certifyingtransfer standards to be used for that purpose.1.2 This practice describes means by which dynamicstreams of ozone in air can be designated as primary ozonestandards.1.3 The values stated in SI units are to be regarded asstandard. No other units of measuremen
4、t are included in thisstandard.1.4 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, health, and environmental practices and deter-mine the applicability of regu
5、latory limitations prior to use.See Section 8 for specific precautionary statements.1.5 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Gui
6、des and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D1356 Terminology Relating to Sampling and Analysis ofAtmospheresD3195 Practice for Rotameter CalibrationD3249 Practice for General Ambient Air Analyz
7、er Proce-duresD3631 Test Methods for Measuring Surface AtmosphericPressureD5011 Practices for Calibration of Ozone Monitors UsingTransfer StandardsE220 Test Method for Calibration of Thermocouples ByComparison TechniquesE591 Practice for Safety and Health Requirements Relatingto Occupational Exposur
8、e to Ozone (Withdrawn 1990)3E644 Test Methods for Testing Industrial Resistance Ther-mometers3. Terminology3.1 DefinitionsFor definitions of terms used in thispractice, refer to Terminology D1356.3.2 Definitions of Terms Specific to This Standard:3.2.1 primary standard, na standard directly defined
9、andestablished by some authority, against which all secondarystandards are compared.3.2.2 secondary standard, na standard used as a means ofcomparison, but checked against a primary standard.3.2.3 standard, nan accepted reference sample or deviceused for establishing measurement of a physical quanti
10、ty.3.2.4 transfer standard, na type of secondary standard. Itis a transportable device or apparatus that, together withoperational procedures, is capable of reproducing pollutantconcentration or producing acceptable assays of pollutantconcentrations.3.2.5 zero air, npurified air that does not contai
11、n ozone,and does not contain any other component that may interferewith the measurement (see 7.1).4. Summary of Practice4.1 This practice is based on the photometric assay of ozone(O3) concentrations in a dynamic flow system. The concentra-tion of O3in an absorption cell is determined from a measure
12、-ment of the amount of 253.7 nm light absorbed by the sample.This determination requires knowledge of (1) the absorptioncoefficient of O3at 253.7 nm, (2) the optical path lengththrough the sample, (3) the transmittance of the sample at a1This practice is under the jurisdiction of ASTM Committee D22
13、on AirQuality and is the direct responsibility of Subcommittee D22.03 on AmbientAtmospheres and Source Emissions.Current edition approved Oct. 1, 2017. Published October 2017. Originallyapproved in 1990. Last previous edition approved in 2010 as D5110 98 (2010).DOI: 10.1520/D5110-98R17.2For referenc
14、ed 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
15、.astm.org.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopmen
16、t of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.1wavelength of 253.7 nm, and (4) the temperature and pressureof the sample. The transmittance is defined as the ratio:I/Iowhere:I = the intensity of light that
17、passes through the cell and issensed by the detector when the cell contains an O3sample, andIo= the intensity of light that passes through the cell and issensed by the detector when the cell contains zero air.It is assumed that all conditions of the system, except for thecontents of the absorption c
18、ell, are identical during measure-ments of I and Io. The quantities defined above are related bythe Beer-Lambert absorption law:Transmittance 5 I/Io5 e2acd(1)where:a = absorption coefficient of O3at 253.7 nm,(308 6 4)106ppm1cm1at 0C and 101.3 kPa (1atm) (1-8),4c =O3concentration, ppm, andd = optical
19、 path length, cm.4.1.1 In practice, a stable O3generator (see 6.1.4) is used toproduce O3concentrations over the required range. Each O3concentration is determined from the measurement of thetransmittance of the sample at 253.7 nm, and is calculated fromthe equation:c 52lnIIoad!(2)The calculated O3c
20、oncentrations must be corrected for O3losses, which may occur in the photometer, and for the tem-perature and pressure of the sample.5. Significance and Use5.1 The reactivity and instability of O3preclude the storageof O3concentration standards for any practical length of time,and precludes direct c
21、ertification of O3concentrations asStandard Reference Materials (SRMs). Moreover, there is noavailable SRM that can be readily and directly adapted to thegeneration of O3standards analogous to permeation devicesand standard gas cylinders for sulfur dioxide and nitrogenoxides. Dynamic generation of O
22、3concentrations is relativelyeasy with a source of ultraviolet (UV) radiation. However,accurately certifying an O3concentration as a primary standardrequires assay of the concentration by a comprehensivelyspecified analytical procedure, which must be performed everytime a standard is needed (9).5.2
23、This practice is not designed for the routine calibrationof O3monitors at remote locations (see Practices D5011).6. Apparatus6.1 Atypical complete UV calibration system consists of anO3generator, an output port or manifold, a photometer, asource of zero air, and other components as necessary. Thecon
24、figuration must provide a stable O3concentration at thesystem output and allow the photometer to assay accurately theoutput concentration to the precision specified for the photom-eter. Fig. 1 shows the system, and illustrates the calibrationsystem. Ozone is highly reactive and subject to losses upo
25、ncontact with surfaces. All components between the O3genera-tor and the photometer absorption cell shall be of inertmaterial, such as glass or TFE-fluorocarbon. Lines and inter-connections shall be as short as possible, and all surfaces shallbe chemically clean. For certification of transfer standar
26、ds thatprovide their own source of O3, the generator and possiblyother components shown in Fig. 1 may not be required (seePractices D5011).6.1.1 UV Photometer, consisting of a low-pressure mercurydischarge lamp, collimation optics (optional), an absorptioncell, a detector, and signal-processing elec
27、tronics, as shown inFig. 1. It shall be capable of measuring the transmittance, I/Io,at a wavelength of 253.7 nm with sufficient precision that thestandard deviation of the concentration measurements does notexceed the greater of 0.005 ppm or 3 % of the concentration. Itshall incorporate means to as
28、sure that no O3is generated in thecell by the UV lamp. This is generally accomplished byabsorbing the 184.9 nm Hg line with a high silica window, orby isolating the 253.7 nm Hg line with an interference filter. Inaddition, at least 99.5 % of the radiation sensed by the detectorshall be 253.7 nm. Thi
29、s is usually accomplished by using asolar blind photodiode tube. The length of the light paththrough the absorption cell shall be known with an accuracy ofat least 0.5 %. In addition, the cell and associated plumbingshall be designed to minimize loss of O3from contact withsurfaces (10).6.1.2 Air Flo
30、w Controller, capable of regulating air flows asnecessary to meet the output stability and photometer precisionrequirements.6.1.3 Flowmeters, calibrated in accordance with PracticeD3195.6.1.4 Ozone Generator, capable of generating stable levelsof O3over the required concentration range. It shall be
31、stableover short periods to facilitate the sequential photometricmeasurement of I and Io, and to allow for stability of themonitor or transfer standard connected to the output manifold.Conventional UV-photolytic type generators may be adequate,but shall have line voltage and temperature regulation.6
32、.1.5 Output Manifold, constructed of glass, TFE-fluorocarbon, or other nonreactive material. It shall be ofsufficient diameter to ensure a negligible pressure drop at thephotometer connection and other output ports. The outputmanifold serves the function of providing an interface betweenthe calibrat
33、ion system and other devices and systems thatutilize the output O3concentrations. It shall have one or moreports for connection of the external instruments or systems, andshall be such that all ports provide the same O3concentrations.The vent, which exhausts excess gas flow from the system andinsure
34、s that the manifold outlet ports are kept at atmosphericpressure for all flowrates, shall be large enough to avoidappreciable pressure drop, and shall be located downstream of4The boldface numbers in parentheses refer to the references listed at the end ofthis practice.D5110 98 (2017)2the output por
35、ts to ensure that no ambient air enters themanifold due to eddy currents, back diffusion, and so forth.6.1.6 Three-Way Valve, constructed of TFE-fluorocarbon, toswitch the flow through the absorption cell from zero air (forthe Iomeasurement) to manifold gas (for the I measurement).6.1.7 Temperature
36、Indicator, accurate to 61C. This indi-cator is needed to measure the temperature of the gas in thephotometric cell to calculate a temperature correction. In mostphotometers, particularly those whose cell is enclosed inside acase or housing with other electrical or electronic components,the cell oper
37、ates at a temperature somewhat above ambientroom temperature. Therefore, it is important to measure thetemperature of the gas inside the cell, and not room tempera-ture. A small thermocouple or thermistor, connected to anexternal readout device, may be attached to the cell wall orinserted through th
38、e cell wall to measure internal cell tempera-ture. The point of temperature sensing shall be representativeof the average cell temperature. The temperature sensingdevice shall be calibrated against a NIST certified thermometerinitially, and at periodic intervals, subject to the laboratoryquality con
39、trol checks (11). See Test Method E220 or TestMethods E644 for calibration procedures.6.1.8 Barometer or Pressure Indicator, accurate to 250 Pa (2torr). The barometer or pressure indicator is used to measurethe pressure of the gas in the cell to calculate a pressurecorrection. Most photometer cells
40、operate at atmosphericpressure. If there are no restrictions between the cell and theoutput manifold, the cell pressure should be very nearly thesame as the local barometric pressure. A certified local baro-metric pressure reading can then be used for the pressurecorrection. If the cell pressure is
41、different from the localbarometric pressure, some means of accurately measuring thecell pressure (manometer, pressure gauge, or pressure trans-ducer) is required. This device shall be calibrated against asuitable pressure standard, in accordance with Test MethodsD3631.6.1.9 Output Indicating Device,
42、 such as continuous stripchart recorder or digital volt meter.6.1.9.1 If a recorder is used, it shall have the followingspecifications:Accuracy 0.25 % of spanChart width no less than 150 mmTime for full-scale travel 1 sFIG. 1 Schematic Diagram of a Typical UV Photometric Calibration SystemD5110 98 (
43、2017)36.1.9.2 If a digital volt meter is used, it shall have anaccuracy of 60.25 % of range.7. Reagents and Materials7.1 Zero AirFree of O3and any substance that by itself orwhose decomposition products from the ozonizer might reactwith O3, absorb 255.7 nm light, or undergo photolysis (forexample NO
44、, NO2, ethylene, and particulate matter). The airshall be purified to remove such substances. Dirty air shall beprecleaned to remove particulate matter, oil mist, liquid water,and so forth.7.1.1 The following describes a system that has been usedsuccessfully: The air is dried with a membrane type dr
45、yer,5followed by a column of indicating silica gel. The air isirradiated with a UV lamp to generate O3, to convert NO toNO2and then passed through a column of activated charcoal (6to 14 mesh) to remove NO2,O3, hydrocarbons, and variousother substances, a column of molecular sieve (6 to 16 mesh,type
46、4A), and a final particulate filter (2 m) to removeparticulate matter. (WarningAn important requirement inphotometer operation is that the zero air supplied to thephotometer during the Iomeasurement is from the same sourceas that used for the generation of O3. The impurities present inzero air from
47、different sources can significantly affect thetransmittance of an air sample. This requirement presents noproblem if the configuration shown in Fig. 1 is used. However,there may be a problem in certifying O3generator transferstandards that have their own source of zero air or O3(seePractices D5011).
48、 The zero air produced in 7.1.1 is very dry.The O3response of some measurement methods (for example,ethylene chemiluminescence, KI bubblers) is affected bychanges in relative humidity. This dependence should be takeninto account when reporting results.)8. Hazards8.1 Safety HazardsSee Practice D3249
49、for safety precau-tions on the use of monitors and electronic equipment.8.1.1 Ozone is a toxic gaseous substance. See Practice E591for biological effects, and for safety and health requirements.8.1.2 The manifold vents and photometer and monitorexhausts must be vented to remove exhaust gases from theworkplace. Care shall be taken to avoid a back pressure in thecell and manifold, and in the monitor or transfer standard beingcalibrated.9. Preparation of Apparatus9.1 ConditioningThe system shall be conditioned byflowing O3at maximum concentration for 10 to 30 minin
copyright@ 2008-2019 麦多课文库（www.mydoc123.com）网站版权所有
备案/许可证编号：苏ICP备17064731号-1