&EPA
United States
Environmental Protection
Agency
REPORT FOR
Biological Inactivation Efficiency by HVAC
In-Duct Ultraviolet Light Systems
Abracair, LLC
In-Duct System
Office of Research and Development
National Homeland Security
Research Center
A CAUTION
THE A R TREATMENT (UV)DEV.CE
PRIOR TO SERVICING.
Alf Puf,f,cal«on System
-------
EPA 600/R-06/085
September 2006
Technology Evaluation Report
Biological Inactivation Efficiency
by HVAC In-Duct Ultraviolet Light
Systems
In-Duct System
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 89119
-------
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
-------
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
-------
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
-------
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 12
6.0 Performance Summary 13
7.0 References 14
v
-------
Figures
Figure 2-1. Device and filter 3
Figure 2-2. Device installed inside the test rig 3
Figure 3-1. Schematic of Test Duct 5
Tables
Table 2-1. Specifications of the Abracair In-Duct System 4
Table 4-1. DQOs for Biological Aerosols 11
Table 5-1. Inactivation Efficiency 12
Table 5-2. Other Information for the Abracair In-Duct System 12
VI
-------
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
-------
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
-------
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 as a result of acts of terror by carrying out performance tests on
homeland security technologies. Under TTEP, RTI recently evaluated the performance of the Abracair
In-Duct System. 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 inactivate. 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 6.9% for B. atrophaeus,
99.8% for S. marcescens and 59% for MS2. Because the UV is pulsed, the irradiance measurements
covered a wide range from 1800 - 5100 |iW/cm2 at 117 cm (46 in.) upstream from the vertical plane of
lamps at 1.01 m3/sec (2150 cfm). The system uses 240 volt electricity and had 12 lamps.
IX
-------
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 as a result of
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 from room air cleaners to duct-mounted ventilation filters.(3>4'5) These bioaerosol methods were
1
-------
based on RTFs extensive experience in the development of parti culate testing methods of various air-
cleaning devices.
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 inactivated and bacterial
spores are more difficult to kill. 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 |im.
The bacterial virus (bactedophage) 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 (polydispersed 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.
-------
2.0 Technology Description
The information in this section was provided by the vendor and was not evaluated by RTI.
The Abracair In-Duct Heating, Ventilation and Air Conditioning (HVAC) system treats air with high-
intensity pulsed ultraviolet light. Twelve high-intensity xenon flash lamps flash within the duct. Within
the plenum this light further activates a special microbe-killing filter made with quartz fibers coated with
titanium dioxide.
The Abracair In-Duct HVAC system has two slide-in assemblies. The actual electronic component
measures 61 cm X 61 cm X 15 cm (24" X 24"X 6") and weighs 25 kg (55 Ibs), containing 12 xenon
flash lamps, 24 capacitors, 12 trigger transformers, and a pressure sensor to ensure proper airflow for
operation. The photochemical filter unit measures 61 cm X 61 cm X 10 cm (24" X 24" X 4") and
weighs 4 kg (8 Ibs). The assembly is constructed of fiberglass and steel.
External to the plenum, the power supply controller measures 61 cm X 61 cm X 20 cm) (24" X 24" X
8") in a NEMA-rated steel electrical enclosure. Power switches and gauges mounted on the front access
panel offer simple controls. Cabling up to 3.7 m (12 feet) allows for juxtaposition with standard high-
voltage transformers. This component mounts on wheels, weighs up to 113 kg (250 Ibs) for 240 VAC
(480 VAC would be less than half this weight.)
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.
Figure 2-1. The device (left) and filter
(right) are held in place with tape.
Power supply is on the floor.
Figure 2-2. Device installed inside the test
rig. There are 12 lamps.
-------
Table 2-1. Specifications of the Abracair In-Duct System
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 boxes
Configuration
Other lamp characteristics
Specification
7020 watts for all 12 lamps (585 watts per lamp)
440 watts UVC (200-280 nm)
100 mW/cm2 at 61 cm (24 inches)
100 mW-s/ cm2 at 61 cm (24 inches)
30 amps at 240 volts
Lamp section is 61 cm X 61 cm X 25 cm (24x24x1 0
of 1 2 xenon flash lamps
inches), comprised
Control box varies with voltage input
Lamps arranged within duct, transformer is outside
Life expectancy of lamp to 70% drop in output is 10,
000 hours
For more information on the Abracair In-Duct System, contact:
David G.Changaris, M.D.
502 445 9471
Abracair, LLC
204 N. 17th Street
Louisville, KY 40203
Tel 502 584 -6852
Fax 502 584 -8379
www. abracair. com
-------
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. ^
Exhaust
to
Room
Room
Air
Blower
ASME
Outlet Filter Bank N°fZ'e
1 Biological
1 1 Sampling
>
|
>
>
y
^
Downstream Mixer
\
fi& ^ ' r"
I
6
t
Inlet Filter
Bank
)
usr
Device
Section
Backup
Filter
Flow Control
Valve
Aerosol
Generator
Biological
Sampling
Figure 3-1. Schematic of Test Duct. UV 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 FtEPA 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 1.01 mVsec (2150 cfm). This flow creates a
typical air velocity (538 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.
The Abracair system uses 30 amps at 240 volts. RTI installed a circuit for this voltage to the area beside
the test rig. The UV lamps were operated for a standard 100-hr "burn-in" period before testing the
device. During the burn-in, one of the lamps failed and broke. The rest of the lamps continued to operate
and the 100 hours were completed. The broken lamp was replaced, but did not have a burn-in as it was
only about 8% of the total irradiance and the reduction in irradiance over 100 hours is very small.
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
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 pressure drop across the device (impacting air handler requirements) and the temperature rise
through the unit, if any (impacting cooling coil energy consumption). The energy required to operate
the unit was not measured because the unit required 240 volts and our power meter would not handle
it.
• A single measurement of the intensity of 254 nm UV radiation (uW/cm2) at a point 117 cm (46 in.)
upstream from the plane of 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
6
-------
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.
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.
The dose was calculated by rearranging Equation 2 to yield:
-ln(Nt/No) (Equations)
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 0.3 x 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.
-------
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.(U)
4.1.2 Instrument Checks
The Abracair In-Duct System was installed in the test duct, and operated and maintained according to
the vendor's instructions throughout the test. During the burn-in, one of the lamps failed and broke. The
rest of the lamps continued to operate and the 100 hours were completed. The broken lamp was
replaced, but did not have a burn-in as it was only about 8% of the total irradiance and the reduction in
irradiance over 100 hours is very small. 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.(UO) 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
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; 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 QA Manager reviewed the test results and determined that the quality objectives of the
approved test/QA plan and amendments were attained with the exception of low correlation (no-light
test) data for B. atrophaeus (0.51) and S. marcescens (0.61). The no light test was run with the quartz
filter in place because the vendor said that the system was set not to run unless the filter was used and so
that it could be parallel to the light test. This change from the anticipated testing procedure had the effect
of capturing bacteria. The filter predictably reduced the number of downstream particles, thus lowering
the no light test data with respect to that envisioned during DQO development. Based on the use of the
filter, the RTI QA Manager determined that it was acceptable to use the data.
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
-------
Table 4-1. DQOs for Biological Aerosols
Parameter
Minimum upstream counts for
samplers
Maximum counts for samplers
100% 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 unit
b PFU = plaque forming unit
c CV = coefficient of variance-the standard deviation divided by the mean
11
-------
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)
6.9
Vegetative bacteria
(S. marcescens)
99.8
Bacterial virus
(MS2
bacteriophage)
59
Table 5-2. Other Information for the Abracair In-Duct System
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
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 (filter in place)
Air temperature rise through the device
Measured or Calculated Values
1.01 m3/sec(2150cfm)
Upstream 23.6 °Ca(74.5°F)
Downstream 25.2 °C (77.4 °F)
447 (376 - 550) uW-s/cm2
1800-5100 uW/cm2 at 117 cm (46 in.)
upstream from the vertical plane of lamps at
1.01 m3/sec(2150cfm)
6480-6720 Wa
109 Pa (0.439 in. H20)
1 .6 °C (2.9 °F)
a - The power meter didn't work for the 240 V circuit used for this device; so the power was calculated using the
ammeter on the Abracair system reading of 27-28 amps.
12
-------
6.0 Performance Summary
This verification report addresses the inactivation efficiency performance (Table 5-1) for the Abracair
In-Duct System UV 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 6.9% for B. atrophaeus,
99.8% for S. marcescens and 59% for MS2. The irradiance was measured as ranging from 1800 - 5100
|iW/cm2 at 117 cm (46 in.) upstream from the vertical plane of lamps at 1.01 m3/sec (2150 cfm). The
system uses 240 volt electricity and had 12 lamps. The spore form of the bacteria 5. atrophaeus is more
resistant to being killed by UV than the vegetative bacteria S. marcescens.
13
-------
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.
14
------- |