Note: Descriptions are shown in the official language in which they were submitted.
2147963
DocketNo: 51629CAN2A
POSITIVE/NEGATIVE AIR PRESSURE ADAPTOR
FOR USE WITH RESPIRATORS
Field of the Invention
The present invention relates to a co,..binalion positive and negative
pressure respirator system, and more particularly, to a positive/negative air
pressure adaptor for use with respirator systems.
Back~round of the Invention
Respirators are used in a variety of hazardous environments, such as
paint booths, grain storage facilities, laboratories, and m~m~f~ctllring f~ilities in
which co~ are present. Respirator masks are typically adapted to receive
a variety of filter cartridges or air supply connectors to provide a source of
breathable air to the wearer so that the same face mask design may be used in a
variety of di~el elll hazardous environments.
The two major classes of respirator systems are positive and negative
pressure respirators. A positive pressure respirator typically includes a positive
pressure air source such as an external pump or pressurized vessel that force clean
air into the face mask. The positive pressure air source provides an excess of
clean, breathable air to a face mask. The net positive pressure in the face maskdue to the positive pressure air source prevents ambient air from being drawn
around the face seal of the mask.
One type of positive pressure air source for use with a positive
pl es~ule respirator system is a powered air purifier respirator (PAPR). A
powered air purifying respirator typically includes a bleall,il-g tube from the face
mask to a battery powered blower unit worn by the user. The blower unit
typically contains a filter to remove col~l~."in~nt~ from the ambient air. Powered
air purifying respirators have the advantage of allowing the user to move freely,
without being tethered to an air line. However, powered air purifying respirators
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tend to be more expensive than continuous flow respirator systems. Additionally,powered air purifying respirators are battery operated and consequently can onlybe used for a limited period of time. Finally, powered air purifying respiratorsgenerally require a large bore ~liAmeter brealhing tube (applo~lnately 25 mm),
5 because battery operated blowers generally can not generate sufficient plessure for
a smaller bore diAmetçr brealhing tube. These large bore di~meter brealhillg tubes
can be cumbersome to the user.
Alternatively, the positive p~essure air source may be a colllpressor or
pressure vessel connected to the user by an air line. Typically, these systems
lo include a filter at the conlpressor to provide the user with breathable air.
However, for some applications, the air line may restrict the user's ability to
pelrollll certain functions. Additionally, the air line may get kinked or the supply
of pressurized air may be accidentally terrnin~te~, potentially exposing the users to
Col~A~ l)A~
1S The other major class of respirators are called negative pressure
respirators because the user's inhalation draws air through a filter cartridge into
the face mask. The filter cartridge may contain a variety of filtering elements,such as blown microfibers or carbon-based systems for gas and vapor protection.
Negative pressure respirators have the advantage of not requiring the wearer to
drag an air line or to wear an e,~l)ensi~e powered-air purifying respirator system.
The disadvantage of negative pressure respirators is that the user must utilize lung
power to draw air through the filter media and the resllltin~ negative pressure in
the face mask can potentially allow co~lA.";I~Ant~ to be drawn in around the face
seal. Additionally, using respiratory lung power to draw air through the filter
2s media tends to heat up the face mask, ~;I.,aling discomfort for the wearer.Consequently, negative pressure respirators generally have a lower protection
level than positive pres~ure respirators.
Summary of the Invention
The present invention is directed to a positive/negative air pres~ure
adaptor for a respirator system. The positive/negative air pressure adaptor has a
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port region for fluidically coupling a filter cartridge to a respirator. The adaptor
has an inlet port for connecting to a positive pressure air source and a first check
valve to restrict the flow of air from the port region to the filter cartridge. A
second check valve may be provided to restrict the flow of air from the respirator
to the port region.
The positive/negative air pressure adaptor may include a porous
structure interposed between the inlet pOn and the port region. The porous
structure may operate as either a muffler or a diffuser, or both. The porous
structure may be a porous polyrneric material, sintered metal such as brass, porous
o ceramic, or other porous material.
The first check valve may be located on the filter cartridge or on the
positive/negative air pressure adaptor. The second check valve may be located onan inhalation port on the positive/negative air pressure adaptor or on the
respirator. The positive/negative air pressure adaptor and filter cartridge may be
constructed as a single unit. Alternatively, the positive/negative air pressure
adaptor and respirator may be constructed as a single unit.
An air line connects the inlet port to a positive pressure air source.
The positive pressure air source may include a portable powered air purifier or a
continuous flow of supplied air from a colllplessor or pressurized vessel. The air
line may include a quick disconnect to permit the wearer to be disconnected fromthe air line. When disconnected from the positive pressure air source, the
respirator operates as a negative pressure respirator. A check valve is preferably
provided between the quick disconnect and the face mask to restrict ambient air
from being drawn into the respirator.
The present invention is directed to a con~indlion positive and
negative pressure respirator system. The present respirator system permits both
positive and negative pressure respirator capabilities on a single inhalation port on
a face mask. The positive/negative air pressure adaptor has a port region for
fluidically coupling an inhalation port on the face mask to at least one filter
cartridge. A positive pressure air source may be connected to the adaptor. At
least one filter cartridge may be attached to the positive/negative air pressure
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adaptor. A check valve is positioned to restrict the flow of air from the positive
air source adaptor to the filter cartridge. A second check valve may be located
proxilllate the face mask to restrict the flow of air from the face mask çh~mh~r to
the positive/negative air pressure adaptor.
The method of the present invention is directed to connecting a
positive pressure air source to an adaptor interposed between a filter cartridge and
a respirator. The flow of air from the positive/negative air pressure adaptor to the
filter cartridge is restricted. The positive pressure air source may then be
disconnected from the positive/negative air pressure adaptor, so that the system0 operates as a negative pressure respirator. The method may also include
recomle~;ling the positive pressure air source to the adaptor at a later time so that
the system operates as a positive pressure respirator.
Definitions used in this application:
"Ambient air" means environm~nt~l air;
"Check valve" means any device for automatically limiting flow to a
single direction.
"Co~ " means a chemical in gaseous, vaporous, or particulate
form that is hazardous to breath.
"External environlnell~" means ambient air external to the respirator;
"Face mask" means a full or partial face covering with a seal engaged
with the face, neck and/or head of a user.
"Overmolding" means pelrolllling a molding process on an item to add
additional molded structure.
"Positive pressure air source" means a device that forces breathable air
to a respirator, inc]u-lin~ a portable air pump, such as a powered air purifyingrespirator (PAPR), a stationary air pump or complessor, or pressurized vessel.
Brief Description of the Drawings
Figure 1 is a sç~em~tic illustration of a respirator system with a
positive/negative air pressure adaptor connected to a positive pressure air source;
Figure 2 is a side view of the respirator of Figure l;
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Figure 3 is a cutaway pe,~pe~ e view of a positive/negative air
pressure adaptor;
Figure 4 is a side sectional view of a respirator system with a
positive/negative air pressure adaptor connected to a positive pressure air source;
Figure S is the re~ alor system of Figure 4 in which the positive
pressure air source has been terminqted or reduced;
Figures 6A and 6B are side sectional views of a positive/negative air
pressure adaptor before and after overmoulding, respe~ ely;
Figures 7A and 7B are perspective views of a Y-fitting for the present
o positive/negative air pressure adaptor system before and after overmoulding,
respectively;
Figure 8 is an alternate configuration of the respirator system of Figure
l;
Figure 9 is a side view ofthe respirator system of Figure 8;
1S Figure 10 is an alternate embodiment ofthe respirator of Figure 1 with
the filter cartridges removed; and
Figure 11 is an alternate full face mask respirator system with a
positive/negative air pressure adaptor connected to a positive pressure air source.
Detailed Description ofthe Plt;r~;lled Embodiment
Figure 1 is a perspective view of a combination positive and negative
pressure respirator system 20. A pair of positive/negative air pressure adapters22, 24 are connected to a partial face mask 26 at respective inhalation ports (see
Figure 4). The face mask 26 has an exhaust port 28 with a check valve (not
shown) and straps 30 for ~qtt~qçhment to a user. The partial face mask 26 generally
encloses the user's mouth and nose. It will be understood that the present
invention may be used with any style face mask.
A pair of filter cartridges 32, 34 are att~q.~hed to the adapters 22, 24,
respectively. An air line 36 with a Y-connector 37 comlecls the adapters 22, 24
with a positive pressure air source 38. Utilizing a pair of adapters 22, 24 and filter
cartridges 32, 34 keeps the respirator 20 generally evenly balanced. However, it
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will be understood that the present invention encomp~cses a respirator system
with a single adaptor and filter cartridge.
A check valve 40 and a quick release mPçh~nicm 42 are provided on
the air line 36 to allow the user to quickly disconnect from the positive pressure
s air source 38. The check valve 40 prevents ambient air from being drawn into the
face mask 26 once air line 36 is disconnected from the positive pressure air source
38. It will be understood that the check valve 40 may be located anywhere along
the air line 36 b~ween the quick release ",eç~ icm 42 and the respirator system
20. A check valve known under the trade ~eci~n~tion ICV Series from Generant
o Company of Butler, New Jersey, is known to be suitable for this purpose. The air
line 36 or check valve 40 may contain a low pressure alarm to warn the user thatthe air flow from the positive pressure air source 38 has been reduced below some
predetermined level and that the filter cartridge 32, 34 is providing at least aportion of their air.
1S Figure 2 is a side view of the respirator system 20 of Figure 1 showing
the air line 36 elctçn~iinp~ forward from the face mask 26. A belt clip 39 is
provided for ~tt~çhin~ the air line 36 to the user so that the respirator system 20 is
not inadvertently pulled from the user's face (not shown).
Figure 3 is a sectional perspective view of the positive/negative air
20 pressure adapters 22, 24 with arrows illustrating the flow of air from the air line
36 into an air distribution channel 50. In the embodiment illustrated in Figure 3,
the air distribution channel 50 extends generally around a port region 52, as will
be tiiccl.cse~ in detail below. However, it will be understood that a variety of air
distribution cha-l-be- configurations may be utilized without departing from the2s sGope of the present invention. A bayonet connector 60 is provided plo~ -ate an
inhalation port 68 on an àdaptor housing 23.
The supplied air illustrated by the arrows enters the air distribution
channel 50 and passes radially through a porous member 54 into the port region
52. The porous member 54 may be constructed of a variety of porous materials
30 such as sintered metal (for example brass), porous poly~ropylene or acetal, porous
ceramic or glass bead structure, or a variety of other porous materials. A porous
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polyethylene with an average pore size of 100 microns rr~mlf~ctured by General
Polymeric of P~e~lin~ Pem~syl~ania is known to be suitable for this purpose.
Air Line Noise ~ttçml~fion Test
Respirator masks were tested for the amount of noise generated due to
the air flow through the air line, adapter, valves, and f~cçm~Q~ haldwale systemin a quiet laboratory setting with carpeting and acoustic ceiling trç~tm~nt The
masks tested were fastened to a ~ e~ in head and a microphone for sound
pickup was positioned 3.5 cm from the head surface at a location corresponding
0 to a leplesell~a~ e ear. The sound generated by the air flow was acquired utili7:ing
a microphone, preamplifier, and signal amplifier Model 2610 available from Bruel& Kjaer, Inc. (Naerum, Denmark) with "A" wçi~hting of the signal. The signal
was analyzed ltili7:in~ a Model 3561A Dynamic Signal Analyzer available form
Hewlett Packard Co. (Everett, WA) set at the 1/3 octave mode with rms. (root
mean square) averaging. The analysis bandwidth was the frequencies from 12.5
Hz to 20 Khz. The microphone, preamplifier, and amplifier were calibrated using
a Model 4230 sound level calibrator available from Bruel & Kjaer, Inc. Half-maskrespirator 3M Brand Easi-Air (TM) 7200 available from 3M Company of St. Paul,
Minnesota was tested at an air flow of 3.304 liters/second with both a 3M W-
3187 airline adapter and the instant invention adapter, with and without the
muffler 54. Porous member 54 had an outside diameter of 4.0 cm, an inside
diameter of 3.3 cm and a height of 1.1 cm. Sound pressure levels measured at themicrophone are listed in Table 1.
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TABLE 1
Sound Pressure level Mea~ule",enls
l~f , ' 250 Hz 500 Hz 1 KHz 2 KHz 4 Khz 10 Khz 20 Khz T " ~ d
C- r~ ot~ (dB)(dB) (dB) (dB) (dB) (dB) (dB) Sound
Pressure
level (dB)
7200 H~lf 56 62 66 89 85 85 74 94.5
Mask with
W-3187
adapter
7200 Half 39 54 64 71 73 98 65 99.7
Mask with
iv~
adapter
without
mumer
7200 Half 39 44 51 63 67 61 51 73.5
Mask with
tiV~
adapter with
mumer
These results demonstrate that the muffler provides a typical 20 dB
5 reduction ofthe integrated sound pressllre level over the frequency range of 12.5
Hz through 20 kHz. This corresponds to a noise level of one quarter the amount
present with adapters without the muffler material. In addition, the porous
member 54 acts as a diffuser to dissipate the intensity of the air flow, red~lçing the
m~ximl-m velocity of the air entering the face mask 26, while providing a
0 continuous flow of supplied air in excess of the user's requirements.
Figure 4 is a side sectional view of a positive/negative air pressure
adaptor 22 or 24 fluidically coupling a filter cartridge 32 or 34 to a single
inhalation port 62 on the face mask 26. The filter cartridge 32 or 34 is attached by
the bayonet connector 60 at the inhalation port 68 on the adaptor 22 or 24 (see
15 also Figure 3). A co~ ,onding bayonet connector 60' is also provided pro~imate
the inhalation port 62 on the face mask 26. In the p,eîelled embodiment, the
bayonet connectors 60, 60' are identical so that a filter cartridge 32, 34 may be
attached directly to the face mask 26. However, it will be understood that for
some applications it may be desirable to alter one of the bayonet connectors 60,20 60' to limit the type of components that may be att~ched thereto. Seals 64, 66
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g
preferably are interposed between the adapters 22, 24 and the filter cartridge 32,
34 and face mask 26. The seals may be constructed of a variety of resilient
materials, such as closed cell ur~lhane rubber or silicone may be suitable for this
purpose.
Although the plerelled embodiment discloses bayonel connectors 60,
60', it will be understood that the present invention is not limited to the type of
connector used to fluidically couple the various components 22, 24, 26, 32, 34.
Other types of conne~ilors uniquely adapted to receive a threaded Illelllber which is
adapted to thread into a corresponding integral cylinder sealed with or without a
0 gasket, both pellllal-elll and det~h~hle, may be colllbined without departing from
the scope of the present invention. Additionally, some of the components may be
constructed as a single unit. For example, the filter cartridge 32, 34 and the
adaptor 22, 24 may be a single unit. Altematively, the inhalation port 62 on theface mask 26 and the adapters 22, 24 may be constructed as a single unit.
As illustrated in Figure 4, once the air passes the porous member 54
and enters into the port region 52, a positive pressure valve 66 restricts air from
passing through the inhalation port 68 and into the filter cartridges 32, 34. The
positive pressure valve 66 is attached to a support 70 which extends generally into
the opening fommed at the inhalation port 68. The pressure of the air forces thepositive pressure valve 66 against a valve seat 72 on the adaptor housing 23 andenhances the seal ofthe valve. In the event that the positive pressure air source 38
does not provide adaquate air flow for the user's need, the inhalation of the user
will create a net negative pressure in the face mask chamber 84. The net negative
pressure draws the valve 66 off of the valve seat 72 and allows air to be drawn
through the cartridge 32, 34. In the embodiment disclosed in Figure 4, the
positive pressure valve 66 is a diaphragm valve constructed from a highly flexible
material such as silicone rubber. It will be understood that a variety of check
valve configurations may be suitable for this purpose and that the present
invention is not limited by the particular type of check valve disclosed.
An inhalation valve 80 located across an opening 82 pro;~illlate the
inhalation port 62 permits the air in the port region 52 to enter a face mask
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chamber 84 defined by the face mask 26 and the face of the user (not shown).
The inhalation valve 82 may also be constructed of a highly flexible material such
as silicone rubber. It will be understood that the inhalation valve 80 may
alternatively be located on the adaptor housing 23. The net positive pressure in5 the face mask ch~llbel 84 during exhalation by the user forces the inhalation valve
80 against a valve seat 86. The excess pressure in the face mask chamber 84 is
released through the exhaust port 28 (see Figure 1).
The positive pressure air source 38 may be reduced or termin~ted for a
variety of reasons. For example, malfunction of a colllpl essor, accidental kink or
o cut of the air line 36, or the user's intentional disconnect of the air line 36 to
provide greater mobility. The arrows in Figure 5 illustrate the air flow through the
respirator system 20 if the positive pressure air source 38 is reduced below theuser's requil elllelll~ or termin~ted The lack of positive pressure in the port region
52 permits the positive pressure valve 66 to be lifted from its valve seat 72 to1S allow air flow through the filter cartridge 32, 34. In the configuration illustrated
in Figure 5, the respirator system 20 is ope~ dLing as a negative pressure system
which relies on the user's lung power to draw air through openings 90 in the filter
cartridge 32, 34, through the filter media 92 and into the face mask chamber 84.As di~cl~ssed in connection with Figure 4, the inhalation valve 80 is forced against
20 its valve seat 86 when the user exhales so that the excess pressure in the face mask
challlber 84 is expelled through the exhaust port 28 (see Figure 1).
In the event the user disconnects the air line 36 from the positive
pressure air source 38, the check valve 40 in the air line 36 prevents co~ ted
air from being drawn up the air line when the respirator system 20 is operating in
25 the negative pressure mode. In the embodiment disclosed in Figure 1, the check
valve 40 is located proximate a quick release mecl-~ .., 42 that permits the user
to disconnect the respirator system 20 from the positive air source 38.
Figures 6A and 6B illustrate an exemplary method of m~nllf~ctllring
the positive/negative air pressure adapters 22, 24. The primary components of the
adaptor are a base 100, a cover 102, the porous member 54, and gaskets 55. The
base 100 has a female bayonet connector 60F for çng~gçment with the bayonet
2I~7963
-- 11
connector 60' on the face mask 26. The base 100 also has a barbed connector 104
with a ferule or some acceptable f~t~ning Inecl-Al~ ~... for relAi~ g the air line 36.
A strain relief spring and relA;n;np. clip may be added to retain the air line 36 to the
barbed connector 104. The base 100 and cover 102 may be constructed from a
variety of polymeric materials, such as polyethylene, poly~ ropylene, poly~yl elle.
Poly~lopylene 6323 available from Himont of Minneapolis, Minnesota has been
found suitable for this purpose.
The air line 36 generally has a 6 mm inner diameter which corresponds
to the outside rli~meter ofthe barbed connector 104, although air lines with 3 mm
0 inner diameters may also be suitable for some purposes. For applications ~ltili~ing
a portable powered-air purifying respirator, an air lines having a 25 mm bore size
is generally required. The outside diameter ofthe barbed connector 104 may be
m~nllf~ctured to accommodate any size air line. Tubing constructed from a 50/50
blend of Shell Kraton G2701 and G2705 available from Shell Chemical Co~"pany
of Houston, Texas may be used for this purpose.
Figure 6B illustrates an exemplary method for attaçhing the air line 36
to the connector 104, and creating a hermetic seal between the base 100 and cover
102. The adaptor housing 23 attaclled to the air line 36 are placed into a mold
where it is overrnolded with a polymeric material 106. Although a variety of
polymeric materials 104 may be used for this purpose, it has been found that thecompatibility of certain polymeric materials result in a chemical bond which
provides ideal mechanical ~llenglll and hermetic sealing. For example, a
polymeric material sold under the trade name Monprene 2850M, available from
Quality Service Technology of St. Albans, Vermont, Kraton identified above or
polypropylene are particularly coll,palil)le with a base and cover 100, 102
constructed from polypropylene and an air line 36 constructed from Kraton or
Monoprene.
Figures 7A and 7B illustrate use of the present overmoulding technique
to forrn a Y-connector 37 for connection to a pair of adapters 22, 24. A Y-fitting
110 is attached to three sections of air line 36. The Y-fitting 110 and air lines 36
2147~6~
-- 12
are then overmoulded as illustrated in Figure 7B using the materials 106 ~ cussed
above.
Figures 8 and 9 illustrate an alternate embodiment of the respirator
system 20 in which the air lines 36 are configured to extend towards the rear ofs the face mask 26. As illustrated in Figure 9, the air line 36 extends towards the
rear of the user so as to not interfere with the user's activities.
Figure 10 is another alternate embodiment of the respirator system 20
in which the filter canridges 32, 34 have been removed, and valve caps 112, 114
have been substituted. In the configuration illustrated in Figure 10, the respirator
0 system 20 operates only as a positive pressure respirator system generally
corresponding to Figure 1.
Figure 11 is an alternate full face mask respirator system 20' with a pair
of positive/negative air pressure adapters 22', 24' connected to a positive pressure
air source 38. The full face mask 20' typically encloses the mouth, nose and eyes
5 of the user.
It will be understood that the exemplary embodiments in no way limit
the scope of the invention. Other modifications of the invention will be apparen~
to those skilled in the an in view of the folegoing descriptions. These descriptions
are int.ontled to provide specific examples of embodiments which clearly disclose
20 the invention. Accordingly, the invention is not limited to the described
embodiments or to the use of specific elements, dimensions, materials or
configurations contained therein. All alternative modifications and variations of
the present invention which fall within the spirit and broad scope of the appended
claims are covered.
2s
