ASTM D5110-98(2004)
(Practice)Standard Practice for Calibration of Ozone Monitors and Certification of Ozone Transfer Standards Using Ultraviolet Photometry
Standard Practice for Calibration of Ozone Monitors and Certification of Ozone Transfer Standards Using Ultraviolet Photometry
SIGNIFICANCE AND USE
The reactivity and instability of O3 preclude the storage of O3 concentration standards for any practical length of time, and precludes direct certification of O3 concentrations as Standard Reference Materials (SRMs). Moreover, there is no available SRM that can be readily and directly adapted to the generation of O3 standards analogous to permeation devices and standard gas cylinders for sulfur dioxide and nitrogen oxides. Dynamic generation of O3 concentrations is relatively easy with a source of ultraviolet (UV) radiation. However, accurately certifying an O3 concentration as a primary standard requires assay of the concentration by a comprehensively specified analytical procedure, which must be performed every time a standard is needed (9).
This practice is not designed for the routine calibration of O3 monitors at remote locations (see Practices D 5011).
SCOPE
1.1 This practice covers a means for calibrating ambient, workplace, or indoor ozone monitors, and for certifying transfer standards to be used for that purpose.
1.2 This practice describes means by which dynamic streams of ozone in air can be designated as primary ozone standards.
This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. See Section for specific precautionary statements.
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Standards Content (Sample)
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Designation: D5110 – 98 (Reapproved 2004)
Standard Practice for
Calibration of Ozone Monitors and Certification of Ozone
Transfer Standards Using Ultraviolet Photometry
This standard is issued under the fixed designation D5110; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope E644 Test Methods for Testing Industrial Resistance Ther-
mometers
1.1 This practice covers a means for calibrating ambient,
workplace, or indoor ozone monitors, and for certifying
3. Terminology
transfer standards to be used for that purpose.
3.1 For definitions of terms used in this practice, refer to
1.2 This practice describes means by which dynamic
Terminology D1356.
streams of ozone in air can be designated as primary ozone
3.2 Definitions of Terms Specific to This Standard:
standards.
3.2.1 primary standard—a standard directly defined and
1.3 This standard does not purport to address all of the
established by some authority, against which all secondary
safety concerns, if any, associated with its use. It is the
standards are compared.
responsibility of the user of this standard to establish appro-
3.2.2 secondary standard—a standard used as a means of
priate safety and health practices and determine the applica-
comparison, but checked against a primary standard.
bility of regulatory limitations prior to use. See Section 8 for
3.2.3 standard—an accepted reference sample or device
specific precautionary statements.
used for establishing measurement of a physical quantity.
2. Referenced Documents 3.2.4 transfer standard—a type of secondary standard. It is
a transportable device or apparatus that, together with opera-
2.1 ASTM Standards:
tional procedures, is capable of reproducing pollutant concen-
D1356 Terminology Relating to Sampling and Analysis of
tration or producing acceptable assays of pollutant concentra-
Atmospheres
tions.
D3195 Practice for Rotameter Calibration
3.2.5 zero air—purifiedairthatdoesnotcontainozone,and
D3249 Practice for General Ambient Air Analyzer Proce-
does not contain any other component that may interfere with
dures
the measurement (see 7.1).
D3631 Test Methods for Measuring Surface Atmospheric
Pressure
4. Summary of Practice
D5011 Practices for Calibration of Ozone Monitors Using
3 4.1 Thispracticeisbasedonthephotometricassayofozone
Transfer Standards
(O ) concentrations in a dynamic flow system. The concentra-
E220 Test Method for Calibration of Thermocouples By
tion of O in an absorption cell is determined from a measure-
Comparison Techniques
ment of the amount of 253.7 nm light absorbed by the sample.
E591 Practice for Safety and Health Requirements Relating
3 This determination requires knowledge of (1) the absorption
to Occupational Exposure to Ozone
coefficient of O at 253.7 nm, (2) the optical path length
through the sample, (3) the transmittance of the sample at a
This practice is under the jurisdiction ofASTM Committee D22 on Sampling
wavelength of 253.7 nm, and (4) the temperature and pressure
and Analysis of Atmospheres and is the direct responsibility of Subcommittee
of the sample. The transmittance is defined as the ratio:
D22.03 on Ambient Atmospheres and Source Emissions.
CurrenteditionapprovedOctober1,2004.PublishedDecember2004.Originally
I/I
o
approved in 1990. Last previous edition approved in 1998 as D5110-98. DOI:
10.1520/D5110-98R04.
where:
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. The boldface numbers in parentheses refer to the references listed at the end of
Withdrawn. this practice.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D5110 – 98 (2004)
connections shall be as short as possible, and all surfaces shall
I = theintensityoflightthatpassesthroughthecellandis
be chemically clean. For certification of transfer standards that
sensed by the detector when the cell contains an O
provide their own source of O , the generator and possibly
sample, and
other components shown in Fig. 1 may not be required (see
I = theintensityoflightthatpassesthroughthecellandis
o
Practices D5011).
sensed by the detector when the cell contains zero air.
Itisassumedthatallconditionsofthesystem,exceptforthe 6.1.1 UV Photometer, consisting of a low-pressure mercury
contents of the absorption cell, are identical during measure- discharge lamp, collimation optics (optional), an absorption
ments of I and I . The quantities defined above are related by cell, a detector, and signal-processing electronics, as shown in
o
the Beer-Lambert absorption law: Fig. 1. It shall be capable of measuring the transmittance, I/I ,
o
at a wavelength of 253.7 nm with sufficient precision that the
2acd
Transmittance5I/I 5e (1)
o
standarddeviationoftheconcentrationmeasurementsdoesnot
exceedthegreaterof0.005ppmor3%oftheconcentration.It
where:
shallincorporatemeanstoassurethatnoO isgeneratedinthe
a = absorption coefficient of O at 253.7 nm,
3 3
−6 −1 −1
(308 64) 310 ppm cm at 0°C and 101.3 kPa (1 cell by the UV lamp. This is generally accomplished by
absorbing the 184.9 nm Hg line with a high silica window, or
atm) (1, 2, 3, 4, 5, 6, 7, 8)
c =O concentration, ppm, and
byisolatingthe253.7nmHglinewithaninterferencefilter.In
d = optical path length, cm.
addition,atleast99.5%oftheradiationsensedbythedetector
4.1.1 Inpractice,astableO generator(see6.1.4)isusedto
shall be 253.7 nm. This is usually accomplished by using a
produce O concentrations over the required range. Each O
solar blind photodiode tube. The length of the light path
3 3
concentration is determined from the measurement of the
throughtheabsorptioncellshallbeknownwithanaccuracyof
transmittanceofthesampleat253.7nm,andiscalculatedfrom
at least 0.5%. In addition, the cell and associated plumbing
the equation:
shall be designed to minimize loss of O from contact with
surfaces (10).
I
2ln
I 6.1.2 Air Flow Controller,capableofregulatingairflowsas
o
c5 (2)
~ad!
necessarytomeettheoutputstabilityandphotometerprecision
requirements.
The calculated O concentrations must be corrected for O
3 3
6.1.3 Flowmeters, calibrated in accordance with Practice
losses, which may occur in the photometer, and for the
D3195.
temperature and pressure of the sample.
6.1.4 Ozone Generator, capable of generating stable levels
5. Significance and Use
of O over the required concentration range. It shall be stable
over short periods to facilitate the sequential photometric
5.1 The reactivity and instability of O preclude the storage
measurement of I and I , and to allow for stability of the
of O concentration standards for any practical length of time, o
monitor or transfer standard connected to the output manifold.
and precludes direct certification of O concentrations as
Conventional UV-photolytic type generators may be adequate,
Standard Reference Materials (SRMs). Moreover, there is no
but shall have line voltage and temperature regulation.
available SRM that can be readily and directly adapted to the
6.1.5 Output Manifold, constructed of glass, TFE-
generation of O standards analogous to permeation devices
fluorocarbon, or other nonreactive material. It shall be of
and standard gas cylinders for sulfur dioxide and nitrogen
oxides. Dynamic generation of O concentrations is relatively sufficient diameter to ensure a negligible pressure drop at the
photometer connection and other output ports. The output
easy with a source of ultraviolet (UV) radiation. However,
accuratelycertifyinganO concentrationasaprimarystandard manifoldservesthefunctionofprovidinganinterfacebetween
the calibration system and other devices and systems that
requires assay of the concentration by a comprehensively
specifiedanalyticalprocedure,whichmustbeperformedevery utilize the output O concentrations. It shall have one or more
portsforconnectionoftheexternalinstrumentsorsystems,and
time a standard is needed (9).
5.2 This practice is not designed for the routine calibration shallbesuchthatallportsprovidethesameO concentrations.
The vent, which exhausts excess gas flow from the system and
of O monitors at remote locations (see Practices D5011).
insures that the manifold outlet ports are kept at atmospheric
6. Apparatus pressure for all flowrates, shall be large enough to avoid
appreciable pressure drop, and shall be located downstream of
6.1 AtypicalcompleteUVcalibrationsystemconsistsofan
the output ports to ensure that no ambient air enters the
O generator, an output port or manifold, a photometer, a
manifold due to eddy currents, back diffusion, and so forth.
source of zero air, and other components as necessary. The
6.1.6 Three-Way Valve, constructed ofTFE-fluorocarbon, to
configuration must provide a stable O concentration at the
switch the flow through the absorption cell from zero air (for
systemoutputandallowthephotometertoassayaccuratelythe
the I measurement) to manifold gas (for the I measurement).
output concentration to the precision specified for the photom-
o
eter. Fig. 1 shows the system, and illustrates the calibration 6.1.7 Temperature Indicator, accurate to 61°C. This indi-
system. Ozone is highly reactive and subject to losses upon cator is needed to measure the temperature of the gas in the
contact with surfaces.All components between the O genera- photometric cell to calculate a temperature correction. In most
tor and the photometer absorption cell shall be of inert photometers, particularly those whose cell is enclosed inside a
material, such as glass or TFE-fluorocarbon. Lines and inter- case or housing with other electrical or electronic components,
D5110 – 98 (2004)
FIG. 1 Schematic Diagram of a Typical UV Photometric Calibration System
the cell operates at a temperature somewhat above ambient ducer) is required. This device shall be calibrated against a
room temperature. Therefore, it is important to measure the suitable pressure standard, in accordance with Test Methods
temperature of the gas inside the cell, and not room tempera- D3631.
ture. A small thermocouple or thermistor, connected to an
6.1.9 Output Indicating Device, such as continuous strip
external readout device, may be attached to the cell wall or
chart recorder or digital volt meter.
inserted through the cell wall to measure internal cell tempera-
6.1.9.1 If a recorder is used, it shall have the following
ture. The point of temperature sensing shall be representative
specifications:
of the average cell temperature. The temperature sensing
Accuracy 60.25 % of span
deviceshallbecalibratedagainstaNISTcertifiedthermometer
Chart width no less than 150 mm
Time for full-scale travel 1 s
initially, and at periodic intervals, subject to the laboratory
quality control checks (11). See Method E220 orTest Methods
E644 for calibration procedures.
6.1.9.2 If a digital volt meter is used, it shall have an
6.1.8 Barometer or Pressure Indicator,accurateto250Pa(2
accuracy of 60.25% of range.
torr). The barometer or pressure indicator is used to measure
the pressure of the gas in the cell to calculate a pressure
7. Reagents and Materials
correction. Most photometer cells operate at atmospheric
pressure. If there are no restrictions between the cell and the 7.1 Zero Air—FreeofO andanysubstancethatbyitselfor
output manifold, the cell pressure should be very nearly the whose decomposition products from the ozonizer might react
same as the local barometric pressure. A certified local baro- with O , absorb 255.7 nm light, or undergo photolysis (for
metric pressure reading can then be used for the pressure example NO, NO , ethylene, and particulate matter). The air
correction. If the cell pressure is different from the local shall be purified to remove such substances. Dirty air shall be
barometric pressure, some means of accurately measuring the precleaned to remove particulate matter, oil mist, liquid water,
cell pressure (manometer, pressure gauge, or pressure trans- and so forth.
D5110 – 98 (2004)
7.1.1 The following describes a system that has been used ontheaccuracyofthephotometer,itisimportanttoensurethat
successfully: The air is dried with a membrane type dryer, the photometer is operating properly and accurately.
followed by a column of indicating silica gel. The air is
9.3.1 A well designed and properly built photometer is a
irradiated with a UV lamp to generate O , to convert NO to
3 precision instrument; once shown to operate adequately, it is
NO andthenpassedthroughacolumnofactivatedcharcoal(6
likely to continue to do so for some time, particularly if it is
to 14 mesh) to remove NO,O , hydrocarbons, and various
2 3
held stationary and used intermittently under laboratory con-
other substances, a column of molecular sieve (6 to 16 mesh,
ditions.Therefore,theperformancechecksmaynotnecessarily
type 4A), and a final particulate filter (2 µm) to remove
have to be conducted every time the photometer is used. The
particulate matter. (Warning—An important requirement in
actual frequency of the checks is a trade-off between confi-
photometer operation is that the zero air supplied to the
denceinthephotometerperformanceandthecostandeffortto
photometerduringtheI measurementisfromthesamesource
o
conductthechecks.Thisisamatterofjudgment,subjecttothe
as that used for the generation of O .The impurities present in
laboratory quality control checks (11). One reasonable ap-
zero air from different sources can significantly affect the
proach is to perform the checks very frequently with a new
transmittance of an air sample. This requirement presents no
photometer, keeping a chronological record of each perfor-
problemiftheconfigurationshowninFig.1isused.However,
mance check, using the QA control chart, and to reduce the
there may be a problem in certifying O generator transfer
frequencyasexperiencedictates.Evenwheretherecordshows
standards that have their own source of zero air or O (see
excellent stability, the checks shall be performed at some
Practices D5011). The zero air produced in 7.1.1 is very dry.
minimum frequency (for example, once every 2 or 3 weeks)
The O response of some measurement methods (for example,
because the possibility of malfunction is always present. A
ethylene chemiluminescence, KI bubblers) is affected by
regular schedule of checks will avoid the r
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