ASTM D5011-17

Standard Practices for Calibration of Ozone Monitors Using Transfer Standards

SIGNIFICANCE AND USE
5.1 The reactivity and instability of O3 precludes the storage of O3 concentration standards for any practical length of time, and precludes direct certification of O3 concentrations as SRM's. 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.  
5.2 The primary UV standard photometers, which are usually used at a fixed location under controlled conditions, are used to certify transfer standards that are then transported to the field sites where the ambient ozone monitors are being used. See Practice D5110.  
5.3 The advantages of this procedure are:  
5.3.1 All O3 monitors in a given network or region may be traced to a single primary standard.  
5.3.2 The primary standard is used at only one location, under controlled conditions.  
5.3.3 Transfer standards are more rugged and more easily portable than primary standards.  
5.3.4 Transfer standards may be used to intercompare various primary standards.
SCOPE
1.1 These practices describe means for calibrating ambient, workplace or indoor ozone monitors, using transfer standards.  
1.2 These practices describe five types of transfer standards:
Practice A—Analytical instruments,
Practice B—Boric acid potassium iodide (BAKI) manual analytical procedure,
Practice C—Gas phase titration with excess nitric oxide,
Practice D—Gas phase titration with excess ozone, and
Practice E—Ozone generator device.  
1.3 These practices describe procedures to establish the authority of transfer standards: qualification, certification, and periodic recertification.  
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.5 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use. See Section 8 for specific precautionary statements.  
1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 30-Sep-2017
• ICS: 13.040.01 - Air quality in general
• Technical Committee: D22 - Air Quality
• Drafting Committee: D22.03 - Ambient Atmospheres and Source Emissions

Relations

• Replaces: ASTM D5011-92(2009) - Standard Practices for Calibration of Ozone Monitors Using Transfer Standards
• Effective Date: 01-Oct-2017
• Refers: ASTM D1356-20 - Standard Terminology Relating to Sampling and Analysis of Atmospheres
• Effective Date: 15-Mar-2020
• Refers: ASTM D4230-20 - Standard Test Method for Measuring Humidity with Cooled-Surface Condensation (Dew-Point) Hygrometer
• Effective Date: 01-Mar-2020
• Refers: ASTM D3249-95(2019) - Standard Practice for General Ambient Air Analyzer Procedures
• Effective Date: 01-Oct-2019
• Refers: ASTM D1071-17 - Standard Test Methods for Volumetric Measurement of Gaseous Fuel Samples
• Effective Date: 01-Apr-2017
• Refers: ASTM D3631-99(2017) - Standard Test Methods for Measuring Surface Atmospheric Pressure
• Effective Date: 01-Mar-2017
• Refers: ASTM D1356-15a - Standard Terminology Relating to Sampling and Analysis of Atmospheres
• Effective Date: 15-Oct-2015
• Refers: ASTM D1356-15 - Standard Terminology Relating to Sampling and Analysis of Atmospheres
• Effective Date: 01-Jul-2015
• Refers: ASTM D1356-14b - Standard Terminology Relating to Sampling and Analysis of Atmospheres
• Effective Date: 01-Dec-2014
• Refers: ASTM D1356-14a - Standard Terminology Relating to Sampling and Analysis of Atmospheres
• Effective Date: 01-May-2014
• Refers: ASTM D1356-14 - Standard Terminology Relating to Sampling and Analysis of Atmospheres
• Effective Date: 15-Jan-2014
• Refers: ASTM D4230-02(2012) - Standard Test Method of Measuring Humidity with Cooled-Surface Condensation (Dew-Point) Hygrometer
• Effective Date: 01-Apr-2012
• Refers: ASTM D3631-99(2011) - Standard Test Methods for Measuring Surface Atmospheric Pressure
• Effective Date: 01-Oct-2011
• Refers: ASTM D3249-95(2011) - Standard Practice for General Ambient Air Analyzer Procedures
• Effective Date: 01-Oct-2011
• Refers: ASTM D5110-98(2010) - Standard Practice for Calibration of Ozone Monitors and Certification of Ozone Transfer Standards Using Ultraviolet Photometry
• Effective Date: 01-Oct-2010

Overview

ASTM D5011-17: Standard Practices for Calibration of Ozone Monitors Using Transfer Standards provides industry-recognized procedures for calibrating ozone (O₃) monitors in ambient, workplace, or indoor environments. Developed by ASTM International, this standard addresses the challenge of ozone’s reactivity and instability, which makes long-term storage or direct certification of ozone concentration standards impractical. Instead, ASTM D5011-17 establishes best practices for using transfer standards-which are portable, secondary standards certified by a primary ultraviolet (UV) photometric ozone standard-for the consistent and reliable calibration of ozone monitoring equipment.

Key Topics

• Calibration Using Transfer Standards: The standard outlines approaches for calibrating ozone monitors by employing certified transfer standards. These devices derive their authority and traceability from primary UV ozone photometric standards.
• Types of Transfer Standards: Five transfer standards are described:
  • Analytical instruments
  • Boric acid potassium iodide (BAKI) manual analytical procedure
  • Gas-phase titration with excess nitric oxide
  • Gas-phase titration with excess ozone
  • Ozone generator device
• Qualification and Certification Procedures: Guidance is provided on qualifying a transfer standard (demonstrating stability and repeatability), certifying it against a primary standard, and periodically recertifying it to ensure ongoing accuracy.
• Key Apparatus and Reagents: The document details the essential equipment and chemical supplies required for each transfer standard method. These include UV photometers, ozone generators, flow controllers, impingers, and high-purity reagents.
• Control of Measurement Variables: Emphasis is placed on controlling and documenting variables such as temperature, line voltage, and barometric pressure, which may influence calibration results.
• Safety Considerations: Due to ozone’s toxic properties, proper handling, venting, and the use of safety protocols are integral parts of the calibration process.

Applications

ASTM D5011-17 is essential for organizations and professionals concerned with accurate ozone monitoring in various settings, including:

• Regulatory Compliance: Supporting traceable calibration of ozone monitors used for compliance with national and international air quality standards.
• Environmental Monitoring: Ensuring high-confidence ozone measurements for ambient air quality networks or pollution studies.
• Industrial Hygiene and Indoor Air Quality: Calibrating monitors for workplace or indoor ozone assessments to protect worker health and ensure safe environments.
• Field Calibration: Facilitating transport and use of robust, certified transfer standards for field-based calibration, reducing downtime and increasing flexibility.
• Inter-Standard Comparison: Enabling the comparison and harmonization of multiple primary standards within and across monitoring networks.

Related Standards

Professionals using ASTM D5011-17 should consider its relationship with other key documents, including:

• ASTM D5110 – Practice for Calibration of Ozone Monitors and Certification of Ozone Transfer Standards Using Ultraviolet Photometry
• ASTM D1193 – Specification for Reagent Water (for reagent grade purity)
• ASTM D1356 – Terminology Relating to Sampling and Analysis of Atmospheres
• ASTM D3195 – Practice for Rotameter Calibration
• 40 CFR Part 50 – EPA Regulations on Ambient Air Monitoring Reference Methods

Practical Value

Implementing ASTM D5011-17 ensures ozone monitors deliver reliable, traceable, and reproducible measurements critical for environmental protection, regulatory reporting, and workplace safety. By standardizing calibration practices using transfer standards, it helps laboratories and monitoring organizations achieve consistency, comparability, and confidence in ozone data-a foundation for informed decision-making and compliance with air quality goals.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D5011 − 17
Standard Practices for
Calibration of Ozone Monitors Using Transfer Standards
This standard is issued under the fixed designation D5011; 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 D1193Specification for Reagent Water
D1356Terminology Relating to Sampling and Analysis of
1.1 These practices describe means for calibrating ambient,
Atmospheres
workplace or indoor ozone monitors, using transfer standards.
D3195Practice for Rotameter Calibration
1.2 Thesepracticesdescribefivetypesoftransferstandards:
D3249Practice for General Ambient Air Analyzer Proce-
Practice A—Analytical instruments,
dures
Practice B—Boric acid potassium iodide (BAKI) manual
D3631Test Methods for Measuring Surface Atmospheric
analytical procedure,
Pressure
Practice C—Gas phase titration with excess nitric oxide,
D3824Test Methods for Continuous Measurement of Ox-
Practice D—Gas phase titration with excess ozone, and
idesofNitrogenintheAmbientorWorkplaceAtmosphere
Practice E—Ozone generator device.
by the Chemiluminescent Method
D4230Test Method of Measuring Humidity with Cooled-
1.3 These practices describe procedures to establish the
authority of transfer standards: qualification, certification, and Surface Condensation (Dew-Point) Hygrometer
D5110Practice for Calibration of Ozone Monitors and
periodic recertification.
CertificationofOzoneTransferStandardsUsingUltravio-
1.4 The values stated in SI units are to be regarded as
let Photometry
standard. No other units of measurement are included in this
E591Practice for Safety and Health Requirements Relating
standard.
to Occupational Exposure to Ozone (Withdrawn 1990)
1.5 This standard does not purport to address all of the
2.2 Other Documents:
safety concerns, if any, associated with its use. It is the
40 CFR Part 50Environmental Protection Agency Regula-
responsibility of the user of this standard to establish appro-
tions on Ambient Air Monitoring Reference Methods
priate safety, health, and environmental practices and deter-
3. Terminology
mine the applicability of regulatory limitations prior to use.
See Section 8 for specific precautionary statements.
3.1 Definitions—For definitions of terms used in this
1.6 This international standard was developed in accor-
standard, see Terminology D1356.
dance with internationally recognized principles on standard-
3.2 Definitions of Terms Specific to This Standard:
ization established in the Decision on Principles for the
3.2.1 primary standard, n—a standard directly defined and
Development of International Standards, Guides and Recom-
established by some authority, against which all secondary
mendations issued by the World Trade Organization Technical
standards are compared.
Barriers to Trade (TBT) Committee.
3.2.2 secondary standard, n—a standard used as a means of
2. Referenced Documents
comparison, but checked against a primary standard.
2.1 ASTM Standards:
3.2.3 standard, n—an accepted reference sample or device
D1071Test Methods for Volumetric Measurement of Gas-
used for establishing measurement of a physical quantity.
eous Fuel Samples
3.2.4 transfer standard, n—a type of secondary standard. It
is a transportable device or apparatus, which, together with
1 operational procedures, is capable of reproducing pollutant
These practices are under the jurisdiction of ASTM Committee D22 on Air
Quality and are the direct responsibility of Subcommittee D22.03 on Ambient concentration or producing acceptable assays of pollutant
Atmospheres and Source Emissions.
concentrations.
Current edition approved Oct. 1, 2017. Published October 2017. Originally
approved in 1989. Last previous edition approved in 2009 as D5011–92 (2009).
DOI: 10.1520/D5011-17. The last approved version of this historical standard is referenced on
For referenced ASTM standards, visit the ASTM website, www.astm.org, or www.astm.org.
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Available from U.S. Government Printing Office, Superintendent of
Standards volume information, refer to the standard’s Document Summary page on Documents, 732 N. Capitol St., NW, Washington, DC 20401-0001, http://
the ASTM website. www.access.gpo.gov.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D5011 − 17
3.2.5 zero air, n—purified air that does not contain ozone
[O ] =O concentration (approximate) at the output
3 RC 3
and does not contain any other component that may interfere
manifold, ppm.
with the measurement. See 7.1.
P = Vapor pressure of HOat T , kPa, wet volume
H O 2 S
standard. (For a dry standard, P =0.) (See
H O
3.3 Symbols: 2
Test Method D4230 for tables of saturation
vapor pressure of water.) See Annex A2.
b = Spectrophotometer cell path length, cm. See
P = Dynamic specification, determined empirically,
Annex A2.
R
to ensure complete reaction of O or NO,
d = Average of discrete single point comparisons.
avg
See Annex A1. ppm/min.
P = Barometric pressure at sampling conditions,
d = Single point comparison. See Annex A1.
i S
F = Diluent air flow, mL/min. kPa. See Annex A2.
D
F ' = New diluent air flow, mL/min. S = Slope of KI calibration curve, mL/mol/cm. See
D c
F = NO flow, mL/min.
Annex A2.
NO
F = Flow through the O generator, mL/min.
s = Standard deviation of single point comparisons.
O 3
d
F = Flowrate corrected to reference conditions
See Annex A1.
R
(25°C and 101.3 kPa), mL/min. See AnnexA2.
s = Relativestandarddeviationofthesixintercepts.
i
F = Flowrate at sampling conditions, mL/min. See
See Annex A1.
S
Annex A2.
s = Relative standard deviation of the six slopes.
m
F = The total flow required at the output manifold
T See Annex A1.
(monitors demand plus 10 to 50% excess), t = Residence time in reaction chamber, min.
R
mL/min. t = Sampling time, min. See Annex A2.
s
I = The intensity of light which passes through the T = Temperature at sampling conditions, °C. See
S
photometer absorption cell and is sensed by the Annex A2
URL = Upper range limit of O or NO monitor, ppm.
detector when the cell contains an O sample.
V = Volume of I solution, mL. See Annex A2
See Annex A4.
i 2
VO = Volume of O absorbed, µL. See Annex A2.
[I ] = ConcentrationofeachI standard,molI /L.See
3 3
2 i 2 2
V = Volume of air sampled, corrected to 25°C and
Annex A2. R
101.3 kPa, mL. See Annex A2.
I = Average intercept. See Annex A1.
avg
V = Volume of the reaction chamber, mL.
I = Individual intercepts. See Annex A1.
RC
i
y =O concentration indicated by the transfer
I = The intensity of light which passes through the i 3
O
standard, ppm. See 10.7.2.
photometer absorption cell and is sensed by the
Z = Recorder response with zero air, % scale.
detector when the cell contains zero air. See
Annex A4.
4. Summary of Practices
m = Average slope. See Annex A1.
avg
4.1 These practices describe the procedures necessary to
m = Individual slopes. See Annex A1.
i
mol I =I released, mols. See Annex A2. establish the authority of ozone transfer standards:
2 2
N = Normality of KIO , equivalent/L. See Annex qualification, certification, and periodic recertification. Quali-
KIO 3
A2.
fication consists of demonstrating that a candidate transfer
[NO] = Diluted NO concentration, ppm. See AnnexA4.
standard is sufficiently stable (repeatable) to be useful as a
[NO] = Original NO concentration, ppm. See Annex
ORIG transfer standard. Repeatability is necessary over a range of
A3.
variables (such as temperature, line voltage, barometric
[NO] = HighestNOconcentrationrequiredattheoutput
OUT
pressure, elapsed time, operator adjustments, relocation, etc.),
manifold, ppm. It is approximately equal to
any of which may be encountered during use of the transfer
90% of the upper range limit of the O concen-
standard. Tests and possible compensation techniques for
tration to be determined. See Annex A3.
several such common variables are described. Detailed certi-
[NO] = NO concentration (approximate) in the reaction
RC
fication procedures are provided, and the quantitative specifi-
chamber, ppm. See Annex A3.
cations necessary to maintain continuous certification of the
[NO] = NO concentration remaining after addition of
REM
transfer standard are also provided.
O , ppm. See Annex A3.
4.2 Practice A—A dedicated ozone monitor is tested as
[NO] = Concentration of the undiluted NO standard,
STD
described in 4.1 to demonstrate its authority as a transfer
ppm.
standard.
n = Number of comparisons. See Eq 4
[O ] = Certified O concentration, ppm.
3 CERT 3 4.3 Practice B—Thisprocedure (1) isbasedonthereaction
[O ] = Diluted certified O concentration, ppm.
3 CERT' 3
between ozone (O ) and potassium iodide (KI) to release
[O ] =O concentration produced by the O generator,
3 GEN 3 3
iodine (I ) in accordance with the following stoichiometric
ppm. See Annex A4.
equation (2):
[O ] = Indicated O concentration, ppm. See Annex
3 OUT 3
A2.
The boldface numbers in parentheses refer to a list of references at the end of
[O ] = Diluted O concentration, ppm.
3 OUT' 3
this standard.
D5011 − 17
2 1
O 12I 12H 5 I 1H O1O (1) 5.2 The primary UV standard photometers, which are usu-
3 2 2 2
ally used at a fixed location under controlled conditions, are
The stoichiometry is such that the amount of I released is
usedtocertifytransferstandardsthatarethentransportedtothe
equaltotheamountofO absorbed.Ozoneisabsorbedina0.1
field sites where the ambient ozone monitors are being used.
N boric acid solution containing 1% KI, and the I released
See Practice D5110.
− −
reacts with excess iodide ion (I ) to form triiodide ion (I ),
which is measured spectrophotometrically at a wavelength of 5.3 The advantages of this procedure are:
352 nm. The output of a stable O generator is assayed in this 5.3.1 All O monitors in a given network or region may be
3 3
manner, and the O generator is immediately used to calibrate
traced to a single primary standard.
the O monitor.
5.3.2 The primary standard is used at only one location,
under controlled conditions.
4.4 Practice C—This procedure is based on the rapid gas
5.3.3 Transfer standards are more rugged and more easily
phase reaction between nitric oxide (NO) and O , as described
portable than primary standards.
by the following equation (3):
5.3.4 Transfer standards may be used to intercompare vari-
NO1O 5 NO1O (2)
3 2
ous primary standards.
When O is added to excess NO in a dynamic system, the
decrease in NO response is equivalent to the concentration of
6. Apparatus
O added. The NO is obtained from a standard NO cylinder,
6.1 Apparatus Common to Practices A Through E:
and the O is produced by a stable O generator. A chemilu-
3 3
6.1.1 UV Photometric calibration system, as shown in Fig.
minescence NO analyzer is used to measure the change in NO
1, consisting of the following:
concentration.TheconcentrationofO addedmaybevariedto
6.1.1.1 Primary Ozone Standard,aUVphotometer,consist-
obtain calibration concentrations over the range desired. The
ing of a low-pressure mercury discharge lamp, collimation
dynamic system is designed to produce locally high concen-
optics (optional), an absorption cell, a detector, and signal-
trationsofNOandO inthereactionchamber,withsubsequent
processing electronics. It shall be capable of measuring the
dilution, to effect complete O reaction with relatively small
transmittance, I/I , at a wavelength of 253.7 nm with sufficient
chamber volumes.
precision that the standard deviation of the concentration
4.5 Practice D—This procedure is based on the rapid gas
measurementsdoesnotexceedthegreaterof0.005ppmor3%
phase reaction between O and nitric oxide (NO) as described
of the concentration. It shall incorporate means to assure that
by the following equation (3):
noO isgeneratedinthecellbytheUVlamp.Thisisgenerally
NO1O 5 NO 1O (3) accomplishedbyfilteringoutthe184.9nmHglinewithahigh
3 2 2
silica filter. In addition, at least 99.5% of the radiation sensed
When NO is added to excess O in a dynamic system, the
bythedetectorshallbe253.7nm.Thisisusuallyaccomplished
decrease in O response observed on an uncalibrated O
3 3
by using a solar blind photodiode tube. The length of the light
monitor is equivalent to the concentration of NO added. By
path through the absorption cell shall be known with an
measuring this decrease in response and the initial response,
accuracy within at least 99.5%. In addition the cell and
the O concentration can be determined. Additional O con-
3 3
associated plumbing shall be designed to minimize loss of O
centrations are generated by dilution. The gas phase titration
from contact with surfaces (4). See Practice D5110.
(GPT) system is used under predetermined flow conditions to
6.1.1.2 Air Flow Controller, capable of regulating air flows
insure that the reaction of NO is complete and that further
as necessary to meet the output stability and photometer
reaction of the resultant nitrogen dioxide (NO ) with residual
precision requirements.
O is negligible.
6.1.1.3 Flowmeters, calibrated in accordance with Practice
4.6 Practice E—A dedicated ozone generator is tested as
D3195.
described in 4.1 to demonstrate its authority as a transfer
6.1.1.4 Ozone Generator,capableofgeneratingstablelevels
standard.
of O over the required concentration range. It shall be stable
over short periods to allow for stability of the monitor or
5. Significance and Use
transfer standard connected to the output manifold. Conven-
tionalUV-photolytictypegeneratorsmaybeadequatebutshall
5.1 ThereactivityandinstabilityofO precludesthestorage
have line voltage and temperature regulation.
of O concentration standards for any practical length of time,
and precludes direct certification of O concentrations as 6.1.1.5 Output Manifold, constructed of glass, TFE-
SRM’s. Moreover, there is no available SRM that can be fluorocarbon, or other relatively inert material. It shall be of
readily and directly adapted to the generation of O standards sufficient diameter to cause a negligible pressure drop at the
analogoustopermeationdevicesandstandardgascylindersfor photometer connection and other output ports. The output
sulfur dioxide and nitrogen oxides. Dynamic generation of O manifoldservesthefunctionofprovidinganinterfacebetween
concentrations is relatively easy with a source of ultraviolet the calibration system and other devices and systems that
(UV) radiation. However, accurately certifying an O concen- utilize the output O concentrations. It shall have one or more
3 3
tration as a primary standard requires assay of the concentra- portsforconnectionoftheexternalinstrumentsorsystems,and
tion by a comprehensively specified analytical procedure, shallbesuchthatallportsprovidethesameO concentrations.
which must be performed every time a standard is needed. The vent, which exhausts excess gas flow from the system and
D5011 − 17
FIG. 1 Schematic Diagram of a Typical UV Photometric Calibration System
insures that the manifold outlet ports are maintained at atmo- 6.1.2 Output Indicating Device, such as Continuous Strip
spheric pressure for all flowrates, shall be large enough to Chart Recorder or Digital Volt Meter—If a recorder is used, it
avoid appreciable pressure drop, and shall be located down- shall have the following specifications:
stream of the output ports to insure that no ambient air enters
Accuracy ±0.25 % of span
Chart width no less than 150 mm
the manifold due to eddy currents, back diffusion, etc.
Time for full-scale travel 1 s
6.1.1.6 Temperature Indicator, accurate to 61°C. This indi-
6.1.2.1 If a digital voltmeter is used, it shall have an
cator is needed to measure the temperature of the gas in the
accuracy of 60.25% of range.
photometric cell in order to calculate a temperature correction.
6.1.2.2 Practice A output indicating device shall be consid-
In most photometers, particularly those whose cell is enclosed
ered as part of the transfer standard, and employed during
inside a case or housing with other electrical or electronic
qualification, certification, and use.
components, the cell operates at a temperature somewhat
6.1.2.3 Practices C, D, and E require two output indicating
above ambient room temperature. Therefore, it is important to
measure the temperature of the gas inside the cell, and not devices.
room temperature. A small thermocouple or thermistor, con- 6.1.3 Variable Autotransformer.
nected to an external readout device, may be attached to the
6.1.4 AC Voltmeter, accurate to 61%.
cell wall or inserted through the cell wall to measure internal
6.2 Apparatus Common to Practices A and D:
temperature.
6.2.1 Ozone Monitor:
6.1.1.7 Barometer or Pressure Indicator, accurate to 6250
6.2.1.1 Practice A—An ozone monitor used as a transfer
Pa. The barometer or pressure indicator is used to measure the
standard shall receive special treatment consistent with its
pressure of the gas in the cell in order to calculate a pressure
authoritative status: that is, careful handling and storage,
correction. Most photometer cells operate at atmospheric
frequent maintenance, a QA program, operation by a compe-
pressure. If there are no restrictions between the cell and the
tentandtrainedtechnician.Inparticular,itshallnotbeusedfor
output manifold, the cell pressure should be very nearly the
ambientmonitoringbetweenusesasatransferstandard,asdust
same as the local barometric pressure. A certified local baro-
and dirt will affect its accuracy.
metric pressure reading can then be used for the pressure
correction. If the cell pressure is different than the local 6.3 Apparatus Common to Practices C and D—Fig. 2,a
barometric pressure, some means of accurately measuring the schematic of a typical GPT apparatus, shows the suggested
cell pressure (manometer, pressure gage, or pressure trans- configuration listed below. All connections shall be glass or
ducer) is required. This device shall be calibrated against a TFE-fluorocarbon. See Ellis (5) for additional information
suitable pressure standard, in accordance with Test Methods regarding the assembly and use of the GPT calibration appa-
D3631. ratus.
D5011 − 17
FIG. 2 Schematic Diagram of a Typical GPT System
6.3.1 Nitric Oxide Flow Controller—A device capable of
maintaining constant NO flow within 62%. Component parts
in contact with NO shall be of a non-reactive material.
6.3.2 Nitric Oxide Flowmeter—A flowmeter capable of
measuring NO flows within 62%, and shall be calibrated
according to Practice D3195.(Warning—Rotameters have
been reported to operate unreliably when measuring low NO
flows, and are not recommended.)
6.3.3 NO Cylinder Pressure Regulator—Thisregulatorshall
FIG. 3 Components of a KI Sampling Train
have non-reactive internal components, and shall include a
purge port.
6.3.4 Reaction Chamber—A glass chamber for the quanti-
meet the requirements of Test Methods D3824 or the perfor-
tative reaction between O and NO. It shall be of sufficient
mance requirements for Reference Methods for NO monitors
volume that the reaction time is less than two minutes.
in 40 CFR Part 50.
6.3.5 Mixing Chamber—A glass chamber to provide for
6.6 Apparatus for Practice D Alone:
mixing of reaction products and dilution air.
6.6.1 Ozone Generator—The generator shall be of the UV
6.4 Apparatus for Practice B Alone:
lamp type, with means to adjust the O concentration over a
6.4.1 Sampling Train (see Fig. 3), consisting of:
convenient range without changing the flowrate. It shall have
6.4.1.1 Glass Midget Impingers—Two impingers connected
an output manifold similar to that described in 6.1.1.5, and a
in series.
zero air supply as described in 7.1.1.1.
6.4.1.2 Air Pump and Flow Controller—Any air pump and
flowcontrollercapableofmaintainingaconstantflowof0.4to
7. Reagents and Materials
0.6L/minthroughtheimpingers.Acriticalorifice,asdescribed
7.1 Reagents Common to Practices A Through E:
by Lodge et al. (6), is recommended. The orifice shall be
7.1.1 Zero Air,freeofO andanysubstancethatmightreact
protected from moisture and particulate matter with a mem-
with O or undergo photolysis (for example, NO, NO ,
3 2
brane filter or trap containing Drierite, silica gel, and glass
ethyleneorotherhydrocarbons,andparticulatematter).Theair
wool. The air pump shall be capable of maintaining a pressure
shall be purified to remove such substances. Dirty air shall be
differential of at least 60 to 70 kPa across the critical orifice.
precleaned to remove particulate matter, oil mist, liquid water,
6.4.2 Spectrophotometer—Capable of measuring absor-
etc.
bance at 352 nm with an absolute accuracy of 61%, and with
7.1.1.1 A system which has been used successfully is
a linear response over the range of 0 to 1.0 absorbance units.
described as follows: the air is dried with a membrane type
The accuracy shall be verified using optical glass filters with
dryer, followed by a column of indicating silica gel. The air is
certified absorbance values at specified wavelengths. Matched
irradiated with a UV lamp to generate O to convert NO to
10-mm or 20-mm cells shall be used.
NO , and passed through a column of activated charcoal (1.40
6.4.3 pH meter, with a resolution of 60.1 pH units.
mm to 3.35 mm) to remove NO,O , hydrocarbons, and
2 3
6.5 Apparatus for Practice C Alone: various other substances, and is followed by a column of
6.5.1 Chemiluminescence Nitric Oxide Monitor—The NO molecular sieve (1.18 mm to 3.35 mm, type 4A), and a final
channel of a chemiluminescence NO/NO /NO monitor shall particulate filter (2 micron) to remove particulate matter.
2 X
D5011 − 17
7.1.1.2 If a chemiluminescent O monitor is being 7.2.11 Standard Solutions:
calibrated, the interference by high humidity shall be checked. 7.2.11.1 Pipet 10 mL of 0.1 N KIO solution (7.2.8) into a
100 mL volumetric flask containing 50 mL of water. Add 1 g
7.2 Reagents and Materials for Practice B Only:
KI (7.2.7)and5mLof1NH SO (7.2.10), dilute to volume
2 4
7.2.1 Purity of Reagents—Reagent grade chemicals shall be
with water, and mix.
usedinalltests.Allreagentsshallconformtothespecifications
7.2.11.2 Immediately before use, pipet 10 mL of the I
of the Committee on Analytical Reagents of the American
6 solution(7.2.11.1)intoa100mLvolumetricflask,anddiluteto
Chemical Society where such specifications are available.
volume with water. Then pipet 10 mL of this solution into a
Other grades may be used, provided it is first ascertained that
200 mLvolumetric flask, and dilute to volume with absorbing
the reagent is of sufficiently high purity to permit its use
reagent (7.2.3).
without lessening the accuracy of the determination.
7.2.11.3 In turn, pipet 5, 10, 15, 20, and 25 mL aliquots of
7.2.2 Purity of Water—References to water shall mean
the final solution (7.2.11.2) into 25 mL volumetric flasks.
reagent water as defined by Type 2 of Specification D1193.
Dilute to volume with absorbing reagent (7.2.3), and mix. To
7.2.3 Absorbing Reagent—Dissolve 6.2 g of boric acid
prevent loss of I by volatilization, the flasks shall remain
(H BO ) in 750 mLof water in an amber 1000 mLvolumetric
3 3
stoppered until absorbance measurements are made. Absor-
flask. The flask may be heated gently to speed dissolution of
bance measurements shall be made within 20 minutes after
the boric acid, but the solution must be cooled to room
preparation of the I standards (see Section A2.4).
temperature or below before proceeding. (While the boric acid
solution is cooling, prepare the H O solution (7.2.6).) When 7.3 Reagents and Materials for Practices C Only:
2 2
cooled, add 10 g of KI to the H BO and dissolve.Add 1 mL 7.3.1 Nitric Oxide Concentration Standard—Compressed
3 3
of H O (7.2.6) solution and mix. Within 5 minutes after gascylindercontaining50to100ppmNOinN .Thisneednot
2 2 2
adding the H O , dilute to volume with water, mix, and be NIST traceable, but a useful check of the transfer stan-
2 2
determine the absorbance of this BAKI solution at 352 nm dard’s accuracy is obtained if the NO standard is traceable to
against water as the reference. The pH of the BAKI solution an NIST Standard Reference Material (SRM 1629). With a
shall be 5.1 6 0.02. traceable NO standard, the transfer standard’s indicated O
7.2.3.1 Set the absorbing solution aside for two hours, and concentration shall agree with the UV standard within−5%
redetermine the absorbance at 352 nm against water as the to+15% (most GPT-NO systems have a positive bias). If it
reference. If the resulting absorbance from the second deter- does not agree within this envelope, a problem with either the
mination is at least 0.008 absorbance units/cm greater than the transfer standard or the primary standard is indicated, and
first determination, the solution is ready for use. If no increase standards shall be established using new sources.
or an increase of less than 0.008 absorbance units/cm is
7.4 Reagents and Materials for Practice D Only:
observed, the KI reagent probably contains an excessive
7.4.1 Nitric Oxide Concentration Standard—Compressed
amountofareducingcontaminant,andmustbediscarded.Ifan
gas cylinder containing 50 to 100 ppm NO in N , traceable to
unacceptable absorbing reagent results from different lots of
an NIST Standard Reference Material (SRM 1629 or SRM
KI,testthepossibilityofcontaminationintheH BO byusing
3 3
1684) or NO Standard Reference Material (SRM 1629). The
a different numbered lot of H BO .
3 3
cylindershallberecertifiedonaregularbasisasdeterminedby
7.2.4 Boric Acid (H BO ).
3 3
a quality control program.
7.2.5 Hydrogen Peroxide (H O )—3% or 30%.
2 2
7.2.6 Hydrogen Peroxide Solution (0.0021%)—Using a 8. Hazards
graduated pipet, add 0.7 mL of 30% or 7.0 mL of 3% H O
2 2
8.1 Safety Hazards—See Practice D3249 for safety precau-
(7.2.5)to200mLofwaterina500mLvolumetricflask,dilute
tions on the use of monitors and electronic equipment.
to volume with water, and mix. Pipet 5 mL of the above
8.1.1 Ozone is a toxic material. See Practice E591 for
solution into 50 mL of water in a 100 mL volumetric flask,
biological effects, and for safety and health requirements.
dilute to volume with water, and mix. Both solutions must be
8.1.2 The manifold vents and photometer and monitor
preparedfresheverytimeafreshbatchofabsorbingsolutionis
exhausts must be vented to remove exhaust gases from the
prepared.
workplace.Measuresmustbetakentoavoidabackpressurein
7.2.7 Potassium Iodide (KI).
the cell and manifold, and in the monitor or transfer standard
7.2.8 Potassium Iodate (KIO ), certified 0.1 N.
being calibrated.
7.2.9 Sulfuric Acid (H SO )—95 to 98%.
2 4
7.2.10 Sulfuric Acid (1 N)—Dilute 28 mL of concentrated
9. Establishing the Authority of Transfer Standards
HSO (7.2.9)tovolumeina1Lvolumetricflaskbyaddingthe
9.1 The primary purpose of an O transfer standard is to
acid to the water.
transfer the authority of a primary O standard from one time
and place to another. Since a transfer standard has no authority
of its own, its authority must be first established by confirming
a high probability or confidence that O concentration stan-
Reagent Chemicals, American Chemical Society Specifications, American 3
Chemical Society, Washington, DC. For suggestions on the testing of reagents not
dards obtained, under a variety of operating conditions, are
listed by the American Chemical Society, see Analar Standards for Laboratory
Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville, Available from National Institute of Standards and Technology (NIST), 100
MD. Bureau Dr., Stop 1070, Gaithersburg, MD 20899-1070, http://www.nist.gov.
D5011 − 17
very nearly as accurate as primary O standard. This confi- under the changing conditions that might be encountered in
dence is first established by determining that the transfer field use. A transfer standard must be assumed unacceptable
standard has adequate reproducibility to qualify it as a transfer until it can be conclusively demonstrated to be acceptable.
standard, then by certifying the transfer standard by relating it
9.3.1 The primary requirement of a transfer standard is
toaprimarystandard,andfinallybyperiodicallyrecertifyingit
repeatability under the stress of variable conditions that may
by reverifying its accuracy and stability.
change between certification in the laboratory and use in the
field.Acandidate transfer standard is qualified by proving that
9.2 Comparing Transfer Standards to Primary Ozone
it is repeatable over an appropriate range for each variable
Standard—Basic to the qualification and certification of an O
likely to change between the time and place of certification,
transfer standard is the need to compare the output (either a
and the time and place of use. According to the specifications
concentration determination or an O concentration) of the
in Annex A1, the repeatability must be between 64%or 64
transfer standard to the primary standard, so that relationships
ppb, whichever is greater, for each condition or variable that
can be determined.
may change between the point of certification and the point of
9.2.1 Assay-Type Transfer Standards—For transfer stan-
use.
dards that provide an assay of an externally generated O
concentration (Practices A and B), the transfer standard is
9.3.2 Selecting the conditions that are likely to vary and
connected to the output manifold shown in Fig. 1 and Fig. 4.
may affect the repeatability is largely a matter of intelligent
There shall be sufficient flow of ozonized air for both the
informed judgment. It is the user’s responsibility to determine
primary and secondary standards. The output of the transfer
all of the conditions to be considered in the demonstration of
standard is an indicated concentration, which is compared
repeatability, and to document the choices, and the reasons for
directly to the primary standard concentration obtained from
them. Common conditions likely to affect a wide variety of
the primary standard.
transfer standards include ambient temperature, line voltage
9.2.2 Ozone-Generation Type Transfer Standards—Transfer
and frequency, barometric pressure, elapsed time, physical
standards that generate O concentrations themselves include
3 shock, and relocation. Conditions not likely to affect the
O generators (Practice E) and may include those assay
3 transferstandardcanbeusuallyeliminatedfromconsideration.
procedures that have an integral source of O (Practices C and
3 The user, however, must be constantly alert for the unusual
D).Three procedures that may be used to compare the transfer
situation where an unexpected condition is present.
standard to the primary standard are described in Annex A5.
9.3.3 It should be noted that a transfer standard does not
They are presented in order of preference.
necessarily need to be constant with respect to the variables,
9.3 Qualification—The first step in establishing the author- but only repeatable or predictable. Demonstration of repeat-
ity of a candidate transfer standard is to prove that it qualifies ability for a candidate transfer standard normally requires
for use as a transfer standard. It must be demonstrated that the testing for each condition that could or may affect it. Typical
output of the transfer standard is reproducible and repeatable tests for common conditions are discussed in Section 10. For
FIG. 4 Schematic Diagram of a Typical UV Photometric Calibration System (Option 1)
D5011 − 17
qualification of procedural candidates such as Practices B, C, important effects are changes in the output of generation
or D, testing may be minimal, provided the user is adequately devices, changes in the sensitivity of O assay systems, and
trained, uses good laboratory technique, and uses a specific changes in the volume of air flows which must be measured
apparatus and set of supplies. For commercially available accurately.
transfer standards, some or all of the testing may have been
10.3.1 Temperature effects may be minimized in several
carried out by the manufacturer. In some cases it may be
ways. The easiest way is to restrict the use of the transfer
possible to judiciously substitute design rationale for actual
standard to a temperature range over which the effects are
testing.Forexample,adevicewhosepowersupplyisdesigned
within the specification. This restriction may be the only
to be highly regulated may not require specific line voltage
practicalapproachforsomecandidatetransferstandards,butit
tests. However, such situations should be viewed with consid-
may preclude use of such a transfer standard in too many
erable skepticism because of the possibility of failure of a
situations. Transfer standard devices may be insensitive to
component.
temperaturechangesbydesign,suchasthermostaticregulation
9.3.4 This brings up the further question of whether candi-
of sensitive components or of the entire device, or by tempera-
date transfer standards must be tested individually or whether
ture compensation.
they can be qualified by type, model, or user. In the case of
10.3.2 Temperature effects on flow measurements may be
procedural candidates such as Practices B, C, or D, each user
minimized by the use of mass flowmeters, which do not
must qualify them in the laboratory/use situation in which it
measure volume, or by the regulation of gas temperature.
will be used, since the procedures have a number of potential
Alternately, ideal-gas-law corrections may be made to adjust
variables. Commercial transfer standards are designed and
measured values. See Practice D3195 for appropriate formulas
manufacturedtobeidentical.Themanufacturercouldcarryout
for corrections.
the necessary qualification tests on representative samples
10.3.3 Testingacandidatetransferstandardforsensitivityto
under this concept. It shall be appropriate to require that the
temperature is facilitated by use of a controlled temperature
manufacturer guarantee that each unit meet appropriate perfor-
chamber. However, temperature tests may be carried out in
mance specifications, and provide documentation accordingly.
many ordinary laboratories where the temperature may be
Again, the user should assume a skeptical attitude, and at least
manually controlled by adjusting thermostats, blocking air
carry out some minimal tests to verify that each unit is
vents or outlets, opening doors or windows, or using supple-
acceptable.
mental heaters or air conditioners. A reasonable temperature
rangeis20°to30°C.Broadertemperaturerangescouldbeused
10. Qualification Tests
if necessary for special situations.
10.1 Some of the more common conditions likely to be
10.3.4 The candidate transfer standard is tested by compar-
encountered or to change while using transfer standards, and
ing its output to a stable concentration reference, which shall
that may affect the repeatability of the device are discussed
be an UV photometer system. See Practice D5110. The
below. The exact conditions or variables that must be consid-
reference may also be another transfer standard known to be
ered depend on the specific nature of the transfer standard or
repeatable and, in particular, insensitive to temperature
procedure. The user (or manufacturer) shall determine the
changes. However, it would be better to locate the reference
conditions for each case on an intelligent judgment basis
outsideofthevariabletemperaturearea.Thecandidatetransfer
derived from a complete understanding of the operation of the
standard shall be tested at several different points over the
device or procedure and supported by appropriate rationale.
temperature range, including the extremes, and at several
10.2 Once the conditions to be considered have been
differentconcentrations.Sufficienttimeshallbeallowedforall
determined, the objective of the qualification tests is either
components of the calibration system to equilibrate each time
10.2.1 or 10.2.2:
the temperature is changed. The test results shall be plotted as
10.2.1 To determine that the candidate transfer standard’s
shown in Fig. 5.
output is not affected by more than 64%or 64 ppb (which-
10.3.5 If the candidate transfer standard has a significant
ever is greater) by the condition over the range likely to be
temperature dependence, additional test points at various
encountered during use of the transfer standard.
concentrations and temperature shall be taken to define the
10.2.2 To demonstrate the candidate transfer standard’s
relationship between output and temperature accurately.
output is repeatable within 64% or 64 ppb (whichever is
Furthermore, if the candidate transfer standard has a depen-
greater) as the variable is changed over the range likely to be
denceonmorethanonevariable,testsshallbecarriedoutover
encountered during use, and to quantify the relationship
the range of both variables simultaneously to determine any
between the output and the variable.
interdependence between the two variables. Once the test data
10.3 Temperature—Changes in ambient temperature are are acquired, they shall be analyzed to determine if some
likely to occur from place to place and from one time to general formula or curve can be derived (either analytically or
another. Temperature changes are likely to affect almost all empirically) to predict the correct O concentration at any
typesoftransferstandardsunlessappropriatemeansareusedto temperatureintherange(seeFig.6).Thecorrectionformulaor
avoid adverse effects.Temperature affects transfer standards in curve shall be accurate within 64%or 64 ppb, whichever is
many ways: changes in action of components, changes in greater. If two or more variables are involved, a family of
chemical reactions or rates of reaction, volume changes of curves may be required; unless the relationship is simple, this
gases, electronic drift, variable warm-up time, etc. The most situation may prove impractical in actual use.
D5011 − 17
FIG. 5 Example of Temperature Qualification Test Results Showing no Dependence on Temperature
FIG. 6 Example of a Temperature Dependence Quantitatively Defined as a Correction Factor
10.4 Line Voltage—Line voltage may vary from place to 10.4.1 Asidefromadequatedesign,linevoltageeffectsmay
place, and from one time to another. Good electrical or be minimized by the addition of a line voltage regulator.
electronicdesignofthetransferstandardshallavoidsensitivity However, such devices may distort the line voltage waveform,
to line voltage variations, but poorly designed equipment may thereby adversely affecting some types of transfer standards. If
easily be affected. In addition, line voltage sensitivity may such regulators are used, it is important the same regulator is
appear only as a long time thermal drift, which is a subtle usedbothduringcertificationanduseofthetransferstandards.
effect. Restriction of the transfer standards to a line voltage range in
D5011 − 17
which effects are insignificant is another alternative, but For Practices B, C, and D, the flow measurement problem
requires monitoring the voltage during use, and may preclude constitutes the only pressure effect. Assay-types such as
use at some sites. PracticeAare directly related to gas density, and the ideal-gas
10.4.2 Testing for line voltage sensitivity may be conducted lawcorrectionmaybeused.(SeePracticeD3195forcorrection
along the same lines as described for temperature testing. The equations.) Pressure tests are not needed for these types. For
line voltage may be varied by means of a variable autotrans- commercially-available devices, the manufacturer is expected
former and measured by an accurate ac voltmeter. Do not use to perform the required qualification tests and to provide
electronic “dimmer” controls which operate on a delayed- documentation.
conduction principle, as such devices cause drastic waveform
10.6 Elapsed Time—As the elapsed time between certifica-
distortions.
tion and use increases, the confidence in the repeatability
10.4.3 A line voltage range of 105 to 125 V should
decreases.Asaresult,periodicrecertificationisrequired.Some
adequately cover the majority of line voltages available.
types of O generation devices have a definite loss of output
10.4.4 If the transfer standard is used when power is from a
(decay) with time. This decay is usually associated with
small power generator, the frequency variation shall be
use-time or on-time rather than with total elapsed time. Since
checked.
the decay rate tends to be quantifiable, it may be accommo-
10.5 Barometric Pressure/Altitude—Since O concentra-
dated with the defined relationship mechanism discussed in
tionsaregaseous,alltransferstandardswillhavesomebasicor connection with temperature effects: the transfer standard is
inherent sensitivity to changes in barometric pressure. It is
equipped with an hours meter, and a series of tests over a
difficult to minimize pressure effects by design. Air pressure sufficient time period may then be used to determine the decay
can be regulated mechanically against an absolute reference,
rate. During use, a correction to the output is applied based on
butmostsuchschemesarenotpracticalwhenworkingwithO the number of hours of on-time since the last certification.
concentrations because of restrictions to inert material such as
10.6.1 Alternately, the transfer standard may be recertified
glass or TFE-fluorocarbon. With Practices B, C, and D, the often enough so the error due to decay never exceeds the
effect is limited primarily to the measurements of flowrates,
specifications in Annex A1.
whichwerediscussedin10.3,andareapplicabletobarometric
10.7 Variability—The preciseness of the relationship be-
pressure changes as well. At a constant altitude, normal
tween a transfer standard and a primary O standard is
day-to-day variations in barometric pressure is only a few
dependentonthevariabilityofthetransferstandard.Variability
percent. If the use of the transfer standards can be restricted to
reduces confidence in the accuracy of a certified transfer
altitudeswithinahundredmetresofthecertificationaltitude,it
standard. A high degree of variability may be the cause for
maybeacceptabletoneglectthebarometriceffect.However,if
disqualifying a device or procedure for use as a transfer
the use of the transfer standard is necessary at altitudes
standard, or for selecting one with lower variability.Although
different than the certification altitude, then pressure effects
the certification procedure in Section 11 includes a test for
may not be ignored.
variability, more extensive tests for variability may be neces-
10.5.1 Although not preventable, pressure effects are likely
sary to qualify a transfer standard because the certification test
to be repeatable. As a result, barometric pressure may be the
is for variability in the slope of the certification relationship
variable most likely to be handled by a defined relationship.
andnotforindividualpointvariability.Furthermore,variability
Thetechniqueissimilartothatusedtodetermineatemperature
may be due to changes in conditions not encountered during
relationship; a unique quantitative relationship will result.
certification.
(Warning—In any work with O concentrations at altitudes
10.7.1 Differenttypesoftransferstandardsmayhaveexces-
significantly above sea level, the concentration units must be
sive variability for a variety of reasons. Qualification variabil-
clearlyunderstood.Thevolumeratioconcentrationunits(ppm,
ity testing is most needed to test for the effect of a variety of
ppb,etc.)areindependentofpressure,whiledensityunitssuch
non-specific or non-quantitative variables that cannot be tested
3 3
as µg/m are related to pressure. The µg/m unit defined and
individually. For example, qualification variability tests for
used by the U.S. EPA is “corrected” to 101.3 kPa and 25°C,
PracticesB,C,andDmayincludetheuseofvariousoperators,
and is therefore related to ppm by a constant.)
various sources of chemicals and water, minor variations or
10.5.2 Testing barometric pressure effects may be difficult.
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D5011 − 92 (Reapproved 2009) D5011 − 17
Standard Practices for
Calibration of Ozone Monitors Using Transfer Standards
This standard is issued under the fixed designation D5011; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 These practices describe means for calibrating ambient, workplace or indoor ozone monitors, using transfer standards.
1.2 These practices describe five types of transfer standards:
(A) Analytical instruments
Practice A—Analytical instruments,
Practice B—Boric acid potassium iodide (BAKI) manual analytical procedure,
Practice C—Gas phase titration with excess nitric oxide,
Practice D—Gas phase titration with excess ozone, and
Practice E—Ozone generator device.
(B) Boric acid potassium iodide (BAKI) manual analytical procedure
(C) Gas phase titration with excess nitric oxide
(D) Gas phase titration with excess ozone
(E) Ozone generator device.
1.3 These practices describe procedures to establish the authority of transfer standards: qualification, certification, and periodic
recertification.
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.5 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 safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use. See Section 8 for specific precautionary statements.
1.6 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
D1071 Test Methods for Volumetric Measurement of Gaseous Fuel Samples
D1193 Specification for Reagent Water
D1356 Terminology Relating to Sampling and Analysis of Atmospheres
D3195 Practice for Rotameter Calibration
D3249 Practice for General Ambient Air Analyzer Procedures
D3631 Test Methods for Measuring Surface Atmospheric Pressure
D3824 Test Methods for Continuous Measurement of Oxides of Nitrogen in the Ambient or Workplace Atmosphere by the
Chemiluminescent Method
D4230 Test Method of Measuring Humidity with Cooled-Surface Condensation (Dew-Point) Hygrometer
D5110 Practice for Calibration of Ozone Monitors and Certification of Ozone Transfer Standards Using Ultraviolet Photometry
E591 Practice for Safety and Health Requirements Relating to Occupational Exposure to Ozone (Withdrawn 1990)
These practices are under the jurisdiction of ASTM Committee D22 on Air Quality and are the direct responsibility of Subcommittee D22.03 on Ambient Atmospheres
and Source Emissions.
Current edition approved March 1, 2009Oct. 1, 2017. Published March 2009October 2017. Originally approved in 1989. Last previous edition approved in 20032009 as
D5011 – 92 (2003).(2009). DOI: 10.1520/D5011-92R09.10.1520/D5011-17.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
The last approved version of this historical standard is referenced on www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D5011 − 17
2.2 Other Documents:
40 CFR Part 50 CFR Part 50, Environmental Protection Agency Regulations on Ambient Air Monitoring Reference Methods
3. Terminology
3.1 Definitions—For definitions of terms used in this standard, see Terminology D1356.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 primary standard—standard, n—a standard directly defined and established by some authority, against which all
secondary standards are compared.
3.2.2 secondary standard—standard, n—a standard used as a means of comparison, but checked against a primary standard.
3.2.3 standard—standard, n—an accepted reference sample or device used for establishing measurement of a physical quantity.
3.2.4 transfer standard—standard, n—a type of secondary standard. It is a transportable device or apparatus, which, together
with operational procedures, is capable of reproducing pollutant concentration or producing acceptable assays of pollutant
concentrations.
3.2.5 zero air—air, n—purified air that does not contain ozone and does not contain any other component that may interfere with
the measurement. See 7.1.
3.3 Symbols:
b = Spectrophotometer cell path length, cm. See Annex A2.
d = Average of discrete single point comparisons. See Annex A1.
avg
d = Single point comparison. See Annex A1.
i
F = Diluent air flow, mL/min.
D
F ' = New diluent air flow, mL/min.
D
F = NO flow, mL/min.
NO
F = Flow through the O generator, mL/min.
O 3
F = Flowrate corrected to reference conditions (25°C and 101.3 kPa), mL/min. See Annex A2.
R
F = Flowrate at sampling conditions, mL/min. See Annex A2.
S
F = The total flow required at the output manifold (monitors demand plus 10 to 50 % excess), mL/min.
T
I = The intensity of light which passes through the photometer absorption cell and is sensed by the detector when the
cell contains an O sample. See Annex A4.
[I ] = Concentration of each I standard, mol I /L. See Annex A2.
2 i 2 2
I = Average intercept. See Annex A1.
avg
I = Individual intercepts. See Annex A1.
i
I = The intensity of light which passes through the photometer absorption cell and is sensed by the detector when the
O
cell contains zero air. See Annex A4.
m = Average slope. See Annex A1.
avg
m = Individual slopes. See Annex A1.
i
mol I = I released, mols. See Annex A2.
2 2
N = Normality of KIO , equivalent/L. See Annex A2.
KIO 3
[NO] = Diluted NO concentration, ppm. See Annex A4.
[NO] = Original NO concentration, ppm. See Annex A3.
ORIG
[NO] = Highest NO concentration required at the output manifold, ppm. It is approximately equal to 90 % of the upper range
OUT
limit of the O concentration to be determined. See Annex A3.
[NO] = NO concentration (approximate) in the reaction chamber, ppm. See Annex A3.
RC
[NO] = NO concentration remaining after addition of O , ppm. See Annex A3.
REM 3
[NO] = Concentration of the undiluted NO standard, ppm.
STD
n = Number of comparisons. See Eq 4
[O ] = Certified O concentration, ppm.
3 CERT 3
[O ] = Diluted certified O concentration, ppm.
3 CERT' 3
[O ] = O concentration produced by the O generator, ppm. See Annex A4.
3 GEN 3 3
[O ] = Indicated O concentration, ppm. See Annex A2.
3 OUT 3
[O ] = Diluted O concentration, ppm.
3 OUT' 3
[O ] = O concentration (approximate) at the output manifold, ppm.
3 RC 3
P = Vapor pressure of H O at T , kPa, wet volume standard. (For a dry standard, P = 0.) (See Test Method D4230
H O 2 S H O
2 2
for tables of saturation vapor pressure of water.) See Annex A2.
P = Dynamic specification, determined empirically, to ensure complete reaction of O or NO, ppm/min.
R 3
P = Barometric pressure at sampling conditions, kPa. See Annex A2.
S
Available from U.S. Government Printing Office, Superintendent of Documents, 732 N. Capitol St., NW, Mail Stop: SDE, Washington, DC 20401,20401-0001,
http://www.access.gpo.gov.
D5011 − 17
S = Slope of KI calibration curve, mL/mol/cm. See Annex A2.
c
s = Standard deviation of single point comparisons. See Annex A1.
d
s = Relative standard deviation of the six intercepts. See Annex A1.
i
s = Relative standard deviation of the six slopes. See Annex A1.
m
t = Residence time in reaction chamber, min.
R
t = Sampling time, min. See Annex A2.
s
T = Temperature at sampling conditions, °C. See Annex A2
S
URL = Upper range limit of O or NO monitor, ppm.
V = Volume of I solution, mL. See Annex A2
i 2
V O = Volume of O absorbed, μL. See Annex A2.
3 3
V = Volume of air sampled, corrected to 25°C and 101.3 kPa (1 atm), mL. See Annex A2.
R
V = Volume of air sampled, corrected to 25°C and 101.3 kPa, mL. See Annex A2.
R
V = Volume of the reaction chamber, mL.
RC
y = O concentration indicated by the transfer standard, ppm. See 10.6.2.
i 3
y = O concentration indicated by the transfer standard, ppm. See 10.7.2.
i 3
Z = Recorder response with zero air, % scale.
4. Summary of Practices
4.1 These practices describe the procedures necessary to establish the authority of ozone transfer standards: qualification,
certification, and periodic recertification. Qualification consists of demonstrating that a candidate transfer standard is sufficiently
stable (repeatable) to be useful as a transfer standard. Repeatability is necessary over a range of variables (such as temperature,
line voltage, barometric pressure, elapsed time, operator adjustments, relocation, etc.), any of which may be encountered during
use of the transfer standard. Tests and possible compensation techniques for several such common variables are described. Detailed
certification procedures are provided, and the quantitative specifications necessary to maintain continuous certification of the
transfer standard are also provided.
4.2 MethodPractice A—A dedicated ozone monitor is tested as described in 4.1 to demonstrate its authority as a transfer
standard.
4.3 MethodPractice B—This methodprocedure (1) is based on the reaction between ozone (O ) and potassium iodide (KI) to
release iodine (I ) in accordance with the following stoichiometric equation (2):
2 1
O 12I 12H 5 I 1H O1O (1)
3 2 2 2
The stoichiometry is such that the amount of I released is equal to the amount of O absorbed. Ozone is absorbed in a 0.1 N
2 3
− −
boric acid solution containing 1 % KI, and the I released reacts with excess iodide ion (I ) to form triiodide ion (I ), which is
2 3
measured spectrophotometrically at a wavelength of 352 nm. The output of a stable O generator is assayed in this manner, and
the O generator is immediately used to calibrate the O monitor.
3 3
4.4 MethodPractice C—This procedure is based on the rapid gas phase reaction between nitric oxide (NO) and O , as described
by the following equation (3):
NO1O 5 NO1O (2)
3 2
When O is added to excess NO in a dynamic system, the decrease in NO response is equivalent to the concentration of O
3 3
added. The NO is obtained from a standard NO cylinder, and the O is produced by a stable O generator. A chemiluminescence
3 3
NO analyzer is used to measure the change in NO concentration. The concentration of O added may be varied to obtain calibration
concentrations over the range desired. The dynamic system is designed to produce locally high concentrations of NO and O in
the reaction chamber, with subsequent dilution, to effect complete O reaction with relatively small chamber volumes.
4.5 MethodPractice D—This procedure is based on the rapid gas phase reaction between O and nitric oxide (NO) as described
by the following equation (3):
NO1O 5 NO 1O (3)
3 2 2
When NO is added to excess O in a dynamic system, the decrease in O response observed on an uncalibrated O monitor is
3 3 3
equivalent to the concentration of NO added. By measuring this decrease in response and the initial response, the O concentration
can be determined. Additional O concentrations are generated by dilution. The gas phase titration (GPT) system is used under
predetermined flow conditions to insure that the reaction of NO is complete and that further reaction of the resultant nitrogen
dioxide (NO ) with residual O is negligible.
2 3
4.6 MethodPractice E—A dedicated ozone generator is tested as described in 4.1 to demonstrate its authority as a transfer
standard.
The boldface numbers in parentheses refer to the a list of references at the end of these practices.this standard.
D5011 − 17
5. Significance and Use
5.1 The reactivity and instability of O precludes the storage of O concentration standards for any practical length of time, and
3 3
precludes direct certification of O concentrations as SRM’s. Moreover, there is no available SRM that can be readily and directly
adapted to the generation of O standards analogous to permeation devices and standard gas cylinders for sulfur dioxide and
nitrogen oxides. Dynamic generation of O concentrations is relatively easy with a source of ultraviolet (UV) radiation. However,
accurately certifying an O 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.
5.2 The primary UV standard photometers, which are usually used at a fixed location under controlled conditions, are used to
certify transfer standards that are then transported to the field sites where the ambient ozone monitors are being used. See Practice
D5110.
5.3 The advantages of this procedure are:
5.3.1 All O monitors in a given network or region may be traced to a single primary standard.
5.3.2 The primary standard is used at only one location, under controlled conditions.
5.3.3 Transfer standards are more rugged and more easily portable than primary standards.
5.3.4 Transfer standards may be used to intercompare various primary standards.
6. Apparatus
6.1 Apparatus Common to MethodsPractices A Through E:
6.1.1 UV Photometric calibration system, as shown in Fig. 1, consisting of the following:
6.1.1.1 Primary Ozone Standard—Standard, a UV photometer, consisting of a low-pressure mercury discharge lamp,
collimation optics (optional), an absorption cell, a detector, and signal-processing electronics. It shall be capable of measuring the
transmittance, I/I , at a wavelength of 253.7 nm with sufficient precision that the standard deviation of the concentration
measurements does not exceed the greater of 0.005 ppm or 3 % of the concentration. It shall incorporate means to assure that no
O is generated in the cell by the UV lamp. This is generally accomplished by filtering out the 184.9 nm Hg line with a high silica
filter. In addition, at least 99.5 % of the radiation sensed by the detector shall be 253.7 nm. This is usually accomplished by using
a solar blind photodiode tube. The length of the light path through the absorption cell shall be known with an accuracy within at
least 99.5 %. In addition the cell and associated plumbing shall be designed to minimize loss of O from contact with surfaces (4).
See Practice D5110.
6.1.1.2 Air Flow Controller—Controller, capable of regulating air flows as necessary to meet the output stability and photometer
precision requirements.
6.1.1.3 Flowmeters—Flowmeters, calibrated in accordance with Practice D3195.
FIG. 1 Schematic Diagram of a Typical UV Photometric Calibration System
D5011 − 17
6.1.1.4 Ozone Generator—Generator, capable of generating stable levels of O over the required concentration range. It shall
be stable over short periods to allow for stability of the monitor or transfer standard connected to the output manifold. Conventional
UV-photolytic type generators may be adequate but shall have line voltage and temperature regulation.
6.1.1.5 Output Manifold—Manifold, constructed of glass, TFE-fluorocarbon, or other relatively inert material. It shall be of
sufficient diameter to cause a negligible pressure drop at the photometer connection and other output ports. The output manifold
serves the function of providing an interface between the calibration system and other devices and systems that utilize the output
O concentrations. It shall have one or more ports for connection of the external instruments or systems, and shall be such that
all ports provide the same O concentrations. The vent, which exhausts excess gas flow from the system and insures that the
manifold outlet ports are maintained at atmospheric pressure for all flowrates, shall be large enough to avoid appreciable pressure
drop, and shall be located downstream of the output ports to insure that no ambient air enters the manifold due to eddy currents,
back diffusion, etc.
6.1.1.6 Temperature Indicator—Indicator, accurate to 61°C. This indicator is needed to measure the temperature of the gas in
the photometric cell in order to calculate a temperature correction. In most photometers, particularly those whose cell is enclosed
inside a case or housing with other electrical or electronic components, the cell operates at a temperature somewhat above ambient
room temperature. Therefore, it is important to measure the temperature of the gas inside the cell, and not room temperature. A
small thermocouple or thermistor, connected to an external readout device, may be attached to the cell wall or inserted through
the cell wall to measure internal temperature.
6.1.1.7 Barometer or Pressure Indicator—Indicator, accurate to 6250 Pa (2 Torr). Pa. The barometer or pressure indicator is
used to measure the pressure of the gas in the cell in order to calculate a pressure correction. Most photometer cells operate at
atmospheric pressure. If there are no restrictions between the cell and the output manifold, the cell pressure should be very nearly
the same as the local barometric pressure. A certified local barometric pressure reading can then be used for the pressure correction.
If the cell pressure is different than the local barometric pressure, some means of accurately measuring the cell pressure
(manometer, pressure gage, or pressure transducer) is required. This device shall be calibrated against a suitable pressure standard,
in accordance with Test Methods D3631.
6.1.2 Output Indicating Device, such as Continuous Strip Chart Recorder or Digital Volt Meter—If a recorder is used, it shall
have the following specifications:
Accuracy ±0.25 % of span
Chart width no less than 150 mm
Time for full-scale travel 1 s
6.1.2.1 If a digital voltmeter is used, it shall have an accuracy of 60.25 % of range.
6.1.2.2 MethodPractice A output indicating device shall be considered as part of the transfer standard, and employed during
qualification, certification, and use.
6.1.2.3 MethodsPractices C, D, and E require two output indicating devices.
6.1.3 Variable Autotransformer.
6.1.4 AC Voltmeter—Voltmeter, Accurateaccurate to 61 %.
6.2 Apparatus Common to MethodsPractices A and D:
6.2.1 Ozone MonitorMonitor:
6.2.1.1 Practice A—Method A: An ozone monitor used as a transfer standard shall receive special treatment consistent with its
authoritative status: that is, careful handling and storage, frequent maintenance, a QA program, operation by a competent and
trained technician. In particular, it shall not be used for ambient monitoring between uses as a transfer standard, as dust and dirt
will affect its accuracy.
6.3 Apparatus Common to MethodsPractices C and D—Fig. 2, a schematic of a typical GPT apparatus, shows the suggested
configuration listed below. All connections shall be glass or TFE-fluorocarbon. See RefEllis 5(5) for additional information
regarding the assembly and use of the GPT calibration apparatus apparatus.(5).
6.3.1 Nitric Oxide Flow Controller—A device capable of maintaining constant NO flow within 62 %. Component parts in
contact with NO shall be of a non-reactive material.
6.3.2 Nitric Oxide Flowmeter—A flowmeter capable of measuring NO flows within 62 %, and shall be calibrated according to
Practice D3195. (Warning—Rotameters have been reported to operate unreliably when measuring low NO flows, and are not
recommended.)
6.3.3 NO Cylinder Pressure Regulator—This regulator shall have non-reactive internal components, and shall include a purge
port.
6.3.4 Reaction Chamber—A glass chamber for the quantitative reaction between O and NO. It shall be of sufficient volume
that the reaction time is less than two minutes.
6.3.5 Mixing Chamber—A glass chamber to provide for mixing of reaction products and dilution air.
6.4 Apparatus for MethodPractice B Alone:
6.4.1 Sampling Train—Train (see Fig. 3), consisting of:
6.4.1.1 Glass Midget Impingers—Two impingers connected in series.
D5011 − 17
FIG. 2 Schematic Diagram of a Typical GPT System
FIG. 3 Components of a KI Sampling Train
6.4.1.2 Air Pump and Flow Controller—Any air pump and flow controller capable of maintaining a constant flow of 0.4 to 0.6
L/min through the impingers. A critical orifice, as described by Lodge et alal. (6), is recommended. The orifice shall be protected
from moisture and particulate matter with a membrane filter or trap containing Drierite, silica gel, and glass wool. The air pump
shall be capable of maintaining a pressure differential of at least 60 to 70 kPa (0.6 to 0.7 atm) across the critical orifice.
6.4.2 Spectrophotometer—Capable of measuring absorbance at 352 nm with an absolute accuracy of 61 %, and with a linear
response over the range of 0 to 1.0 absorbance units. The accuracy shall be verified using optical glass filters with certified
absorbance values at specified wavelengths. Matched 10-mm or 20-mm cells shall be used.
6.4.3 pH meter—meter, with a resolution of 60.1 pH units.
6.5 Apparatus for MethodPractice C Alone:
D5011 − 17
6.5.1 Chemiluminescence Nitric Oxide Monitor—The NO channel of a chemiluminescence NO/NO /NO monitor shall meet
2 X
the requirements of Method Test Methods D3824 or the performance requirements for Reference Methods for NO monitors in
40 CFR Part 50.
6.6 Apparatus for MethodPractice D Alone:
6.6.1 Ozone Generator—The generator shall be of the UV lamp type, with means to adjust the O concentration over a
convenient range without changing the flowrate. It shall have an output manifold similar to that described in 6.1.1.5, and a zero
air supply as described in 7.1.1.1.
7. Reagents and Materials
7.1 Reagents Common to MethodsPractices A Through E:
7.1.1 Zero Air—Air, free of O and any substance that might react with O or undergo photolysis (for example, NO, NO ,
3 3 2
ethylene or other hydrocarbons, and particulate matter). The air shall be purified to remove such substances. Dirty air shall be
precleaned to remove particulate matter, oil mist, liquid water, etc.
7.1.1.1 A system which has been used successfully is described as follows: the air is dried with a membrane type dryer, followed
by a column of indicating silica gel. The air is irradiated with a UV lamp to generate O to convert NO to NO , and passed through
3 2
a column of activated charcoal (6 to 14 mesh)(1.40 mm to 3.35 mm) to remove NO , O , hydrocarbons, and various other
2 3
substances, and is followed by a column of molecular sieve (6 to 16 mesh,(1.18 mm to 3.35 mm, type 4A), and a final particulate
filter (2 micron) to remove particulate matter.
7.1.1.2 If a chemiluminescent O monitor is being calibrated, the interference by high humidity shall be checked.
7.2 Reagents and Materials for MethodPractice B Only:
7.2.1 Purity of Reagents—Reagent grade chemicals shall be used in all tests. All reagents shall conform to the specifications of
the Committee on Analytical Reagents of the American Chemical Society where such specifications are available. Other grades
may be used, provided it is first ascertained that the reagent is of sufficiently high purity to permit its use without lessening the
accuracy of the determination.
7.2.2 Purity of Water—References to water shall mean reagent water as defined by Type 2 of Specification D1193.
7.2.3 Absorbing Reagent—Dissolve 6.2 g of boric acid (H BO ) in 750 mL of water in an amber 1000 mL volumetric flask. The
3 3
flask may be heated gently to speed dissolution of the boric acid, but the solution must be cooled to room temperature or below
before proceeding. (While the boric acid solution is cooling, prepare the H O solution (7.2.6).) When cooled, add 10 g of KI to
2 2
the H BO and dissolve. Add 1 mL of H O (7.2.6) solution and mix. Within 5 minutes after adding the H O , dilute to volume
3 3 2 2 2 2
with water, mix, and determine the absorbance of this BAKI solution at 352 nm against water as the reference. The pH of the BAKI
solution shall be 5.160.02. 5.1 6 0.02.
7.2.3.1 Set the absorbing solution aside for two hours, and redetermine the absorbance at 352 nm against water as the reference.
If the resulting absorbance from the second determination is at least 0.008 absorbance units/cm greater than the first determination,
the solution is ready for use. If no increase or an increase of less than 0.008 absorbance units/cm is observed, the KI reagent
probably contains an excessive amount of a reducing contaminant, and must be discarded. If an unacceptable absorbing reagent
results from different lots of KI, test the possibility of contamination in the H BO by using a different numbered lot of H BO .
3 3 3 3
7.2.4 Boric Acid (H BO ).
3 3
7.2.5 Hydrogen Peroxide (H O )—3 %(H O )—3 % or 30 %.
2 2 2 2
7.2.6 Hydrogen Peroxide Solution (0.0021 %)—Using(0.0021 %)—Using a graduated pipet, add 0.7 mL of 30 % or 7.0 mL of
3 % H O (7.2.5) to 200 mL of water in a 500 mL volumetric flask, dilute to volume with water, and mix. Pipet 5 mL of the above
2 2
solution into 50 mL of water in a 100 mL volumetric flask, dilute to volume with water, and mix. Both solutions must be prepared
fresh every time a fresh batch of absorbing solution is prepared.
7.2.7 Potassium Iodide (KI).
7.2.8 Potassium Iodate (KIO )—(KIO ), certified 0.1 N.
3 3
7.2.9 Sulfuric Acid (H SO )—95(H SO )—95 to 98 %.
2 4 2 4
7.2.10 Sulfuric Acid (1N)—Dilute (1 N)—Dilute 28 mL of concentrated H SO (7.2.9) to volume in a 1 L volumetric flask by
2 4
adding the acid to the water.
“ReagentReagent Chemicals, American Chemical Society Specifications,” Am.Specifications, American Chemical Soc.,Society, Washington, DC. For suggestions on the
testing of reagents not listed by the American Chemical Society, see “AnalarAnalar Standards for Laboratory U.K.Chemicals, Chemicals,” BDH Ltd., Poole, Dorset, U.K.,
and the “United States Pharmacopeia.”United States Pharmacopeia and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville, MD.
D5011 − 17
7.2.11 Standard Solutions:
7.2.11.1 Pipet 10 mL of 0.1 N KIO solution (7.2.8) into a 100 mL volumetric flask containing 50 mL of water. Add 1 g KI
(7.2.7) and 5 mL of 1 N H SO (7.2.10), dilute to volume with water, and mix.
2 4
7.2.11.2 Immediately before use, pipet 10 mL of the I solution (7.2.11.1) into a 100 mL volumetric flask, and dilute to volume
with water. Then pipet 10 mL of this solution into a 200 mL volumetric flask, and dilute to volume with absorbing reagent (7.2.3).
7.2.11.3 In turn, pipet 5, 10, 15, 20, and 25 mL aliquots of the final solution (7.2.11.2) into 25 mL volumetric flasks. Dilute to
volume with absorbing reagent (7.2.3), and mix. To prevent loss of I by volatilization, the flasks shall remain stoppered until
absorbance measurements are made. Absorbance measurements shall be made within 20 minutes after preparation of the I
standards (See (see Section A2.4).
7.3 Reagents and Materials for MethodsPractices C Only:
7.3.1 Nitric Oxide Concentration Standard—Compressed gas cylinder containing 50 to 100 ppm NO in N . This need not be
NBSNIST traceable, but a useful check of the transfer standard’s accuracy is obtained if the NO standard is traceable to an NIST
Standard Reference Material (SRM 1629). With a traceable NO standard, the transfer standard’s indicated O concentration shall
agree with the UV standard within −5 % to + 15 %to +15 % (most GPT-NO systems have a positive bias). If it does not agree
within this envelope, a problem with either the transfer standard or the primary standard is indicated, and standards shall be
established using new sources.
7.4 Reagents and Materials for MethodPractice D Only:
7.4.1 Nitric Oxide Concentration Standard—Compressed gas cylinder containing 50 to 100 ppm NO in N , traceable to an NIST
Standard Reference Material (SRM 1629 or SRM 1684) or NO Standard Reference Material (SRM 1629). The cylinder shall be
recertified on a regular basis as determined by a quality control program.
8. Hazards
8.1 Safety Hazards—See Practice D3249 for safety precautions on the use of monitors and electronic equipment.
8.1.1 Ozone is a toxic material. See Practice E591 for biological effects, and for safety and health requirements.
8.1.2 The manifold vents and photometer and monitor exhausts must be vented to remove exhaust gases from the workplace.
Measures must be taken to avoid a back pressure in the cell and manifold, and in the monitor or transfer standard being calibrated.
9. Establishing the Authority of Transfer Standards
9.1 The primary purpose of an O transfer standard is to transfer the authority of a primary O standard from one time and place
3 3
to another. Since a transfer standard has no authority of its own, its authority must be first established by confirming a high
probability or confidence that O concentration standards obtained, under a variety of operating conditions, are very nearly as
accurate as primary O standard. This confidence is first established by determining that the transfer standard has adequate
reproducibility to qualify it as a transfer standard, then by certifying the transfer standard by relating it to a primary standard, and
finally by periodically recertifying it by reverifying its accuracy and stability.
9.2 Comparing Transfer Standards to Primary Ozone Standard—Basic to the qualification and certification of an O transfer
standard is the need to compare the output (either a concentration determination or an O concentration) of the transfer standard
to the primary standard, so that relationships can be determined.
9.2.1 Assay-Type Transfer Standards—For transfer standards that provide an assay of an externally generated O concentration
(Methods(Practices A and B), the transfer standard is connected to the output manifold shown in Fig. 1 and Fig. 4. There shall be
sufficient flow of ozonized air for both the primary and secondary standards. The output of the transfer standard is an indicated
concentration, which is compared directly to the primary standard concentration obtained from the primary standard.
9.2.2 Ozone-Generation Type Transfer Standards—Transfer standards that generate O concentrations themselves include O
3 3
generators (Method(Practice E) and may include those assay procedures that have an integral source of O (Methods(Practices C
and D). Three procedures that may be used to compare the transfer standard to the primary standard are described in Annex A5.
They are presented in order of preference.
9.3 Qualification—The first step in establishing the authority of a candidate transfer standard is to prove that it qualifies for use
as a transfer standard. It must be demonstrated that the output of the transfer standard is reproducible and repeatable under the
changing conditions that might be encountered in field use. A transfer standard must be assumed unacceptable until it can be
conclusively demonstrated to be acceptable.
9.3.1 The primary requirement of a transfer standard is repeatability under the stress of variable conditions that may change
between certification in the laboratory and use in the field. A candidate transfer standard is qualified by proving that it is repeatable
over an appropriate range for each variable likely to change between the time and place of certification, and the time and place
of use. According to the specifications in Annex A1, the repeatability must be between 64 % 64 % or 64 ppb, whichever is
greater, for each condition or variable that may change between the point of certification and the point of use.
Available from National Institute of Standards and Technology (NIST), 100 Bureau Dr., Stop 1070, Gaithersburg, MD 20899-1070, http://www.nist.gov.
D5011 − 17
FIG. 4 Schematic Diagram of a Typical UV Photometric Calibration System (Option 1)
9.3.2 Selecting the conditions that are likely to vary and may affect the repeatability is largely a matter of intelligent informed
judgment. It is the user’s responsibility to determine all of the conditions to be considered in the demonstration of repeatability,
and to document the choices, and the reasons for them. Common conditions likely to affect a wide variety of transfer standards
include ambient temperature, line voltage and frequency, barometric pressure, elapsed time, physical shock, and relocation.
Conditions not likely to affect the transfer standard can be usually eliminated from consideration. The user, however, must be
constantly alert for the unusual situation where an unexpected condition is present.
9.3.3 It should be noted that a transfer standard does not necessarily need to be constant with respect to the variables, but only
repeatable or predictable. Demonstration of repeatability for a candidate transfer standard normally requires testing for each
condition that could or may affect it. Typical tests for common conditions are discussed in Section 10. For qualification of
procedural candidates such as MethodsPractices B, C, or D, testing may be minimal, provided the user is adequately trained, uses
good laboratory technique, and uses a specific apparatus and set of supplies. For commercially available transfer standards, some
or all of the testing may have been carried out by the manufacturer. In some cases it may be possible to judiciously substitute design
rationale for actual testing. For example, a device whose power supply is designed to be highly regulated may not require specific
line voltage tests. However, such situations should be viewed with considerable skepticism because of the possibility of failure of
a component.
9.3.4 This brings up the further question of whether candidate transfer standards must be tested individually or whether they
can be qualified by type, model, or user. In the case of procedural candidates such as MethodsPractices B, C, or D, each user must
qualify them in the laboratory/use situation in which it will be used, since the procedures have a number of potential variables.
Commercial transfer standards are designed and manufactured to be identical. The manufacturer could carry out the necessary
qualification tests on representative samples under this concept. It shall be appropriate to require that the manufacturer guarantee
that each unit meet appropriate performance specifications, and provide documentation accordingly. Again, the user should assume
a skeptical attitude, and at least carry out some minimal tests to verify that each unit is acceptable.
10. Qualification Tests
10.1 Some of the more common conditions likely to be encountered or to change while using transfer standards, and that may
affect the repeatability of the device are discussed below. The exact conditions or variables that must be considered depend on the
specific nature of the transfer standard or procedure. The user (or manufacturer) shall determine the conditions for each case on
an intelligent judgment basis derived from a complete understanding of the operation of the device or procedure and supported
by appropriate rationale.
10.2 Once the conditions to be considered have been determined, the objective of the qualification tests is either 10.1.110.2.1
or 10.1.210.2.2:
D5011 − 17
10.2.1 To determine that the candidate transfer standard’s output is not affected by more than 64 % or 64 ppb (whichever is
greater) by the condition over the range likely to be encountered during use of the transfer standard.
10.2.2 To demonstrate the candidate transfer standard’s output is repeatable within 64 % or 64 ppb (whichever is greater) as
the variable is changed over the range likely to be encountered during use, and to quantify the relationship between the output and
the variable.
10.3 Temperature—Changes in ambient temperature are likely to occur from place to place and from one time to another.
Temperature changes are likely to affect almost all types of transfer standards unless appropriate means are used to avoid adverse
effects. Temperature affects transfer standards in many ways: changes in action of components, changes in chemical reactions or
rates of reaction, volume changes of gases, electronic drift, variable warm-up time, etc. The most important effects are changes
in the output of generation devices, changes in the sensitivity of O assay systems, and changes in the volume of air flows which
must be measured accurately.
10.3.1 Temperature effects may be minimized in several ways. The easiest way is to restrict the use of the transfer standard to
a temperature range over which the effects are within the specification. This restriction may be the only practical approach for some
candidate transfer standards, but it may preclude use of such a transfer standard in too many situations. Transfer standard devices
may be insensitive to temperature changes by design, such as thermostatic regulation of sensitive components or of the entire
device, or by temperature compensation.
10.3.2 Temperature effects on flow measurements may be minimized by the use of mass flowmeters, which do not measure
volume, or by the regulation of gas temperature. Alternately, ideal-gas-law corrections may be made to adjust measured values.
See Practice D3195 for appropriate formulas for corrections.
10.3.3 Testing a candidate transfer standard for sensitivity to temperature is facilitated by use of a controlled temperature
chamber. However, temperature tests may be carried out in many ordinary laboratories where the temperature may be manually
controlled by adjusting thermostats, blocking air vents or outlets, opening doors or windows, or using supplemental heaters or air
conditioners. A reasonable temperature range is 20° to 30°C [68° to 86°F]. 30°C. Broader temperature ranges could be used if
necessary for special situations.
10.3.4 The candidate transfer standard is tested by comparing its output to a stable concentration reference, which shall be an
UV photometer system. See Practice D5110. The reference may also be another transfer standard known to be repeatable and, in
particular, insensitive to temperature changes. However, it would be better to locate the reference outside of the variable
temperature area. The candidate transfer standard shall be tested at several different points over the temperature range, including
the extremes, and at several different concentrations. Sufficient time shall be allowed for all components of the calibration system
to equilibrate each time the temperature is changed. The test results shall be plotted as shown in Fig. 5.
10.3.5 If the candidate transfer standard has a significant temperature dependence, additional test points at various
concentrations and temperature shall be taken to define the relationship between output and temperature accurately. Furthermore,
if the candidate transfer standard has a dependence on more than one variable, tests shall be carried out over the range of both
FIG. 5 Example of Temperature Qualification Test Results Showing no Dependence on Temperature
D5011 − 17
variables simultaneously to determine any interdependence between the two variables. Once the test data are acquired, they shall
be analyzed to determine if some general formula or curve can be derived (either analytically or empirically) to predict the correct
O concentration at any temperature in the range (see Fig. 6). The correction formula or curve shall be accurate within 64 % or
64 ppb, whichever is greater. If two or more variables are involved, a family of curves may be required; unless the relationship
is simple, this situation may prove impractical in actual use.
10.4 Line Voltage—Line voltage may vary from place to place, and from one time to another. Good electrical or electronic
design of the transfer standard shall avoid sensitivity to line voltage variations, but poorly designed equipment may easily be
affected. In addition, line voltage sensitivity may appear only as a long time thermal drift, which is a subtle effect.
10.4.1 Aside from adequate design, line voltage effects may be minimized by the addition of a line voltage regulator. However,
such devices may distort the line voltage waveform, thereby adversely affecting some types of transfer standards. If such regulators
are used, it is important the same regulator is used both during certification and use of the transfer standards. Restriction of the
transfer standards to a line voltage range in which effects are insignificant is another alternative, but requires monitoring the voltage
during use, and may preclude use at some sites.
10.4.2 Testing for line voltage sensitivity may be conducted along the same lines as described for temperature testing. The line
voltage may be varied by means of a variable autotransformer and measured by an accurate ac voltmeter. Do not use electronic
“dimmer” controls which operate on a delayed-conduction principle, as such devices cause drastic waveform distortions.
10.4.3 A line voltage range of 105 to 125 V should adequately cover the majority of line voltages available.
10.4.4 If the transfer standard is used when power is from a small power generator, the frequency variation shall be checked.
10.5 Barometric Pressure/Altitude—Since O concentrations are gaseous, all transfer standards will have some basic or inherent
sensitivity to changes in barometric pressure. It is difficult to minimize pressure effects by design. Air pressure can be regulated
mechanically against an absolute reference, but most such schemes are not practical when working with O concentrations because
of restrictions to inert material such as glass or TFE-fluorocarbon. With MethodsPractices B, C, and D, the effect is limited
primarily to the measurements of flowrates, which were discussed in 10.210.3, and are applicable to barometric pressure changes
as well. At a constant altitude, normal day-to-day variations in barometric pressure is only a few percent. If the use of the transfer
standards can be restricted to altitudes within a hundred metersmetres of the certification altitude, it may be acceptable to neglect
the barometric effect. However, if the use of the transfer standard is necessary at altitudes different than the certification altitude,
then pressure effects may not be ignored.
10.5.1 Although not preventable, pressure effects are likely to be repeatable. As a result, barometric pressure may be the variable
most likely to be handled by a defined relationship. The technique is similar to that used to determine a temperature relationship;
a unique quantitative relationship will result. (Warning—In any work with O concentrations at altitudes significantly above sea
level, the concentration units must be clearly understood. The volume ratio concentration units (ppm, ppb, etc.) are independent
FIG. 6 Example of a Temperature Dependence Quantitatively Defined as a Correction Factor
D5011 − 17
3 3 8
of pressure, while density units such as μg/m are related to pressure. The μg/m unit defined and used by the U.S. EPA is
“corrected” to 101.3 kPa (1 atm) and 25°C, and is therefore related to ppm by a constant.)
10.5.2 Testing barometric pressure effects may be difficult. The use of a variable pressure chamber is the best approach, but few
laboratories have access to one. It is conceivable that various pressures may be obtained in a manifold setup, but construction of
such an apparatus is difficult, and of questionable validity. The use of a mobile laboratory which may be driven to several altitudes
to conduct tests may offer the best solution. Some types of transfer standards may not require pressure tests because their pressure
variations are well known. For MethodsPractices B, C, and D, the flow measurement problem constitutes the only pressure effect.
Assay-types such as MethodPractice A are
...