U.S. patent number 3,926,597 [Application Number 05/326,608] was granted by the patent office on 1975-12-16 for cabinet for biohazardous materials.
Invention is credited to Jerome J. Landy.
United States Patent |
3,926,597 |
Landy |
December 16, 1975 |
Cabinet for biohazardous materials
Abstract
An imperforate tubular-like cabinet is disclosed having a hinged
viewing panel in the front portion providing a gap at the lower
portion of the hinged viewing panel with the balance of the cabinet
for the two-fold purpose of admitting makeup recirculatory air and
permitting the hands of an operator to work with biohazardous
material atop a tray provided in the inner portion of the cabinet.
A blower and plenum chamber as well as recirculatory and exhaust
filters are provided to recirculate laminar flow air and filter the
same before exhaust. The hinged viewing panel is provided with an
airfoil section for the two-fold purpose of creating a negative
pressure and accelerated airflow in front of the access opening at
its lower portion, and to permit the operator to position the head
for viewing the work table interiorly of the outer confines of the
cabinet.
Inventors: |
Landy; Jerome J. (Miami,
FL) |
Family
ID: |
23272940 |
Appl.
No.: |
05/326,608 |
Filed: |
January 26, 1973 |
Current U.S.
Class: |
55/338; 454/59;
55/473; 55/DIG.29 |
Current CPC
Class: |
B08B
15/023 (20130101); B08B 2215/003 (20130101); Y10S
55/29 (20130101) |
Current International
Class: |
B08B
15/00 (20060101); B08B 15/02 (20060101); B08B
015/02 () |
Field of
Search: |
;55/502,310,473,311,484,467,501,413,470,414,481,499,338,521,436,DIG.18,437
;98/115,115LH,36 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Other References
"Lab Con Co.," copyright 1966, Labconco Corp., pp. 40, 44..
|
Primary Examiner: Lutter; Frank W.
Assistant Examiner: Greenblum; Neil F.
Claims
What is claimed is:
1. A cabinet for biohazardous materials having a rectangular
housing comprising, in combination,
vertical tube defining a portion of said cabinet,
a blower mounted interiorly of said housing,
a plenum chamber in open communication with said blower for
directing contaminated air upwardly in the rear portion of said
tube,
a recirculating filter and an exhaust filter in airflow
communication with said plenum chamber,
a work tray positioned in a midportion of said tube,
an opening having upper, lower, and side edges in said vertical
tube the major portion of which is above the work tray,
a curvilinear viewing panel secured to said upper edge of the
opening and depending downwardly and inwardly therefrom and thence
forwardly thereby defining an airfoil recess with its deepest
penetration in the upper half of said viewing panel,
said recirculating filter being positioned adjacent to and above
said viewing panel,
a slot at the lower portion of said viewing panel permitting
operator access to the work tray and for admitting make up air
laterally spaced from said work tray, whereby interiorly
recirculating laminar flow air passes over the viewing panel
thereby further directing the makeup air through the makeup air
slot and inhibiting the outward flow of the contaminated air.
2. In the cabinet of claim 1
a double wall construction in spaced relation to the vertical tube
with the space thereby defined being in airflow communication with
negative pressure inside the vertical tube to thereby assist in
reducing potential leakage of biohazardous material.
3. In the cabinet of claim 1,
removable support means for said tray,
means defining uniform openings in said support means for uniformly
transmitting the air around the periphery of said tray.
4. In the cabinet of claim 1,
said tube being formed of imperforate welded construction,
said tube having a front face and rear face which are substantially
parallel with the front face being interrupted by the viewing panel
and a base and top substantially perpendicular to said front and
rear faces.
5. In the cabinet of claim 1,
said filters being parallel with the work table and substantially
perpendicular to the air flow.
6. In the cabinet of claim 1,
said removable viewing screen being secured to the unit by means of
hang-on-type hinges,
gasket means interposed in pressure relationship to the marginal
edges and bottom of said viewing screen and along the top edge,
and
pressure locking means at the lower portion of said viewing screen
to secure the same in non-communicable airtight relationship to the
cabinet when in the fixed working position.
7. In the cabinet of claim 1,
a lower major portion of said viewing screen being positioned at an
angle substantially 15.degree. with the vertical,
the upper minor portion of said viewing panel curving in from the
upper edge of the viewing panel and then outwardly at an angle
approximately 15.degree. with the vertical and then terminating at
an air makeup slot at its lower portion.
8. In the cabinet of claim 1,
a support above the recirculating filter defining a second plenum
chamber above the filter and serving to support the blower.
9. In the cabinet of claim 1,
blower means provided in the lower portion in open communication
with the plenum chamber which is under positive pressure, and in
open communication with the work tray and double wall which are
under negative pressure.
10. In the cabinet of claim 1,
said blower being mounted at a lower and rearward portion of the
cabinet, and
means defining a kneehole beneath a portion of the work tray and
the viewing panel, whereby an operator may conveniently sit at the
cabinet, place his hands through the makeup air slot, and view the
work table at a natural inclined position.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to the handling of biohazardous and
potentially hazardous material such as cancer tumors, T.B., fungi,
virsues, parasites, bacteria, tissue cultures, dust, radioactive
material, allergens, toxic materials, and preparation of materials
for tissue culture and microbiological investigation, and can also
be used where ultra clean air is required as for plate pouring,
packaging, and sterility testing. Federal Standard 209a, Class 100,
is directed to the environmental air control within clean rooms and
clean work stations. Units commercially available in the prior art
include the CCI Bioharzard Laminar Airflow Safety Hoods
manufactured by Contamination Control, Inc., of Culpsville,
Pennsylvania; a Bioguard Hood Vertical Laminar Flow Cabinet
manufactured by the Baker Company of Sanford, Maine; Biohazard
Safety Cabinet of S. Blickman, Inc., of Weehawken, New Jersey; and
the Biological Cabinet of Bioquest Division of Becton, Dickinson
and Company of Cockeysville, Maryland. The units are closed
recirculatory systems using HEPA filters (high efficiency,
particulate air) which remove organisms and particles 0.3 micron in
size with a 99.97% efficiency.
2. Description of the Prior Art
The prior art of the character set forth above to pinpoint the
field of invention are generally rectangular tubular cabinets
having a breakfront inspection panel at the front portion. The
breakfront extends outwardly from the general outline of the
cabinets, and in most instances is covered by glass or other
transparent material to permit interior inspection. The opening at
the lower portion may be of a glovebox-type, or unobstructed for
access by the hands of the worker. In the prior art the interior
airflow is diverted from the vertical by positioning the HEPA
filters at an angle, rather than perfectly horizontal. The airflow
further is disrupted from laminar and full control by the
breakfront cabinets which generally break at an angle of 14.degree.
to 15.degree. outwardly thereby permitting the air in the laminar
flow to expand at that point adjacent the opening where the same
can escape and render the conditions hazardous for the operator.
Furthermore, the full standing units of the prior art are
fabricated from several panels bolted in place requiring extensive
gasketing and other sealing to insure a closed system without
leaks. Cabinets of the character just described having an outwardly
extending front are exemplified in U.S. Pat. No. 3,470,679. Further
indicating the failure of the prior art to develop a circulatory
flow in biohazardous insulated relationship is U.S. Pat. No.
3,494,112 where, see FIG. 5(b), the air is directed out towards the
worker.
SUMMARY OF INVENTION
The present invention is directed to a cabinet for biohazardous
materials being formed of an imperforate recirculatory rectangular
tube and having a viewing panel providing access of the interior
elements which has an aerodynamic airfoil-type recess for directing
the downward flow of the air at an accelerated rate as compared to
the balance of the air in the unit and also permitting the operator
to position the head at the recessed portion of the viewing panel
thereby obtaining a closer view of the work table provided in the
interior portion. The work table or tray is removably secured in a
horizontal plane in the interior portion of the cabinet atop a
perforated support which is also removable. The viewing panel is
hinged at its upper portion and removable therefrom permitting the
positioning interiorly of the cabinet of large work pieces which
would not otherwise pass through the gap provided at the lower
portion of the viewing screen fro the twofold purpose of permitting
access of the hands, and also admitting makeup air. The aerodynamic
characteristics including the plenum chamber, blower, and filters
is such that the airflow rate immediately in front of the unit at
the gap for permitting the hands to enter is greater than that
interiorly of the unit and also at a negative pressure thereby
insuring that the makeup air moves inwardly as distinguished from
any interior recirculatory contaminated air moving outwardly.
In view of the foregoing, it is a principal object of the present
invention to provide a cabinet for biohazardous materials in which
the airflow is so confined to inhibit the exhausting of the
potentially contaminated air within the unit, while at the same
time facilitating a closer view to the operator of the materials
being handled on the work tray.
Another object of the present invention is to provide a cabinet
construction which is generally imperforate thereby eliminating the
leaks which may otherwise occur during the degradation of gasket
materials where a plurality of panels are bolted in place. A
related and more detailed object of the invention is to provide
such cabinet which nevertheless provides ready access to the
removal of the HEPA filters, work tray, motor, and other units
which may require repair and replacement during the lifetime of the
use of the cabinet.
A further object of the present invention is the added safety
obtained by the double wall construction which surrounds the
positive pressure element of the full standing unit.
Still another object of the present invention is to provide a
viewing panel which is hinged in position with removable hinges so
that the same can be easily opened for the insertion of large
objects, or completely removed for cleaning and servicing the unit
including the removal of filters.
Yet another object of the present invention is to provide a cabinet
for biohazardous materials the main elements of which can be
readily modified for a desk top unit from a full standing unit with
knee access therebeneath.
DESCRIPTION OF DRAWINGS
Further objects and advantages of the present invention will become
apparent as the following description of an illustrative embodiment
takes place taken in conjunction with the accompanying drawings in
which:
FIG. 1 is a front partially perspective view illustrating the
subject cabinet and its principal exterior elements.
FIG. 2 is a front perspective view of an alternative desk model
cabinet illustrating its principal elements viewed externally.
FIG. 3 is a vertical sectional view taken along section line 3--3
of FIG. 1 of the larger cabinet illustrative of the present
invention.
FIG. 4 is a transverse sectional view of the subject cabinet taken
along section line 4--4 of FIG. 3.
FIG. 5 is an enlarged broken transverse sectional view illustrating
the gasketed mating relationship between the viewing panel and the
body of the cabinet.
FIG. 6 is a further vertical sectional view of the subject cabinet
taken along section line 6--6 of FIG. 3 and illustrating the
relationship between the plenum chamber, blower, work table, and
filters.
FIG. 7 is a vertical sectional view of the desk top alternative
embodiment cabinet taken along section line 7--7 of FIG. 2.
DETAILED DESCRIPTION
THe subject cabinet for biohazardous materials 10 as shown in FIG.
1 is fully encased in an imperforate closed tubular housing 11 with
the exception of those openings provided for the viewing panel 20
in front, and the exhaust filter 14 at the rear top. The
biohazardous materials which are positioned atop the work tray 15
are the subject of a bath of recirculating filtered air which
circulates in the interior of the cabinet 10. Any openings in the
closed tubular housing 11, therefore, are a possible source of a
leak whereby such biohazardous materials may pass into the workroom
and infect persons working there. Thus with only two openings to
the closed tubular housing 11 as pointed out above, only two areas
of potential difficulty need be dealt with in the sealing of the
cabinet 10.
Referring now to FIG. 3, it will be seen there that the
recirculating filter 12 is positioned interiorly of the closed
tubular housing 11 and in airflow communication with the plenum
chamber 19. The exhaust filter 14, however, can be positioned atop
or within the uppermost aspect of the unit and diverts
recirculating air, preferably in the quantity of 20 to 25 percent,
to the outside. Conventional ducting may be used to convey the
exhausted air out of the room into exhaust ducts or to a remote air
incinerator.
Airflow is provided by means of a blower 18 driven by an electric
motor which pumps air from the kneehole chamber 27 as the same
passes through the perforated support 30 for the worktray 15. The
blower 18 has its speed controlled through one of the control
members on the control panel 29 (see FIG. 1) and is so adjusted to
maintain a laminar flow of air in the cabinet 10 above the worktray
15 at approximately 100 ft. a minute. The viewing panel 20, as will
be particularly observed in FIG. 3, is provided with an airfoil
recess 22 terminating at a makeup air slot 25 at its lower portion,
the makeup air slot being defined by the support legs 24 of the
viewing panel 20. The viewing panel 20 is formed into the shape
required, and also transparent to the operator. It will be noted
that the makeup air slot 25 also provides the hand access for the
worker to the materials positioned atop the worktray 15.
The nature of the airfoil recess 22 is to accelerate the flow of
air immediately adjacent its surface, and provide a negative
pressure portion doownstream of the maximum point of penetration of
the airfoil recess 22. This accelerated flow creates a slight
negative pressure over the viewing panel 20 and particularly
adjacent the makeup air slot 25 to the end that the makeup air is
constantly being drawn into the interior of the cabinet 10, and
affirmatively inhibited from exiting through the makeup air slot 25
even though passing around the hands and forearms of the technician
utilizing the cabinet 10. In addition the makeup air is directed
beneath the work tray by the negative pressure from the motor
blower and does not contaminate work being carried out on the work
tray. A further advantage created by the utilization of the airfoil
recess 22 is that it is close to the approximate position where the
operator will position his head to look downardly at his specimens
on the worktable 15. Normal studies have indicated that the average
person inclines his body at approximately 14.degree. to 16.degree.
when working over a flat surface in order to obtain the best view
of his work. To this end, the angle of the viewing panel with the
vertical approximately 15.degree. thereby providing the best access
for the operator, as well as sufficient highlift characteristics to
the airfoil recess 22 to achieve the acclerated airflow rate and
negative pressure at the makeup air slot 25. For the further
comfort of the operator, a kneehole recess 26 is provided beneath
the forward position of the work tray 15 and its associated support
30. The kneehole recess 26, in turn, defines a kneehole chamber 27
which serves as the collecting area for the blower 18 which
thereafter recirculates the air upwardly through the plenum chamber
19.
Removability for servicing is also accommodated in the construction
shown. For example, it will be seen that the worktray 15 is gravity
supported in a perforated support 30. As noted in FIG. 4, the
perforated support 30 has a plurality of perforations 33. The
support is also removably fitted atop the support legs 32 which
define the undertable opening 34 which is in airflow open
communication with the kneehole chamber 27. The worktray 15 may be
removed for cleaning as well as its perforated support 30. To
further facilitate removal, the viewing panel 20 is secured by
means of liftout hinges 21 to the front of the closed tubular
portion 11 of the cabinet 10. When a large specimen is to be
positioned atop the worktray 15, raising the viewing panel 20
readily permits the same. In addition, the viewing panel 20 may be
readily removed from its hinges 21, and the transparent portion
cleaned, sterilized, or otherwise serviced.
In addition, while the viewing panel 20 is removed, access may be
had by the technician from underneath to the recirculating HEPA
filter 12 and from above to the motor 17 and blower 18. The light
box 28 provided at the front upper portion of the viewing panel 20
may be easily serviced without removing the viewing panel 20 or
entering the cabinet 10.
The shape of the plenum chamber 19 is best shown in FIG. 6 where it
will be seen that if flares outwardly and upwardly to the
horizontal portion 19 of the plenum chamber at the top of the
cabinet 10. The air therefore circulates in the rear of the cabinet
10 in a chamber defined by sidewalls which are interior of the back
31 of the working area, and the back of the cabinet 10 defined by
the closed tube housing 11. Desirably the housing is provided with
a double wall construction 45 to further inhibit leakage. Air
within its confines is under negative pressure and sucked back by
the blower to be recirculated.
To further insure against air leaks of the recirculating air within
the interior of the cabinet 10, a gasket 35 is provided around the
marginal closed edges of the viewing panel 20 and engages an offset
sealing edge 38 provided around the marginal edges of the viewing
panel 20, and at its upper edge portion where the same is hinged by
means of hinges 21 to the cabinet 10. Specifically as shown in FIG.
5, the serrated gasket 35 has a plurality of ridges 37, and is
positioned within a channel 36 which is slightly undersized so that
the resiliency of the gasket 35 secures the same in place, and is
further reinforced by means of the pressure of the sealing edge 38
against the ridges 37.
ALTERNATIVE EMBODIMENT
The alternative embodiment or desk model 50 is illustrated in FIGS.
2 and 7. As will be observed, all of the reference numerals in
connection with the description of the desk model 50 are the same
where they are common with the elements of the freestanding cabinet
10. Turning now to FIG. 7, it will be seen that the principal
difference in construction relates to the provision of a desk top
chamber 54 beneath the worktray 15 and its perforated support 30
and receives recirculating air in open communication with the
undertable opening 34. By mounting the blower motor 51 above the
closed tubular housing 11 of the desk model 50, and on support
plate 55, a plenum chamber 19 is provided below the blower and
above the filter 12. A diverting baffle 56 is positioned below the
output of the blower to distribute the air flow across the filter
12. A communicating duct 57 directs air to be exhausted from the
plenum chamber 19 to the exhaust filter 14. The provisions for
mounting the viewing panel 20 and its removable features remain the
same in the desk model 50 as in the freestanding unit 10.
In a typical commercial embodiment of the freestanding cabinet 10,
the same is 53 inches wide and 761/2 inches high with a depth of 30
inches. A 2-foot wider unit is also commercially available.
Provision can be further made to direct the exhaust air to an air
incinerator, should additional security be desired. The kneehole
depth is 12 inches and the kneehole access provided is 261/2 inches
high. Desk top models are commercially available in 3-, 4-, and
6-foot widths.
The viewing panel 20 of the commercial embodiment cabinets 10 and
50 are as wide as the work area. The curved portion in the viewing
panel 20 defining the airfoil recess 22 is recessed approximately 6
inches from the vertical plane defined by the viewing panel 20.
Also in the commercial embodiment of the freestanding unit the
support ledge 32 which supports the removable perforated support 30
and worktray 15 serves as a spill tray which may be cleaned at the
time the worktray 15 and its associated support 30 are removed for
cleaning.
Although particular embodiments of the invention have been shown
and described in full here, there is no intention to thereby limit
the invention to the details of such embodiments. On the contrary,
the invention is to cover all modifications, alternatives,
embodiments, usages and equivalents of a cabinet for biohazardous
materials as fall within the spirit and scope of the invention,
specification and the appended claims.
* * * * *