&EPA
United Slates
Environment) Protection
Agency
Research and
Development
E PA-600/R-94-001
January 1994
SUPPLEMENT TO:
STANDARD MEASUREMENT PROTOCOLS
Florida Radon Research Program
Prepared for
State of Florida
Department of Community Affairs
Prepared by
Air and Energy Engineering Research
Laboratory
Research Triangle Park NC 27711
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— TECHNICAL REPORT DATA
! _ , fflease read I/iurvctions on the reverse before complei
1 REPORT NO. 2.
EPA-600/R-94-001
3.'
4. TITLE AND SUBTITLE
Supplement to: Standard Measurement Protocols,
Florida Radon Research Program
5. REPORT DATE
January 1994
6. PERFORMING ORGANIZATION CODE
SRI- EN V- 92-943- 7400
7. AUTHOR(S)
Ashley D. Williamson and Joe M. Finkel
8. PERFORMING ORGANIZATION REPORT NO.
EPA/0RD
9. performing orOanization name and address
Southern Research Institute
P.C. Box 55305
Birmingham, Alabama 35255-5305
10. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
CR 818413 and EPA IAG
RWFL'933783-04-0
12. SPONSORING AGENCY NAME AND ADDRESS
EPA, Office of Research and Development
Air and Energy Engineering Research Laboratory
Research Triangle Park, NC 27711
13. TYPE OF REPORT AND PERIOD COVERED
Final Report; 2 /92 - 7/93
14. SPONSORING AGENCY CODE
EPA/600/13
15. supplementary notesaeerl project officer ig David C. Sanchez, Mail Drop 54, 919/541-
2979. Report supplements EPA-600/8-91-212 (NTIS PB92-115292). November 1991.
16, The report supplements earlier published standard protocols for key mea-
surements where data quality is vital to the Florida Radon Research Program. The
report adds measurement of small canister radon flux and soil water potential to the
section on soil measurements. It adds indoor radon progeny measurement, radon
entry rate estimation, and duct system leakage measurement to the section on buil-
ding measurements. ^ ***
17. KEY WORDS AND DOCUMENT ANALYSIS
a. DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS
c. COSATl Field/Group
Pollution Buildings
Radon Ducts
Measurement Leakage
Estimating
Sampling
Soils
Pollution Control
Stationary Sources
13B 13M
07B 13K
14 B
14 G
08G, 08M,.
13. DISTRIBUTION STATEMENT
Release to Public
19. SECURITY CLASS /This Report}
Unclassified
21. NO. OF P/ !
/
20 SECURITY CLASS (This page)
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
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EPA REVIEW NOTICE
This report has been reviewed by the U.S. Environmental Protection Agency, and
approved for publication. Approval does not signify that the contents necessarily
reflect the views and policy of the Agency, nor does mention of trade names or
commercial products constitute endorsement or recommendation for use.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
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EPA-600/R-94-001
January 1994
Supplement io:
STANDARD MEASUREMENT PROTOCOLS
Florida Radon Research Program
by
Ashley D. Williamson and Joe M. Finkel
Southern Research Institute
2000 Ninth Avenue South
P.O. Box 55305
Birmingham, AL 35255-5305
EPA Interagency Agreement RWFL933783-04-0
DCA Contract 93RD-66-15-00-22-006
EPA Cooperative Agreement CR818413
DCA Project Officer: Mohammad Madani
State of Florida
2740 Centerview Drive
Tallahassee, FL 32399
EPA Project Officer: David C. Sanchez
Air and Energy Engineering Research Laboratory
Research Triangle Park, NC 27711
Prepared for
State of Florida
Department of Community Affairs
2740 Centerview Drive
Tallahassee, FL 32399
and
U.S. Environmental Protection Agency
Office of Research and Development
Washington, DC 20460
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ABSTRACT
This report is a supplement to Standard Measurement Protocols, Florida Radon Research
Program, published by the U.S. Environmental Protection Agency, November 1991 (EPA-600/8-
91-212). It includes five new protocols: Small Canister Radon Flux, Soil Water Potential, Indoor
Radon Progeny, Radon Entry Rate, and Duct System Leakage.
ii
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CONTENTS
Section Paoe No. Revision
"ABSTRACT ! . ~ ! i 7. i ! ! I . 7 . . ^ ....... . 7 ! . ii
CONVERSION FACTORS iv
INTRODUCTION v
REFERENCES vi
1.0 SOIL MEASUREMENTS 1-1
1.1 Permeability/Soil Radon/Soil Fill
Sample Collection 1-2 0
1.2 In-Situ Soil Density 1-13 0
1.3 Soil Classification 1-18 0
1.4 Penetrometer Analysis 1-23 0
1.5 Soil Moisture 1-41 0
1.6 Soil Radium Content/Radon Emanation 1-42 0
1.7 Soil Particle-Size Analysis 1-47 0
1.8 Specific Gravity of Soils 1-48 0
1.9 Standard Proctor 1-49 0
1.10 Laboratory Permeability 1-50 0
1.11 Radon Diffusion Coefficient 1-54 0
1.12 Radon Flux 1-71 0
1.12.1 Small Canister Radon Flux 1-88 0
1.13 Soil Water Potential 1-94 0
2.0 BUILDING MEASUREMENTS 2-1
2.1 Sub-Slab Radon 2-2 0
2.2 Sub-Slab Communications Test 2-9 0
2.3 Differential Pressure Measurements 2-13 0
2.4 Building Leakage 2-16 0
2.4.1 Blower Door 2-16 0
2.4.2 Tracer Dilution 2-21 0
2.4.3 Site Detection 2-25 0
2.5 Indoor Radon 2-26 0
2.6 Indoor Radon Progeny 2-27 0
2.7 Radon Entry Rate 2-32 0
2.8 Duct System Leakage 2-40 0
* Pages iv-vi, 1-1 through 1-87, and 2-1 through 2-26 are in the basic report,
EPA-600/8-91-212
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Section No:1.12.1
Revision No: _0
Date; Mav 1993
Page : 1 of 6
1.12.1 Small Canister Radon Flux Measurement
Abstract
A third method for radon flux measurements is presented in this section. It has been used by
Florida Radon Research Program project members. This method is similar to the University
of Florida version (see Section No. 1.12), except that it reduces the air space between the soil
surface and the charcoal bed to minimize biases from disturbed radon profiles.
Applicability
Radon flux is a localized indicator of radon source strength, and has been used to define
regulatory limits for radon emissions from uranium mill tailings piles, phosphogypsum stacks,
etc. Radon flux measurements also may help identify the potential of building sites to cause
elevated indoor radon levels.
Relationship to Other Methods
This method is a variant of the two similar methods for radon flux measurements given in
Section 1.12. Radon flux measurements give an indication of radon source potential at a site.
Source potential in turn is affected by soil radium and radon emanation, whose protocols are
found in Section 1.6, and diffusivity, which is related to Section 1.11.
1-88
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Section No: 1.12.1
Revision No: 0
Dace: May 1993
Page: 2 of 6
Rogers & Associates Engineering Corporation
P.O. Box 330, Salt Lake City, Utah 84110-0330 • (801) 263-1600
Protocol for
Small-Canister Radon Flux Measurement
Revised from RAE QAP 5.6, May 1990
1. Background and Purpose
Radon. (222Rn) ^he rate of radon gas emission from a unit area of 3oil in a
unit time period, and is usually measured in units of picocuries of radon per square
meter of soil per second (pCi/m2s). It is a localized indicator of radon source strength,
and has been used to define regulatory limits for radon emissions from uranium mill
tailings piles, phosphogypsum stacks, etc.1Radon flux measurements also may help
identify the potential of building sites to cause elevated indoor radon levels.
The following, small-canister CSC) protocol for measuring radon flux has been
shown to give equivalent results1^ to U.S. Environmental Protection Agency (EPA)
Method 115,' ^ while improving on several potential problems with the EPA method. It
should be noted that there is no calibration standard for radon flux. Instead, sampling
devices are required to provide complete radon collection over the area and time sampled,
and calibrations address only the measurement of radon on the charcoal sampling
medium. The sample collection device and protocol are therefore important to assure
accurate measurements, and should avoid air gaps, excessive sampling times, or other
problems that have been shown to bias the radon flux sample.^-4)
The SC radon flux samplers cover a smaller area than the Method 115 samplers
(approximately 0.005 m2 vs. 0.1 m2)/5) but they offer lower cost, easier deployment and
retrieval, and some important technical advantages. These include (a) more than twice
the charcoal mass per unit area used by Method 115; (b) reduced air space between the
soil surface and the charcoal bed to minimize biases from disturbed radon profiles; (c)
permanently-packaged charcoal to avoid losses during open-air transfer of granulated
charcoal to counting containers; and (d) immediate sealing of the canister upon retrieval
to avoid losses to ambient air during transport to a field charcoal transfer station. In
side-by-side comparisons, the SC method differed from Method 115 (BL)^ by less than
9%, and was well within its l-<3 uncertainty range. The SC method has served as a basis
for uranium mill tailings cover designs,'®^ and has been used in other U.S. Nuclear
Regulatory Commission studies.^ Protocols for sampling radon flux are identical to the
Method 115 protocols except as specifically indicated.
1-89
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Section No: 1.12.1
Revision No: 0
Date: Mav 1993
Page: 3 of 6
2. Equipment and Facilities
2.1 Sampling Equipment
The equipment and configuration for radon flux sampling is illustrated in Figure
1. The charcoal canister is placed on the soil surface, separated only by a permeable
paper filter to avoid canister contamination. It is covered by a metal can of similar
diameter and height to define the sampling area and to prevent radon losses to the
atmosphere. The following equipment is used for sample collection:
• Charcoal canister (chemical gas-mask cartridge for organic vapors,
Type GMA, Mine Safety Appliances Co., Pittsburgh, PA or equivalent).
• Metal can (8.3 cm diameter x 4.1 cm, 8-oz. Ness Can, Embarcadero
Home Cannery, Oakland, CA, or equivalent).
• Paper or Cloth Filter (8-9 cm diameter, Handi Wipes, Colgate, New
York, NY, 10022-7499, or equivalent).
• Plastic Bag, re-sealable, to contain canister (7x8-inch, 4-mil heavy-
gauge freezer bag, Zipioc Brand, DowBrands Inc., Indianapolis, IN, or
equivalent).
• Clock, notebook and markers to record deployment & retrieval times and
to label the canister bag.
^S»VN.S«S.S.S.\.MVMS*S'S*MSS<
^iS>\«StS»S*SSi
^•S*(,«SiS*Si<»*SiS*S«S*SS
charcoal canister
^S«S#SiS«S»S«S«\iS#VS»N«^«\»>*VMVVS«S«S»V>*SiS«Si
^•S*S«S
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Section No: 112.1
Revision No: 0
Dace: Hav 1993
Page: 4 of 6
The following equipment and facilities should be available for sample analysis:
• Gamma-ray Spectrometer (shielded, with high-voltage bias power and
digital scaler or multi-channel analyzer).
• Calibration standard or check source relatable to a calibration standard.
¦ Blank sample
• Clock and notebook to record count times and results.
3. Sampling Procedure
3.1 A new or dried-and-aged charcoal canister is transported to the field sampling
location sealed in a plastic bag. Previously-used canisters shall be prepared for
re-use by drying for at least 8 h at 130 ± 10° C, and sealing in plastic bags for
storage until use.
Z2 The sampling location is cleared of dense turf-grass, or is (preferably) placed
between plants on exposed soil to facilitate pressing the metal can into the soil
surface. The filter material is placed on the soil surface, and the charcoal
canister is placed on the filter with the large (black) side facing down. The
metal can then is inverted over the canister and pressed 1-2 cm into the soil to
minimize void space in- the can, or 1-2 cm of surrounding soil is pressed
against the base of the can to seal it to the soil surface (Figure 1). The sampler
deployment time is recorded to the nearest 5 minutes.
13 After a collection period of approximately 24 h (at least 2 h, and less than 30 h),
the charcoal canister shall be retrieved. For retrieval, the can is removed, and
the canister is immediately (within <1 min.) sealed in a plastic bag or metal
can for transport to the laboratory. The retrieval time shall be recorded to the
nearest 5 minutes. Sampling shall not be conducted within 24 hours of
significant rainfall, and samples shall not be considered valid if rain during
the sampling period caused ponding or compromised the sampler seal to the
soil surface.
4. Analysis Procedure
4.1 Analysis of the charcoal canister shall occur at least 2 hours after sample
retrieval, and generally within 3-4 days of sample retrieval. The canister shall
be maintained sealed in its plastic bag from the time of retrieval until after
analysis.
42 The charcoal canister shall be counted with the calibrated laboratory counting
system for an appropriate, fixed time interval (generally on the order of 10
minutes), and the time at the beginning of the count shall be recorded to the
nearest 5 minutes.
4.3 The gamma-ray counts in the selected energy region shall be integrated and
recorded.
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Section No: 1.12.1
Revision No: Q
Dace: Mav 1993
Page: 5 of 6
4.4 A sealed, blank charcoal canister (a field blank if available) shall be counted
using the same system and its gam ma-ray counts in the same selected energy
region shall be integrated and recorded
45 A check source or reference standard shall be counted within 8 h of the sample
count using the same system, and its gamma-ray counts in the same selected
energy region shall be integrated and recorded. Its standard count rate for the
given detector system, at the time of calibration, shall be used as "a" in the flux
calculation in Figure 2. If a different-sized sampling can is used, the a factor
should be multiplied by 0.00535 m^/A, where A is the sampling-can area.
46 The radon flux shall be calculated by the equation given in Figure 2.
47 Following analysis, charcoal canisters shall be dried as in step 3.1, and
immediately upon cooling, shall be sealed in plastic bags for storage. They
shall not be re-used within the first 15 days of drying unless background
activity levels are confirmed by gamma-ray analyses.
RECORDED DATA
Sample ID / Location
Sampler Deployed / / at :
Sampler Retrieved / / at :
Sample Counted / / at :
Counting Duration T2 = min.
Canister Activity counts
Blank Canister Activity counts
Standard Activity counts
CONSTANTS
Radon Decay 1= 1.26x10"* min*1 Flux2 =
0t
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Section No:1.1 2.1
Revision No: _0_
Date: Mav 1993
Page: 6 of 6
5. References
1. EPA, National Emission Standards for Hazardous Air Pollutants; Radionuclides; Final
Rule and Notice of Reconsideration. U.S. Environmental Protection Agency, 40 CFR
Part 61, Federal Register 54: 51654-51715, 1989.
2. Rogers, V.C., Nielson, K.K., Sandquist, G.M., and Rich, D.C., "Radon Flux
Measurement and Computational Methodologies, U.S. Department of Energy report
UMTRA-DOE/AL-2 700-201, 1984.
3. Young, J.A., Thomas, V.W., and Jackson, P.O., "Recommended Procedures for
Measuring Radon Fluxes from Disposal Sites of Residual Radioactive Materials,"
U.S. Nuclear Regulatory Commission report NUREG/CR-3166, 1983.
4. Nielson, K.K., Rogers, V.C., Rich, D.C., Nederhand, F.A., Sandquist, G.M., and
Jensen, C.M., "Laboratory Measurements of Radon Diffusion Through Multilayered
Cover Systems for Uranium Tailings," U.S. Department of Energy report UMT/0206,
1981.
5. Hartley, J.N. and Freeman, H.D., "Radon Flux Measurements on Gardinier and Royster
Phosphogypsum Piles Near Tampa and Mulberry, Florida," U.S. Environmental
Protection Agency report EPA-520/5-85-029 (NT/S PB86-161874), 1986.
6. Rogers, V.C. and Nielson, K.K., "Radon Attenuation Handbook for Uranium Mill
Tailings Cover Design," U.S. Nuclear Regulatory Commission report NUREG/CR-3533,
1984.
1-93
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Section No: 1.13
Revision No: 0
Date: Mav 1993
Page: 1 of 5
1.13 Soil Water Potential
Abstract
This method is used for field measurements of soil moisture potential. The moisture potential
is defined to be the pressure of the tensiometer water necessary to equilibrate mechanically
and hydraulicaily with the soil solution phase.
Applicability
This method is specified as a field procedure and measurement to be conducted in the
research house projects of the Florida Radon Research Program. As presented here, it is a
"stand-alone" procedure used for long-term monitoring.
This method may not give a truly representative result if dissolved gases come out of the
solution or if the water in the tensiometer system is reduced to the level of the vapor pressure
of water at the ambient temperature of the system, or if the difference between the gas
pressure and the pressure in the tensiometer cup water forces a gas phase through the wetted
porous cup. Any of these phenomena that introduce a gas phase into the tensiometer system
will seriously interfere with its operation. These conditions are most likely to occur when the
soil is very dry.
Relationship to Other Methods
This method is related to the determination of soil moisture as given in Section 1.5, in that
the soil moisture and soil water potential for any given soil are monotonically related one to
another.
1-94
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Section No: 1.13
Revision No: 0
Date: Mav 1993
Page: 2 of 5
Field Procedures for Soil Water (Moisture) Potential
Measurements Using Tensiometry
1. Scope
1.1 This procedure covers the field determination of the water (moisture) potential
of soil by tensiometry.
1.2 For studies involving water transport and storage in soils, the energy status of
the soil solution phase (soil water) is required rather than the actual soil water content. The
soil water potential is defined to be the pressure of the tensiometer water necessary to
equilibrate mechanically or hydraulically with the soil solution phase. The common term for
this potential is usually the soil moisture suction or tension in units of pressure (centibars,
kilopascals, inches of water column).
1.3 This procedure does not give true representative results for: soils with large
macropores, such as root and worm holes; soil and air temperatures below freezing: wide
fluctuations of air and soil temperature (especially at shallow depths); or sands at low water
content and finer textured soils with high specific surface. For situations such as these, a
modified method of testing or data calculation may be established to give results consistent
with the purpose of the measurement.
2. Summary of Procedure
2.1 The porous ceramic tip or cup of the tensiometer is sealed to a barrel or
connecting tube. A removable air-tight cap, through which water is introduced, is used to seal
the barrel. A device to measure the pressure in the water in the tensiometer cup (a Bourdon-
vacuum gauge) is attached near the upper end of the barrel. The connecting tube and all
pores in the porous cup are filled with deaerated water. As the water content of the soil
surrounding the water-filled porous tensiometer cup decreases, the energy level of the soil
water decreases relative to that of the water in the tensiometer cup, and water moves out of
the tensiometer through the pores in the tensiometer cup and into the soil. The pressure in
the water in the tensiometer cup is reduced. If the soil surrounding the porous cup receives
additional water, the soil water pressure is increased, and soil water flows through the walls
of the porous cup into the tensiometer, thereby increasing the pressure of the water in the
tensiometer cup. The energy status of the soil water (soil water matric potential) is estimated
from that of the tensiometer water, assuming that the latter is relatively close to being in
equilibrium with the soil water.
1-95
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Section No: 1.13
Revision No: 0
Date: May 1993
Page: 3 of 5
3. Significance and Use
3.1 For many soil types, the soil water matric potential is one of the most significant
index properties used in establishing a correlation between soil behavior and an index property.
3.2 A tensiometer measures the potential of the solution phase, including the effects
of gas phase pressure (sometimes not atmospheric), adsorptive forces (important in sands at
low water content and in finer textured materials with high specific surface), and overburden
load (important in swelling soils). The potential so obtained is the proper one to be used in
analyses of direction and rate of flow based on the Darcy equation.
3.3 The response time of a tensiometer is a measure of its responsiveness to changes
in soil water pressure head at the external surface of the cup. Increasing the cup conductance
and the gauge sensitivity will decrease the response time of the tensiometer. If the hydraulic
conductivity of the soil surrounding the cup is sufficiently low, the response of the instrument
may become limited by the conductivity of the soil.
3.4 If the pressure of the water in the tensiometer system decreases (the soil is very
dry), dissolved gases may come out of the solution. If the pressure in the water in the
tensiometer system is reduced to the level of the vapor pressure of water at the ambient
temperature of the system, the liquid water will spontaneously convert to water vapor. If the
difference between the gas phase pressure and the pressure in the tensiometer cup water
equals or exceeds that required to force a gas phase through a wetted porous cup, air will be
drawn into the cup. Any of these phenomena that introduce a gas phase into the tensiometer
system will seriously interfere with its operation.
4. Apparatus
4.1 A tensiometer constructed with a ceramic sensing tip (cup) of conductance on
the order of 1-3 * 10"5 cm2/s is sufficient for most field studies. For manual data collection,
the pressure (suction) is usually measured by a mercury-water manometer or a Bourdon
vacuum gauge. For automated data collection systems, electrical pressure transducers provide
an electrical output that may be used. It is useful to provide a space in the tensiometer barrel
above the point of connection of the vacuum sensing element to serve as a gas trap. This
upper portion of the barrel should be transparent. Tensiometer barrels are typically
approximately 20 mm in diameter and are available in lengths appropriate for installation of
the porous cup at depths of 15, 30, 45, 61, 76, 91, 106, 122, or 152 cm below the soil
surface.
4.2 Kits for complete servicing of tensiometers are generally available and
recommended for use. Sometimes these include a colored additive to be mixed with the
tensiometer water to inhibit algae growth and to provide greater visual contrast between the
water and accumulated air. If one is not supplied with the service kit, a plastic filler bottle
(0.5 L or 16 oz) and a filling tube will be needed. The service kit usually supplies a vacuum
hand pump used to deaerate the tensiometer water or fluid. A deep sink or bucket and a
board may be useful in the filling and deaerating processes.
1-96
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Section No: 1.13
Revision No: 0
Date: May 1993
Page: 4 of 5
4.3 If firm soils are going to be sampled, a properly sized coring or insertion tool will
also be needed. This tool will usually need to be driven by a mallet or hammer. For shallow
depths, a spade may be used to dig a hole rather than a coring tool.
5. Procedure
5.1 Prepare a solution of the tensiometer fluid (or use water without the additive).
Fill the tensiometer body full of fluid. Allow the tensiometer to remain in a vertical position
until fluid completely saturates the sensing tip and begins to drip from the end of the tip. If
a group of tensiometers is being filled, they can be placed in a deep sink or empty bucket for
support during the tip wetting process. Let the fluid drip from the tip for about 5 minutes to
wet thoroughly.
5.1.1 When the sensing tip is thoroughly wetted, fill the unit completely to the top and
pull a vacuum within the tensiometer using the vacuum hand pump. Let the sensing tip of the
tensiometer sit on a board for support while the rubber end of the vacuum hand pump is held
in tight contact with the "O" ring cap seal of the tensiometer. Pull up on the pump handle to
cause air to bubble out from the stem of the dial gauge. After each pumping, refill the
tensiometer completely to the top with fluid. This pumping operation should be repeated four
or five times until no further air is seen to bubble from the stem of the dial gauge. Seal the
unit by screwing the service cap in place.
5.2 Core a hole in the soil to accept the tensiometer. The hole should be the right
size to insure a snug fit between the ceramic sensing tip and the soil. Drive the coring or
insertion tool into the soil by a mallet or hammer to the depth required. Remove the coring
or insertion tool.
5.3 Push the tensiometer down into the soil until the bottom of the dial gauge is 5
to 8 cm (2 to 3 in.) above the soil surface. Tamp the soil around the body tube at the surface
to seal around the body tube and prevent surface water from running down around the body
tube.
5.3.1 If a rock or other impediment is encountered, move to an adjacent location to
avoid possible damage to the tensiometer when putting it in place.
6. Operation, Maintenance, and Servicing
6.1 After installation, wait several hours before reading the tensiometer. This delay
is because of the disturbance to the soil caused by the installation procedure. The correct
reading will be reached more quickly in moist soils than in dry soils.
6.2 If the soil in which the tensiometer has been installed is moist and the soil suction
readings are low, very little air will accumulate in the body tube of the tensiometer. If the
tensiometer has been installed in relatively dry soil and soil suction values are in the range of
40 to 60 kPa (or cbar), air will accumulate rather quickly for the first few days after
installation. After initial installation, check the tensiometer every day or two and service the
unit for accumulated air. Refill the tensiometer with fluid when the accumulated air level is
1 to 3 cm {0.5 to 1 in.) or more below the service cap. After the first few air removal
servicing operations, the rate of air accumulation will drop off markedly, and air removal
servicing will then be required only on a weekly or longer basis.
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Section No: 1.13
Revision No: 0
Date: Mav 1993
Page: 5 of 5
6.3 If a gauge has been left unattached for a long period of time at a high soil suction
value and the fluid level is very low or not observable, the unit should be refilled and then
pumped with the vacuum hand pump to make sure that all air is removed.
7. Report
7.1 The report (data sheet) shall include the following:
7.1.1 Identification of the sample being measured by location, station number, test
number, etc.
7.1.2 Soil water (moisture) potential reading from the gauge to the nearest centibar
(kPa).
7.1.3 Dates and times of insertion or last maintenance and of current measurement.
7.1.4 Approximate time and amount of rainfall since the last measurement, if known.
7.1.5 Depth of tensiometer sensing tip.
7.1.6 Indication of accumulated air in the body tube of the tensiometer and any air
removal servicing that was accomplished.
8. Precision and Accuracy
8.1 The dissolution of dissolved gases and the spontaneous vaporization of the water
cause the tensiometer not to be accurate at suctions of greater than about 85
kPa (cbar) when the ambient atmospheric pressure is approximately 76 cm of
mercury. The operating range of tensiometers used at higher elevations with
lower ambient pressures is correspondingly reduced.
8.2 The sensitivity of measurement of the pressure in the tensiometer with a Bourdon
vacuum gauge is about 1 to 2 kPa (cbar) (10 to 20 cm of water).
8.3 Other requirements for the precision and accuracy of this procedure have not yet
been developed.
REFERENCE
1. Cassel, D.K. and A. Klute. Water Potential: Tensiometry. In: Methods of Soil Analysis.
Part 1, 2nd ed., A. Klute, ed. ASA and SSSA, Madison, Wisconsin, 1986. pp. 563-
596.
1-98
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Section No: 2.6
Revision No: 0
Date: Mav 1993
Page: 1 of 5
2.6 Indoor Radon Progeny
Indoor Radon and Radon Decay Product Measurement Device Protocols.
EPA-402/R-92-004 (NTIS PB92-206176), U.S. Environmental Protection Agency,
Washington, D.C.
Abstract
The referenced document contains indoor radon decay product measurement protocols by
three commonly used techniques. The method most suitable for use in FRRP projects is
Protocol 3.1 (Continuous Working Level Monitors). Other radon and decay product methods
are also included which either are already covered in the initial manual (Protocol 2.5 - Indoor
Radon) or are less likely to be applicable to the program. The protocol describes the method
deployment strategies, operation, documentation, analysis, and quality assurance
considerations.
Applicability
This method is generally applicable to the FRRP research house projects, but may be
applicable to any other FRRP project that requires information concerning radon progeny.
Generally continuous working level monitors will be used in these projects. They will be
deployed at least once a quarter when continuous baseline indoor radon measurements are
being made. Such continuous simultaneous radon and radon progeny measurements will be
made for at least two consecutive days each quarter. If occupant risks, progeny levels, or
equilibrium ratios are of interest in any other of the specialty studies (de-pressurized
conditions, various HVAC conditions, etc.) of any of the research house groups, then similar
continuous simultaneous measurements may be taken. For certain of these special-purpose
measurements, standard deployment procedures (closed house conditions, etc.) may
deliberately be ignored. Because progeny measurements may be made under a variety of
conditions, care must be taken to document the actual house conditions at the time of the
measurement. For instance, the occupancy status, the HVAC operational mode, the
open/closed conditions of interior as well as exterior doors and windows, and any pressurized
or depressurized conditions should be noted.
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Section 3: INDOOR RADON DECAY PRODUCT
MEASUREMENT DEVICE PROTOCOLS
3.1 PROTOCOL FOR USING CONTINUOUS WORKING LEVEL MONITORS (CW)
TO MEASURE INDOOR RADON DECAY PRODUCT CONCENTRATIONS
3.1.1 Purpose
This protocol provides guidance for using continuous working level monitors (CW) to obtain accurate and reproducible
measurements of indoor radon decay product concentrations. Adherence to this protocol will help ensure uniformity
among measurement programs and allow valid intercomparison of results. Measurements made in accordance with
this protocol will produce results representative of closed-building conditions. Measurements made under closed-
building conditions have a smaller variability and are more reproducible than measurements made when the building
conditions are not controlled. The investigator should also follow guidance provided by the EPA in "Protocols for
Radon and Radon Decay Product Measurements in Homes" (U.S. EPA, Washington, DC, June, 1993, EPA 402-R-92-
003, NTIS PB-93-204014) or other appropriate EPA measurement guidance documents.
3.1.2 Scope
This protocol covers, in general terms, the sample collection and analysis method, the equipment needed, and the
quality control objectives of measurements made with CW. It is not meant to replace an instrument manual but,
rather, provides guidelines to be incorporated into standard operaing procedures by anyone providing measurement
services. Questions about these guidelines should be directed to the U.S. Environmental Protection Agency, Office
of Radiation Programs, Radon Division (6604J), Problem Assessment Branch, 401 M Street, S.W., Washington,
D.C., 20460.
3.1.3 Method
The CW method samples the ambient air by filtering airborne particles as the air is drawn through a filter cartridge
at a low flow rate of about 0.1 to one liter per minute. An alpha detector such as a diffused-junction or surface-
barrier detector counts the alpha particles produced by the radon decay products as they decay on the filter. The
detector is set normally to detect alpha particles with energies between two and eight MeV. The alpha particles
emitted from the radon decay products radium A (PO-218) and radium C' (Po-214) are the significant contributors
to the events that are measured by the detector. All CW detectors are capable of measuring individual radon and
thoron decay products, while some can be adapted to measure the percentage of thoron decay products. The event
count is directly proportional to the number of alpha particles emitted by the radon decay products on the filter. The
unit contains typically a microprocessor that stores the number of counts and elapsed time. The CW detector can
be set to record the total counts registered over specified time periods. The unit must be calibrated in a calibration
facility to convert count rate to Working Level (WL) values. This may be done initially by the manufacturer, and
should be done periodically thereafter by the operator.
3.1.4 Equipment
In addition to the CW detector, equipment needed includes replacement filters, a readout or programming device (if
not part of the detector), an alpha-emitting check source, and an air flow rate meter.
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3.1.5 Predeolovment Considerations
The plans of the occupant during the proposed measurement period should be considered before deployment. The
CW measurement should not be made if the occupant will be moving during the measurement period. Deployment
should be delayed until the new occupant is settled in the house.
The CW detector should not be deployed if the user's schedule prohibits terminating the measurement at the
appropriate time.
3.1.5.1 Pre-Sampling Testing The CW detector should be tested carefully before and after each measurement in
order to:
Verify that a new filter has been installed and the input parameters and clock are set properly;
Measure the detector's efficiency with a check source such as Am-241 or Th-230 and ascertain that
it compares well with the technical specifications for the unit; and
Verify the operation of the pump.
When feasible, the unit should be checked after ever)' fourth 48-hour measurement or week of operation to measure
the background count rate using the procedures that are in the operating manual for the instrument.
In addition, participation in a laboratory intercomparison program should be conducted initially and at least once every
12 months thereafter, and after equipment repair, to verify that the conversion factor used by the microprocessor Is
accurate. This is done by comparing the unit's response to a known radon decay product concentration. At this time,
the correct operation of the pump also should be verified by measuring the flow rate.
3.1.6 Measurement Criteria
The reader should refer to Section 1.2.2 for the list of general conditions that must be met to ensure standardization
of measurement conditions.
3.1.7 Deployment and Operation
3.1.7.1 Location Selection. The reader should refer to Section 1.2.3 for standard criteria
that must be considered when choosing a measurement device location.
3.1.7.2 Operation. The CW detector should be programmed to run continuously, recording the -periodic integrated
WL and, when possible, the total integrated average WL. The sampling period should be 48 hours, with a grace
period of two hours (i.e., a sampling period of 46 hours is acceptable if conditions prohibit terminating sampling after
exactly 48 hours). The longer the operating time, the smaller the uncertainty associated with using the measurement
result to estimate a longer-term average concentration. The integrated average WL over the measurement period
should be reported as the measurement result. If results are also reported in pCi/L, it should be stated that this
approximate conversion is based on a 50 percent equilibrium ratio, which is typical of the home environment, and
any individual environment may have a different relationship between radon and decay products.
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3.1.8 Retrieval of Detectors
When the measurement is terminated, the operator should note the stop-date and -time and whether the standardized
conditions are still in effect.
3.1.9 Documentation
The reader should refer to Section 1.2.4 for the list of standard information that must be documented so that data
interpretation and comparison can be made.
In addition, the serial number of the CW detector and calibraton factor used should be recorded.
3.1.10 Analysis Requirements
3.1.10.1 Sensitivity. All known commercially available CW detectors are capable of a lower limit of detection
(LLD [calculated using methods described by Altshuler and Pasteroack 1963J)1 of 0.01 WL or less.
3.1.10.2 Precision. Precision should be monitored and recorded using the results of side-by-side measurements
described in Section 3.1.11.3 of this protocol. This method can produce duplicate measurements with a coefficient
of variation of 10 percent or less at 0.02 WL or greater. An alternate measure of precision is a relative percent
difference, defined as the difference between two duplicate measurements divided by their mean; note that these two
measures of precision are not identical quantities. It is important that precision be monitored frequently over a range
of radon concentrations and that a systematic and documented method for evaluating changes in precision be part of
the operating procedures.
3.1.11 Quality Assurance
The quality assurance program for a CW system includes four parts: (1) calibration and known exposures, (2)
background measurements, (3) duplicate measurements, and (4) routine instrument checks. The purpose of a quality
assurance program is to identify the accuracy and precision of the measurements and to ensure that the measurements
are not influenced by exposure from sources outside the environment to be measured. The quality assurance program
should include the maintenance of control charts (Goldin 1984)2; general information is also available (Taylor 1987\
U.S. EPA 1984)4.
3.1.11.1 Calibration and Known Exposures. Every CW detector should be calibrated in a radon calibration chamber
before being put into service, and after any repairs or modifications. Subsequent recalibrations should be done once
every 12 months, with cross-checks to a recently calibrated instrument at least semiannually.
3.1.11.2 Background Measurements. Background count rate checks must be conducted after at least every 168 hours
(fourth 48-hour measurement) of operation and whenever the unit is calibrated. The CW should be purged with clean,
aged air or nitrogen in accordance with the procedures given in the instrument's operating manual. In addition, the
background count rate may be monitored more frequently by operating the CW in a low radon environment.
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3.1.11.3 Duplicate Measurements. When two or more CW detectors are available, the precision of the
measurements can be estimated by operating the detectors side-by-side. The analysis of duplicate results should follow
the methodology described by Goldin (section 5.3 in Goldin L984)ft"d, by Taylor (Taylor 1987)ik4', or by the EPA
(U.S. EPA 1984)lbid. Whatever procedures are used must be documented prior to beginning measurements.
Consistent failure in duplicate agreement may indicate a problem in the measurement process and should be
investigated.
3.1.11.4 Routine Instrument Checks. Checks using an Am-241 or similar-energy alpha check source must be
performed before and after each measurement. In addition, it is important to check regularly all components of the
equipment that affect the result.
Pump and flow meters should be checked routinely to ensure accuracy of volume measurements. This may be
performed using a dry-gas meter or other flow measurement device of traceable accuracy.
1 Altshuler, B. and Pasternack, B., 1963, "Statistical Measures of the Lower Limit of Detection of a Radioactivity
Counter," Health Physics. Vol. 9, pp. 293-298.3.1.10.2.
2 Goldin, A.F., 1984, "Evaluating Internal Quality Control Measurements and Radioassavs." Health Phvsics. Vol.47,
No. 3, pp. 361-364.
3 Taylor, J.K., 1987, Quality Assurance of Chemical Measurements. Lewis Publishing, Chelsea, MI.
4 US EPA, Dec. 1984, "Quality Assurance Handbook for Air Pollution Measurement Systems, Vol. 1," EPA-600/9-
76-005 (NTIS PB254658), Research Triangle Park, NC.
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2.7 Radon Entry Rate
Abstract
This section contains a test procedure for estimating the radon entry rates through portions
of the building envelope in communication with the soil or soil gas under controlled
depressurization.
This method is for measuring radon concentrations inside a building after fixed times of
controlled depressurization, during which careful measurements of the indoor-outdoor pressure
differential and the exhaust flows are made to ensure as close to constant levels as possible.
The method is most accurate when small temperature differentials and low wind-pressure
conditions are maintained. This method requires fairly simple measurements and produces
results that characterize the radon entry rates at various levels of depressurization. This can
be extrapolated down to normal ranges of building pressure differentials.
Applicability
This method will be used as a building diagnostic tool on several Florida Radon Research
Program projects, including the Research House projects and the New House Evaluation
Program projects. The test should not be run when strong wind and large indoor-outdoor
temperature differentials are likely. Because of differences between the various conditions
under which a building may be found and the test conditions on any given day, such
measurements cannot be interpreted as direct measurements of radon entry rates that would
occur on any given day. If the building has a very high leakage rate, or if the radon source
potential is very low, then the radon concentrations under depressurized, high exhaust flow
conditions may be near or below detection limits of the instruments. However, buildings with
these features tend not to have severe indoor radon concentration problems.
Relationship to Other Methods
This method uses much of the same equipment as the Standard Test Method for Determining
Air Leakage Rate by Fan Pressurization (Section 2.4.1; ASTM E779-87) and Alpha Scintillation
Cell Grab Samples (Section 2.1) and Indoor Radon by grab sampling (Section 2.5).
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Test Procedure for
Estimating Radon Entry Rate by Fan De-pressurization
1. Scope
1.1 This test procedure describes an experimental technique for estimating the radon
entry rates through the portions of the building envelope in communication with the soil or soil
gas under controlled de-pressurization.
1.2 This test procedure is applicable to small temperature differentials and low wind-
pressure conditions. For tests conducted in the field, it must be recognized that field
conditions may be less than ideal. Nevertheless, strong winds and, to a lesser degree, large
indoor-outdoor temperature differentials should be avoided.
1.3 The proper use of this test procedure requires a knowledge of the principles of
air flow and pressure measurements and of indoor radon concentration measurements.
1.4 This test procedure is intended to produce a measure of radon entry into a
structure. Because of differences between natural load and test conditions, however, such
measurements cannot be interpreted as direct measurements of radon entry rates that would
occur under natural conditions. However, they may provide a measurement which can be
performed in less than a day, is less variable than other short term tests that may be tried, and
has reduced possibility of tampering than most other tests.
2. Other Referenced Protocols
2.1 Florida Radon Research Program Protocols,
EPA-600/8-91-212 (NTIS PB92-115294)
Section 2.1 Alpha Scintillation Cell Grab Samples
Section 2.4.1 Building Leakage by Blower Door Measurements
2.2 ASTM Standard:
E 779 Test Method for Determining Air Leakage Rate by Fan Pressurization
3. Definitions
3.1 building envelope - the boundary or barrier separating the interior volume of a
building from the outside environment.
3.2 exhaust flow rate - the volume of air movement per unit time out of the
structure.
3.3 expected mean radon potential - the estimated radon concentration derived from
dividing the expected radon entry rate by the typical infiltration rate (with
appropriate unit conversions).
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3.4 expected radon entry rate - the estimated radon entry rate at the typical level of
depressurization the structure is expected to have, extrapolated from the radon
entry graph.
3.5 fan de-pressurization response curve - the graph that shows the relationship of
measured air flow rates to the corresponding measured pressure differences
(usually plotted on a log-log scale).
3.6 radon entry graph - the graph that shows the relationship of calculated radon
entry rates to the corresponding measured pressure differences.
3.7 radon entry rate - radioactivity of radon gas that enters a structure per unit of
time, calculated by multiplying the equilibrium radon concentration in radioactivity
per unit volume by the measured exhaust flow rate in volume of air per unit time
(normally expressed as picocuries per second, pCi/s).
3.8 test pressure difference - the actual pressure difference across the building
envelope, expressed in pascals or inches of water.
3.9 typical infiltration rate - the infiltration rate at the typical level of de-pressurization
the structure is expected to have, extrapolated from the air-leakage graph.
4. Summary of Test Procedure
4.1 This test procedure consists of mechanically de-pressurizing a structure to levels
greater than the mean environmental de-pressurization, measuring the resulting air flow rates
at given indoor-outdoor static pressure differences, measuring the indoor radon concentrations
after a delay to reach a steady state, and then repeating the sequence at two higher levels of
de-pressurization. From the air flow rates and radon concentrations, the radon entry rate for
each pressure difference can be determined. From the relationship between the radon entry
rates and pressure differences, the radon entry rates and expected mean radon potential of
the structure can be evaluated.
5. Significance and Use
5.1 A performance evaluation of radon resistance of houses based on standard short-
term measurement protocols may not be completely satisfactory. The wide variability of
radon concentrations in a single house may require measurement periods too long, or threshold
levels too low, for public acceptance of a standard enforced by such measurement. There
is also the potential problem of tampering with measurements that take more than one day
when the structure cannot be monitored continuously.
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5.2 Radon entry into houses is believed to be primarily due to pressure-driven flow of
soil gas, although a diffusive component may also be present.
5.3 For typical Florida sandy soil and low permeability sub-slab fill, soil gas entry rates
should be relatively low. Soil radon entry rates should vary linearly with applied pressure, and
no significant local depletion of radon should occur with increased soil gas entry.
5.4 Applying external driving forces in excess of the natural thermally induced pressure
differentials should reduce the relative fluctuations in radon entry, so more reproducible
measurements should be possible.
5.5 The house/soil system should reach a meaningful steady state within a few hours
after a change in applied pressure.
5.6 The effects of central HVAC systems should not dominate the effects induced by
the de-pressurizations imposed.
5.7 The fan-de-pressurization procedure should provide an unambiguous alternative test
which may be completed in less than a day with reduced possibility of tampering and less
variability of radon concentrations.
6. Apparatus
6.1 The following description of apparatus is general in nature. Any arrangement of
equipment using the same principles and capable of performing the test procedure within the
allowable tolerances may be used.
6.2 Major Components:
6.2.1 Air-Moving Equipment - A fan, blower, or blower door assembly that is capable
of moving air out of the conditioned space at required flow rates under a range of test
pressure differences. The system shall provide constant air flow at each incremental pressure
difference at fixed pressure for the period required to obtain samples of indoor radon
concentrations after a meaningful steady state has been reached.
6.2.2 Pressure-Measuring Device - A manometer or pressure indicator to measure
pressure difference with an accuracy of ±2.5 Pa (±0.01 in H20).
6.2.3 Air Flow or Velocity-Measuring System - A device to measure air flow within
±6% of the average value. The calibration of this air flow-measuring system shall follow the
manufacturer's instructions, and be recorded as such. The instrument may also be calibrated
in a calibrating wind tunnel.
6.2.4 Wind Speed-Measuring Device, to give an accuracy with ±0.25 m/s (5 mph).
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Perform wind speed measurements at a distance three to five building heights away from the
structure. List the height above ground at which wind speed is measured.
6.2.5 Temperature-Measuring Device, to give an accuracy of ±0.5°C (1 °F).
6.2.6 Air Flow-Regulating System - A device such as a damper, variable motor speed
control, or valve(s), that will regulate and maintain air flow and pressure difference to specific
limits.
6.2.7 Alpha-Scintillation Radon Monitors or Counting Station, for Lucas-type radon grab
sample cells.
6.2.8 Calibrated Alpha Scintillation Cells, for radon grab sampling. Two stem (flow-
through) cells are preferable.
6.2.9 Pump Assembly, for filling scintillation cells, capable of flow rate range from 0.5 -
2.0 1/min (or vacuum of -28 in. Hg or less if single stem cells are used).
6.2.10 Clock/Timer, to give an accuracy of ± 1 sec.
6.2.11 The size of the air duct and the capacity of the fan or blower shall be matched
so that the linear flow velocity within the air duct falls within the range of measurement of
the air flow meter.
7. Hazards
7.1 Glass should not break at the pressure differences normally applied to the test
structure. However, for added safety, adequate precautions such as the use of eye protection
should be taken to protect the personnel.
7.2 The test is most likely conducted in the field. Therefore, safety equipment required
for general field work also applies, such as safety shoes, hard hats, etc.
7.3 Because air-moving equipment is involved in this test, provide a proper guard or
cage to house the fan or blower and to prevent accidental access to any moving parts of the
equipment.
7.4 When the blower or fan is operating, a volume of air is being forced out of the
structure. Provide adequate shields or guards at the outlet of the air duct.
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7.5 Noise may be generated by moving air or the equipment used. Therefore, make
available hearing protection for personnel who must be close to the noise.
7.6 Care should be exercised not to suck debris or exhaust gases from fireplaces and
flues into the interior of the structure.
8. Procedure
8.1 All interconnecting doors (except for closets, which should be closed) in the space
being tested should be opened such that a uniform pressure will be maintained within a range
of less than 10% of the measured inside/outside pressure difference. This condition should
be verified by selected differential pressure measurement throughout the structure at the
highest pressure contemplated.
8.2 HVAC balancing dampers and registers should not be adjusted. Fireplace and other
operable dampers should be closed.
8.3 Establish baseline conditions for the structure for at least one hour before
proceeding.
8.4 Measure and record the wind speed and direction, indoor and outdoor
temperatures, and the time of day at the beginning and the end of the test. Fill duplicate
Lucas alpha-scintillation cells with house air to get baseline radon concentration before de-
pressurizing. Note time and set aside for at least four hours.
8.5 Perform fan de-pressurization test per ASTM E779-87 with the following
modification. At the 10 Pa de-pressurization, calculate the exhaust flow rate and determine
the volume of the living area. Maintain the 10 Pa de-pressurization for at least one hour or
the time sufficient to exhaust three air changes. Fill duplicate Lucas alpha-scintillation cells
with house air in line with the intake of the de-pressurization flow. Note time and flow rate.
Set aside for at least four hours. Raise structure de-pressurization to 20 Pa and maintain for
1 hour or 3 air changes, whichever is longer. Note time and flow rate. Fill two more Lucas
cells and set aside. Raise the de-pressurization to about 30 Pa and record the exhaust flow
rate and de-pressurization. Raise structure de-pressurization to 40 Pa and maintain for 1 hour
or 3 air changes, whichever is longer. Note time and flow rate. Fill two more Lucas cells and
set aside. Raise the structure de-pressurization to 50 Pa and 60 Pa if possible, and record the
exhaust flow rates and de-pressurization, completing the fan de-pressurization test.
8.6 Disassemble test apparatus. The remainder of the test sequence need not be
performed at the structure.
8.7 Using the calibrated scintillation cell counting station or radon monitor, count each
cell for 1 minute or 100 counts, whichever is longer. Allow at least 4 hours after collection
before starting to count. Convert cell counts to radon concentrations in pCi/1 using pre-
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determined calibration factors. To be valid, counts in duplicate cells should not differ by more
than the greater of 20% or 50 counts. Average each pair of calculated radon concentrations
to obtain a single concentration at each de-pressurization.
9. Data Analysis and Calculations
9.1 Using the measured exhaust flow rate Q and the calculated radon concentration
C for each de-pressurization dP, calculate the approximate radon entry rate R for each dP as
follows:
R (pCi/sec) = 0.47(1 -min/ft3 -sec)C(pCi/1 )Q(cfm)
or
R(pCi/sec) = 1000(1/m3) C(pCi/1 }Q(m3 /sec}
9.2 Plot R versus dP and extrapolate to dP = 0. If the data do not appear to be linear,
especially at higher AP, then the experiment may have to be repeated at three levels of de-
pressurization where linearity is expected. Estimate the value for R where dP is about 2.4 Pa,
the estimated mean structure de-pressurization. Call this value Rtyp, the expected radon entry
rate.
9.3 Using the fan de-pressurization response curve, extrapolate to obtain the estimated
air exhaust rate at 2.4 Pa. This will be assumed to represent a typical infiltration rate for the
house Qtyp.
9.4 Define Ctyp, the expected mean radon potential of the structure, by
Ctvp(pCi/l) = Rn.r( pCi/sec) = R^tpCi/sec)
1000 (l/m3)QIy()(m3/sec) O^yd-min/ft^secJQ^tcfm!
10.1 Report at least the following information:
10.1.1 Building Description:
10.1.1.1 Location and construction
10.1.1.2 Floor area of conditioned space
10.1.1.3 Volume of conditioned space
10.1.2 De-pressurization Measurements:
10.1.2.1 Equipment used
10.1.2.2 Measurement results
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10.1.3 Radon Concentration Measurements
10.1.4 Weather:
10.1.4.1 Wind speed/direction
10.1.4.2 Temperature (indoor and outdoor, both before and after the experiment)
10.1.4.3 Humidity (indoor and outdoor), if obtainable
10.1.5 Fan De-pressurization Response Curve
10.1.6 Radon Entry Graph
10.1.7 The expected radon entry rate, R^, and the estimated mean structure de-
pressurization used to approximate it.
10.1.8 The typical infiltration rate for the structure used in the calculations, Q(yp.
10.1.9 The expected mean radon potential of the structure, CtYP.
10.1.10 An estimate of the standard error of the mean radon potential of the structure.
11. Precision and Bias
11.1 The precision and bias of this test procedure is largely dependent on the
instrumentation and apparatus used and on the ambient conditions under which the data are
taken.
11.2 It is more precise to take pressure and flow data at a higher pressure difference
than at lower differences. Therefore, special care should be exercised when measurements
are taken at low pressure differences. However, the typical infiltration rate for the structure
used in the calculations is approximated from a low pressure difference, usually between 1
and 4 Pa. There is inherently poor precision in measurements made in this range, so the
extrapolated values will have low precision as well.
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2.8 Duct System Leakage
Abstract
This section contains a simple heating and air conditioning duct leakage testing protocol for
determining first if the air handler operation has a strong influence on the house pressure
differential and then a quantification of gross duct leakage. If either or both of these
simplified protocols produce measurable results, then a more involved protocol is introduced
for determining the external air leakage characteristics of the air distribution systems by fan
pressurization. The actual procedures for this more involved protocol are still being tested by
an ASTM sub-committee; so they cannot be reproduced here for general distribution. A
source to contact concerning the procedures is given.
Applicability
These methods will be used as building diagnostic tools on several Florida Radon Research
Program projects, including some Research House projects and the New House Evaluation
projects. The tests should not be run on days with strong winds or large indoor-outdoor
temperature differentials. Because of the difficulty in isolating the air handling system or its
component parts from various zones of the building structures, it is not possible to determine
precisely the duct leakage by these protocols. The problems vary as widely as the differences
in individual houses and their unique air handling systems.
Relationship to Other Methods
This method is an extension of the Standard Test Method for Determining Air Leakage Rate
by Fan Pressurization (Section 2.4.1; ASTM E 779-87}. Indeed it incorporates and supersedes
the last four pages of Sectio 2.4.1, Test Method for Determining the HAC Duct System
Leakage. It is also related to Trace Dilution Methods (Section 2.4.2; ASTM E 741-83).
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Simplified Heating/Air Conditioning (HAC) Duct Leakage Testing Protocols
Kenneth J. Gadsby
Princeton University
I. Measurement of HAC Operation Influence on House Pressure Differential
A. This method describes a simplified technique to quantify the pressure differential
across the building envelope with the HAC system operating.
B. Apparatus
1. Pressure-Measuring Device - A manometer or pressure indicator to measure
pressure difference with an accuracy of ±0.5 PA (±0.002 in WG).
2. Plastic tubing.
3. Sealant (rope-caulk, duct tape, etc.)
C. Procedure
1. Open all interior doors, except closet doors.
2. Close all exterior doors and windows.
3. Close all fireplace and other operable dampers that control flow between the
interior and exterior of the house.
4. Do not adjust HAC balancing dampers.
5. Route plastic tubing from central location in the interior of house to the outside
through partially opened window or other convenient pathway and locate outside end
so as not to be directly affected by wind (could be connected to manifolding that
would have input tubes from each side of the house).
a. Interior location should not be near HAC registers to avoid localized pressure
anomalies.
b. The tubing may be connected to a 1 liter reservoir or to a fitting with
hypodermic tubing as an orifice to damp pressure oscillations.
6. Seal opening through which tubing was passed with rope caulk or other non-
staining, easily removed material.
7. Connect outside tubing to reference (or low side) port of micromanometer or other
sensitive pressure measuring device, after zeroing instrument. This makes the outside
ambient the reference pressure.
8. Record pressure reading with HAC and all other fans that connect to the outside
of the house in the OFF position. Pay particular attention to sign of pressure
readings.
9. Turn on the HAC distribution fan and record the pressure difference reading after
2 minutes of operation.
a. A positive reading means that the house is pressurized by the HAC system,
conversely, a negative reading means HAC depressurization of the house.
10. Turn off HAC fan.
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11. Record pressure difference.
12. Repeat 9.
1 3. Turn off HAC fan.
14. Record pressure difference.
15. Average pressure differences, 9-11 and 12-14. This averaged pressure difference
is the pressure influence of the HAC on the structure.
16. Preferred test conditions are wind speed of 0 to 4.5 m/s (0 to 10 mph) and an
outside temperature from 5 to 35 C (41 to 95 F).
17. This technique may be used to test the effects of other fan system operation on
house pressure differentials by turning on and off those fans other than the HAC
fan.
II. Quantification of Gross Duct Leakage
A. This method describes a technique to measure the gross duct leakage under controlled
depressurization and/or pressurization.
B. Reference Document
1. ASTM Standard
a. E779-87 Determining Air Leakage Rate by Fan Pressurization
B. Apparatus
1. Same as E779-87
C. Procedure
1. Same setup as E779-87
2. With HAC system and all other ventilating fans in the off position, depressurize the
house in 6 increments of 10 Pa, from 10 to 60 Pa and record flow/pressure data.
3. Turn on the HAC fan.
4. Repeat 2 and record flow/pressure data.
5. Data analysis and calculations are the same as E779-87:
a. Convert flows to m3/sec (ft3/min) at reference conditions.
b. Plot the measured leakages against the corresponding pressure differences on
a log-log plot for both HAC off and HAC on.
c. Calculate effective leakage area as per E779-87 for HAC off and HAC on.
6. The difference between the flows, HAC off and HAC on, at any pressure
difference, is the net leakage of the duct system at that pressure difference.
a. If the flow through the blower door is higher with the HAC fan on, the return
system leaks dominate - the HAC fan is pressurizing the house.
b. If the flow through the blower door is lower with the HAC fan on, the supply
leaks dominate - the HAC fan is depressurizing the house.
7. If pressurization is used, all pressure operated dampers to the outside must be
sealed. These include bathroom and range vents, and whole house fan louvers.
8. Preferred test conditions are wind speeds of 0 to 4.5 m/sec (0 to 10 mph) and an
outside temperature from 5 to 35 C (41 to 95 F).
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Section No: 23.
Revision No: Q_
Date: Mav 1993
Page: 4 of 5
Summary of Draft Standard Test Method for
Determining the External Air Leakage Characteristics
of Air Distribution Systems for Fan Pressurization
Contact:
Mark P. Modera
Bldg. 90 Rm. 3074
Lawrence Berkeley Laboratory
Berkeley, CA 94720
415/486-4678
1. Scope
This test method is intended to produce a measure of the air tightness between an air
distribution system and its surroundings exterior to the conditioned spaces of a building. Two
standardized techniques are described and are applicable to small temperature differentials and
wind pressures, the uncertainties in the measured results increasing with increasing wind
speeds and temperature variations.
2. Referenced Documents
ASTM Standard: E 779 - Standard Test Method for Determining Air Leakage Rate by Fan
Pressurization.
3. Test Methods
The test method consists of mechanical pressurization and depressurization of an air
distribution system and the conditioned space of the building through which it passes, and
measurements of air flow rates at different pressure differentials between the distribution
system and its surroundings outside the conditioned portion of the building. From the
relationship between the measured air flow rates and pressure differences, the air leakage
characteristics of the external leaks on the supply and return sides of the air distribution
systems can be separately evaluated. Two alternative measurement techniques are specified,
one of which is recommended for leakier ducts, the other for tighter ducts.
4. Significance and Use
Air leakage between an air distribution system and unconditioned spaces affects the energy
losses from the distribution system, the ventilation rate of the building, and potentially the
entry rate of various pollutants.
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Section No: 2j|
Revision No: 0_
Date: May 1993
Page: 5 of 5
Air infiltration with and without an air distribution system operation may be measured
directly using a tracer dilution method. The fan pressurization method provides an indirect
way to relate the infiltration rate to the leakage of the structure and the leakage of the air
distribution system. The fan pressurization method thus has several advantages over the
tracer dilution method.
5. Apparatus
Major components are as follows: (1) air moving equipment, (2) a pressure-measuring
device, (3) a direct pressure measuring probe with a small velocities-pressure coefficient, (4)
a device to measure air flow within ± 3% of the true value, (5) a duct air flow measuring
system to measure air flow into or out of an air distribution register within ± 6% of the true
value, {6} a wind speed measuring device to give an accuracy within ± 0.25 m/s (0.5 mph)
at 2.5 m/s (5 mph) , (7) a temperature measuring device to give an accuracy of ± 0.5°C
(1 °F), (8) a simultaneous pressure and flow measurement system - three alternative systems
are: (a) a computerized data acquisition system, (b) a multi-channel sampler and hold
system, or (c) an interleaved multi-pylon sampling technique, (9) and air flow regulating
system that will regulate and maintain air flow and pressure difference within specific limits,
and (10) a blower door - a door mounted fan or blower that is adjustable to fit common door
openings. The fan or blower should possess a variable-speed motor to accommodate the
wide range of required flow rates up to 1.4 m3/s (3000 cfm).
6. Procedure
Because this procedure is undergoing ASTM review, it can not be reproduced here.
Therefore, for details of the procedure and analysis of data, the reader is requested to contact
Mark P. Modera at the Lawrence Berkeley Laboratory.
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