U.S. patent application number 10/098846 was filed with the patent office on 2003-01-09 for adjustable air sampler for pathogens and psychrometrics.
Invention is credited to Spurrell, Leon Bryan.
Application Number | 20030008341 10/098846 |
Document ID | / |
Family ID | 25409936 |
Filed Date | 2003-01-09 |
United States Patent
Application |
20030008341 |
Kind Code |
A1 |
Spurrell, Leon Bryan |
January 9, 2003 |
Adjustable air sampler for pathogens and psychrometrics
Abstract
An adjustable air sampler device and method for collecting
airborne pathogens and psychrometric data for room or remote air
samples wherein the sample volume is electronically controlled.
Particulates in the air are caused to impact the surface of the
growth/inhibitor media contained in the pathogen dish thereby
depositing pathogenic microorganisms in the media. The
growth/inhibitor media may be a solid, liquid, gel, or mixture
thereof. After the pathogen dish is incubated, colony forming units
are counted for determination of air quality parameters. A
chip-based sensor measures psychrometric properties of the air
sample.
Inventors: |
Spurrell, Leon Bryan;
(Etobicoke, CA) |
Correspondence
Address: |
WILSON ENTERPRISES
2333 BRIGHTON FARMS BLVD.
KNOXVILLE
TN
37932
US
|
Family ID: |
25409936 |
Appl. No.: |
10/098846 |
Filed: |
March 16, 2002 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
10098846 |
Mar 16, 2002 |
|
|
|
09898715 |
Jul 3, 2001 |
|
|
|
Current U.S.
Class: |
435/34 ;
435/287.1 |
Current CPC
Class: |
G01N 2001/245 20130101;
G01N 1/2205 20130101; G01N 1/24 20130101; G01N 2001/2223 20130101;
G01N 2015/0261 20130101; G01N 1/2208 20130101; G01N 2001/244
20130101 |
Class at
Publication: |
435/34 ;
435/287.1 |
International
Class: |
C12Q 001/24; C12Q
001/04; C12M 001/34 |
Claims
What is claimed is:
1. An adjustable and portable air sampling apparatus for collecting
airborne pathogens and psychrometric data comprising; a base, a
casing removably disposed on said base, said casing having at least
one top air inlet and a plurality of side air outlets and a sample
chamber disposed between said inlet, outlets, and base. at least
one pathogen dish removably disposed on said casing above said top
air inlet and generally transverse to said top air inlet airflow
path, a cap removably disposed on said casing, said cap at least
partially enclosing said pathogen dish, a perforated impact plate
removably disposed on said cap, said plate having at least one
perforated size pattern selectively activated by the user, a
printed circuit board removably disposed on said base inside said
sample chamber, a fan removably disposed on said casing and inside
said sample chamber, a means for controlling said fan, a means for
measuring psychrometric data inside said sample chamber, and a
means for communicating with an external data acquisition and
control system.
2. The apparatus of claim 1 wherein said perforated impact plate
comprises a single plate with multiple perforation sizes arranged
so that selectable patterns of perforation sizes can be
activated.
3. The apparatus of claim 1 wherein said perforated impact plate
comprises multiple plates, each plate having preselected
perforation sizes and patterns wherein at least one individual
plate portion can be selectively activated.
4. The apparatus of claim 1 wherein said pathogen dish comprises a
growth/inhibitor media selected from at least one of the group
consisting of distilled water, pure water, agar and mixtures
thereof.
5. The apparatus of claim 1 wherein said removable perforated
impact plate is disposed at a preselected distance from said
pathogen dish of between approximately 0 to 6 inches.
6. The apparatus of claim 1 wherein said pathogen dish is disposed
at a preselected distance from said air outlets of between
approximately 0 to 12 inches.
7. The apparatus of claim 1 wherein said pathogen dish is disposed
at a preselected distance from said air inlet of between
approximately 0 to 6 inches.
8. The apparatus of claim 1 wherein said fan is disposed at a
preselected distance from said air inlet of between approximately 0
to 6 inches.
9. The apparatus of claim 1 wherein said the effective outside
diameter of said impact plate is adjustable to a preselected
distance of between approximately 0 to 6 inches.
10. The apparatus of claim 1 wherein the largest outside dimension
of said adjustable sampler is between approximately 0 to 8
inches.
11. The apparatus of claim 1 wherein said cap further comprises a
remote collection assembly having a remote sampler head, a remote
sensor assembly, and interconnecting tubing.
12. The apparatus of claim 1 wherein said printed circuit board
further comprises an electrical plug for supplying alternating or
direct current directly to said circuit board or to rechargeable
batteries.
13. The apparatus of claim 1 wherein said means for controlling
said fan comprises electrical power having a voltage between
approximately 0 to 120 volts.
14. The apparatus of claim 1 wherein said means for controlling
said fan comprises electrical power having a frequency between
approximately 0 to 60 hertz.
15. The apparatus of claim 1 wherein said means for controlling
said fan comprises an electrical power source selected from at
least one of the group consisting of line voltage, battery, solar
and electronic motor controller.
16. The apparatus of claim 1 wherein said means for controlling
said fan comprises an electronic component on said circuit board
that maintains fan speed for a preselected run time.
17. The apparatus of claim 1 wherein said means for measuring
psychrometric data comprises an electronic component on said
circuit board that senses, stores, and displays relative humidity,
absolute humidity, and dry bulb temperature of the air in said
sample chamber.
18. The apparatus of claim 1 wherein said means for communicating
with an external data acquisition and control system comprises a
two-way network selected from the group consisting of wired and
wireless.
19. The apparatus of claim 1 wherein said fan is a type selected
from the group consisting of axial, centrifugal, and tubular.
20. An air sampling method comprising the steps of: adjusting the
impact plate to activate a preselected perforation size and
pattern, starting the adjustable sampler fan, either manually or
automatically, with a means for controlling said sampler fan,
impacting said air sample on a cap having a pathogen dish, said
pathogen dish further comprising a growth/inhibitor media,
measuring the psychrometric properties of said air sample with a
means for measuring psychrometric data located on a printed circuit
board inside the sample chamber, communicating said psychrometric
properties with a data acquisition and control system, removing
said pathogen dish from the sampler, incubating said pathogen dish
for a preselected time period in a controlled environment, and
counting the colony forming units in the growth/inhibitor
media.
21. The method of claim 20 wherein said perforated impact plate
comprises a single plate with multiple perforation sizes arranged
such that selectable patterns of perforation sizes can be
activated.
22. The method of claim 20 wherein said perforated impact plate
comprises multiple plates, each plate having preselected
perforation sizes and patterns wherein an individual plate or a
combination of plates can be selectively activated.
23. The method of claim 20 wherein said pathogen dish comprises a
growth/inhibitor media selected from at least one of the group
consisting of distilled water, pure water, agar and mixtures
thereof.
24. The method of claim 20 wherein said removable perforated impact
plate is disposed at a preselected distance from said pathogen dish
of between approximately 0 to 6 inches.
25. The method of claim 20 wherein said pathogen dish is disposed
at a preselected distance from said air outlets of between
approximately 0 to 12 inches.
26. The method of claim 20 wherein said pathogen dish is disposed
at a preselected distance from said air inlet of between
approximately 0 to 6 inches.
27. The method of claim 20 wherein said fan is disposed at a
preselected distance from said air inlet of between approximately 0
to 6 inches.
28. The method of claim 20 wherein said the effective outside
diameter of said impact plate is adjustable to a preselected
distance of between approximately 0 to 6 inches.
29. The method of claim 20 wherein largest outside dimension of
said adjustable sampler is between approximately 0 to 8 inches.
30. The method of claim 20 wherein said cap further comprises a
remote collection assembly having a remote sampler head, a remote
sensor assembly, and interconnecting tubing.
31. The method of claim 20 wherein said printed circuit board
further comprises an electrical plug for supplying alternating or
direct current directly to said circuit board or to rechargeable
batteries.
32. The method of claim 20 wherein said means for controlling said
fan comprises electrical power having a voltage between
approximately 0 to 120 volts.
33. The method of claim 20 wherein said means for controlling said
fan comprises electrical power having a frequency between
approximately 0 to 60 hertz.
34. The method of claim 20 wherein said means for controlling said
fan comprises an electrical power source selected from at least one
of the group consisting of line voltage, battery, solar and
electronic motor controller.
35. The method of claim 20 wherein said means for controlling said
fan comprises an electronic component on said circuit board that
maintains fan speed for a preselected run time.
36. The method of claim 20 wherein said means for measuring
psychrometric data comprises an electronic component on said
circuit board that senses, stores, and displays relative humidity,
absolute humidity, and dry bulb temperature of the air in said
sample chamber.
37. The method of claim 20 wherein said means for communicating
with an external data acquisition and control system comprises a
wireless network selected from the group consisting of wired and
wireless.
38. The method of claim 20 wherein said fan is a type selected from
the group consisting of axial, centrifugal, and tubular.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part of U.S.
application Ser. No. 09/898,715 filed Jul. 3, 2001, the entirety of
which is herein incorporated by reference.
FIELD OF THE INVENTION
[0002] This invention relates generally to air samplers and, more
particularly, to an adjustable air sampler assembly for collecting
airborne pathogens and psychrometric data from a room or remote
locations wherein the sampler configuration is adjustable and the
sample volume is electronically controlled.
BACKGROUND OF THE INVENTION
[0003] The air inside buildings often is contaminated with
particles and chemicals that adversely affect the health of the
occupants. These pollutants have been brought indoors from the
outside or arise from sources indoors. Airborne pathogens,
sometimes referred to as biological contaminants or aerosols
include;
[0004] 1. Infectious agents such as bacteria, viruses, and fungi
which may cause tuberculosis; legionellosis; Pontiac fever;
measles; influenza; colds; aspergillosis; coccidioidomycosis;
histoplasmosis; and
[0005] 2. Allergenic agents such as bacteria, fungi, insects,
algae, pollen, animals, and products of microbiological metabolism
that may cause sensitivity to B. subtills; allergic asthma;
rhinitis; hypersensitivity to molds; sensitivity to house dust
mites, cockroaches, houseflies, moths, carpet beetles, aphids,
crickets, mosquitoes, and weevils; hypersensitivity reaction to
endotoxins from gram-negative bacteria, cotton dust (some
mycotoxins are potent carcinogens); hayfever from ragweed pollen;
sensitivities to grass and tree pollens; and allergic rhinitis and
asthma from bird and mammal dusts.
[0006] The pathogens often manifest themselves as human health
symptoms such as mucus membrane irritation, headache, and fatigue.
These symptoms are associated with what is termed the "sick
building syndrome." Biological aerosols have been the predominant
cause of complaints in 1-5% of problem office buildings
investigated by the U.S. National Institute for Occupational Safety
and Health (NIOSH). Airborne biological contamination may be a
larger problem in homes where there is a greater variety of source
materials and very different types of activities that contribute to
the presence of microorganisms, and plant and animal matter.
[0007] Assessment of biological aerosols in studies of indoor air
quality requires knowledge of many specialties because complaints
may be due to aerosols of bacteria, viruses, fungi, algae, house
dust mite particles, or pollen grains. One may also need advice
from epidemiologists, statisticians, and from medical professionals
to diagnose infections and allergies. An understanding of
ventilation systems and the movement of air through buildings is
also essential, as is a knowledge of how small particles travel
through the air and how they can be collected, identified, and
quantified. Psychrometric properties of air such as relative
humidity, absolute humidity, and dry bulb temperature help
determine ambient conditions suitable for growth of pathogens.
Building pressurization information helps identify the pathogen
source and subsequent remediation options.
[0008] A vast array of sampling instruments has been developed for
airborne microorganisms. A summary of a number of devices of this
type can be found in Air-Sampling Instruments for Evaluation of
Atmospheric Contaminants, 8th Edition (1995), American Conference
on Governmental Industrial Hygienics. Two of these instruments, the
Andersen cascade impactor and the all-glass impinger, have proven
useful and reliable enough to be considered standard sampling
instruments. The Andersen cascade impactor has remained popular,
because it is convenient to use pre-poured plates, the distribution
of particle sizes can be determined, and the sampling rate is
fairly high (28 L/min). Liquid impingers are used when the
organisms require rapid rehydration, to collect soluble materials,
e.g., Tyco- or bacterial endo-toxins and some antigens, or when the
total number of cells must be determined rather than the number of
contaminate particles. Readily-identifiable pollen grains, algal
cells, fungal spores, and fragments of nonviable organisms can be
collected with a rotorod sampler or on air filters for
identification with a light or electron microscope.
[0009] After suspended particles have been collected on or in a
suitable medium, the viable microorganisms, those that will
multiply when provided the appropriate conditions, contained in
orion these particles can then be counted and identified. The
techniques used to extract viable cells and particles carrying them
from the air are also used by environmental scientists looking for
nonviable particles. The most efficient methods of removing
suspended particles from the air, e.g., filtration through fine
pore matrices, might be adequate for resistant forms of
microorganisms, such as spores, but can damage less environmentally
resistant, vegetative cells. The absence of these sensitive cells
from a sample could cause one to mistakenly conclude that they were
not present in the environment sampled. The total number of cells
present can be estimated by microscopic examination of collected
dust, sometimes with the help of stains or fluorescent tags. NIOSH
has suggested the following indoor concentrations of bacteria and
fungi as indicative of situations deserving of further attention:
air concentration>103 colony-forming units per cubic meter
(cfu/m3), dust samples>105 cfu/g, water samples>105
cfu/ml.
[0010] The proposed NIOSH sampling protocol uses the last stage of
the Andersen impactor to collect samples onto standard petri dishes
of medium. Different media are used for collecting fungi and
bacteria. The total number of viable particles is reported, and
when useful, the isolates are identified. This procedure will
identify cases of heavy contamination, but further tests might be
needed in some situations. A more comprehensive approach would
include using a spore trap with visual identification of spores and
pollen in the collected dust, a viable sampler with at least three
types of culturing media, and a filter or a liquid impinger sample
for bioassays, biochemical tests, and immunological analyses.
[0011] The accurate measurement of the gas flow rate is very
important in air filter sampling because the contaminant
concentration is determined by the ratio of the sampled contaminant
quantity to the sampled air volume. One widely used conventional
flowmeter in air sampling is the rotameter. Rotameters are
sensitive to pressure changes in upstream and downstream airflows.
Most flowmeters are calibrated at atmospheric pressure, and many
require pressure corrections when used at other pressures. When the
flowmeter is used in air sampling, it should be downstream of the
filter to exclude the possibility of sample losses in the
flowmeter. Therefore, the sampled air is at a pressure below
atmospheric due to the pressure drop across the filter.
Furthermore, if the filter resistance increases due to the
accumulation of dust, the pressure correction is not a constant
factor. During the sampling period, the filter tends to be plugged
and the flow rate may decrease as filter resistance increases.
These factors make it difficult to measure the flow rate
accurately.
[0012] Critical orifices have been widely used in flow rate control
for air sampling because they are simpler, reliable and
inexpensive. When the pressure drop across the critical orifice is
more than 47% of the upstream pressure, the speed of sound is
achieved in the throat and the velocity will not change with a
further reduction in downstream pressure. Under these conditions,
the flow rate is kept constant if upstream conditions are constant.
However, commercially available orifices were found to lack the
required precision and accuracy because they differed from the
nominal flowrate by up to 15%. Another disadvantage of most
critical orifice designs is that a pressure drop in excess of 47
kPa is required to ensure a stable flow. To achieve this pressure
drop, a special high power vacuum pump must be used. Some
commercial flow limiting orifices even require a vacuum as high as
72 kPa.
BRIEF SUMMARY OF THE INVENTION
[0013] An adjustable, portable device and method for collecting an
electronically controlled sample of air that impacts a pathogen
dish mounted substantially transverse to the overall airflow
pattern to capture airborne pathogens and farther having a
psychrometric sensor that measures psychrometric properties of the
air sample. Particulates in the air are caused to impact the
surface of the growth/inhibitor media contained in the pathogen
dish thereby depositing pathogenic microorganisms in the media. The
growth/inhibitor media may be a solid, liquid, gel, or mixture
thereof. A chip-based sensor measures psychrometric properties of
the air sample.
[0014] Room air is sampled through an adjustable calibrated
perforated impactor plate. Remote air samples are collected through
an adjustable calibrated remote sensor assembly.
[0015] An advantage of the invention is the means for controlling
the sample volume wherein the fan is activated and controlled for a
predetermined time period programmed for the specific type of
sample being collected. Each remote collection assembly and each
room air collection assembly has a specific control algorithm
designed for the entire collection device. All components are low
airside pressure drop items to enable using of a small, low power
fan.
[0016] Another advantage of the invention is the ability to collect
airborne pathogen data and psychrometric data simultaneously
thereby providing more complete information on the quality of the
air being sampled.
[0017] Another advantage of the invention is that the sampler is
simple, inexpensive, and portable. Rechargeable battery power
allows the sampler to be used at any location and multiple samples
can be drawn with a single battery charge. Each sample may contain
a different growth/inhibitor media for collection of spores,
pollen, dust, pathogens, and bioassays.
[0018] Yet another advantage of the invention is that the sampler
is adjustable for specific sampling requirements.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1 is a side view of the room air sampler.
[0020] FIG. 2 is an isometric view of the room air sampler.
[0021] FIG. 3 is an exploded view of the room air sampler showing
some of the components.
[0022] FIG. 4 is an isometric rendering of the remote air
sampler.
[0023] FIG. 5 is side view of the remote air sampler.
[0024] FIG. 6 is an isometric of the remote air sampler connected
to the air sampling port of a wall cavity sensor assembly.
[0025] FIG. 7 is an isometric of the remote air sampler connected
to a section view of a wall cavity sensor assembly.
[0026] FIG. 8 is an isometric of the remote air sampler connected
to a ductwork assembly.
DETAILED DESCRIPTION
[0027] An integrated adjustable air sampler and psychrometric
sensor is used to detect airborne pathogens and associated
psychrometric properties of the air sample in order to identify
pathogenic indoor air pollutants and the sources of those
pollutants. The sample volume is controlled by knowing the static
pressure imposed on the fan by the sampler components and
determining the flow rate from the fan performance curve. The fan
is then electronically controlled and timed to stop when a
preselected volume of air has been sampled.
EXAMPLE
[0028] The sampler fan delivers 10 liters per minute (LPM) of
standard temperature and pressure (STP) air at 0.5 inches water
gage (WG) external static pressure according to the certified fan
performance curve at 1800 revolutions per minute (RPM). The
external static pressure imposed on the fan by the sampler
components is 0.5 inches WG. The preselected sample volume is 20
liters, therefore, sample run time is 2 minutes for the 10 LPM flow
rate. The electronic flow controller measures the current to the
sampler fan motor to maintain 1800 RPM for 2 minutes before
shutting down the fan motor. The entire 20-liter air sample impacts
the pathogen dish and deposits particulate on the growth/inhibitor
media for determination of colony forming unit (CFU) counts.
Downstream of the pathogen dish, the psychrometric sensor measures
relative humidity, absolute humidity, and dry bulb temperature,
displays the data on an LED readout device mounted on the air
sampler casing, and stores the data for later downloading. After
the first sample is complete, the pathogen dish is removed and
replaced with a clean dish, the electronic flow controller is
reset, and another sample is taken. The electrical power source for
the sampler is either 120 volts A/C, DC power from a converter or
other DC power source, or a rechargeable DC battery.
[0029] The psychrometric sensor (e.g. Hygrometrix model HMX 2000)
is part of a printed circuit board that senses, stores, and
displays relative humidity, absolute humidity, dry bulb
temperature, and other psychrometric properties of the sampled air.
The printed circuit board is capable of two-way communication with
a data acquisition and control system such as a building energy
management system. The printed circuit board is also capable of
two-way wired or wireless communication such that remote start-stop
and control can be performed. For a specific elevation or
atmospheric pressure, two psychrometric properties are measured and
the remaining properties are derived from formulas or tables. These
air properties determine the ability of the air to support growth
of pathogens and other airborne microorganisms.
[0030] The growth/inhibitor media is comprises a solid, liquid,
gel, or mixture thereof and is selected from the group consisting
of distilled water, pure water, and agar. Each constituent of a
mixture could be in a range from 0% to 99.99% depending on the
sampling requirements.
[0031] A remote air sample can be taken from a wall cavity, floor
cavity, ceiling area, another room, or a specific source point to
determine pathogen counts, relative humidity, absolute humidity,
and dry bulb temperature thereby enabling determination of building
pressure differences, air leakage, building
pressurization/depressurization due to stack effect, ventilation
system imbalance and the probability of mold growth and structural
damage. The psychrometric properties and pathogen counts of air in
adjacent building zones and the associated wall cavities or
barriers determine the direction of heat and moisture transfer
between the zones thereby identifying a potential source of
airborne pollutants.
[0032] FIGS. 1 through 5 show the air sampler base 10, the casing
18, the cap 22 and perforated impact plate 24, all removably
attached to form the outer shell of the sampler. Inside the sample
chamber are the printed circuit board 12, the electrical plug 14
with a connector protruding through the casing 18, the fan 16, and
the pathogen dish 20. The fan 16 is manually started by a switch
(not shown) connected to the printed circuit board 12, or
automatically by the program on the printed circuit board 12, or
remotely by a two-way communication device that is either wired or
wireless. The air sample is drawn through the perforated impact
plate 24 that is disposed at a preselected distance from the
pathogen dish 20. The fan 16 is typically a low-pressure axial fan,
similar to a propeller fan or "muffin" fan, disposed such that
proper airflow is obtained for each sample. The fan 16 can also be
centrifugal or tubular type. The sample is separated into air jets
by the perforated impact plate 24 before impacting the surface of
the growth/inhibitor media 23 contained in the pathogen dish 20
thereby depositing particulate matter in the media 23. The active
portion of the perforated impact plate 24 and 24' is adjustable
such that a specific hole size and pattern can be selectively
activated by the user. After impacting the media 23, the air sample
disperses radially outward from the media surface and flows over
the outer perimeter of the pathogen dish 20 in route to the intake
of the fan 16 that is removably attached by an airtight connection
19 directly below the top air inlet of the casing 18. The airtight
connection 19 is sealed in a manner to ensure that the sample
chamber 17 comprising the printed circuit board 12 and the
psychrometric sensor is only exposed to sample air, not ambient
air, during the sampling period. The airtight connection 19 also
enables sample volume calibration for various flow components on
the suction side of the fan, including the remote sampling
assemblies, by ensuring that the fan operates at designed flow rate
against the full static pressure drop of the suction side
components without any air leakage. The air sample then passes
through the sample chamber 17 and contacts the printed circuit
board 12 for measuring the psychrometric properties of the air
sample. These properties are measured, stored, and then displayed
on an LED readout device (not shown). The printed circuit board 12
has flash memory for retaining stored data during power
interruptions. The printed circuit board 12 is capable of two-way
communication with a data acquisition and control system, like a
building energy management and control system, such that
psychrometric data collected from the sampler can be used to
control mechanical systems in buildings. Building zone temperatures
and relative humidity as measured by the sampler enable control of
airflow quantities, economizer cycles, building pressurization,
exhaust/return fans, and other functions in building UVAC systems.
The data acquisition and control system can also communicate with
the sampler to activate the sampler in a programmed fashion for
drawing samples at certain times. The sample then exits the sample
chamber 17 through a plurality of side air outlets in the casing
18. After the preselected run time of the fan is completed, which
corresponds with a measured sample volume, the printed circuit
board resets the counter for the next sample to be drawn. The
pathogen dish 20 is changed out for each new sample. The sampler
casing 18 is designed to house two different sizes of pathogen dish
20. Automated change-out of the pathogen dish 20 can be performed
by mechanical means such that multiple samples can be taken in a
preselected time period. The automated change-out can be controlled
by the data acquisition and control system.
[0033] For remote sensing, FIGS. 4 through 8 show a remote sensing
assembly comprising the remote sensing head 26 that is removably
mounted over the cap 22 to enable interconnected tubing 28 to be
run to a remote sensor assembly such as a ductwork section 30 or a
wall cavity sensor assembly 31. The wall cavity sensor assembly 31
has an air sampling port enabling fluid communication between the
wall cavity and the sampler. Sensor sampling ports in the wall
cavity sensor assembly 31 enable separate and specific fluid
communication with room air, cavity air, adjacent space air, and
other points of interest. Each sensor sampling port houses a
psychrometric sensor 32 for measuring air properties. The
psychrometric sensors transmit data to a data display, storage, and
collection device in the wall cavity sensor assembly that can
communicate with a central data analysis system through a wired or
wireless communication network. The wall cavity sensor can be
adapted and installed in any building structure component including
floors, ceilings, partitions, roofs, interior walls, and exterior
walls. The sampler fan run time is programmed for a specific remote
sensor assembly that imposes a predetermined external static
pressure on the fan 16. Remote locations include such areas as
adjacent building spaces, interior and exterior wall cavities,
ductwork, and any suspected source spot of airborne
contaminants.
[0034] The performance and configuration of the sampler is
adjustable to fit various conditions encountered during sampling.
The perforated impact plate 24 can be either a single plate with
multiple perforation sizes arranged such that selectable patterns
of perforation sizes can be activated, or the perforated impact
plate 24' can be multiple plates removably disposed in the cap 22
with each plate having preselected perforation sizes and patterns
wherein an individual plate or a combination of plates is disposed
for use during sampling. Multiple plates can be sequentially
stacked and indexed such that rotating the plates to a specific
position relative to each other will open appropriate perforation
sizes for sampling. The perforated impact plate 24 is replaceable
and able to slide/snap in or out of the cap 22 from the side,
bottom or top. Any type of catch or fastening device is suitable to
hold the perforated impact plate 24 in place to make the perimeter
seal essentially airtight.
[0035] In addition, adjustable component positions and features of
the adjustable air sampler are critical to accurate sampling.
Adjustable component positions and features include:
[0036] a. The distance between the perforated impact plate 24 and
the pathogen dish 20 is adjustable to a preselected distance of
between approximately 0 to 6 inches. This adjustment optimizes fan
performance that ensures appropriate airflow patterns and volumes
impact the pathogen dish 20. Both the perforated impact plate 24
and the pathogen dish 20 are removably disposed in the sampler such
that either or both can be adjusted to the desired preselected
distance.
[0037] b. The distance between the pathogen dish 20 and the air
outlets 11 is adjustable to a preselected distance of between
approximately 0 to 12 inches. This adjustment optimizes fan
performance to ensure fully developed uniform laminar airflow
impacting the pathogen dish 20 and minimizes pressure drops
associated with fan entrance and exit losses. The air outlets 11
are also adjustable such that the optimum size, orientation and
configuration of the air outlets 11 can be selected to ensure
uniform airflow.
[0038] c. The distance between the pathogen dish 20 and the air
inlet 21 is adjustable to a preselected distance of between
approximately 0 to 6 inches. This adjustment optimizes fan
performance to ensure fully developed uniform laminar airflow
impacting the pathogen dish 20 and minimizes the pressure drop
associated with fan entrance losses.
[0039] d. The distance between the fan 16 and the air inlet 21 is
adjustable to a preselected distance of between approximately 0 to
6 inches. This adjustment optimizes fan performance to ensure fully
developed uniform laminar airflow impacting the pathogen dish 20
and minimizes the pressure drop associated with fan entrance
losses.
[0040] e. The effective outside diameter of the perforated impact
plate 24 is adjustable to a preselected distance of between
approximately 0 to 6 inches. This adjustment allows control of the
active portion of the perforated impact plate 24 and the resulting
airflow impact profile on the pathogen dish 20.
[0041] f. The largest outside dimension of the adjustable air
sampler can be between approximately 0 to 8 inches. The shape of
the sampler can be any geometric configuration required to fit a
specific sampling location. All internal components sizes are
adjusted proportional to the largest outside dimension.
[0042] g. The electrical power voltage can be between approximately
0 to 120 volts and the associated power frequency can be between
approximately 0 to 60 hertz. The electrical power source is
selected from at least one of the group consisting of line voltage,
battery, solar and electronic motor controller.
[0043] Limited embodiments are shown and described for this
invention and those skilled in the art will envision other
embodiments that are considered part of this invention.
* * * * *