&EPA
United States
Environmental Protection
Agency
TECHNOLOGY EVALUATION REPORT
Biological Inactivation Efficiency by HVAC
In-Duct Ultraviolet Light Systems
American Ultraviolet Corporation
ACP-24/HO-4
Office of Research and Development
National Homeland Security
Research Center
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EPA 600/R-06/054
May 2006
Technology Evaluation Report
Biological Inactivation Efficiency
by HVAC In-Duct Ultraviolet Light
Systems
American Ultraviolet Corporation
ACP-24/HO-4
By
Karin Foarde, Deborah Franke, Tricia Webber, James Hanley, and
Kathleen Owen
RTI International
3040 Cornwallis Road
Research Triangle Park, NC 27709
Eric Koglin
Task Order Project Officer
National Homeland Security Research Center
Office of Research and Development
U.S. Environmental Protection Agency
944 East Harmon Ave.
Las Vegas, NV 8911
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Notice
The U.S. Environmental Protection Agency (EPA), through its Office of Research and Development's
National Homeland Security Research Center (NHSRC), funded and managed this technology
evaluation through a Blanket Purchase Agreement (BPA) under General Services Administration
contract number GS23F0011L-3 with Battelle, with RTI under subcontract to Battelle. This report has
been peer and administratively reviewed and has been approved for publication as an EPA document.
Mention of trade names or commercial products does not constitute endorsement or recommendation for
use of a specific product.
11
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Foreword
The U.S. Environmental Protection Agency (EPA) is charged by Congress with protecting the nation's
air, water, and land resources. Under a mandate of national environmental laws, the Agency strives to
formulate and implement actions leading to a compatible balance between human activities and the
ability of natural systems to support and nurture life. To meet this mandate, the EPA's Office of
Research and Development (ORD) provides data and science support that can be used to solve
environmental problems and to build the scientific knowledge base needed to manage our ecological
resources wisely, to understand how pollutants affect our health, and to prevent or reduce environmental
risks.
In September 2002, EPA announced the formation of the National Homeland Security Research Center
(NHSRC). The NHSRC is part of the Office of Research and Development; it manages, coordinates, and
supports a variety of research and technical assistance efforts. These efforts are designed to provide
appropriate, affordable, effective, and validated technologies and methods for addressing risks posed by
chemical, biological, and radiological terrorist attacks. Research focuses on enhancing our ability to
detect, contain, and clean up in the event of such attacks.
NHSRC's team of world renowned scientists and engineers is dedicated to understanding the terrorist
threat, communicating the risks, and mitigating the results of attacks. Guided by the roadmap set forth in
EPA's Strategic Plan for Homeland Security, NHSRC ensures rapid production and distribution of
security-related products.
The NHSRC has created the Technology Testing and Evaluation Program (TTEP) in an effort to provide
reliable information regarding the performance of homeland security related technologies. TTEP
provides independent, quality assured performance information that is useful to decision makers in
purchasing or applying the tested technologies. It provides potential users with unbiased, third-party
information that can supplement vendor-provided information. Stakeholder involvement ensures that
user needs and perspectives are incorporated into the test design so that useful performance information
is produced for each of the tested technologies. The technology categories of interest include detection
and monitoring, water treatment, air purification, decontamination, and computer modeling tools for use
by those responsible for protecting buildings, drinking water supplies and infrastructure, and for
decontaminating structures and the outdoor environment.
The evaluation reported herein was conducted by RTI International under contract to Battelle as part of
the TTEP program. Information on NHSRC and TTEP can be found at
http ://www. epa. gov/ordnhsrc/index. htm.
in
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Acknowledgments
The authors wish to acknowledge the support of all those who helped plan and conduct the evaluation,
analyze the data, and prepare this report. We would like to thank Dr. Leslie E. Sparks, USEPA, and Dr.
W. Gene Tucker, James Madison University, for their reviews of this report. We also acknowledge the
assistance and participation of our stakeholder group for their input to the test plan.
IV
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Contents
Notice ii
Foreword iii
Acknowledgments iv
Abbreviations/Acronyms vii
Executive Summary ix
1.0 Introduction 1
2.0 Technology Description 3
3.0 Test Procedures 5
3.1 Operation of the Test Duct 5
3.2 Preparation and Generation of Bioaerosol Challenges 6
3.3 Sampling the Bioaerosols 7
3.4 Bioaerosol Control Efficiency Calculation 7
3.5 Average Dose of UV Delivered by the Device 8
4.0 Quality Assurance/Quality Control 9
4.1 Equipment Calibration 9
4.1.1 Reference Methods 9
4.1.2 Instrument Checks 9
4.2 Audits 9
4.2.1 Performance Evaluation Audit 9
4.2.2 Technical Systems Audit 9
4.2.3 Data Quality Audit 10
4.3 QA/QC Reporting 10
5.0 Test Results 11
6.0 Performance Summary 12
7.0 References 13
v
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Figures
Figure 2-1. Ballast box installed on the outside of the test rig 4
Figure 2-2. Device installed inside the test rig 4
Figure 3-1. Schematic of Test Duct 5
Tables
Table 2-1. Specifications of the ACP-24/HO-4 3
Table 4-1. DQOs for Biological Aerosols 10
Table 5-1. Inactivation Efficiency 11
Table 5-2. Other Information for the ACP-24/HO-4 11
VI
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Abbreviations/Acronyms
A
ANSI
ARTI
ASHRAE
ASME
ATCC
B
BG
BWA
°C
cfm
CPU
cm
CV
DQO
EPA
°F
fpm
ft
HVAC
in.
J
KC1
m
mL
NEMA
nm
NHSRC
QA
QC
OPC
ORD
Pa
PE
PFU
ampere
American National Standards Institute
Air-Conditioning and Refrigeration Technical Institute
American Society of Heating, Refrigerating and Air-Conditioning Engineers
American Society of Mechanical Engineers
American Type Culture Collection
Bacillus
Bacillus atrophaeus (formerly B. subtilis var. niger and Bacillus globigii)
biological warfare agent
degrees Celsius
cubic feet per minute
colony forming unit(s)
centimeter(s)
coeffi ci ent of vari ati on
data quality objective
U.S. Environmental Protection Agency
degrees Fahrenheit
feet per minute
feet
heating, ventilation and air-conditioning
inch(es)
joule
potassium chloride
meter(s)
milliliter(s)
micrometer(s)
microwatts(s)
National Electrical Manufacturers Association
nanometer(s)
National Homeland Security Research Center (EPA)
quality assurance
quality control
optical particle counter
Office of Research and Development (EPA)
pascal(s)
performance evaluation
plaque forming unit(s)
vn
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psig pounds per square inch gauge
QMP quality management plan
QSA quality system assessment
RMS root mean square
RTI Research Triangle Institute (RTI International)
S Serratia
sec second(s)
TSA technical system assessment
TTEP Technology Testing and Evaluation Program
UV Ultraviolet; the C band is used for disinfection
V volt(s)
W watt(s)
Vlll
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Executive Summary
The U.S. Environmental Protection Agency's (EPA's) National Homeland Security Research Center
(NHSRC) Technology Testing and Evaluation Program (TTEP) is helping to protect human health and
the environment from adverse impacts resulting from acts of terror by carrying out performance tests on
homeland security technologies. Under TTEP, RTI recently evaluated the performance of the American
Ultraviolet Corporation ACP-24/HO-4. The objective of testing the device was to evaluate its bioaerosol
inactivation efficiency as a heating, ventilation and air-conditioning (HVAC) in-duct ultraviolet light
system.
The product was tested using a test plan approved by EPA, Test/QA Plan for Biological Inactivation
Efficiency by HVAC In-Duct Ultraviolet Light Air Cleaners^ The tests were conducted using three
organisms, two bacteria {Bacillus atrophaeus and Serratia marcescens) and one bacterial virus (MS2).
These organisms were selected because their sizes, shapes and susceptibility toUV inactivation make
them reasonable surrogates for biological warfare agents (BWAs). Generally, vegetative bacteria are
readily killed and bacterial spores are more difficult. To model use in an HVAC system, RTI used a test
duct designed for testing filtration and inactivation efficiencies of aerosol, bioaerosol, and chemical
challenges.
The bioaerosol inactivation efficiencies calculated for the three organisms were 9% for B. atrophaeus.,
399.96% for S. marcescens and 75% for MS2. The irradiance was measured as 1190 |iW/cm2 at 161 cm
(63 in.) upstream from the lamps with an airflow of 0.93 m3/sec (1970 cfm). The system had four lamps
that were burned in for 100 hours prior to measurements.
IX
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1.0 Introduction
The U.S. Environmental Protection Agency's (EPA's) National Homeland Security Research Center
(NHSRC) is helping to protect human health and the environment from adverse impacts resulting from
intentional acts of terror. With an emphasis on decontamination and consequence management, water
infrastructure protection, and threat and consequence assessment, NHRSC is working to develop tools
and information that will help detect the intentional introduction of chemical or biological contaminants
in buildings or water systems, the containment of these contaminants, the decontamination of buildings
and/or water systems, and the disposal of material resulting from cleanups.
NHSRC's Technology Testing and Evaluation Program (TTEP) works in partnership with recognized
testing organizations; with stakeholder groups consisting of buyers, vendor organizations, and
permitters; and with the full participation of individual technology developers in carrying out
performance tests on homeland security technologies. The program evaluates the performance of
innovative homeland security technologies by developing test plans that are responsive to the needs of
stakeholders, conducting tests, collecting and analyzing data, and preparing peer-reviewed reports. All
evaluations are conducted in accordance with rigorous quality assurance (QA) protocols to ensure that
data of known and high quality are generated and that the results are defensible. TTEP provides high-
quality information that is useful to decision makers in purchasing or applying the tested technologies. It
provides potential users with unbiased, third-party information that can supplement vendor-provided
information. Stakeholder involvement ensures that user needs and perspectives are incorporated into the
test design so that useful performance information is produced for each of the tested technologies.
UV lamps have been used to inactivate airborne microorganisms for many years.
Much of the early work was directed at the control of very infectious microorganisms (particularly
Mycobacterium tuberculosis, the causative agent of tuberculosis), often in medical facilities.
Wavelengths within the short wave, or C band of UV light (UVC), were found to be the most effective
germicidal light wavelengths. UVC usually is generated by use of UVC fluorescent lamps. These lamps
use electrical discharge through low-pressure mercury vapor enclosed in a glass tube that transmits UVC
light (primarily at the mercury wavelength of 253.7 nm). Because this wavelength has been found to be
about the optimum for killing microorganisms, UVC from mercury lamps also is referred to as UVG to
indicate that it is germicidal. UVG has been shown to inactivate viruses, mycoplasma, bacteria, and
fungi when used appropriately.
Numerous past studies of UVC to inactivate microorganisms have been conducted for a variety of
purposes and with a variety of methods. No standard method exists for evaluating culturable bioaerosol
inactivation by these devices. However, as part of the project entitled, "Defining the Effectiveness of
UV Lamps Installed in Circulating Air Ductwork" funded by the Air-Conditioning and Refrigeration
Technology Institute (ARTI), RTI developed a test method for measuring culturable bioaerosol
inactivation efficiencies by UV lights.(2) This method was derived from earlier bioaerosol air cleaner
test methods developed for determining the bioaerosol filtration efficiencies of various air cleaning
devices including room air cleaners and duct-mounted ventilation filters.(3'4'5) These bioaerosol methods
were based on RTFs extensive experience in the development of parti culate testing methods of various
air-cleaning devices.
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The current TTEP effort focuses on UV systems that are mounted in the HVAC ducting (in-duct UV
light systems) and that operate on a "fly-through" basis. That is, they are designed to destroy
bioaerosols in the flowing air stream as it passes through the device. This is distinguished from UV
devices that are designed to treat specific surfaces within the HVAC system, in particular, the cooling
coils and the condensate drain pan, to prevent biological growth on those surfaces. This program tested
inactivation of airborne bioaerosols; inactivation of microorganisms on surfaces was not evaluated.
The bioaerosol tests were conducted using three organisms, consisting of two bacteria (spore-forming
Bacillus atrophaeus and the vegetative bacterium Serratia marcescens) and one bacterial virus (MS2)
that cover the range of potential interest for biological warfare agent (BWA) applications. These
organisms were selected because their sizes, shapes and susceptibility toUV inactivation make them
reasonable surrogates for BWAs. Generally, vegetative bacteria are readily killed and bacterial spores
are more difficult. The spore form of the bacteria^ac/'/te atrophaeus (formerly B. subtilis var. niger
and Bacillus globigii or BG) was used as the surrogate for gram-positive spore-forming bacteria. The
BG spore is elliptically shaped with dimensions of 0.7 to 0.8 by 1 to 1.5 jim. Serratia marcescens was
used as the surrogate for rod-shaped gram-negative bacteria. S. marcescens is 0.5 to 0.8 by 0.9 to 2.0
The bacterial virus (b acted ophage) MS2, having approximately the same aerosol characteristics as a
human virus, was used as a surrogate for the viruses of similar and larger size and shape. Although the
individual virus particles are in the 0.02 - 0.03 jim size range, the test particle size for the virus tests
spanned a range of sizes (poly dispersed bioaerosol) in the micron range. This test was not designed to
study the inactivation efficiencies for individual virus singlets; rather, it was designed to determine the
inactivation efficiencies for virus particles as they are commonly found indoors. A representative
challenge would be a polydispersed aerosol containing the bacteriophage because:
$ The aerosols created from sneezing and coughing vary in size from < 1 to 20 |im, but the largest
particles settle out and only the smaller sizes remain in the air for extended periods for potential
removal by an air cleaner; (6)
$ For some viruses (e.g., Coxsackie virus), few viruses have been found associated with the smallest
particles; (7) and
$ Nearly all 1 - 2 jim particles are deposited in the respiratory tract, while larger particles may not be
respired.
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2.0 Technology Description
The information in this section was provided by the vendor and was not evaluated by RTI.
The American Ultraviolet Company's ACP-24/HO-4 is part of the ACP Series in-line Duct Sterilizers
that are designed to install into air duct sections to position high output UVC lamp(s) perpendicular to
passing airflow for "pass-by" air sterilization purposes as well as surface sterilization. The ballast
enclosure mounts directly to the duct exterior with lamp(s) protruding into the duct section through a
cutout in the duct wall. Type 304 stainless steel construction utilized for long life. Outdoor ballast
enclosures are available as an option. The GML435 High Output UVC Lamp is used in the system.
Table 2-1 provides information on the system as supplied by the vendor. Figures 2-1 and 2-2 provide
views of the device as tested, installed in accordance with the manufacturer's specifications.
Table 2-1. Specifications of the ACP-24/HO-4
Attribute
Total power for the lamp (watts)
Total UVC power for the lamp (watts)
Irradiance (output) of the lamp, give distance
and other information (e.g., airflow) (W/cm2)
Dosage (J/cm2 or W-s/cm2)
Ballast root mean square (RMS) voltage and
current
Dimensions of the lamp
Dimensions of the ballast box
Configuration
Other lamp characteristics
Specification
240 total watts
81 total UVC watts
840 uW/cm2 @ 1 meter [7.2 °C (45 °F), 400 FPM airflow]
N/A
Available as 1 20 / 230 / 277 VAC
2.2/1.1 /1 A
534 mm (21 .02) arc length
30.8 cm (12. 125 in.) length x 10.8 cm (4.25 in.) width x 10.2
cm (4 in.) height
(4) Lamp unit with ballasts mounted in exterior enclosure
N/A
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Figure 2-1. Ballast box installed on the
outside of the test rig.
Figure 2-2. Device installed inside the test
rig. There are 4 lamps and 3 support rods.
For more information on the ACP-24/HO-4, contact:
Meredith Stines (President / CEO)
212 South Mount Zion Road
Lebanon, Indiana 46052
Phone: 765-483-9514, extension 201
Fax: 765-483-9525
mstines@americanultraviolet.com
www.americanultraviolet.com
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3.0 Test Procedures
3.1 Operation of the Test Duct
The testing was conducted in the test duct shown schematically in Figure 3-1. The test section of the
duct is 0.61 m by 0.61 m (24 in. by 24 in.). The locations of the major components, including the
sampling probes, the device section (where the UV device is installed), and the aerosol generator (site of
bioaerosol injection) are shown. The test duct is operated following procedures in the ANSI/ASHRAE
(American National Standards Institute/American Society of Heating, Refrigerating and Air-
Conditioning Engineers) Standard 52.2-1999, Method of Testing General Ventilation Air-Cleaning
Devices for Removal Efficiency by Particle Size.(8)
Exhaust
to
Room
Test
\.
ASME
Outlet Filter Bank N°fzle
i Biological
1 1 Sampling
|
1
^
Downstream Mixer
\
*£& ^ ' ^
Inlet Filter
Bank
Filter
Holder
Flow Control
Valve
Aerosol
Generator
Device
Section
Figure 3-1.
(Used When Schematic of
Dust-loading) _ TT.T
Biological Duct. UV
Sampling system is placed in device section.
While Figure 3-1 shows the test duct without recirculation, during testing, the duct may be operated with
or without recirculation. The decision for recirculation mode is based on building HVAC considerations.
Because of the HEP A filters at the beginning and the end of the duct, the recirculation mode does not
affect the test data as long as all other criteria are met.
The air flow rate through the duct during this testing was 0.93 mVsec (1970 cfm). This flow creates a
typical air velocity (492 fpm) in the duct, and has been used extensively in prior testing of air cleaning
devices in this rig. The air temperature entering the device was approximately 23 °C. Air flow rate and
temperature can have an impact on lamp performance, and the values used in this testing are consistent
with vendor specifications. As explained in the VanOsdell and Foarde report,(2) lamps are designed for
an optimal temperature, and either higher or lower values may lower the irradiance.
Prior to testing the device, the UV lamps were operated for a standard 100-hr "burn-in" period.
In a given run, one of the three challenge bioaerosols - prepared as described in Section 3.2 - was
injected upstream of the device. A no-light test was performed with the UV lights turned off, to
determine the microorganism loss that would occur simply as the result of deposition in the test duct,
and as the result of kill caused by the physical rigors of flowing through the device. See Section 4.3 for
the acceptable range of the penetration for this test. As discussed later, the performance of the device
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was then reported as the device's efficiency in inactivating the organism with the light on, corrected to
account for the loss of organisms observed in the absence of UV light.
In addition to the measurement of the concentration of culturable organisms upstream and downstream
of the device, other measurements that were made include:
• The energy required to operate the unit, including the direct total power consumption by the lamp
and ballast, the pressure drop across the device (impacting air handler requirements), and the
temperature rise through the unit, if any (impacting cooling coil energy consumption).
• A single measurement of the intensity of 254 nm UV radiation (uW/cm2) at a point 161 cm (63 in.)
upstream from the lamps, to demonstrate that the lamps were functioning and to provide a test
reference value for the laboratory for documentation purposes.
3.2 Preparation and Generation of Bioaerosol Challenges
The bioaerosol tests were conducted using three organisms, two bacteria (Bacillus atrophaeus and
Serratia marcescens) and one bacterial virus (MS2). The selection of the bioaerosols was discussed in
Section 1.
The microbial challenge suspensions were prepared by inoculating the test organism onto solid or into
liquid media, incubating the culture until mature, wiping organisms from the surface of the pure culture
(if solid media), and eluting them into sterile fluid to a known concentration to serve as a stock solution.
The organism preparation was then diluted into sterile nebulizing fluid. The nebulizing fluid was
composed of salts (buffering), peptone and antifoam (S. marcescens only). The composition of the
nebulizing fluid should have provided a protective effect similar to organic matter (dirt, debris, etc.) for
the S. marcescens and possibly the MS2 against the inactivation of the UVC. Based on the ARTI study,
little or no effect was anticipated for the B. atrophaeus as spores were found to be relatively unaffected
by protective factors.(2) The nebulizing fluid was quantified on trypticase soy agar to enumerate the
bacteria.
The bacteriophage challenge was prepared by inoculating a logarithmic phase broth culture of the host
bacteria (E. coif) with bacteriophage and allowing it to multiply overnight or until the majority of the
host bacteria were lysed (ruptured or broken down). The mixture was processed to collect and
concentrate the bacteriophage. Then, the bacteriophage stock was filter sterilized (0.2 jim) to remove the
bacteria. The bacteriophage stock was used as the challenge aerosol. The concentration of the
bacteriophage stock was approximately 1 x 109 or higher plaque forming units (PFU)/mL. The virus
assay used a standard double agar layer plaque assay, in which host cell Escherichia coli C3000 (ATCC
15597) in the log phase of growth and serial dilutions of the MS2 virus stock (ATCC 15597-B1) were
combined and top agar added and then poured onto bottom agar plates.(9) After incubation, at least
overnight, at 37 °C, plaques (loci of infection) were counted against an opaque lawn of host cell E. coli
C3000.
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The challenge organism suspensions were aerosolized using a Collison nebulizer (BGI, Waltham, MA)
at 15 psi air pressure. The Collison nebulizer generated droplets with an approximate volume mean
diameter of 2 jim. The particle diameter after the water evaporated depended on the solids content of
the suspension and the size of the suspended particles. Prior experience has shown that the bacterial
organism aerosols generated by this procedure are primarily singlets.
3.3 Sampling the Bioaerosols
All the bioaerosols were collected in liquid impingers, AGI-4 (Ace Glass Inc., Vineland, NJ). Because
exposure to UV radiation is a common environmental hazard, cells have developed a number of repair
mechanisms to counteract UV-induced damage that must be considered when experimentally measuring
UV effects. Collecting in impinger fluid maximized the collection of damaged organisms. After
sampling, the impinger fluid was plated and incubated at appropriate times and temperatures for the test
organism being used. To quantify the microbial counts, the plates were incubated at the appropriate
temperature and time for the test organism (overnight to a week). Colonies or plaques were counted.
3.4 Bioaerosol Control Efficiency Calculation
The efficiency of the device for inactivating airborne bioaerosols was then calculated as:
Airborne Inactivation Efficiency (%) = 100 (1 - Survival Ratecorrected) (Equation 1)
The calculation of the test organism survival rate (culturable transmission) was based on the ratio of the
downstream to upstream culturable organism counts. To remove system bias, the Survival Rate was
corrected by the results of the blank no-light transmission test. The blank no-light transmission rate
(light was not turned on in the test duct) was calculated the same as the survival rate test, but using the
culturable organism counts from the no-light tests.
3.5 Average Dose of UV Delivered by the Device
The equation used to describe the effect of UV on a single species population of airborne
microorganisms is:
Nt/No = exp(- k • dose) (Equation 2)
where:
Nt = the number of microorganisms at time t,
No = the number of microorganisms at the start,
k = a microorganism-dependent rate constant, in cm2/|iW-s.
The fractional inactivation achieved by the device is (l-Nt/No), as indicated in Equation 1.
We calculate the dose by rearranging Equation 2 to yield
Dose = - ln(Nt/No) (Equation 3)
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Mean dose was computed from Equation 3 using the values of Nt and No obtained with B. atrophaeus
and using the organism-specific value of k for this organism (1.6 x 10"4 V 0.3x 10"4 cm2/|iW-s). B.
atrophaeus was selected for determining dose based on earlier RTI measurements as discussed in
Amendment 1 of the test plan.
The UV dose calculated in this manner is the mean dose to a single organism having an "average"
trajectory through the device. It is reported here as a characteristic of the device being tested. Dose is
shown as a mean and a range plus standard deviation, reflecting the natural variation in a population of
microorganisms.
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4.0 Quality Assurance/Quality Control
Quality assurance/quality control (QA/QC) procedures were performed in accordance with the program
QMP and the test/QA plan for this evaluation.(10'1}
4.1 Equipment Calibration
4.1.1 Reference Methods
As noted in Chapter 1, while reference methods were not available for determining the inactivation
efficiency of the device, accepted methods developed and used in related work were used. Test
specifications given in the appendices of the approved test/QA plan were derived from the related
ASHRAE 52.2 method, with additional specifications and quality control checks relevant to this
testing.(1'8)
4.1.2 Instrument Checks
The ACP-24/HO-4 was installed in the test duct, and operated and maintained according to the vendor's
instructions throughout the test. No maintenance was required during the test.
4.2 Audits
4.2.1 Performance Evaluation Audit
No PE audits were performed during this test.
4.2.2 Technical Systems Audit
The RTI Quality Manager conducted a combined QSA/TSA to ensure that the technology evaluation
was performed in accordance with the approved test/QA plan and the TTEP QMP. (1'10) Using a prepared
checklist reflecting the test/QA plan, the RTI Quality Manager reviewed task systems as well as
technology-specific sampling and analysis methods used, compared actual test procedures with those
specified in the test/QA plan, and reviewed data acquisition and handling procedures.(1) Observations
from this audit were documented and submitted to the RTI Task Manager. No significant findings were
noted in this assessment that might impact the quality of the evaluation results. The records concerning
the TSA are permanently stored with the RTI Task Manager.
The EPA Quality Manager conducted a combined QSA/TSA to independently assess conformance to
the approved test/QA plan of project activities.(1) No significant findings were noted in this assessment
that might impact the quality of the evaluation results. Minor recommendations were made and are
being implemented.
4.2.3 Data Quality Audit
At least 10% of the data acquired during the evaluation was audited by the RTI Quality Manager who
traced the data from the initial acquisition, through reduction and statistical analysis, to final reporting,
to ensure the integrity of the reported results. All calculations performed on the data undergoing the
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audit were checked. This activity is summarized in a technology-specific report to the RTI Task
Manager.
4.3 QA/QC Reporting
Each assessment and audit was documented in accordance with the test/QA plan.(1) Once the assessment
report was prepared, the RTI Task Manager ensured that a response was provided as appropriate. For
this technology evaluation, no significant findings were noted in any assessment or audit, and no follow-
up corrective action was necessary.
The testing followed quality assurance and quality control requirements as given in the test/QA plan.
The RTI Quality Assurance Manager reviewed the test results and the quality control data and
concluded that the data quality objectives as shown in Table 4-1 and in Amendment 1 of the test/QA
plan were attained.
Table 4-1. DQOs for Biological Aerosols
Parameter
Minimum upstream counts for
samplers
Maximum counts for samplers
1 00% Penetration
(no light)
(correlation test)
Upstream CPUs
Upstream PFUs
Frequency and description
Each efficiency test.
Each efficiency test.
Performed at least once per test
sequence per organism.
Each test. Statistical check of
data quality.
Each test. Statistical check of
data quality.
Control Limits
Minimum of 10 CFUa/plate or PFUb/plate
Maximum of 500 CFU/plate or 800
PFUb/plate
Test Acceptable
Oraanism Penetration Ranae
B. atrophaeus 0.85 to 1 .15
S. marcescens 0.80 to 1 .20
MS2 0.75 to 1.25
CVC # 0.25
CVC#0.35
CFU = colony forming units
b PFU = plaque forming unit
c CV = coefficient of variance
Data quality objectives (DQOs) are qualitative and quantitative statements designed to ensure that the
type, quality, and quantity of data used are appropriate for the intended application. In addition, the
minimum and maximum upstream counts help to ensure that the challenge concentration of each
organism entering the UV device remains at an acceptably steady value that is sufficiently low such that
device performance should be independent of the concentration at the test conditions used in this study.
10
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5.0 Test Results
The bioaerosol inactivation efficiency results, derived using Equation 1, are given in Table 5-1. Table 5-
2 provides other information about the UV system.
Table 5-1. Inactivation Efficiency
Inactivation
efficiency, (UV light
on) %
Test organism
Spore form of bacteria
(B. atrophaeus)
9
Vegetative bacteria
(S. marcescens)
E99.963
Bacterial virus
(MS2 bacteriophage)
75
a - the value 99.96 represents a 95% confidence limit for S. marcescens. There were no downstream counts
measured.
Table 5-2. Other Information for the ACP-24/HO-4
Attribute
Test duct operating conditions
Air flow rate
Inlet and outlet temperature
UV exposure conditions provided by device
Mean dosage calculated from Equation 3 and range resulting
from standard deviation of the k value
A single irradiance measurement at 254 nm
Measures of energy consumption by the unit
Power consumed by the lamps/ballasts and by any
ancillary equipment required by the vendor
Pressure drop across the device
Air temperature rise through the device
Measured or Calculated Values
0.93 m3/sec(1 970 cfm)
Upstream 23.0 °Ca (73.4°F) , Downstream
23.2 °Ca (73.8 °F)
582(490-716) uW-s/cm2
1190 uW/cm2 at 161 cm (63 in.) upstream
from the lamps at 0.93 m3/sec (1970 cfm)
169.1 W
<8Pab(0.03in.H20)
0.2 °Ca (0.4 °F)
a - the accuracy of the thermometers are V0.5 °C; therefore, temperature variations below that are not
necessarily significant.
b - the pressure drop was less than the maximum allowable pressure drop measurement for an empty test
section as specified in ANSI/ASHRAE 52.2-1999.(8)
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6.0 Performance Summary
This verification report addresses the inactivation efficiency performance (Table 5-1) for the American
Ultraviolet Corporation ACP-24/HO-4 ultra-violet light system that operates in an HVAC system. Other
measures are given in Table 5-2. Users may wish to consider other performance parameters such as
service life and cost when selecting a UV light system for their application.
The bioaerosol inactivation efficiencies calculated for the three organisms were 9% for B. atrophaeus,
399.96% for S. marcescens and 75% for MS2. The irradiance was measured as 1190 |iW/cm2 at 161 cm
(63 in.) upstream from the lamps with an airflow of 0.93 m3/sec (1970 cfm). The system had four lamps
that were burned in for 100 hours prior to measurements. The spore form of the bacteria 5. atrophaeus is
more resistant to being killed by UV than the vegetative bacteria S. marcescens.
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7.0 References
1. RTI. 2005. Test/QA Plan for Biological Inactivation Efficiency by HVAC In-Duct Ultraviolet Light
Air Cleaners. Research Triangle Institute, Research Triangle Park, NC.
2. VanOsdell, D. and K. Foarde. 2002. Final Report ARTI-21CR/610-40030-01 Project -Defining the
Effectiveness of UV Lamps Installed in Circulating Air Ductwork, Air-Conditioning and
Refrigeration Technology Institute, 4100 N. Fairfax Drive, Suite 200, Arlington, Virginia 22203.
http ://www. arti-21 cr. org/research/completed/fmalreports/4003 0-fmal .pdf
3. Foarde, K. and J. Hanley. 2001. Determine the Efficacy of Antimicrobial Treatments of Fibrous Air
Filters. ASHRAE Transactions. Volume 107, Part 1. 156-170.
4. Foarde, K.K. and J.T. Hanley. 1999. A New Laboratory Method for Measuring the Bioaerosol
Filtration Efficiency of Air Cleaners. Proceedings: 1999 Air Filtration Conference: Fall Topical
Conference pp. 47-54.
5. Foarde, K.K., J.T. Hanley, D.S. Ensor, andP.F. Roessler. 1999. Development of a Method for
Measuring Single-Pass Bioaerosol Removal Efficiencies of a Room Air Cleaner. Aerosol Science
and Technology. 30: 223-234.
6. Knight, V 1973. Viral and Mycoplasmal Infections of the Respiratory Tract, Lea & Febiger,
Philadelphia, PA.
7. Buckland, F.E., and Tyrell, D.A.S. 1962. Loss of Infectivity on Drying Various Viruses, Nature
195: 1063-1064.
8. ANSI/ASHRAE (American National Standards Institute/American Society of Heating, Refrigerating
and Air-Conditioning Engineers). 1999. ANSI/ASHRAE Standard 52.2-1999, Method of Testing
General Ventilation Air-Cleaning Devices for Removal Efficiency by Particle Size, Section 5.16.2,
Atlanta, GA.
9. Adams, M.G. (1959). Bacteriophages. Interscience, New York.
10. Battelle. Quality Management Plan (QMP) for the Technology Testing and Evaluation Program
(TTEP), Version 1, January 2005. Columbus, OH.
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