ASTM E2029-11(2019)

Standard Test Method for Volumetric and Mass Flow Rate Measurement in a Duct Using Tracer Gas Dilution

SIGNIFICANCE AND USE
5.1 The method presented here is a field method that may be used to determine mass and volume flow rates in ducts where flow conditions may be irregular and nonuniform. The gas flowing in the duct is considered to be an ideal gas. The method may be especially useful in those locations where conventional pitot tube or thermal anemometer velocity measurements are difficult or inappropriate due either to very low average flow velocity or the lack of a suitable run of duct upstream and downstream of the measurement location.  
5.2 This test method can produce the volumetric flow rate at standard conditions without the need to determine gas stream composition, temperature, and water vapor content.  
5.3 This test method is useful for determining mass or volumetric flow rates in HVAC ducts, fume hoods, vent stacks, and mine tunnels, as well as in performing model studies of pollution control devices.  
5.4 This test method is based on first principles (conservation of mass) and does not require engineering assumptions.  
5.5 This test method does not require the measurement of the area of the duct or stack.  
5.6 The test method does not require flow straightening.  
5.7 The test method is independent of flow conditions, such as angle, swirl, turbulence, reversals, and hence, does not require flow straightening.  
5.8 The dry volumetric airflow can be determined by drying the air samples without measuring the water vapor concentration.
SCOPE
1.1 This test method describes the measurement of the volumetric and mass flow rate of a gas stream within a duct, stack, pipe, mine tunnel, or flue using a tracer gas dilution technique. For editorial convenience all references in the text will be to a duct, but it should be understood that this could refer equally well to a stack, pipe, mine tunnel, or flue. This test method is limited to those applications where the gas stream and the tracer gas can be treated as ideal gases at the conditions of the measurement. In this test method, the gas stream will be referred as air, though it could be any another gas that exhibits ideal gas law behavior.  
1.2 This test method is not restricted to any particular tracer gas although experimental experience has shown that certain gases are used more readily than others as suitable tracer gases. It is preferable that the tracer gas not be a natural component of the gas stream.  
1.3 Use of this test method requires a knowledge of the principles of gas analysis and instrumentation. Correct use of the formulas presented here requires consistent use of units.  
1.4 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 to determine the applicability of regulatory limitations prior to use. For specific precautionary statements, see Section 7.  
1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 14-Apr-2019
• ICS: 13.040.01 - Air quality in general
• Technical Committee: E06 - Performance of Buildings
• Drafting Committee: E06.41 - Air Leakage and Ventilation Performance

Relations

• Replaces: ASTM E2029-11 - Standard Test Method for Volumetric and Mass Flow Rate Measurement in a Duct Using Tracer Gas Dilution
• Effective Date: 15-Apr-2019
• Refers: ASTM E631-15 - Standard Terminology of Building Constructions
• Effective Date: 01-Mar-2015
• Refers: ASTM E631-14 - Standard Terminology of Building Constructions
• Effective Date: 01-Nov-2014
• Refers: ASTM E631-06 - Standard Terminology of Building Constructions
• Effective Date: 01-Jun-2006
• Refers: ASTM E631-93a(1998)e1 - Standard Terminology of Building Constructions
• Effective Date: 28-Jul-2000

Overview

ASTM E2029-11(2019): Standard Test Method for Volumetric and Mass Flow Rate Measurement in a Duct Using Tracer Gas Dilution provides a rigorous procedure for determining volumetric and mass flow rates in air streams within ducts, stacks, pipes, mine tunnels, or flues. Developed by ASTM International, this standard offers a field-based method that is especially beneficial when conventional measurement tools like pitot tubes or thermal anemometers are impractical due to factors such as low flow velocities, irregular duct geometry, or insufficient straight run lengths.

The method relies on injecting a tracer gas and analyzing its dilution downstream in the airflow, enabling precise calculation of both mass and volumetric flow rates. The technique's fundamentals are rooted in the conservation of mass and do not require the measurement of gas composition, temperature, water vapor content, or duct cross-sectional area.

Key Topics

• Applicability to Irregular and Nonuniform Flows

  • Effective in situations where traditional velocity measurements fail, especially in complex or nonuniform duct conditions.
  • Suitable for ideal gas behavior and where tracer and sample gases are compatible.

• Tracer Gas Dilution Technique

  • Involves injecting a tracer gas of known concentration at a controlled rate.
  • Downstream air samples are analyzed for tracer concentration to determine the dilution and, consequently, the flow rate.

• Independence from Flow Conditions

  • Accurate regardless of flow direction, presence of swirl or turbulence, and does not require straight runs or flow straightening devices.
  • No need to measure the area of the duct or stack.

• Dry Volumetric Airflow Measurement

  • Allows for the determination of dry airflow rates by using dried air samples, bypassing direct water vapor measurements.

• Flexible Tracer Gas Options

  • The standard does not mandate a specific tracer gas, provided it is detectable and not already present in the system.

• Emphasis on Safety

  • Guides users to observe appropriate safety, health, and environmental practices, including tracer gas exposure limits and proper handling of compressed gases.

Applications

The tracer gas dilution method specified in ASTM E2029-11(2019) is widely applicable across various industries and research areas, such as:

• HVAC Duct Flow Measurement
  • Precise airflow analysis for heating, ventilation, and air conditioning systems, especially in complex building environments.
• Industrial Ventilation Systems
  • Assessing flow rates in fume hoods, vent stacks, or process exhausts where traditional measurements are not feasible.
• Mine Ventilation
  • Ensuring adequate airflow in underground mining operations, supporting worker safety and air quality.
• Pollution Control Studies
  • Used in model studies or evaluations of pollution control equipment performance.
• Research and Diagnostics
  • Favored in laboratory or field studies where high accuracy and reliability are required, regardless of duct geometry.

Related Standards

For comprehensive airflow measurement and instrumentation, ASTM E2029-11(2019) is often referenced alongside:

• ASTM E631 - Terminology of Building Constructions
• ANSI/ASME TC19.1 - Measurement Uncertainty: Instrument Apparatus

Other relevant standards may include the ISO 3966 (measurement of fluid flow in closed conduits) and national standards regarding tracer gas methods and occupational exposure limits.

---

Keywords: ASTM E2029, tracer gas dilution, volumetric flow rate, mass flow rate, duct airflow measurement, HVAC testing, nonuniform flow, stack emission monitoring, industrial ventilation, mine airflow, flow measurement standards, tracer gas safety

This standard is essential for professionals seeking robust and flexible air flow measurement methods in challenging field conditions, supporting accuracy and compliance in performance testing and environmental monitoring.

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: E2029 − 11 (Reapproved 2019)
Standard Test Method for
Volumetric and Mass Flow Rate Measurement in a Duct
Using Tracer Gas Dilution
This standard is issued under the fixed designation E2029; 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 2. Referenced Documents
2.1 ASTM Standard:
1.1 This test method describes the measurement of the
E631Terminology of Building Constructions
volumetric and mass flow rate of a gas stream within a duct,
2.2 ANSI/ASME Standard:
stack, pipe, mine tunnel, or flue using a tracer gas dilution
ANSI/ASMETC19.1–1985(1994) Measurement Uncer-
technique. For editorial convenience all references in the text
tainty: Instrument Apparatus
will be to a duct, but it should be understood that this could
referequallywelltoastack,pipe,minetunnel,orflue.Thistest
3. Terminology
method is limited to those applications where the gas stream
3.1 Definitions:
andthetracergascanbetreatedasidealgasesattheconditions
3.1.1 For definitions of general terms related to building
of the measurement. In this test method, the gas stream will be
construction used in this test method, refer to Terminology
referred as air, though it could be any another gas that exhibits
E631.
ideal gas law behavior.
3.2 Definitions of Terms Specific to This Standard:
1.2 Thistestmethodisnotrestrictedtoanyparticulartracer 3.2.1 ideal gas, n—a gas or gas mixture for which the ratio
of the pressure divided by product of the density and tempera-
gas although experimental experience has shown that certain
ture is a constant.
gasesareusedmorereadilythanothersassuitabletracergases.
It is preferable that the tracer gas not be a natural component
3.2.2 mass flow, n—the total mass of air passing the sam-
of the gas stream.
pling point per unit time (kg/s, lb/min).
3.2.3 tracer gas, n—a gas that can be mixed with air and
1.3 Use of this test method requires a knowledge of the
measured in very low concentrations.
principles of gas analysis and instrumentation. Correct use of
3.2.4 tracer gas analyzer, n—a device that measures the
the formulas presented here requires consistent use of units.
concentration of tracer gas in an air sample.
1.4 This standard does not purport to address all of the
3.2.5 tracer gas mass concentration, n—the ratio of the
safety concerns, if any, associated with its use. It is the
mass of tracer gas in air to the total mass of the air-tracer
responsibility of the user of this standard to establish appro-
mixture. For an ideal gas, the mass concentration is indepen-
priate safety, health, and environmental practices and to
dent of temperature and pressure.
determine the applicability of regulatory limitations prior to
3.2.6 tracer gas molar concentration, n—the ratio of the
use. For specific precautionary statements, see Section 7.
number of moles of tracer gas in air to the total number of
1.5 This international standard was developed in accor-
moles of the air-tracer mixture.
dance with internationally recognized principles on standard-
3.2.7 tracer gas volume concentration, n—the ratio of the
ization established in the Decision on Principles for the
volume of tracer gas in air to the total volume of the air-tracer
Development of International Standards, Guides and Recom-
mixture. For an ideal gas, the volume concentration is inde-
mendations issued by the World Trade Organization Technical
pendent of temperature and pressure and is equal to the molar
Barriers to Trade (TBT) Committee.
concentration.
1 2
This test method is under the jurisdiction of ASTM Committee E06 on For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Performance of Buildings and is the direct responsibility of Subcommittee E06.41 contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
on Air Leakage and Ventilation Performance. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved April 15, 2019. Published April 2019. Originally the ASTM website.
approved in 1999. Last previous edition approved in 2011 as E2029–11. DOI: Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
10.1520/E2029–11R19. 4th Floor, New York, NY 10036, http://www.ansi.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E2029 − 11 (2019)
3.2.8 volumetric flow, n—the total volume of air passing the mass or volumetric flow rate. Downstream of the injection
3 3
sampling point per unit time (m /s, ft /min). point gas samples are taken and are analyzed for the resulting
tracerconcentration.Theratiooftheinjectionflowrateandthe
3.3 Symbols:
downstream concentration represents the dilution volume per
unit time or volumetric flow rate in the duct.
C = mass concentration of tracer gas (ppb-mass, ppm-
5. Significance and Use
mass, ppt-mass)
C = upstream mass concentration of tracer gas (ppb-
U 5.1 Themethodpresentedhereisafieldmethodthatmaybe
mass, ppm-mass, ppt-mass)
used to determine mass and volume flow rates in ducts where
C = downstream mass concentration of tracer gas (ppb-
D
flow conditions may be irregular and nonuniform. The gas
mass, ppm-mass, ppt-mass)
flowingintheductisconsideredtobeanidealgas.Themethod
C = injection stream mass concentration of tracer gas
I
maybeespeciallyusefulinthoselocationswhereconventional
(ppb-mass, ppm-mass, ppt-mass)
pitot tube or thermal anemometer velocity measurements are
c = volume concentration of tracer gas (ppb, ppm, ppt)
difficult or inappropriate due either to very low average flow
c = upstream volume concentration of tracer gas (ppb,
U
velocity or the lack of a suitable run of duct upstream and
ppm, ppt)
downstream of the measurement location.
c = downstream volume concentration of tracer gas
D
5.2 Thistestmethodcanproducethevolumetricflowrateat
(ppb, ppm, ppt)
standard conditions without the need to determine gas stream
c = injection volume concentration of tracer gas (ppb,
I
composition, temperature, and water vapor content.
ppm, ppt)
F = mass flow rate (kg⁄s, g/min, lb/min)
5.3 This test method is useful for determining mass or
F = injection mass flow rate (kg⁄s, g/min, lb/min)
I
volumetricflowratesinHVACducts,fumehoods,ventstacks,
F = upstream mass flow rate (kg⁄s, g/min, lb/min)
U
and mine tunnels, as well as in performing model studies of
F = downstream mass flow rate (kg⁄s, g/min, lb/min)
D
5 3 pollution control devices.
f = volumetric flow rate (m /s, L/min, cfm)
std 5 3
f = volumetric flow rate at standard conditions (m /s, 5.4 This test method is based on first principles (conserva-
L/min, cfm)
tion of mass) and does not require engineering assumptions.
5 3
f = injection volumetric flow rate (m /s, L/min, cfm)
I
5.5 This test method does not require the measurement of
5 3
f = upstream volumetric flow rate (m /s, L/min, cfm)
U
5 3 the area of the duct or stack.
f = downstreamvolumetricflowrate (m /s,L/min,cfm)
D
std 5
f = injection volumetric flow rate at standard conditions 5.6 The test method does not require flow straightening.
I
(m /s, L/min, cfm)
5.7 The test method is independent of flow conditions, such
std 5
f = upstreamvolumetricflowrate atstandardconditions
U
as angle, swirl, turbulence, reversals, and hence, does not
(m /s, L/min, cfm)
require flow straightening.
std 5
f = downstream volumetric flow rate at standard condi-
D
5.8 Thedryvolumetricairflowcanbedeterminedbydrying
tions (m /s, L/min, cfm)
6 3 3
the air samples without measuring the water vapor concentra-
ρ = density (kg⁄m , g/L, lb/ft )
6 3
tion.
ρ = density ofgasstreamwithoutanytracer(kg/m ,g/L,
a
lb/ft )
6 3 3
6. Apparatus
ρ = density of the tracer gas (kg/m , g/L, lb/ft )
t
6 3
ρ = density of the injection gas mixture (kg/m , g/L,
I
6.1 Theapparatusincludesasourceoftracergas,meansfor
lb/ft )
distributing the tracer gas in the duct, means for obtaining air
6 3
ρ = density of the upstream gas mixture (kg/m , g/L,
U
samplesfromtheduct,andagasanalyzertomeasuretracergas
lb/ft )
concentrations in the air samples.
6 3
ρ = density of the downstream gas mixture (kg/m , g/L,
D
6.2 TracerGas—SeeAppendixX1forinformationontracer
lb/ft )
t 6
gases and equipment used to measure their concentrations.
ρ = density of the tracer gas at upstream conditions
U
3 3
AppendixX1alsocontainstracergastargetconcentrationsand
(kg/m , g/L, lb/ft )
t 6
safety information.
ρ = density of the tracer gas at downstream conditions
D
3 3
(kg/m , g/L, lb/ft )
6.3 Tracer Gas Injection Source—This normally is a cylin-
der of compressed tracer gas either pure or diluted in a carrier
4. Summary of Test Method
such as air or nitrogen. Tracer release from the cylinder is
4.1 This test method describes the use of a tracer gas
controlled by a critical orifice or nozzle, a metering valve, an
dilution technique to infer the volumetric flow rate through a
electronicmassflowmeterormassflowcontroller,orothergas
duct. In practice, tracer gas is injected into a duct at a known
flow rate measurement and control device. A rotameter is not
recommended for this measurement unless of special design,
calibration, and a corresponding decrease in measurement
Equationsinthistestmethodassumethatallmassorvolumeconcentrationsare
in the same units. accuracy is acceptable.
Equations in this test method assume that all mass or volume flow rates are in
6.4 Tracer Gas Distribution—A single tube or a tubing
the same units.
Equations in this test method assume that all densities are in the same units. network is inserted into the duct to dispense tracer gas. The
E2029 − 11 (2019)
tubeortubesmayhaveeitherasingleormultiplereleasepoints 7.2 Health Limitations—Use current OSHAinformation on
for tracer gas. For large cross-section ducts a network that the permissible exposure limit (PEL), or theACGIH threshold
distributes tracer gas over a wide area will facilitate measure-
limit value (TLV) if the particular tracer is not listed with a
ment.
PEL,todeterminethesafeconcentrationforthegaschosenfor
the test. Never exceed the maximum safe concentration. It is
6.5 Tracer Sampling—This is performed using tubing in-
goodpracticetouseaconcentrationthatisatmostonetenthof
sertedintotheductdownstreamoftheinjectionpoint.Asingle
the maximum safe concentration.Avoid using tracer gases for
tubeisinsertedintotheduct.Airsamplesareremovedfromthe
which no PEL or TLV exists.
ductbymeansofasamplingpumptodistributetracerladenair
to the analyzer either directly or by means of syringe samples.
7.3 Compressed Gas Equipment—Observe the supplier’s
6.6 Gas Analyzer—This device must be suited for the tracer
safety information and CGAinformation on the transportation,
gas used and the concentrations expected in the duct being
use, and storage of compressed gas cylinders, regulators, and
measured. It should be calibrated properly and exhibit a
related equipment.
accuracy of better than 63% at concentrations employed in
the measurement.
8. Procedure for Measuring Mass and Volumetric
Flowrate
7. Hazards
8.1 Inject tracer of known concentration, C(c), and at a
I I
7.1 Safety is the responsibility of the user of this test
known rate, F(f), into a flowing duct using procedures
I I
method. Tracer gases have safe maximum concentration limits
provided in Section 9.
due to health and, in some cases, explosive potential. Table 1
8.1.1 If the tracer gas analyzer is field calibrated using a
presents, as a guide, the maximum allowable concentration in
single point method, the injection rate, or injection
air for some tracer gasses that can be used for airflow
concentration, or a combination thereof, should be adjusted to
measurements.ThetracergassuppliermustprovideaMaterial
Safety Data Sheet (MSDS) that will provide information about produce a concentration at the sample location that is the same
health, fire, and explosion hazards. as the calibration concentration to within 620%.
TABLE 1 Tracer Gases and Safety Issues
A
Tracer Gas TLV Toxicity Chemical Reactivity Comments
Hydrogen Asphyxiant Nontoxic Highly reactive in Fire and explosion hazard
presence of heat, when exposer to heat,
flame, of O flame, or O
2 2
Helium Asphyxiant Nontoxic Inert
Carbon Monoxide 25 ppm Combines with Highly reactive Fire and explosion hazard
hemoglobin to with O when exposed to heat or
cause anoxia flame
Carbon Dioxide 5000 ppm Can be an eye Reacts vigorously
irritant with some metals;
soluble in water
Sulfur Hexafluoride 1000 ppm Nontoxic Inert Thermal decomposition
yields highly toxic
compounds
Nitrous Oxide 25 ppm Moderately toxic Violent reaction Can form explosive
with aluminum; mixture with air; ignites
water soluble at high temperature
Ethane Asphyxiant Nontoxic Flammable Incompatible with
chlorine and oxidizing
materials
Methane Asphyxiant Nontoxic Flammable Incompatible with
chlorine and oxidizing
materials
Octofluorocyclobutane 1000 ppm Low toxicity Nonflammable Thermal decomposition
(Halocarbon C-318 yields highly toxic
compounds
Bromotrifluoromethane 500 ppm Moderately toxid Incompatible with Dangerous in a fire
(Halocarbon 13B1) by inhalation aluminum
Dichlorodifluoromethane 1000 ppm Central nervous Nonflammable; Thermal decomposition
(Halocarbon 12) system and eye can react violently yields highly toxic
irritant; can be with aluminum compounds
narcotic at high
levels
Dichlorotetrafluoromethane 1000 ppm Can be asphyxiant, Can react violently Thermal decomposition
(Halocarbon 116) mildly irritating, with aluminum yields highly toxic
narcotic at high compounds
levels
A
Threshold Limit Values for Chemical Substances in the Work Environment, American Conference of Governmental Industrial Hygienists (ACGIH), 1997.
E2029 − 11 (2019)
TABLE 2 Minimum Number of Down Stream Sample Locations ρ
n
where r [ is the ratio of the density of the main
na
2 2
ρ
Duct Cross Sectional Area m (ft ) Number of Areas Number of Samples a
constituentoftheinjectiongasmixturetothedensityofthegas
Less then 0.2 (2) 4 5
stream without any tracer. If c = 1, than r =1.
0.2 to 2.3 (2 to 25) 12 13
I na
Greater than 2.3 (25) 20 21
8.6 The volumetric flow rate in the duct at standard condi-
tions is given by:
c 2 r c 2 ~1 2 r !c c
I na D na I D
std std
f 5 ·f volumeconcentrations (7)
~ !
8.1.2 If the tracer gas analyzer is field calibrated using two U I
c 2 c
~ !
D U
calibrationpoints,theinjectionrate,orinjectionconcentration,
8.7 The dry gas flow rate in the duct at standard conditions
or a combination thereof, should be adjusted to produce a
is given by:
concentration at the sample location that lies between the two
calibration points. c c
I I
d std std
~ !
f 5 ·f if ,0.001 dryvolumeconcentrations (8)
~ !
U d d I
~ !
c 2 c c
8.1.3 Ifthetracergasanalyzerisfieldcalibratedusingmore ~ !
D U D
than two calibration points, the injection rate, or injection
where the superscript (d) refers to quantities at dry condi-
concentration, or a combination thereof, should be adjusted to
tions.
produce a concentration at the sample location that lies at the
8.7.1 Dry volume concentrations are obtained by drying the
approximate midpoint of the calibration range.
gas sample before analysis. It is important that the drying
8.2 Obtain at least N measurements of the resulting
technique used should not remove any of the tracer gas. This
i
concentrations, C , at least ten diameters, or equivalent
D
can be checked by drying a sample of the calibration standard
hydraulic diameters for nonround cross section ducts, down-
using the drying techniques and comparing the measured dry
stream of the injection at the center of N-1 equal areas of the
concentrations with the calibration standard. The two concen-
ductcrosssectionandoneatthecenteroftheduct.Thenumber
trationsshouldbethesamewithintheprecisionoftheanalyzer
N is determined by Table 2 depending on the duct size.
as determined in Appendix X2.
i
8.3 Ifrecirculationispossibleorlikely,Nsamples C inthe
U
center of duct upstream of the injection point should be taken
9. Procedures for Injecting Tracer Gas
within 10 s of the time a downstream sample is taken. If
9.1 Injecttracergasataknown,constantrateusingmetered
recirculation does not exist, take at least one upstream sample
injection. To accomplish this a critical orifice, critical orifice
before and after taking the downstream samples.
metering valve, an electronic mass flow meter or an electronic
8.4 At each time a downstream sample is taken, the injec-
mass flow controller may be used in conjunction with a source
i
tion flow rate F shall be recorded.
I of pure or diluted tracer gas. The flow measuring device shall
be calibrated and its accuracy certified by a method that is
8.5 Calculate the following quantities in either mass,
traceable to National Institute of Standards and Technology
volume, or dry concentration depending on results desired:
(NIST). The calibration shall be performed with an injection
8.5.1 The average downstream concentration C :
D
gasofthesameapproximateconcentrationaswillbeusedinan
N
D
i
actual measurement.
C 5 C (1)
D ( D
N
i51
D
9.1.1 Reliance on scale factors to convert a flow meter
where N is the number of downstream sample locations.
calibration using one gas to predict the calibration on a second
D
8.5.2 The average upstream concentration C :
gas is not acceptable unless the accuracy of the conversion
U
N
factor has been demonstrated experimentally for the type of
U
i
C 5 C (2)
meter used.
U ( U
N
i51
U
9.1.2 The total uncertainty (uncertainty in flowrate and
where N is the number of upstream sample locations.
U
uncertainty in injection concentration) in the tracer gas injec-
8.5.3 The average injection flow F (or the corresponding
I
tion rate shall be less than 3%. The bias of the assumed
volumetric flow rate):
injection rate shall be no more than 3% of the true rate.
N
I
i
9.2 Injection of tracer gas may be via a single tube or via a
F 5 F (3)
I ( I
N
i51
I
manifold consisting of several tubes connected to the flow
injection metering device. In the case of a manifold, flow
where N is the number of flow rate measurements.
I
through each branch of the manifold should be approximately
8.5.3.1 The mass flow rate in the duct is given by:
equal. The tube or tubes may have either a single or multiple
C 2 C
~ !
I D
F 5 F massconcentrations (4) release points for tracer gas.
~ !
U I
~C 2 C !
D U
8.5.3.2 The volumetric flow rate in the duct is given by:
10. Procedures for Sampling Tracer Gas
C 2 C ρ
~ !
I D I
10.1 Samplingisperformedusingasingletubeconnectedto
f 5 · ·f ~massconcentrations! (5)
U I
~C 2 C ! ρ
D U U
a pump that draws air samples to the exterior of the duct for
I
c 2 r c 2 1 2 r c c ρ
~ ! analysis. Use a separate sampling tube for the downstream and
I na D na I D t
f 5 · ·f volumeconcentrations (6)
~ !
U U I
c 2 c ρ for the upstream air sample.
~ !
D U t
E2029 − 11 (2019)
10.2 Samplesofairmayberouteddirectlytotheanalyzeror 11.5 It must be demonstrated using the procedure of Ap-
grab samples using syringes, sample bags, or other appropriate pendix X3 that the gas analyzer response is not affected by
containers may be taken for subsequent analysis. potential interference due to other gases that may be present in
7 the duct. To demonstrate this one can sample the duct in the
10.3 Ifgoodmixing isnotobtained,enhancethemixingby
absence of tracer and note the analyzer response, if any.
one of the following procedures:
10.3.1 Move thesamplepointfurtherdownstreamfromthe
12. Calculation of Test Errors
tracer injection point. When flowing air encounters a rapid
12.1 The uncertainty of the test results depends on the
change in direction, mixing within the duct is assisted; hence,
instrumentation used and on the mixing obtained in the test.
moving the sample point to a location past one or more bends
The bias, ∆F, of the results is given by the following equation:
in the flow will enhance mixing.
2 2 2 2
10.3.2 Move the tracer injection point further upstream
∆F ∆C ∆F ∆C 1 ∆C
~ ! ~ !
I I D U
5Π1 1 (9)
S D S D
from the sample point. When flowing air encounters a rapid
F C F ~C 2 C !
I I D U
change in direction, mixing within the duct is assisted; hence,
where:
movingtheinjectionpointtoalocationpastoneormorebends
∆C = the uncertainty in the injection gas concentration,
in the flow will materially enhance mixing. Often moving the I
∆F = the uncertainty in the injection flow rate,
I
injection point upstream of an air handling fan can enhance
∆C = the calibration uncertainty in the downstream con-
D
mixing.Notethatcentrifugalfansarenotasefficientatmixing
centration (Appendix X2), and
as are vaneaxial fans.
∆C = the calibration uncertainty in the upstream concen-
U
10.3.3 Enhance the uniformity of the tracer injection by
tration (Appendix X2).
increasing the number of injection tubes or the number of
12.2 The precision ∂F in the flow is given by the following
injection holes in each tube.
equation:
11. Tracer Gas Analysis Requirements
2 2
]F ]F ]~C 2 C !
I D U
5 t~N 21,0.95!Π1 (10)
2 2
11.1 The tracer gas analyzer shall be calibrated using
F F C 2 C
~ ! ~ !
I D U
calib
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