ASTM D7911-19
(Guide)Standard Guide for Using Reference Material to Characterize Measurement Bias Associated with Volatile Organic Compound Emission Chamber Test
Standard Guide for Using Reference Material to Characterize Measurement Bias Associated with Volatile Organic Compound Emission Chamber Test
SIGNIFICANCE AND USE
5.1 Chamber testing is a globally-accepted method for measuring the emissions of VOCs from building materials and products. Chamber emission test data have a variety of uses including identification and labeling of products as low-VOC emitting for improved indoor air quality, manufacturing quality control, and development of new and improved products for reduced VOC emissions.
5.2 Currently, an inter-laboratory study (ILS) is the most frequently used method for assessing the bias of a laboratory’s VOC emission test results. An ILS typically relies on a VOC source with an uncharacterized emission rate. Consequently, a large number of participants (Practice E691 recommends 30, with a minimum requirement of six) are needed to produce the data required to calculate a laboratory’s performance relative to the central tendency and distribution of the results for all participants. Due to the participant size requirement and other logistical issues, an ILS involves significant planning and coordination to achieve useful results.
5.3 Inter-laboratory studies have often shown significant variations in measured VOC emission rates among participating laboratories for a given source. Variability in the emission rate from the source often is suspected to be a contributing factor, but it is difficult to be certain of the cause. Thus, better characterized sources are needed for evaluating the ability of laboratories to generate VOC emission test results with acceptable bias as discussed in 8.6.
5.4 Proficiency tests (PT) for VOC emission testing typically focus on a laboratory’s analytical capabilities. For example, an analytical PT relies on a certified standard prepared by an accredited vendor as a reference. A laboratory analyzes the PT sample without knowledge of its concentration value. Acceptance of the results is judged by the deviation from the known value. Use of reference materials can expand analytical PT schemes to also include the impacts of test sample handlin...
SCOPE
1.1 This guide provides procedures for using a reference material with a known emission rate of a volatile organic compound (VOC) to estimate the bias associated with a VOC emission chamber test.
1.2 This guide may be used to assess measurements of VOC emissions conducted in a variety of environmental chambers, such as small-scale chambers, full-scale chambers, emission cells, and micro-scale chambers.
1.3 This guide may be used to assess measurements of VOC emissions from a variety of sources including “dry” materials (for example, carpet, floor tile and particleboard) and “wet” materials (for example, paint and cleaning products).
1.4 This guide can be used to support quality control efforts by emissions testing laboratories, third party accreditation of testing laboratories participating in emissions testing programs, and quality control efforts by manufacturers of building and other materials.
1.5 This guide may be used to support the determination of precision and bias of other commonly used VOC emission standards including Guide D5116, Test Method D6007, ISO 16000-9, ANSI/BIFMA M7.1, and CDPH/EHLB/Standard Method V1.2.
1.6 This guide also describes the attributes of a suitable emission reference material and the different methods available to independently determine the reference material’s VOC emission rate.
1.7 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.8 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.
1.9 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles ...
General Information
- Status
- Published
- Publication Date
- 31-Oct-2019
- Technical Committee
- D22 - Air Quality
- Drafting Committee
- D22.05 - Indoor Air
Relations
- Effective Date
- 01-Nov-2019
- Effective Date
- 01-Dec-2023
- Effective Date
- 01-Sep-2023
- Effective Date
- 01-Sep-2023
- Effective Date
- 01-Sep-2020
- Effective Date
- 15-Mar-2020
- Effective Date
- 01-Mar-2020
- Effective Date
- 01-Aug-2019
- Effective Date
- 01-Sep-2018
- Effective Date
- 01-Mar-2018
- Effective Date
- 15-Dec-2017
- Effective Date
- 15-Nov-2017
- Effective Date
- 01-Nov-2017
- Effective Date
- 01-May-2017
- Effective Date
- 01-Mar-2017
Overview
ASTM D7911-19 is the Standard Guide for Using Reference Material to Characterize Measurement Bias Associated with Volatile Organic Compound (VOC) Emission Chamber Test. Published by ASTM International, this guide establishes procedures for utilizing reference materials with known emission rates to assess and correct measurement bias in VOC emission chamber tests. Chamber testing is globally recognized for quantifying VOC emissions from building materials and products, which plays a critical role in improving indoor air quality, manufacturing quality control, and product development.
Key Topics
- Reference Material Use: The standard details how to use reference materials with certified emission rates to estimate measurement bias in VOC emission tests across various chamber types.
- Chamber Types: Applicable to small-, full-scale, emission cells, and micro-scale chambers, enabling flexible method integration into different laboratory setups.
- Material Types: Provides guidance for testing emissions from both "dry" materials (e.g., carpet, floor tile, particleboard) and "wet" materials (e.g., paint, cleaning products).
- Measurement Precision and Quality Control: Supports laboratories and manufacturers in quality assurance, third-party accreditation, and regulatory compliance by aiding in the determination of precision and bias.
- Attributes of Reference Materials: Outlines necessary qualities for emission reference materials, such as homogeneity, stability, similarity to real-world products, and proper response to environmental conditions.
- Procedures for Bias Assessment: Offers step-by-step instructions for shipping, storage, chamber preparation, sample loading, air sampling, and chamber performance evaluation using statistical hypothesis testing.
Applications
ASTM D7911-19 provides significant practical value for:
- Testing Laboratories: Assists in the certification and proficiency testing of laboratories conducting VOC emission analyses. Laboratories can identify, quantify, and minimize sources of measurement bias, thereby improving the reliability of VOC emission data.
- Manufacturers: Supports product development and continuous improvement by providing a framework for routine control of VOC emissions, facilitating the labeling of low-emitting products to meet green building or health certification requirements.
- Regulatory Compliance and Accreditation: Aids third-party organizations and accreditation bodies by offering consistent methodologies to evaluate laboratory performance and precision, which is essential for participation in emission testing programs.
- Quality Assurance: Integrates with existing quality control protocols, such as inter-laboratory studies (ILS), proficiency tests (PT), and traceability schemes, to ensure VOC emission test results meet national and international standards.
Related Standards
ASTM D7911-19 is closely related to several important standards in VOC emission measurement, sampling, and analysis:
- ASTM D5116: Guide for Small-Scale Environmental Chamber Determinations of Organic Emissions from Indoor Materials/Products
- ASTM D6007: Test Method for Determining Formaldehyde Concentrations in Air from Wood Products Using a Small-Scale Chamber
- ISO 16000-9: Determination of the Emission of Volatile Organic Compounds from Building Products and Furnishing-Emission Test Chamber Method
- ANSI/BIFMA M7.1: Test Method for Determining VOC Emissions from Office Furniture Systems and Seating
- CDPH/EHLB/Standard Method V1.2: Standard Method for the Testing and Evaluation of Volatile Organic Chemical Emissions from Indoor Sources Using Environmental Chambers
- ISO/IEC 17025: General Requirements for the Competence of Testing and Calibration Laboratories
Additional referenced standards provide comprehensive methodologies and terminology supporting the use of reference materials, statistical quality assurance, and environmental chamber testing.
By leveraging the guidance and procedures set out in ASTM D7911-19, organizations engaged in VOC emission testing can enhance the accuracy, traceability, and comparability of their measurements, contributing to healthier indoor environments and increased confidence in emission data.
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Frequently Asked Questions
ASTM D7911-19 is a guide published by ASTM International. Its full title is "Standard Guide for Using Reference Material to Characterize Measurement Bias Associated with Volatile Organic Compound Emission Chamber Test". This standard covers: SIGNIFICANCE AND USE 5.1 Chamber testing is a globally-accepted method for measuring the emissions of VOCs from building materials and products. Chamber emission test data have a variety of uses including identification and labeling of products as low-VOC emitting for improved indoor air quality, manufacturing quality control, and development of new and improved products for reduced VOC emissions. 5.2 Currently, an inter-laboratory study (ILS) is the most frequently used method for assessing the bias of a laboratory’s VOC emission test results. An ILS typically relies on a VOC source with an uncharacterized emission rate. Consequently, a large number of participants (Practice E691 recommends 30, with a minimum requirement of six) are needed to produce the data required to calculate a laboratory’s performance relative to the central tendency and distribution of the results for all participants. Due to the participant size requirement and other logistical issues, an ILS involves significant planning and coordination to achieve useful results. 5.3 Inter-laboratory studies have often shown significant variations in measured VOC emission rates among participating laboratories for a given source. Variability in the emission rate from the source often is suspected to be a contributing factor, but it is difficult to be certain of the cause. Thus, better characterized sources are needed for evaluating the ability of laboratories to generate VOC emission test results with acceptable bias as discussed in 8.6. 5.4 Proficiency tests (PT) for VOC emission testing typically focus on a laboratory’s analytical capabilities. For example, an analytical PT relies on a certified standard prepared by an accredited vendor as a reference. A laboratory analyzes the PT sample without knowledge of its concentration value. Acceptance of the results is judged by the deviation from the known value. Use of reference materials can expand analytical PT schemes to also include the impacts of test sample handlin... SCOPE 1.1 This guide provides procedures for using a reference material with a known emission rate of a volatile organic compound (VOC) to estimate the bias associated with a VOC emission chamber test. 1.2 This guide may be used to assess measurements of VOC emissions conducted in a variety of environmental chambers, such as small-scale chambers, full-scale chambers, emission cells, and micro-scale chambers. 1.3 This guide may be used to assess measurements of VOC emissions from a variety of sources including “dry” materials (for example, carpet, floor tile and particleboard) and “wet” materials (for example, paint and cleaning products). 1.4 This guide can be used to support quality control efforts by emissions testing laboratories, third party accreditation of testing laboratories participating in emissions testing programs, and quality control efforts by manufacturers of building and other materials. 1.5 This guide may be used to support the determination of precision and bias of other commonly used VOC emission standards including Guide D5116, Test Method D6007, ISO 16000-9, ANSI/BIFMA M7.1, and CDPH/EHLB/Standard Method V1.2. 1.6 This guide also describes the attributes of a suitable emission reference material and the different methods available to independently determine the reference material’s VOC emission rate. 1.7 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.8 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. 1.9 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles ...
SIGNIFICANCE AND USE 5.1 Chamber testing is a globally-accepted method for measuring the emissions of VOCs from building materials and products. Chamber emission test data have a variety of uses including identification and labeling of products as low-VOC emitting for improved indoor air quality, manufacturing quality control, and development of new and improved products for reduced VOC emissions. 5.2 Currently, an inter-laboratory study (ILS) is the most frequently used method for assessing the bias of a laboratory’s VOC emission test results. An ILS typically relies on a VOC source with an uncharacterized emission rate. Consequently, a large number of participants (Practice E691 recommends 30, with a minimum requirement of six) are needed to produce the data required to calculate a laboratory’s performance relative to the central tendency and distribution of the results for all participants. Due to the participant size requirement and other logistical issues, an ILS involves significant planning and coordination to achieve useful results. 5.3 Inter-laboratory studies have often shown significant variations in measured VOC emission rates among participating laboratories for a given source. Variability in the emission rate from the source often is suspected to be a contributing factor, but it is difficult to be certain of the cause. Thus, better characterized sources are needed for evaluating the ability of laboratories to generate VOC emission test results with acceptable bias as discussed in 8.6. 5.4 Proficiency tests (PT) for VOC emission testing typically focus on a laboratory’s analytical capabilities. For example, an analytical PT relies on a certified standard prepared by an accredited vendor as a reference. A laboratory analyzes the PT sample without knowledge of its concentration value. Acceptance of the results is judged by the deviation from the known value. Use of reference materials can expand analytical PT schemes to also include the impacts of test sample handlin... SCOPE 1.1 This guide provides procedures for using a reference material with a known emission rate of a volatile organic compound (VOC) to estimate the bias associated with a VOC emission chamber test. 1.2 This guide may be used to assess measurements of VOC emissions conducted in a variety of environmental chambers, such as small-scale chambers, full-scale chambers, emission cells, and micro-scale chambers. 1.3 This guide may be used to assess measurements of VOC emissions from a variety of sources including “dry” materials (for example, carpet, floor tile and particleboard) and “wet” materials (for example, paint and cleaning products). 1.4 This guide can be used to support quality control efforts by emissions testing laboratories, third party accreditation of testing laboratories participating in emissions testing programs, and quality control efforts by manufacturers of building and other materials. 1.5 This guide may be used to support the determination of precision and bias of other commonly used VOC emission standards including Guide D5116, Test Method D6007, ISO 16000-9, ANSI/BIFMA M7.1, and CDPH/EHLB/Standard Method V1.2. 1.6 This guide also describes the attributes of a suitable emission reference material and the different methods available to independently determine the reference material’s VOC emission rate. 1.7 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.8 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. 1.9 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles ...
ASTM D7911-19 is classified under the following ICS (International Classification for Standards) categories: 13.040.20 - Ambient atmospheres; 71.080.01 - Organic chemicals in general. The ICS classification helps identify the subject area and facilitates finding related standards.
ASTM D7911-19 has the following relationships with other standards: It is inter standard links to ASTM D7911-14, ASTM D6299-23a, ASTM D7440-23, ASTM D7706-17(2023), ASTM D1356-20a, ASTM D1356-20, ASTM D6330-20, ASTM D6803-19, ASTM D6670-18, ASTM D7339-18, ASTM D6299-17b, ASTM D6299-17a, ASTM D5116-17, ASTM D7706-17, ASTM D7143-17. Understanding these relationships helps ensure you are using the most current and applicable version of the standard.
ASTM D7911-19 is available in PDF format for immediate download after purchase. The document can be added to your cart and obtained through the secure checkout process. Digital delivery ensures instant access to the complete standard document.
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: D7911 − 19
Standard Guide for
Using Reference Material to Characterize Measurement Bias
Associated with Volatile Organic Compound Emission
Chamber Test
This standard is issued under the fixed designation D7911; 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 priate safety, health, and environmental practices and deter-
mine the applicability of regulatory limitations prior to use.
1.1 This guide provides procedures for using a reference
1.9 This international standard was developed in accor-
material with a known emission rate of a volatile organic
dance with internationally recognized principles on standard-
compound (VOC) to estimate the bias associated with a VOC
ization established in the Decision on Principles for the
emission chamber test.
Development of International Standards, Guides and Recom-
1.2 ThisguidemaybeusedtoassessmeasurementsofVOC
mendations issued by the World Trade Organization Technical
emissions conducted in a variety of environmental chambers,
Barriers to Trade (TBT) Committee.
such as small-scale chambers, full-scale chambers, emission
cells, and micro-scale chambers.
2. Referenced Documents
1.3 ThisguidemaybeusedtoassessmeasurementsofVOC
2.1 ASTM Standards:
emissions from a variety of sources including “dry” materials
D1356 Terminology Relating to Sampling and Analysis of
(for example, carpet, floor tile and particleboard) and “wet”
Atmospheres
materials (for example, paint and cleaning products).
D5116 Guide for Small-Scale Environmental Chamber De-
terminations of Organic Emissions from Indoor Materials/
1.4 This guide can be used to support quality control efforts
Products
by emissions testing laboratories, third party accreditation of
D5197 Test Method for Determination of Formaldehyde and
testinglaboratoriesparticipatinginemissionstestingprograms,
OtherCarbonylCompoundsinAir(ActiveSamplerMeth-
and quality control efforts by manufacturers of building and
odology)
other materials.
D5466 Test Method for Determination of Volatile Organic
1.5 This guide may be used to support the determination of
Compounds in Atmospheres (Canister Sampling Method-
precision and bias of other commonly used VOC emission
ology)
standards including Guide D5116, Test Method D6007, ISO
D6007 TestMethodforDeterminingFormaldehydeConcen-
16000-9, ANSI/BIFMA M7.1, and CDPH/EHLB/Standard
trations in Air from Wood Products Using a Small-Scale
Method V1.2.
Chamber
1.6 This guide also describes the attributes of a suitable
D6196 Practice for Choosing Sorbents, Sampling Param-
emissionreferencematerialandthedifferentmethodsavailable
eters and Thermal Desorption Analytical Conditions for
to independently determine the reference material’s VOC
Monitoring Volatile Organic Chemicals in Air
emission rate.
D6299 Practice for Applying Statistical Quality Assurance
and Control Charting Techniques to Evaluate Analytical
1.7 The values stated in SI units are to be regarded as
Measurement System Performance
standard. No other units of measurement are included in this
D6330 Practice for Determination of Volatile Organic Com-
standard.
pounds(ExcludingFormaldehyde)EmissionsfromWood-
1.8 This standard does not purport to address all of the
Based Panels Using Small Environmental Chambers Un-
safety concerns, if any, associated with its use. It is the
der Defined Test Conditions
responsibility of the user of this standard to establish appro-
D6617 Practice for Laboratory Bias Detection Using Single
This guide is under the jurisdiction of ASTM Committee D22 on Air Quality
and is the direct responsibility of Subcommittee D22.05 on Indoor Air. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Nov. 1, 2019. Published December 2019. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 2014. Last previous edition approved in 2014 as D7911 – 14. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/D7911-19. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7911 − 19
Test Result from Standard Material of Reference Material Producers
D6670 Practice for Full-Scale Chamber Determination of ISO/IECGuide98 GuidetotheExpressionofUncertaintyin
Volatile Organic Emissions from Indoor Materials/ Measurement (GUM)
Products ISO Guide 30 Terms and Definitions Used in Connection
D6803 PracticeforTestingandSamplingofVolatileOrganic with Reference Materials
Compounds (Including Carbonyl Compounds) Emitted ISO Guide 33 Uses of Certified Reference Materials
from Architectural Coatings Using Small-Scale Environ- ISO Guide 35 Reference Materials—General and Statistical
mental Chambers Principles for Certification
D7143 Practice for Emission Cells for the Determination of
2.3 Other Standards:
Volatile Organic Emissions from Indoor Materials/
ANSI/BIFMA M7.1 2011 Test Method for Determining
Products
VOC Emissions from Office Furniture Systems,
D7339 Test Method for Determination of Volatile Organic
Components, and Seating
Compounds Emitted from Carpet using a Specific Sorbent
CDPH/EHLB/Standard Method V1.2 Standard Method for
Tube and Thermal Desorption / Gas Chromatography
the Testing and Evaluation of Volatile Organic Chemical
D7440 Practice for Characterizing Uncertainty in Air Qual-
Emissions from Indoor Sources Using Environmental
ity Measurements
Chambers, Version 1.2, 2017
D7706 Practice for Rapid Screening of VOC Emissions
Method TO-17 “Determination of Volatile Organic Com-
from Products Using Micro-Scale Chambers
pounds in Ambient Air Using Active Sampling Onto
D8141 Guide for Selecting Volatile Organic Compounds
Sorbent Tubes,” Compendium of Methods for the Deter-
(VOCs) and Semi-Volatile Organic Compounds (SVOCs)
mination of Toxic Organic Compounds in Ambient Air,
Emission Testing Methods to Determine Emission Param-
Second Edition (EPA/625/R-96/010b), 1999
eters for Modeling of Indoor Environments
E691 Practice for Conducting an Interlaboratory Study to 3. Terminology
Determine the Precision of a Test Method
3.1 Definitions—For definitions and terms commonly used
E741 Test Method for Determining Air Change in a Single
in Commitee D22 standards, refer to Terminology D1356. For
Zone by Means of a Tracer Gas Dilution
definitions and terms commonly used when testing materials
E1333 Test Method for Determining Formaldehyde Concen-
and products for VOC emissions, refer to Guide D5116. For
trations in Air and Emission Rates from Wood Products
definitions and terms commonly used to describe reference
Using a Large Chamber
materials, refer to ISO Guide 30.
2.2 ISO Standards:
3.2 Definitions of Terms Specific to This Standard:
ISO 12219-3 InteriorAir of Road Vehicles—Part 3: Screen-
3.2.1 constant emission source, n—an emission source
ing Method for the Determination of the Emissions of
where the concentration of the chemical at the material surface
Volatile Organic Compounds from Vehicle Interior Parts
does not change with time.
and Materials—Micro-Scale Chamber Method
3.2.2 diffusion-controlled source, n—an emission source
ISO 16000-3 Indoor Air—Part 3: Determination of Formal-
that is limited by the movement of contaminants within the
dehyde and Other Carbonyl Compounds in IndoorAir and
material boundaries.
Test Change Air—Active Sampling Method
3.2.2.1 Discussion—The rate of diffusion depends on the
ISO 16000-6 IndoorAir—Part 6: Determination of Volatile
diffusivityoftheVOC,thetemperature,andthestructureofthe
Organic Compounds in Indoor and Test Chamber Air by
material.
Active Sampling on Tenax TA Sorbent, Thermal Desorp-
tion and Gas Chromatography Using MS or MS-FID
3.2.3 dynamic emission source, n—an emission source
ISO 16000-9 Indoor Air—Part 9: Determination of the
where the concentration of the chemical at the material surface
Emission of Volatile Organic Compounds from Building
changes with time.
Products and Furnishing—Emission Test Chamber
3.2.3.1 Discussion—A dynamic source can still generate
Method
emissions in a predictable and consistent manner.
ISO 16000-10 Indoor Air—Part 10: Determination of the
3.2.4 evaporative-controlled source, n—an emission source
Emission of Volatile Organic Compounds from Building
that is limited by the ability of a contaminant to transfer from
Products and Furnishing—Emission Test Cell Method
the material surface through a boundary layer to the surround-
ISO 16000-11 Indoor Air—Part 11: Determination of the
ing air.
Emission of Volatile Organic Compounds from Building
3.2.4.1 Discussion—The rate of mass transfer at the surface
Products and Furnishing—Sampling, Storage of Samples
and Preparation of Test Specimens
ISO/IEC 17025 General Requirements for the Competence 4
Available from Business + Institutional Furniture Manufacturers Association
of Testing and Calibration Laboratories (BIFMA), 678 Front Ave. NW, Ste. 150, Grand Rapids, Michigan 49504-5368,
https://www.bifma.org.
ISO/IEC 17034 General Requirements for the Competence
Available from California Department of Public Health (CDPH), PO Box
997377, MS 0500, Sacramento, CA 95899-7377, http://www.cdph.ca.gov.
AvailablefromUnitedStatesEnvironmentalProtectionAgency(EPA),William
Available from International Organization for Standardization (ISO), 1, ch. de Jefferson Clinton Bldg., 1200 Pennsylvania Ave., NW, Washington, DC 20460,
la Voie-Creuse, CP 56, CH-1211 Geneva 20, Switzerland, http://www.iso.org. http://www.epa.gov.
D7911 − 19
of an evaporative-controlled source is dependent on VOC 5. Significance and Use
volatility, air velocity, and turbulence near the material surface.
5.1 Chamber testing is a globally-accepted method for
3.2.5 primary reference measurement procedure,
measuring the emissions of VOCs from building materials and
n—“Reference measurement procedure used to obtain a mea-
products. Chamber emission test data have a variety of uses
surement result without relation to a measurement standard for
including identification and labeling of products as low-VOC
a quantity of the same kind” (1).
emittingforimprovedindoorairquality,manufacturingquality
3.2.6 reference emission rate value, n—the independently-
control, and development of new and improved products for
determined mass of VOC emitted per unit of time from a
reduced VOC emissions.
reference emission source at specified conditions.
5.2 Currently, an inter-laboratory study (ILS) is the most
3.2.6.1 Discussion—If the reference emission rate value is
frequently used method for assessing the bias of a laboratory’s
“certified,” the reference value and associated uncertainty will
VOC emission test results. An ILS typically relies on a VOC
be available on the accompanying certificate for the reference
source with an uncharacterized emission rate. Consequently, a
material.
large number of participants (Practice E691 recommends 30,
3.2.7 reference material, n—a material that is “sufficiently
with a minimum requirement of six) are needed to produce the
homogeneous and stable with respect to one or more specified
datarequiredtocalculatealaboratory’sperformancerelativeto
properties, which has been established to be fit for its intended
the central tendency and distribution of the results for all
use in a measurement process” (ISO Guide 30).
participants. Due to the participant size requirement and other
3.2.7.1 Discussion—Acertifiedreferencematerialsprovides
logistical issues, an ILS involves significant planning and
traceability assurance through ISO/IEC 17034. A reference coordination to achieve useful results.
material can also be produced that is not directly traceable
5.3 Inter-laboratory studies have often shown significant
through ISO/IEC 17034 but rather is fit for purpose.
variations in measured VOC emission rates among participat-
ing laboratories for a given source. Variability in the emission
4. Summary of Guide
rate from the source often is suspected to be a contributing
4.1 This guide describes procedures for using a reference
factor, but it is difficult to be certain of the cause. Thus, better
material to evaluate the measurement bias associated with tests
characterized sources are needed for evaluating the ability of
of VOC emissions from materials and products. The reference
laboratories to generateVOC emission test results with accept-
materials described in this guide have independently-
able bias as discussed in 8.6.
determined emission rates that can be measured in an environ-
5.4 Proficiency tests (PT) for VOC emission testing typi-
mental test chamber according to commonly used VOC emis-
cally focus on a laboratory’s analytical capabilities. For
sion and analytical standards and by following the instructions
in the reference material’s accompanying documentation. example, an analytical PT relies on a certified standard
prepared by an accredited vendor as a reference. A laboratory
4.2 In general, reference materials used in laboratory emis-
analyzesthePTsamplewithoutknowledgeofitsconcentration
sion tests can provide traceability for test results determined at
value.Acceptanceoftheresultsisjudgedbythedeviationfrom
different times and in different laboratories using the same
the known value. Use of reference materials can expand
environmental conditions (for example, chamber airflow rate,
analytical PT schemes to also include the impacts of test
temperature, and relative humidity). Chamber air samples are
sample handling, test specimen preparation, chamber
collected at specific times and analyzed according to refer-
operation, and chamber air sampling.
enced standards. If no analytical standard is prescribed,
samples are analyzed according to a laboratory’s standard
5.5 Laboratories accredited under ISO/IEC 17025 are re-
operating procedures. Chamber concentrations and source
quired to derive uncertainty estimates for their test results.
emission rates are calculated. The measured emission rates, at
Typically,thisisdonebydevelopinganuncertaintybudgetand
defined time periods, are then compared with the known value
estimating an expanded uncertainty (ISO/IEC Guide 98, Prac-
for the reference material to estimate the measurement bias of
ticeD7440).ReferencematerialsnotaccreditedunderISO/IEC
the value obtained in the emission chamber. If applicable, the
17025 should still be delivered with documented uncertainty
value of the measurement bias can be compared with accep-
budgets. An uncertainty budget for a VOC emission test
tance criteria for the emission testing program of interest to the
combines relevant sources of measurement uncertainty for all
user.
steps in the testing process from test specimen preparation
4.3 This guide also describes the qualities of an emission through air sample analysis. A more efficient approach to
reference material, the different methods available to indepen- determining the overall bias and precision for a VOC emission
dently determine the VOC emission rate of a reference test is with repeated testing of a reference material (see
material,andthechamberoperatingparametersthatpotentially ISO/IEC Guide 98, ISO Guide 33). This guide addresses the
influence a reference material’s emission results.
estimationofbiasthroughcomparisonofthemeasuredvalueto
the reference material value. The precision is determined
through repeated testing of multiple reference materials, ide-
7 ally from the same production batch (see Practices D6299 and
The boldface numbers in parentheses refer to the list of references at the end of
this standard. E691).
D7911 − 19
5.6 Other uses of an emissions reference material include 6.2.3 The reference material should emit VOCs that are
verifying quality control emission measurements of manufac- measurable by the same sampling and analytical techniques
tured product batches and providing traceability for third party
used in VOC emission testing (for example, Test Method
certification. D5197, Test Method D7339, and ISO 16000-9). Although
canisters can be used to sample VOCs, they are not typically
6. Reference Material Attributes employed for chamber emission testing. Chemical emissions
shouldresultinchamberconcentrationsappropriatetothelevel
6.1 AccordingtoISOGuide30,areferencematerialwithan
for which the measurement process is intended. Thus, refer-
“assigned quantity value” can be used to improve the accuracy
ence materials of different sizes or numbers may be required
of test methods and analysis, to evaluate laboratory equipment
for different types and sizes of test chambers.
performance characteristics, and to establish metrological
6.2.4 The reference material should be packaged and
traceability. For material VOC emission testing, the assigned
shipped to prevent physical damage and minimize loss or
quantity value for the reference material is its emission rate of
degradation of the material. Short-term stability tests are
a specific VOC (see Guide D5116 for a discussion of material
described in ISO Guide 35.
emission rates).
6.2.5 The reference material shelf life should be known.
6.2 To meet ISO Guide 30 criteria, a reference material for
ISO Guide 35 provides further information regarding long-
material emission testing should consist of a known amount of
term stability tests. Ideally, the shelf life should be several
VOC that transfers to the surrounding air at a predictable rate.
months or longer.
Inadditiontomeetingthis“homogeneousandstable”criterion,
reference materials for material emission testing should have
6.3 The temporal emission characteristics should be known
the following characteristics.
for both constant and dynamic emission sources.
6.2.1 An ideal reference material has a similar chemical
6.3.1 A reference material with a constant emission rate of
matrix to a typical indoor material (for example, building
a VOC allows test chamber air to reach a steady-state concen-
product, furniture component, paint or cleaning product) and
tration. The time to reach near steady-state conditions is
emits VOCs in a similar manner. For the purpose of this
roughly three times the inverse of the air change rate. Thus,
standard, the test item is referred to as a “material” regardless
sampling should not occur until at least 3 h after the start of a
of its actual composition or description. In general, mass
test operating with a 1 1/h air change rate. An example of a
transfer rates of VOCs from materials are controlled by
constant emission source is a filled liquid inner-tube diffusion
evaporative mass transfer from the surface, desorption of
film emission source described inWei et al. (3). One advantage
adsorbed compounds, or diffusion within the material, or a
of a constant emission source is that chamber samples can be
combination thereof (Guide D5116).
collectedafteronlyafewhours,allowingresultstobeobtained
6.2.1.1 The dominating mass transfer process depends upon
quickly.
the age and type of material. For example,VOC emission rates
6.3.2 A reference material with a dynamic emission rate is
from so-called “dry” materials (carpets, floor tiles, and par-
representative of a dry material whose emissions change with
ticleboard) are initially affected by evaporation, but are ulti-
time as the source becomes depleted. To evaluate sampling at
mately controlled by internal diffusion processes. The VOC
multiple concentrations, chamber air samples should be col-
emission rates from so-called “wet” materials (for example,
lected at a minimum of two elapsed times (for example, 24 and
paintsandcleaningproducts)tendtobemoredynamicthandry
72 h) in order to generate an emission profile. An example of
materials with a high initial emission rate. The initial emission
a dynamic emission source is a polymer film loaded to
rate is primarily controlled by evaporation. Once most of the
equilibrium with a VOC as described in Cox et al. (4).A
solvent has evaporated from a material, the emission rate is
dynamic emission source also allows for the assessment of a
controlled by internal diffusion processes as described for dry
laboratory’s ability to measure analytes at different concentra-
materials.
tion levels.
6.2.1.2 The reference material’s VOC emission rate should
6.4 According to NIST (5), there are several ways to
respond to laboratory chamber conditions similar to the way
determine a reference material’s emission rate value.
typical test materials respond. Therefore, the emission rate
6.4.1 A “certified” reference value is determined using at
should be sensitive to environmental conditions that affect
least two independent measurement methods. The optimal
mass transfer processes (for example, temperature, relative
approach to determine a material’s reference value is with a
humidity, airflow rate and air velocity). Additionally, the
primary reference measurement procedure. For example, gra-
reference material’s response to these different environmental
vimetric determination is a primary method to measure the
factors should be well understood.
chemical content of a standard gas mixture.
6.2.2 For commercial distribution, the reference material
6.4.2 Non-certified, reference values may be determined by
should be produced in batch quantities (typically on the order
of hundreds of units) that are determined to be consistent (2). one or multiple laboratories using a single method. For
example, an ILS may be designed to determine an average
Stratified random sampling and a null-hypothesis statistical
approachisusedtoverifythe“homogeneity”ofthebatch(ISO reference value for a small subset of samples from a single
batch. The resulting ILS value and uncertainty are then
Guide 35). Additional requirements for reference material
producers are discussed in ISO/IEC 17034. assigned to the remaining samples from that batch.
D7911 − 19
6.5 Temporal emission profiles may be determined by midity may also affect VOC emissions from materials that are
modeling. For example, the emission rates of VOCs from a hygroscopicsincetheadsorbedwatermaychangethediffusion
relatively homogeneous polyvinyl chloride (PVC) flooring properties of the material and how the VOC desorbs from the
product have been well-characterized by fundamental mass surface. A commonly used relative humidity setpoint for
transfer models (4, 6, 7). Although not commonly used to chamber testing is 50 % with an associated precision of 65%
assign reference values, such models may provide additional and accuracy of 610 % (Guide D5116). Some existing refer-
information regarding the performance of a test chamber. Cox ence materials contain hydrophobic compounds and mimic
et al. (4) developed a mass transfer model to predict the sources that don’t contain significant amounts of water.
emission rate of toluene from a dynamic emission source.And, 7.2.3 Air change rate determines the rate of contaminant
Weietal. (3) developed a mass transfer model to predict the remova
...
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: D7911 − 14 D7911 − 19
Standard Guide for
Using Reference Material to Characterize Measurement Bias
Associated with Volatile Organic Compound Emission
Chamber Test
This standard is issued under the fixed designation D7911; 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 This guide provides procedures for using a reference material with a known emission rate of a volatile organic compound
(VOC) to estimate the bias associated with a VOC emission chamber test.
1.2 This guide may be used to assess measurements of VOC emissions conducted in a variety of environmental chambers, such
as small-scale chambers, full-scale chambers, emission cells, and micro-scale chambers.
1.3 This guide may be used to assess measurements of VOC emissions from a variety of sources including “dry” materials (for
example, carpet, floor tile and particleboard) and “wet” materials (for example, paint and cleaning products).
1.4 This guide can be used to support quality control efforts by emissions testing laboratories, third party accreditation of testing
laboratories participating in emissions testing programs, and quality control efforts by manufacturers of building and other
materials.
1.5 This guide may be used to support the determination of precision and bias of other commonly used VOC emission standards
including Guide D5116, Test Method D6007, ISO 16000-9, ANSI/BIFMA M7.1, and CDPH/EHLB/Standard Method V1.1.V1.2.
1.6 This guide also describes the attributes of a suitable emission reference material and the different methods available to
independently determine the reference material’s VOC emission rate.
1.7 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.8 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.
1.9 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:
D1356 Terminology Relating to Sampling and Analysis of Atmospheres
D5116 Guide for Small-Scale Environmental Chamber Determinations of Organic Emissions from Indoor Materials/Products
D5197 Test Method for Determination of Formaldehyde and Other Carbonyl Compounds in Air (Active Sampler Methodology)
D5466 Test Method for Determination of Volatile Organic Compounds in Atmospheres (Canister Sampling Methodology)
D6007 Test Method for Determining Formaldehyde Concentrations in Air from Wood Products Using a Small-Scale Chamber
D6196 Practice for Choosing Sorbents, Sampling Parameters and Thermal Desorption Analytical Conditions for Monitoring
Volatile Organic Chemicals in Air
D6299 Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measure-
ment System Performance
This guide is under the jurisdiction of ASTM Committee D22 on Air Quality and is the direct responsibility of Subcommittee D22.05 on Indoor Air.
Current edition approved Sept. 1, 2014Nov. 1, 2019. Published September 2014December 2019. Originally approved in 2014. Last previous edition approved in 2014 as
D7911 – 14. DOI: 10.1520/D7911-14.10.1520/D7911-19.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’sstandard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7911 − 19
D6330 Practice for Determination of Volatile Organic Compounds (Excluding Formaldehyde) Emissions from Wood-Based
Panels Using Small Environmental Chambers Under Defined Test Conditions
D6617 Practice for Laboratory Bias Detection Using Single Test Result from Standard Material
D6670 Practice for Full-Scale Chamber Determination of Volatile Organic Emissions from Indoor Materials/Products
D6803 Practice for Testing and Sampling of Volatile Organic Compounds (Including Carbonyl Compounds) Emitted from
Architectural Coatings Using Small-Scale Environmental Chambers
D7143 Practice for Emission Cells for the Determination of Volatile Organic Emissions from Indoor Materials/Products
D7339 Test Method for Determination of Volatile Organic Compounds Emitted from Carpet using a Specific Sorbent Tube and
Thermal Desorption / Gas Chromatography
D7440 Practice for Characterizing Uncertainty in Air Quality Measurements
D7706 Practice for Rapid Screening of VOC Emissions from Products Using Micro-Scale Chambers
D8141 Guide for Selecting Volatile Organic Compounds (VOCs) and Semi-Volatile Organic Compounds (SVOCs) Emission
Testing Methods to Determine Emission Parameters for Modeling of Indoor Environments
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
E741 Test Method for Determining Air Change in a Single Zone by Means of a Tracer Gas Dilution
E1333 Test Method for Determining Formaldehyde Concentrations in Air and Emission Rates from Wood Products Using a
Large Chamber
2.2 ISO Standards:
ISO 12219-3 Interior Air of Road Vehicles—Part 3: Screening Method for the Determination of the Emissions of Volatile
Organic Compounds from Vehicle Interior Parts and Materials—Micro-scaleMaterials—Micro-Scale Chamber Method
ISO 16000-3 Indoor Air—Part 3: Determination of Formaldehyde and Other Carbonyl Compounds in Indoor Air and Test
Change Air—Active Sampling Method
ISO 16000-6 Indoor Air—Part 6: Determination of Volatile Organic Compounds in Indoor and Test Chamber Air by Active
Sampling on Tenax TA Sorbent, Thermal Desorption and Gas Chromatography Using MS or MS-FID
ISO 16000-9 Indoor Air—Part 9: Determination of the Emission of Volatile Organic Compounds from Building Products and
Furnishing—Emission Test Chamber Method
ISO 16000-10 Indoor Air—Part 10: Determination of the Emission of Volatile Organic Compounds from Building Products and
Furnishing—Emission Test Cell Method
ISO 16000-11 Indoor Air—Part 11: Determination of the Emission of Volatile Organic Compounds from Building Products and
Furnishing—Sampling, Storage of Samples and Preparation of Test Specimens
ISO/IEC 17025 General Requirements for the Competence of Testing and Calibration Laboratories
ISO/IEC 1704317034 Conformity Assessment—General Requirements for Proficiency TestingGeneral Requirements for the
Competence of Reference Material Producers
ISO/IEC Guide 98 Guide to the Expression of Uncertainty in Measurement (GUM)
ISO Guide 30 Terms and Definitions Used in Connection with Reference Materials
ISO Guide 33 Uses of Certified Reference Materials
ISO Guide 34 General Requirements for the Competence of Reference Material Producers
ISO Guide 35 Reference Materials—General and Statistical Principles for Certification
2.3 Other Standards:
ANSI/BIFMA M7.1 2011 Test Method for Determining VOC Emissions from Office Furniture Systems, Components, and
Seating
CDPH/EHLB/Standard Method V1.1 2010 V1.2 Standard Method for the Testing and Evaluation of Volatile Organic Chemical
Emissions from Indoor Sources Using Environmental Chambers, Version 1.11.2, 2017
Method TO-17 1999 “Determination of Volatile Organic Compounds in Ambient Air Using Active Sampling Onto Sorbent
Tubes,” Compendium of Methods for the Determination of Toxic Organic Compounds in Ambient Air, Second Edition
(EPA/625/R-96/010b)(EPA/625/R-96/010b), 1999
3. Terminology
3.1 Definitions—For definitions and terms commonly used in Commitee D22 standards, refer to Terminology D1356. For
definitions and terms commonly used when testing materials and products for VOC emissions, refer to Guide D5116. For
definitions and terms commonly used to describe reference materials, refer to ISO Guide 30.
3.2 Definitions of Terms Specific to This Standard:
Available from International Organization for Standardization (ISO), 1, ch. de la Voie-Creuse, CP 56, CH-1211 Geneva 20, Switzerland, http://www.iso.org.
Available from Business + Institutional Furniture Manufacturers Association (BIFMA), 678 Front Ave. NW, Ste. 150, Grand Rapids, Michigan 49504-5368,
https://www.bifma.org.
Available from California Department of Public Health (CDPH), PO Box 997377, MS 0500, Sacramento, CA 95899-7377, http://www.cdph.ca.gov.
Available from United States Environmental Protection Agency (EPA), William Jefferson Clinton Bldg., 1200 Pennsylvania Ave., NW, Washington, DC 20004,20460,
http://www.epa.gov.
D7911 − 19
3.2.1 constant emission source, n—an emission source where the concentration of the chemical at the material surface does not
change with time.
3.2.2 diffusion-controlled source, n—an emission source that is limited by the movement of contaminants within the material
boundaries.
3.2.2.1 Discussion—
The rate of diffusion depends on the diffusivity of the VOC, the temperature, and the structure of the material.
3.2.3 dynamic emission source, n—an emission source where the concentration of the chemical at the material surface changes
with time.
3.2.3.1 Discussion—
A dynamic source can still generate emissions in a predictable and consistent manner.
3.2.4 evaporative-controlled source, n—an emission source that is limited by the ability of a contaminant to transfer from the
material surface through a boundary layer to the surrounding air.
3.2.4.1 Discussion—
The rate of mass transfer at the surface of an evaporative-controlled source is dependent on VOC volatility, air velocity, and
turbulence near the material surface.
3.2.5 primary reference measurement procedure, n—“Reference measurement procedure used to obtain a measurement result
without relation to a measurement standard for a quantity of the same kind” (1).
3.2.6 reference emission rate value, n—the independently-determined mass of VOC emitted per unit of time from a reference
emission source at specified conditions.
3.2.6.1 Discussion—
If the reference emission rate value is “certified,” the reference value and associated uncertainty will be available on the
accompanying certificate for the reference material.
3.2.7 reference material, n—a material that is “sufficiently homogeneous and stable with respect to one or more specified
properties, which has been established to be fit for its intended use in a measurement process” (ISO Guide 30).
3.2.7.1 Discussion—
A certified reference materials provides traceability assurance through ISO/IEC 17034. A reference material can also be produced
that is not directly traceable through ISO/IEC 17034 but rather is fit for purpose.
4. Summary of Guide
4.1 This guide describes procedures for using a reference material to evaluate the measurement bias associated with tests of
VOC emissions from materials and products. The reference materials described in this guide have independently-determined
emission rates that can be measured in an environmental test chamber according to commonly used VOC emission and analytical
standards and by following the instructions in the reference material’s accompanying documentation. Example instructions
associated with published uses of reference materials are provided in Appendix X1.
4.2 In general, reference materials used in laboratory emission tests can provide traceability for test results determined at
different times and in different laboratories using the same environmental conditions (for example, chamber airflow rate,
temperature, and relative humidity). Chamber air samples are collected at specific times and analyzed according to referenced
standards. If no analytical standard is prescribed, samples are analyzed according to a laboratory’s standard operating procedures.
Chamber concentrations and source emission rates are calculated. The measured emission rates, at defined time periods, are then
compared with the known value for the reference material to estimate the measurement bias of the value obtained in the emission
chamber. If applicable, the value of the measurement bias can be compared with acceptance criteria for the emission testing
program of interest to the user.
The boldface numbers in parentheses refer to the list of references at the end of this standard.
D7911 − 19
4.3 This guide also describes the qualities of an emission reference material, the different methods available to independently
determine the VOC emission rate of a reference material, and the chamber operating parameters that potentially influence a
reference material’s emission results.
5. Significance and Use
5.1 Chamber testing is a globally-accepted method for measuring the emissions of VOCs from building materials and products.
Chamber emission test data have a variety of uses including identification and labeling of products as low-VOC emitting for
improved indoor air quality, manufacturing quality control, and development of new and improved products for reduced VOC
emissions.
5.2 Currently, an inter-laboratory study (ILS) is the most frequently used method for assessing the bias of a laboratory’s VOC
emission test results. An ILS typically relies on a VOC source with an uncharacterized emission rate. Consequently, a large number
of participants (Practice E691 recommends 30, with a minimum requirement of six) are needed to produce the data required to
calculate a laboratory’s performance relative to the central tendency and distribution of the results for all participants. Due to the
participant size requirement and other logistical issues, an ILS involves significant planning and coordination to achieve useful
results.
5.3 Inter-laboratory studies have often shown significant variations in measured VOC emission rates among participating
laboratories for a given source. Variability in the emission rate from the source often is suspected to be a contributing factor, but
it is difficult to be certain of the cause. Thus, better characterized sources are needed for evaluating the ability of laboratories to
generate VOC emission test results with acceptable bias as discussed in 8.6.
5.4 Proficiency tests (PT) for VOC emission testing typically focus on a laboratory’s analytical capabilities. For example, an
analytical PT relies on a certified standard prepared by an accredited vendor as a reference. A laboratory analyzes the PT sample
without knowledge of its concentration value. Acceptance of the results is judged by the deviation from the known value. Use of
reference materials can expand analytical PT schemes to also include the impacts of test sample handling, test specimen
preparation, chamber operation, and chamber air sampling.
5.5 Laboratories accredited under ISO/IEC 17025 are required to derive uncertainty estimates for their test results. Typically,
this is done by developing an uncertainty budget and estimating an expanded uncertainty (ISO/IEC Guide 98, Practice D7440).
Reference materials not accredited under ISO/IEC 17025 should still be delivered with documented uncertainty budgets. An
uncertainty budget for a VOC emission test combines relevant sources of measurement uncertainty for all steps in the testing
process from test specimen preparation through air sample analysis. A more efficient approach to determining the overall bias and
precision for a VOC emission test is with repeated testing of a reference material (see ISO/IEC Guide 98, ISO Guide 33). This
guide addresses the estimation of bias through comparison of the measured value to the reference material value. The precision
is determined through repeated testing of multiple reference materials, ideally from the same production batch (see Practices
D6299 and E691).
5.6 Other uses of an emissions reference material include verifying quality control emission measurements of manufactured
product batches and providing traceability for third party certification.
6. Reference Material Attributes
6.1 According to ISO Guide 30, a reference material with an “assigned quantity value” can be used to improve the accuracy
of test methods and analysis, to evaluate laboratory equipment performance characteristics, and to establish metrological
traceability. For material VOC emission testing, the assigned quantity value for the reference material is its emission rate of a
specific VOC (see Guide D5116 for a discussion of material emission rates).
6.2 To meet ISO Guide 30 criteria, a reference material for material emission testing should consist of a known amount of VOC
that transfers to the surrounding air at a predictable rate. In addition to meeting this “homogeneous and stable” criterion, reference
materials for material emission testing should have the following characteristics.
6.2.1 An ideal reference material has a similar chemical matrix to a typical indoor material (for example, building product,
furniture component, paint or cleaning product) and emits VOCs in a similar manner. For the purpose of this standard, the test item
is referred to as a “material” regardless of its actual composition or description. In general, mass transfer rates of VOCs from
materials are controlled by evaporative mass transfer from the surface, desorption of adsorbed compounds, or diffusion within the
material, or a combination thereof (Guide D5116).
6.2.1.1 The dominating mass transfer process depends upon the age and type of material. For example, VOC emission rates
from so-called “dry” materials (carpets, floor tiles, and particleboard) are initially affected by evaporation, but are ultimately
controlled by internal diffusion processes. The VOC emission rates from so-called “wet” materials (for example, paints and
cleaning products) tend to be more dynamic than dry materials with a high initial emission rate. The initial emission rate is
primarily controlled by evaporation. Once most of the solvent has evaporated from a material, the emission rate is controlled by
internal diffusion processes as described for dry materials.
6.2.1.2 The reference material’s VOC emission rate should respond to laboratory chamber conditions similar to the way typical
test materials respond. Therefore, the emission rate should be sensitive to environmental conditions that affect mass transfer
D7911 − 19
processes (for example, temperature, relative humidity, airflow rate and air velocity). Additionally, the reference material’s
response to these different environmental factors should be well understood.
6.2.2 For commercial distribution, the reference material should be produced in batch quantities (typically on the order of
hundreds of units) that are determined to be consistent (2). Stratified random sampling and a null-hypothesis statistical approach
is used to verify the “homogeneity” of the batch (ISO Guide 35). Additional requirements for reference material producers are
discussed in ISO Guide 34.ISO/IEC 17034.
6.2.3 The reference material should emit VOCs that are measurable by the same sampling and analytical techniques used in
VOC emission testing (for example, Test Method D5197, Test Method D7339, and ISO 16000-9). Although canisters can be used
to sample VOCs, they are not typically employed for chamber emission testing. Chemical emissions should result in chamber
concentrations appropriate to the level for which the measurement process is intended. Thus, reference materials of different sizes
or numbers may be required for different types and sizes of test chambers.
6.2.4 The reference material should be packaged and shipped to prevent physical damage and minimize loss or degradation of
the material. Short-term stability tests are described in ISO Guide 35.
6.2.5 The reference material shelf life should be known. ISO Guide 35 provides further information regarding long-term
stability tests. Ideally, the shelf life should be several months or longer.
6.3 The temporal emission characteristics should be known for both constant and dynamic emission sources.
6.3.1 A reference material with a constant emission rate of a VOC allows test chamber air to reach a steady-state concentration.
The time to reach near steady-state conditions is roughly three times the inverse of the air change rate. Thus, sampling should not
-1
occur until at least 3 h after the start of a test operating with a 1 h1/h air change rate. An example of a constant emission source
is a filled liquid inner-tube diffusion film emission source described in Wei et al. (3). One advantage of a constant emission source
is that chamber samples can be collected after only a few hours, allowing results to be obtained quickly.
6.3.2 A reference material with a dynamic emission rate is representative of a dry material whose emissions change with time
as the source becomes depleted. To evaluate sampling at multiple concentrations, chamber air samples should be collected at a
minimum of two elapsed times (for example, 24 and 72 h) in order to generate an emission profile. An example of a dynamic
emission source is a polymer film loaded to equilibrium with a VOC as described in Cox et al. (4). A dynamic emission source
also allows for the assessment of a laboratory’s ability to measure analytes at different concentration levels.
6.4 According to NIST (5), there are several ways to determine a reference material’s emission rate value.
6.4.1 A “certified” reference value is determined using at least two independent measurement methods. The optimal approach
to determine a material’s reference value is with a primary reference measurement procedure. For example, gravimetric
determination is a primary method to measure the chemical content of a standard gas mixture.
6.4.2 Non-certified, reference values may be determined by one or multiple laboratories using a single method. For example,
an ILS may be designed to determine an average reference value for a small subset of samples from a single batch. The resulting
ILS value and uncertainty are then assigned to the remaining samples from that batch.
6.5 Temporal emission profiles may be determined by modeling. For example, the emission rates of VOCs from a relatively
homogeneous polyvinyl chloride (PVC) flooring product have been well-characterized by fundamental mass transfer models (4,
6 and 76, 7). Although not commonly used to assign reference values, such models may provide additional information regarding
the performance of a test chamber. Cox et al. (4) developed a mass transfer model to predict the emission rate of toluene from a
dynamic emission source. And, Wei et al. (3) developed a mass transfer model to predict the emission rate of toluene from a
constant emission source.
6.6 When a new batch of reference materials is introduced, the associated reference emission rate value and its uncertainty
should be re-established through accepted methods. An expanded uncertainty for a reference emission rate value may be
determined using procedures in ISO/IEC Guide 98.
7. Apparatus and Operating Parameters
7.1 The state of the art for measuring VOC emissions from indoor materials is environmental chamber testing. An
environmental chamber test exposes a material or representative portion of a material of known dimension (typically the material
area, but results also may be normalized to material length or mass as appropriate) to a specified temperature, relative humidity
and airflow rate. At these conditions, VOCs diffuse or evaporate from the material surface to chamber air. At a specified elapsed
time, the resulting concentration of a VOC in chamber air is measured to determine the material’s VOC emission rate or
area-specific emission rate, termed emission factor rate (Guide D5116). Reference materials are designed to mimic material sources
that are commonly evaluated for VOC emissions by chamber testing.
7.2 The emissions of VOCs during a test primarily depend upon the physicochemical properties and application of the material
sample and the environmental exposure conditions. Chamber operating parameters have the potential to affect VOC emission rates.
Thus, use of a reference material whose emission rate is also impacted by these parameters provides a check of chamber
performance. Chamber parameters are addressed in the documentation accompanying a reference material. Detailed descriptions
of the impacts of chamber parameters on VOC emission rates from materials can be found elsewhere (Guide D5116 and Practice
D6670). A brief summary is provided here.
D7911 − 19
7.2.1 Temperature affects a VOC’s volatility and diffusivity properties. As such, higher material and ambient air temperatures
will result in faster emission rates. A commonly used temperature setpoint for chamber testing is 23°C with an associated precision
and accuracy of 60.5°C (Guide D5116). A relatively small deviation in chamber temperature can significantly affect a material’s
emission rate, and some reference materials can behave similarly. For example, a chamber study of environmental factors using
a diffusion bottle source (3) estimated that the emission rate of toluene at 23.5°C was approximately 10 % higher than the emission
rate for the same source at 22.5°C.
7.2.2 Relative humidity can impact the emission rates of water-soluble compounds such as formaldehyde. Relative humidity
may also affect VOC emissions from materials that are hygroscopic since the adsorbed water may change the diffusion properties
of the material and how the VOC desorbs from the surface. A commonly used relative humidity setpoint for chamber testing is
50 % with an associated precision of 65 % and accuracy of 610 % (Guide D5116). Some existing reference materials contain
hydrophobic compounds and mimic sources that don’t contain significant amounts of water.
7.2.3 Air change rate determines the rate of contaminant removal from the chamber system. When describing the amount of
chamber air dilution, the air change rate is often normalized by the material surface area (area specific airflow rate). By the process
of dilution with clean air, VOC concentrations in the chamber air will be lower for higher air change rates. In
...
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