ASTM D5116-17

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: D5116 − 17
Standard Guide for
Small-Scale Environmental Chamber Determinations of
Organic Emissions from Indoor Materials/Products
This standard is issued under the fixed designation D5116; 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 provide only a portion of the emission profile of interest. For
example, the rate of emissions from the application of high
1.1 Thisguideprovidesdirectiononthemeasurementofthe
solvent materials (for example, paints and waxes) by means of
emissions of volatile organic compounds (VOCs) from indoor
brushing, spraying, rolling, etc. are generally higher than the
materials and products using small-scale environmental test
rate during the drying process. Small chamber testing cannot
chambers.
be used to evaluate the application phase of the coating
1.2 This guide pertains to chambers that fully enclose a
process. Large (or full-scale) chambers may be more appropri-
material specimen to be tested and does not address other
ate for many of these applications. For guidance on full-scale
emission chamber designs such as emission cells (see instead
chamber testing of emissions from indoor materials refer to
Practice D7143).
Practice D6670.
1.3 As anASTM standard, this guide describes options, but
1.6 This guide does not provide specific directions for the
does not recommend specific courses of action. This guide is
selection of sampling media or for the analysis of VOCs. This
not a standard test method and must not be construed as such.
information is provided in Practice D6196.
1.4 The use of small environmental test chambers to char-
acterize the emissions of VOCs from indoor materials and 1.7 This guide does not provide specific directions for
products is still evolving. Modifications and variations in determining emissions of formaldehyde from composite wood
equipment, testing procedures, and data analysis are made as
products,sincechambertestingmethodsforsuchemissionsare
the work in the area progresses. For several indoor materials, welldevelopedandwidelyused.Formoreinformationreferto
more detailedASTM standards for emissions testing have now
Test Methods E1333 and D6007. It is possible, however, that
been developed. Where more detailed ASTM standard prac-
the guide can be used to support alternative testing methods.
tices or methods exist, they supersede this guide and should be
1.8 This guide is not applicable to the determination of
used in its place. Until the interested parties agree upon
emissions of semi-volatile organic compounds (SVOCs) from
standard testing protocols, differences in approach will occur.
materials/products largely due to adsorption of these com-
This guide will continue to provide assistance by describing
pounds on materials commonly used for construction of
equipment and techniques suitable for determining organic
chambers suitable forVOC emissions testing.Alternate proce-
emissions from indoor materials. Specific examples are pro-
duresarerequiredforSVOCs.Forexample,itmaybepossible
vided to illustrate existing approaches; these examples are not
to screen materials for emissions of SVOCs using micro-scale
intended to inhibit alternative approaches or techniques that
chambers operated at temperatures above normal indoor con-
will produce equivalent or superior results.
ditions (see Practice D7706).
1.5 Small chambers have obvious limitations. Normally,
only samples of larger materials (for example, carpet) are 1.9 This guide is applicable to the determination of emis-
tested. Small chambers are not applicable for testing complete sions from products and materials that may be used indoors.
assemblages (for example, furniture). Small chambers are also The effects of the emissions (for example, toxicity) are not
inappropriate for testing combustion devices (for example,
addressedandarebeyondthescopeoftheguide.GuideD6485
kerosene heaters) or activities (for example, use of aerosol provides an example of the assessment of acute and irritant
sprayproducts).Forsomeproducts,smallchambertestingmay
effectsofVOCemissionsforagivenmaterial.Specificationof
“target” organic species of concern is similarly beyond the
scope of this guide. As guideline levels for specific indoor
This guide is under the jurisdiction of ASTM Committee D22 on Air Quality
contaminants develop, so too will emission test protocols to
and is the direct responsibility of Subcommittee D22.05 on Indoor Air.
provide relevant information. Emissions databases and mate-
Current edition approved Nov. 1, 2017. Published November 2017. Originally
rial labeling schemes will also be expected to adjust to reflect
approved in 1990. Last previous edition approved in 2010 as D5116–10. DOI:
10.1520/D5116-17. the current state of knowledge.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D5116 − 17
1.10 Specifics related to the acquisition, handling, Collected by the Activated Charcoal Tube Adsorption
conditioning, preparation, and testing of individual test speci- Method
mens may vary depending on particular study objectives. D6007TestMethodforDeterminingFormaldehydeConcen-
Guidelines for these aspects of emissions testing are provided trations in Air from Wood Products Using a Small-Scale
here, specific direction is not mandated. The purpose of this Chamber
guide is to increase the awareness of the user to available D6177Practice for Determining Emission Profiles of Vola-
techniques for evaluating organic emissions from indoor tile Organic Chemicals Emitted from Bedding Sets
materials/products by means of small chamber testing, to D6196Practice for Choosing Sorbents, Sampling Param-
identify the essential aspects of emissions testing that must be eters and Thermal Desorption Analytical Conditions for
controlled and documented, and therefore to provide Monitoring Volatile Organic Chemicals in Air
information, which may lead to further evaluation and stan- D6330Practice for Determination of Volatile Organic Com-
dardization. pounds(ExcludingFormaldehyde)EmissionsfromWood-
Based Panels Using Small Environmental Chambers Un-
1.11 Within the context of the limitations discussed in this
der Defined Test Conditions
section, the purpose of this guide is to describe the methods
D6485Guide for Risk Characterization ofAcute and Irritant
and procedures for determining organic emission rates from
Effects of Short-Term Exposure to Volatile Organic
indoor materials/products using small environmental test
Chemicals Emitted from Bedding Sets
chambers.Thetechniquesdescribedareusefulforbothroutine
D6670Practice for Full-Scale Chamber Determination of
product testing by manufacturers and testing laboratories and
Volatile Organic Emissions from Indoor Materials/
for more rigorous evaluation by indoor air quality (IAQ)
Products
researchers.AppendixX1providesreferencestostandardsthat
D6803PracticeforTestingandSamplingofVolatileOrganic
are widely employed to measure emissions of VOCs from
Compounds (Including Carbonyl Compounds) Emitted
materials and products used in the interiors of buildings. Some
from Paint Using Small Environmental Chambers
of these standards directly reference this guide.
D7143Practice for Emission Cells for the Determination of
1.12 The values stated in SI units are to be regarded as
Volatile Organic Emissions from Indoor Materials/
standard. No other units of measurement are included in this
Products
standard.
D7339Test Method for Determination of Volatile Organic
1.13 This standard does not purport to address all of the CompoundsEmittedfromCarpetusingaSpecificSorbent
safety concerns, if any, associated with its use. It is the
Tube and Thermal Desorption / Gas Chromatography
responsibility of the user of this standard to establish appro- D7706Practice for Rapid Screening of VOC Emissions
priate safety, health, and environmental practices and deter-
from Products Using Micro-Scale Chambers
mine the applicability of regulatory limitations prior to use. D7911Guide for Using Reference Material to Characterize
1.14 This international standard was developed in accor-
MeasurementBiasAssociatedwithVolatileOrganicCom-
dance with internationally recognized principles on standard- pound Emission Chamber Test
ization established in the Decision on Principles for the E355PracticeforGasChromatographyTermsandRelation-
Development of International Standards, Guides and Recom-
ships
mendations issued by the World Trade Organization Technical E1333TestMethodforDeterminingFormaldehydeConcen-
Barriers to Trade (TBT) Committee.
trations in Air and Emission Rates from Wood Products
Using a Large Chamber
2. Referenced Documents
3. Terminology
2.1 ASTM Standards:
D1193Specification for Reagent Water
3.1 Definitions—For definitions and terms used in this
D1356Terminology Relating to Sampling and Analysis of
guide, refer to Terminology D1356. For an explanation of
Atmospheres
units,symbols,andconversionfactors,refertoPracticeD1914.
D1914PracticeforConversionUnitsandFactorsRelatingto
3.2 Definitions of Terms Specific to This Standard:
Sampling and Analysis of Atmospheres
3.2.1 air change rate, n—theflowrateofclean,conditioned
D3195Practice for Rotameter Calibration
air into the chamber divided by the net chamber volume;
D3609Practice for Calibration Techniques Using Perme-
usually expressed in units of 1/h.
ation Tubes
3.2.2 chamber loading ratio, n—the total amount of test
D3686Practice for Sampling Atmospheres to Collect Or-
specimen exposed in the chamber divided by the net or
ganic Compound Vapors (Activated Charcoal Tube Ad-
corrected internal air volume of the chamber.
sorption Method)
3.2.2.1 Discussion—Net internal air volume of the chamber
D3687Practice for Analysis of Organic Compound Vapors
is calculated as the internal volume of the chamber enclosure
minus the volume internally displaced by test specimen,
holder, inlet/exhaust manifolds, etc.The chamber loading ratio
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
is typically expressed as the ratio of the exposed specimen
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
surfacearea, A,tonetchambervolume(1/m)butdependingon
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. the nature of the test specimen, can also be expressed as 1/m ,
D5116 − 17
m/m ,andunitlessforunit,line,andvolumeemissionsources, Thus, the emission rate is proportional to the difference in
respectively. Chamber loading also can be expressed in terms vaporpressurebetweenthesurfaceandtheoverlyingair.Since
of area-specific airflow rate calculated as the ratio of the the vapor pressure is directly related to the concentration, the
chamber’s volumetric inlet airflow rate, Q, divided by the emission rate is proportional to the difference in concentration
specimen surface area, A, that is Q/A (m/h). between the surface and the overlying air. The mass transfer
coefficient is a function of the diffusion coefficient (in air) for
3.2.3 test chamber, n—an enclosed test volume constructed
thespecificcompoundofinterestandthelevelofturbulencein
of chemically inert materials with a clean air supply and
the bulk flow.
exhaust.
4.2.2 The desorption rate of compounds adsorbed on mate-
3.2.3.1 Discussion—These chambers are designed to permit
rials can be determined by the retention time (or average
testing of emissions from samples of building materials and
residence time) of an adsorbed molecule:
consumer products. The internal volume of small-scale cham-
2Q/RT
bers usually ranges from a few litres to a few cubic metres.
τ 5τ e (2)
o
Micro-scale chambers are typically less than one litre in
where:
volumeandfurtherdifferfromsmall-scalechambersinthatthe
τ = retention time, s,
entire airflow rate at the chamber exhaust is sampled (see
−12 −15
τ = constant with a typical value from 10 to 10 s, and
Practice D7706). o
Q = molar enthalpy change for adsorption (or adsorption
energy), J/mol.
4. Significance and Use
The larger the retention time, the slower the rate of desorp-
4.1 Objectives—The use of small chambers to evaluate
tion.
VOC emissions from indoor materials has several objectives:
4.2.3 The diffusion mass transfer within the material is a
4.1.1 DeveloptechniquesforscreeningofproductsforVOC
function of the diffusion coefficient (or diffusivity) of the
emissions;
specific compound. The diffusion coefficient of a given com-
4.1.2 Determine the effect of environmental variables (that
pound within a given material is a function of the compound’s
is, temperature, humidity, air speed, and air change rate) on
physical and chemical properties (for example, molecular
emission rates;
weight,size,andpolarity),temperature,andthestructureofthe
4.1.3 Rank various products and product types with respect
materialwithinwhichthediffusionisoccurring.Thediffusivity
to their emissions profiles (for example, emission factors,
of an individual compound in a mixture is also affected by the
specific organic compounds emitted);
composition of the mixture.
4.1.4 Provide compound-specific data on various organic
sourcestoguidefieldstudiesandassistinevaluatingindoorair 4.2.4 Variables Affecting Mass Transfer—While a detailed
quality in buildings; discussion of mass transfer theory is beyond the scope of this
4.1.5 Provide emissions data for the development and veri- guide, it is necessary to examine the critical variables affecting
fication of models used to predict indoor concentrations of mass transfer within the context of small chamber testing:
organic compounds; and
4.2.4.1 Temperature affects the vapor pressure, desorption
4.1.6 Develop data useful to stakeholders and other inter-
rate, and the diffusion coefficients of the organic compounds.
ested parties for assessing product emissions and developing
Thus, temperature impacts both the mass transfer from the
control options or improved products.
surface (whether by evaporation or desorption) and the diffu-
sionmasstransferwithinthematerial.Increasesintemperature
4.2 Mass Transfer Considerations—Small chamber evalua-
cause increases in the emissions due to all three mass transfer
tion of emissions from indoor materials requires consideration
processes.
of the relevant mass transfer processes. Three fundamental
4.2.4.2 The air change rate indicates the amount of dilution
processes control the rate of emissions of organic vapors from
andflushingthatoccursinindoorenvironments.Thehigherthe
indoormaterials;evaporativemasstransferfromthesurfaceof
air change rate the greater the dilution, and assuming the
the material to the overlying air, desorption of adsorbed
outdoorairiscleaner,thelowertheindoorconcentration.Ifthe
compounds, and diffusion within the material.
concentration at the surface is unchanged, a lower concentra-
4.2.1 The evaporative mass transfer of a given VOC from
tion in the air increases the evaporative mass transfer by
thesurfaceofthematerialtotheoverlyingaircanbeexpressed
increasing the difference in concentration between the surface
as:
and the overlying air.
ER 5Ak ~VP 2 VP !MW⁄RT (1)
m s a
4.2.4.3 Air Speed—Surface air speed is a critical parameter
where:
for evaporative-controlled sources as the mass transfer coeffi-
ER = emission rate, mg/h, cient (k ) is affected by the air speed and turbulence at the
m
A = source area, m , air-side of the boundary layer. Generally, the higher the air
k = mass transfer coefficient, m/h,
speed and turbulence, the greater the mass transfer coefficient.
m
VP = vapor pressure at the surface of the material, Pa,
s In a practical sense for most VOCs, above a certain air speed
VP = vapor pressure in the air above the surface, Pa,
a
and turbulence, the resistance to mass transfer through the
MW = molecular weight, mg/mol,
boundary layer is minimized (that is, the mass transfer coeffi-
R = gas constant, 8.314 J/mol-K or Pa m /mol-K, and
cient reaches its maximum value). In chamber testing, some
T = temperature, K.
investigators prefer to use air speeds high enough to minimize
D5116 − 17
the mass transfer resistance at the surface. For example, air
speeds of 0.3 to 0.5 m/s have been used in evaluating
formaldehyde emissions from wood products. Such air speeds
are higher than those observed in normal residential environ-
ments by Matthews et al., where in six houses they measured
airspeedsusinganomni-directionalheatedsphereanemometer
with a mean of 0.07 m/s and a median of 0.05 m/s.Thus, other
investigatorsprefertokeeptheairspeedsintherangenormally
found indoors. In either case, an understanding of the effect of
air speed on the emission rate is needed in interpreting small
chamber emissions data.
4.3 Other Factors Affecting Emissions—Most organic com-
pounds emitted from indoor materials and products are non-
reactive, and chambers are designed to reduce or eliminate
FIG. 1 Small Chamber Test Facility Schematic
reactions and adsorption on the chamber surfaces (see 5.3.1).
In some cases, however, surface adsorption can occur. Some
relatively high molecular weight, high boiling compounds can
react (that is, with ozone) after being deposited on the surface.
contamination of test specimens and to stabilize specimens in
Insuchcases,thesimultaneousdegradationandbuilduponand
terms of both temperature and moisture content.
the ultimate re-emission from the chamber walls can affect the
5.3 Design and Operation of Small-Scale Chambers—
final chamber concentration and the time history of the
Small-scale test chambers are designed to permit the testing of
emission profile. Unless such factors are properly accounted
samples of various types of building materials and consumer
for, incorrect values for the emission rates will be calculated
products. They can range in size from a few litres to a few
(see 9.4). The magnitude of chamber adsorption and reaction
cubicmetres.Otherchambers,suchasfull-scalechambers(see
effects can be evaluated by way of mass balance calculations
Practice D6670), permit the testing of complete assemblages
(see 9.5).
(for example, furniture); they may also be used to evaluate
4.4 Use of the Results—Itisemphasizedthatsmallchamber
activities (for example, spray painting). For the purpose of this
evaluations are used to determine source emission rates.These
guide, small chambers are assumed to be used to test samples
rates are then used in IAQ models to predict indoor concen-
of larger materials and products, as opposed to full scale
tration of the compounds emitted from the tested material.
materialsorprocesses.Micro-scalechambersaretypicallyless
ConsultationwithIAQmodelersmayberequiredtoensurethat
than one litre in volume and differ from small-scale chambers
thesmallchambertestregimeisconsistentwiththeIAQmodel
inthattheentireairflowrateatthechamberexhaustissampled
assumptions. The concentrations observed in the chambers
(see Practice D7706). Micro-scale chambers are typically used
themselves should not be used as a substitute for concentra-
to screen homogeneous materials that can be represented by
tions expected in full-scale indoor environments.
very small specimens for emissions of VOCs.
5.3.1 Construction—Small-scale test chambers should have
5. Facilities and Equipment
non-adsorbent, chemically inert, smooth interior surfaces so as
nottoadsorborreactwithcompoundsofinterest.Caremustbe
5.1 A facility designed and operated to determine organic
taken in their construction to avoid the use of caulks and
emission rates from building materials and consumer products
adhesives that emit or adsorb volatile organic compounds.
found indoors should contain the following: test specimen
Electropolished stainless steel and glass are common interior
conditioning environment, test chambers, clean air generation
surfaces.The chamber must have an access door with air tight,
system,monitoringandcontrolsystems,samplecollectionand
non-adsorbent seals. The chambers must be fitted with inlet
analysis equipment, and standards generation and calibration
and exhaust ports for air flow. Ports for temperature and
systems.Fig.1isaschematicshowinganexamplesystemwith
humidity probes may also be required. Ports for sample
two test chambers.
collection are needed only if the sampling is not conducted in
5.2 Specimen Conditioning Environment—Acclimatization
the exhaust air (see 6.2).
of test specimens to stable environmental conditions of
5.3.1.1 Measure or calculate the internal volume of the
temperature, relative humidity, and clean air change rate prior
chamber enclosure. Additionally, measure or calculate the
to emissions testing is commonly required by standardized test
volumes of the internal components of the chamber such as
protocols. Care must be taken to ensure that the conditioning
specimen holders, racks or supports, temperature/humidity
environmentmeetsallspecificationsintendedtopreventcross-
probes, inlet/exhaust manifolds, etc.
5.3.1.2 The sizes, surface areas, and volumes of internal
components of the chamber should be minimized to the extent
Matthews,T. J.,Thompson, C.V.,Wilson, D. L., Hawthorne,A. R., and Mage,
practical. Also as practical, internal components should have
D. T., “Air Velocities inside Domestic Environments: An Important Parameter for
similar surface characteristics as the interior surface of the
Passive Monitoring,” Indoor Air ‘87—Proceedings of the 4th International Confer-
chamber to minimize losses of compounds of interest due to
ence on Indoor Air Quality and Climate, Institute for Water, Soil andAir Hygiene,
West Berlin, Vol 1, August 1987, pp. 154–158. adsorption or reactions.
D5116 − 17
5.3.2 Mixing—The chamber and its air moving components the additional advantage during sample collection of ensuring
should be designed to ensure good mixing of the incoming air that pumped flow through the sample tube is continuous and
with the chamber air. While contaminant concentration gradi- that seals for the tube are intact (by observing a maintained
ents are expected to exist in the chamber, particularly near the slight dip in the chamber pressure). Minimize any void
emissions source, the mixing issue concerns only the unifor- volumes associated with the pressure sensor and use inert
mityofthedistributionoftheairenteringthechamber.Mixing materials for all exposed surfaces.
fans and multi-port inlet and exhaust manifolds are two
5.3.6 Lights—Small chambers are normally operated with-
techniquesthathavebeenusedsuccessfullytoensureadequate
out lights. If the effect of lighting on emissions is to be
mixing of air in the chamber. Refer to 5.4 for procedures for
determined, appropriate interior illumination should be pro-
assessing the mixing characteristics of the chamber.
vided. If lighting is used, care should be taken to avoid either
5.3.3 Surface Air Speed—As discussed in 4.2.4.3, the air heating of the chamber interior or radiant heating of the test
speed near the surface of the material being tested can affect specimen. The possible impact of lighting fixtures on chamber
the mass transfer coefficient. Thus, sources with evaporative VOC background and sink characteristics must be carefully
(gas-phase limited) emissions should be tested under typical considered.
indoorvelocities(forexample,5-10cm/s).Chambersdesigned
5.3.7 Clean Air Generation System—Clean air must be
specifically to provide stable air speeds over the specimen
generated and delivered to the chambers. A typical clean air
surface independent of air change rate may be used.
systemmightuseanoillesscompressordrawinginambientair
Alternatively, a small fan can be used to achieve such air
followed by removal of moisture (for example, using a
speeds. Some investigators have had success with DC voltage
membrane dryer) and trace organics (for example, by catalytic
computerfans.Thefancanbesuspendedabovethesourcewith
oxidation units). Other options include gas cylinders or char-
wire. A diffuser should be used to eliminate the calm spot
coal filtered outside or laboratory air. If granular media (for
downstreamofthefanhub.Iftheairstreamisdirectedupward,
example, charcoal) are used for control of organics, a filter
the air will circulate and flow across the source. Air speed
should be used downstream to remove particulate matter.
measurements can be made with omni-directional heated
Calculations should be conducted regarding the required air-
sphere anemometers. These devices typically have lower
flowratebeforeadecisionisreachedonthesupplysystem.For
detection limits of 3 to 5 cm/s.Air speeds should be measured
most sources to be tested, extremely clean air is needed. Inlet
close to the source; for example, a height of 1 cm above the
concentrations should not exceed 2 µg/m for any single
surface of a horizontal source. An average air speed can be
compound or 10 µg/m for the sum of all VOCs. The purity of
based on measurements at several locations. For example, a
theairshouldbeverifiedbyroutineanalysisofbackgroundair
source area could be divided into grid sectors (for example, 2
samples from a clean chamber.
by3,3by4,andsoforth)andmeasurementsmadeatthesector
5.3.8 Humidity Control—Humidity control of the chamber
mid-points. Without a fan, air speeds near the source surface
air is achieved by adding deionized water (see Specification
can be below the detection limit of the anemometer. If the
D1193) or HPLC grade distilled water to the air stream.
emissionsfromthesourcebeingtestedarelimitedbydiffusion
Injectionbysyringepumpsfollowedbyheatingtovaporizethe
within the source, a fan is not necessary provided the chamber
water can achieve desired humidity levels, although syringe
hasbeenshowntobewellmixed.Wheneverafanisemployed,
pumps are prone to breakdown during prolonged, continuous
its potential contribution to the chamber temperature, VOC
use. Other types of pumps (for example, HPLC) might also
background, and its sink characteristics must be carefully
providesufficientaccuracy.Humidificationcanalsobeaccom-
considered. If evaporative sources are tested using either
plished by bubbling a portion of the airstream through deion-
material supports/substrates (for example, wallboard used as
ized water at a controlled temperature (for example, in a water
substrate for investigation of emissions from paint) or speci-
bath). The saturated air is then mixed with dry air to achieve
men holders, then the surface air speed above the specimen
the desired humidity. Steam humidification can also be used.
should be characterized with the substrate or holder in place.
Coiled lines inside the constant temperature environment can
5.3.4 Temperature Control—Temperature control can be be used for inlet temperature equilibration before delivery to
achieved by placing the test chambers in incubator cabinets or the test chambers.
other controllable constant temperature environments. The
5.3.9 Environmental Measurement and Control Systems—
temperature of the inlet air can be controlled by using
Measurement and control are required for airflow rate, tem-
conditioning coils.
perature (see 5.3.4), humidity (see 5.3.8), and differential
5.3.5 Pressure Control—Operate the chamber in such a pressure (see 5.3.5). Airflow rate can be automatically moni-
mannerthataslightpositivepressureismaintainedatalltimes tored and controlled by electronic mass flow controllers, or
relative to the surrounding environment. This is particularly manual flow control (for example, needle valve, orifice plate)
important while collecting air samples from the chamber and measurement (for example, bubble meter, rotameter) (see
exhaust air. Transient pressure fluctuations may result from Practice D3195) can be used.Temperature control is discussed
normal operation of the lab environment (door and HVAC in 5.3.4. Temperature measurement can be accomplished
system operation, etc.).Apositive pressurization of the cham- automatically by means of thermocouples or thermistors;
ber of approximately 10 Pa should provide sufficient margin to manual dial or stem thermometers can also be used. Control of
protect the chamber from becoming negative relative to its humidity depends on the humidification system employed. If
surroundings. Continuous monitoring of chamber pressure has liquid injection is used, water flow is controlled by the pump
D5116 − 17
setting. Control of humidity (see 5.3.8) by saturated air inlet air tracer gas concentration is <1 % of the initial chamber
requires temperature control of the water and flow control of concentration, C may be calculated with Eq 6 rather than Eq
m
the saturated air stream. Humidity measurement can be done 5.
by several types of sensors, including dew point detectors and n
C t 2 C t t 2 t
@ ~ ! ~ ! ~ !#
thin-film capacitors. Temperature and humidity sensors should ? ?
( i m i i i21
i50
η 5 1 2 100% (3)
belocatedinsidethechamberatleast5cmfromtheinsidewall n
5 6
C t t 2 t
@ ~ !~ !#
and near the midpoint between the air inlet and exhaust
( m i i i21
i50
manifolds.
C ~t ! 5 C~t ! (4)
m 0 0
5.3.10 Automatic Systems—Computer-based data acquisi-
C t 5 C t 2 C t e -N t 2 t 1C t (5)
~ ! @~ ~ !! ~ !# ~ ~ !! ~ !
m i m i in i21 i i21 in i21
tionandcontrol(DAC)systemscanbeusedtosetairflowrates
C t 5 C t e -N t 2 t (6)
and monitor temperature, relative humidity, and airflow rate ~ ! ~ ! ~ ~ !!
m i m i21 i i21
during the course of experiments. Analog signals from
ifmaximum C t ,0.01 C t
~ ! ~ !
in 0
temperature, relative humidity, pressure, and flow sensors are
converted to digital units that can be stored electronically, then
where:
processed to engineering units using appropriate calibration
η = mixing level,
th
factors. In this way, chamber environmental data can be
C(i) = exhaust air concentration at i concentration
continuously monitored, then compiled and reduced for archi-
measurement, mg/m ,
val storage or display with minimal operator effort. DAC C(0) = exhaust air concentration measurement at t =0,
mg/m ,
systems are also capable of certain control functions. Digital
th
C (i) = calculated perfectly mixed concentration at i con-
signals can be output to control valves or converted to analog m
centration measurement, mg/m ,
signals and sent out as set point signals to mass flow control-
th
C (i) = inletairconcentrationmeasurementat i concentra-
in
lers.Agraphicsoverlayprogramcanbeusedtodisplaycurrent
tion measurement, mg/m ,
set points and measured values on a system schematic.
n = number of discreet measurements,
5.3.11 Manual Systems—While DAC systems provide en- th
t = time of i concentration measurement (h),
i
3 1
hanced data collection and control, they also may be relatively
N = chamber air change rate, ventilation rate (m /h )
expensiveandcomplex.Thesimplicityandlowcostofmanual
divided by net chamber volume (m ), 1/h, and
systems may be preferable in some circumstances.
t = time constant of chamber = 1/N.
n
5.4 Characterization of Chamber Performance—Before a If the mixing level, η, as determined using Eq 3, is above
chamber is used for emissions testing, its mixing and sink
90%, then the air mixing within the chamber may be consid-
characteristics should be evaluated and compared to minimum ered adequate.
performance criteria. In addition to the guidance provided
5.4.3 Sink Effect—While the selection of materials used in
below, Guide D7911 describes the use of reference materials
the construction of the chamber should help to minimize the
for characterizing the performance of chambers.
adsorptionofVOCsonitsinteriorsurfaces,this“sink”effectis
5.4.1 Assessment of Air Mixing—The adequacy of air mix- likely to occur to some extent, and will affect the accuracy of
ing in the chamber can be assessed using a tracer gas decay emission testing results. Sink effect evaluation should be
test, but other approaches may also be useful. Tests to performed after the chamber’s mixing performance has been
determine the adequacy of mixing should be determined not confirmed. Sink effect is a compound-specific phenomenon, so
onlyinanemptychamber,butalsowithsubstratesandsamples ideally, the magnitude of this effect should be determined for
of the types used in actual tests to determine if the placement each of the specific compounds to be measured under the
chamber operating conditions for which an emission test is to
of substrates and samples in the chamber will negatively
be conducted. Refer to Practice D6670, Section 8.6, for a
impact mixing.
detailed procedure for characterizing reversible and irrevers-
5.4.2 Decay Test for Quantifying Mixing—The decay ap-
ible sink effects in emissions chambers.
proachinvolvesestablishingauniformtracergasconcentration
5.4.4 Using a Mass Balance to Determine Chamber Wall
withinthechamberandmonitoringthetracergasconcentration
Sink Effects—If the adsorption of a compound by chamber
decay in the exhaust air and the inlet air over time.Auniform
walls and internal chamber components is reversible, as in
concentration can be established by injecting tracer at a
most cases, one way to determine the adsorption by chamber
constantrateandwaitinguntiltheexhaustairconcentrationhas
walls and components is to introduce the test compound into
reached equilibrium. The monitoring of the decay should start
thechamberthroughpulseinjectionorflashvaporization.After
as soon as the tracer gas injection is stopped and continue for
steady-stateisreached,takeairsamplestodeterminetheinitial
at least one time constant, t , where t equals the inverse of the
n n
exhaust air concentration, C . Then flush the chamber with
chamber air change rate. The tracer gas concentration should 0
cleanairandkeepmonitoringtheconcentrationdecayuntilthe
be measured concurrently in the exhaust air and the inlet air at
exhaust air concentration reaches the method quantification
relatively high frequency, for example, not less than one
limit. The total mass of test compound adsorbed by the
sample per minute, if the inlet air concentration is >1 % of the
chamberwallsandinternalcomponentscanbeestimatedfrom:
initialchamberconcentration.Thedegreeofmixingisassessed
by determining a mixing level, η, is described in Eq 3-5.Ifthe M 5QS 2 C 2 C V (7)
@~ ! #
s c 0 i
D5116 − 17
where: preventinstabilitiesinthechambersystemflow.Generally,this
will require that the sampling flow rate be limited to <50% of
M = mass of compound adsorbed to chamber walls and
s
the chamber flow rate. Valves and a vacuum gage may be
internal components, mg,
incorporated into the system to permit verification of system
S = totalareaunderthetime-concentrationcurve,mg-h/m
c
integrity before samples are drawn. The entire system can be
(see 9.5.2),
Q = test chamber inlet airflow rate, m /h, and connected to a programmable electronic timer to permit
V = test chamber net air volume, m . unattended sample collection.
5.4.4.1 The difference between the mass of the compound 6.3 Sample Collection Media—Selection of appropriate
introduced and the mass leaving the chamber is an indicator of
sample collection technique(s) will depend upon factors such
a problem with either internal chamber losses or possibly the as boiling point, polarity, and concentration ranges of the
sampling/analytical method (refer to 9.5 for detailed calcula-
compoundsofinterest,aswellastheamountofwatervaporin
tion steps). the sample airstream. No single sample collection,
concentration, and delivery system will be adequate for all
6. Sample Collection and Analysis
analytes of interest, and the user must understand the limita-
tions of any system used to characterize source emissions. If
6.1 Indoor sources of VOC emissions vary widely in both
the sample is collected by way of syringe or closed-loop
the strength of their emissions and the type and number of
sampling, it is injected directly into a GC system or other
compounds emitted. Differences in emissions rates of several
instrument for analysis. Collection in a gas sampling bag or
orders of magnitude among sources is not unusual. To charac-
vessel (for example, glass, stainless steel) allows for larger
terize organic emissions fully, the sample collection/analysis
samples. For many small chamber evaluations of indoor
system must be capable of quantitative collection and analysis
materials, low concentrations of the compounds of interest
of polar, and non-polar VOCs over a broad range of volatility.
requirelargevolumesamples,andcollectiononanappropriate
Any small chamber sampling and analysis technique or strat-
adsorbent medium is required. Several sorbent materials are
egydevelopedmustconsidertheemissioncharacteristicsofthe
available for use, singly or in combination, including activated
specific source being evaluated. The design and operation of
carbon (see Practices D6196 and D3686). The selection of the
samplecollectionandanalysissystemsmustbeappropriatefor
sorbent (or sorbent combination) depends on the compound(s)
the VOCs (and their concentrations) being sampled. Such
to be collected. If sorbent collection is used, the laboratory
systems generally include sampling devices (for example,
must be equipped with appropriate storage capabilities. Air
syringes, pumps), sample collectors (for example, syringes,
tight glass tubes or chemically inert bags are both appropriate.
adsorbent media, evacuated canisters), and instruments to
Flushing the storage containers with high purity nitrogen prior
analyze organic emissions (for example, gas chromatographsy
to use will help assure their cleanliness. If required, samples
(GC), see Practice E355). The remainder of this section
should be stored in a freezer at–20°C. If possible, sorbent
provides a discussion of the alternatives available for small
samples should be desorbed and analyzed within 48 h of
chamber sampling and analysis of VOC emissions; technical
collection.
details of specific systems are not included.
6.3.1 Whensorbentsareusedforsamplecollection,desorp-
6.2 Sampling Devices—The exhaust flow (for example,
tion and concentration is necessary (see Practice D3687).
chamber exhaust) is normally used as the sampling point,
Commercial instruments are available for the automated
although separate sampling ports in the chamber can be used.
desorption,concentration,andinjectionofthecompoundsonto
A multiport sampling manifold can provide flexibility for
the GC column. Supercritical fluid or solvent extraction and
duplicatesamples.Amixingchamberbetweenthetestchamber
liquid injection to the GC can also be employed. Other
and the manifold can be used to permit addition and mixing of
concentrationtechniquesarealsoavailable,includingcryotrap-
internal standard gases with the chamber air stream. Sampling
ping.
ports with septums are needed if syringe sampling is to be
conducted.Thesamplingsystemshouldbeconstructedofinert 6.4 OrganicAnalysis Instrumentation—Avarietyofanalyti-
material (for example, glass, stainless steel), and the system cal instruments is available for determining the concentrations
should be maintained at the same temperature as the test of VOCs sampled from the chamber, with GCs being the most
chambers. The exhaust from the sampling system should be commonly used technique. GC has a wide variety of capillary
ducted into a fume hood, ensuring that any hazardous chemi- columns available for separating organic compounds. Several
cals emitted by the test materials are isolated from the detectors can be used depending on the purpose of the test and
laboratory environment. the compounds of interest. Mass spectrometry (MS) combined
6.2.1 Samples can be drawn into gas tight syringes, GC with GC (GC/MS) can be used in the scan mode to identify
sampling loops, evacuated canisters, or through sorbent car- unknown compounds. When used in the scan mode, a conven-
tridges using sampling pumps. Gas tight syringes and closed- tional electron ionization (EI) MS has a sensitivity of about
–9
loops are frequently used when chamber concentrations are 10 g.Aniontrapdetectormayhaveasensitivityapproaching
–12
highandsamplevolumesmustbesmalltopreventoverloading 10 ginthescanmode.IfEIMSisbeingusedtoanalyzefor
of the analytical instrument. Larger volume samples can be knowncompounds,itmaybeoperatedintheselectedionmode
pulled through sorbent cartridges using sampling pumps. Flow toincreasesensitivity.MScanbemadeevenmoresensitiveby
rate can be controlled by an electronic mass flow controller or meansofnegativeionization.Flameionizationdetectors(FID)
other means. The sampling flow rate should be regulated to arealsowidelyused.Theyrespondtoawidevarietyoforganic
D5116 − 17
–11
compounds and have a sensitivity of 10 g. Electron capture the amount of dilution and flushing that occurs and can have a
detectors (ECD) are used for analyzing electronegative com- major impact on chamber concentrations.
pounds (for example, halogenated organics) and have a sensi-
7.2.4 Chamber Loading Ratio (1/m), [L] is the ratio of the
–13
tivity of 10 g. Some compounds are not easily measured
testspecimen’sexposedemittingsurfaceareatothechamber’s
with GCs; for example, low molecular weight aldehydes
corrected internal volume. This variable allows product con-
require other instrumentation (for example, high performance
figuration in the test chambers to correspond to typical use
liquid chromatography (HPLC) or wet chemical colorimetric
patterns of the product in “full scale” environments. Studies
techniques).
have shown that formaldehyde emission rates are proportional
to the ratio of air change rate (N) to product loading (L).Thus,
6.5 Standards Generation and System Calibration—
(N/L) in units of m/h is often selected as a parameter in
Calibration gas may be added to the test chamber or sampling
designing chamber experiments. In some cases, the configura-
manifold from permeation ovens (see Practice D3609), gas
tion of the source makes product loading based on specimen
cylinders, or dilution bottles. Calibration (or tracer) gas is
surface area an inappropriate parameter. For example, studies
added through the test chamber in tests to determine chamber
of sealants often employ elongated beads where the diameter
mixing, check for leaks, or to evaluate chamber “sink” effects.
and length of the bead are the relevant experimental design
Internal standards for quality control may be added at the head
parameters. Special specimen holders may be employed to
of the sampling system. The internal standard should not be
provide more realistic emission conditions for such materials,
addedtothechamberduetothepotentialforadsorptiononthe
for example, an appropriately sized channel for application of
material being tested. Quality control can also be achieved by
caulk and sealant products.
spiked samples.
7.2.4.1 The volume of chamber internal contents including
7. Experimental Design the volume of the test specimen is sometimes ignored in
determining the chamber air change rate and the chamber
7.1 Test Objectives—The first step in designing an experi-
loading ratio. This practice of ignoring net chamber volume
ment for chamber tests of indoor materials/products is to
may be acceptable if the content volume is a small fraction of
determine the test objectives. For example, a builder or
the volume of the chamber enclosure itself, for example <5 %.
architect would be interested in emissions from a variety of
7.2.4.2 Another approach, which avoids the challenge of
materials to be used under a given set of conditions for a
determining net chamber volume and which facilitates direct
specific building. In this case, the experiment would be
comparisons to typical product scenarios in full scale environ-
designed to handle many materials with one set of environ-
ments is to configure tests based on area-specific airflow rate
mental conditions. A manufacturer might want to know the
wherethechamber’svolumetricinletairflowrate,Q,isdivided
emissionscharacteristicsofasingleproductunderbothnormal
by the specimen surface area, A, that is Q/A in units of m/h.
and extreme conditions and would design a test to cover the
Note that tests run at the same Q/A in chambers of different
appropriate range of environmental variables. IAQ researchers
sizes will have different ratios of specimen area to chamber
interestedint
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