Respirator negative pressure fit check devices and methods

TECHNICAL FIELD

0001This disclosure relates to respiratory protection devices, in particular a respiratory protection device including a shut-off valve.

BACKGROUND

0002Respiratory protection devices commonly include a mask body and one or more filter cartridges that are attached to the mask body. The mask body is worn on a person's face, over the nose and mouth, and may include portions that cover the head, neck, or other body parts, in some cases. Clean air is made available to a wearer after passing through filter media disposed in the filter cartridge. In negative pressure respiratory protection devices, air is drawn through a filter cartridge by a negative pressure generated by a wearer during inhalation. Air from the external environment passes through the filter medium and enters an interior space of the mask body where it may be inhaled by the wearer.

0003In order to effectively deliver breathable air to a wearer, respiratory protection devices desirably provide an adequate seal to prevent unfiltered air from entering the mask. Various techniques have been proposed for testing the integrity of a seal provided by a respiratory protection device. In a positive pressure test, an exhalation valve of the respiratory protection device is blocked while the wearer exhales into the mask. An adequate seal may be signaled by an increased internal pressure due to the inability of air within the mask to escape through an exhalation valve if a leak is not present. Alternatively, negative pressure tests have been proposed in which a filter cartridge port is blocked while a wearer inhales while wearing the mask. An adequate seal may be signaled by a reduced internal pressure due to the inability of air to enter the mask if a leak is not present.

0004<patcit id="pcit0001" dnum="WO2013187279A1"><text>WO 2013/187279 A1</text></patcit> describes a respiratory protective device having a facepiece formed to be suctioned and exhausted, said facepiece having a plurality of filter units, each of said filter units being breathably connected to said facepiece, each of said filter units having air flow paths that merge with each other at their tips extending toward said facepiece, and said respiratory protection has an intake hole at the point where said air flow paths merge that leads to the inside of said facepiece and temporarily closes said intake hole to temporarily block intake air from flowing into said facepiece. said respiratory protective device has a fit checker capable of determining whether said respiratory protective device is in good condition by temporarily blocking the inflow of intake air into said facepiece, and said fit checker temporarily closes said air intake hole using an inspection valve contained therein.

SUMMARY

0005The present disclosure provides a respiratory mask according to the main claim. The respiratory mask including a mask body defining a breathable air zone for a wearer and having two or more inlet ports configured to receive two or more breathing air source components, the two or more inlet ports are in fluid communication with a single fluid chamber (621) defining an opening (624) to allow fluid communication between the two or more inlet ports and the breathable air zone, and a shut-off valve operable between a closed position and an open position, wherein in the closed position the shut-off valve prevents fluid communication between the two or more inlet ports and the breathable air zone. The shut-off valve includes a seal, an actuator and a retainer, the actuator and seal being coupled together and the retainer being positioned between the actuator and seal and securing the actuator to the mask body. The actuator formed of an outwardly extending flange and a span extending inwardly from the flange, wherein the flange is positioned between a projection (662) of the mask body and the retainer (653) and is attached to the mask body, wherein the flange is sealed against the mask body, so that ingress of unfiltered air from the external environment between the flange and mask body is prevented when the shut-off valve is in an open, closed, or intermediate position. The outer shape of the actuator and flange, when viewed in a plane view in a direction that is perpendicular to a direction of displacement for the span, is round, in the open position of the shut-off valve, the span, when viewed in cross-section in a plane that is parallel with the direction of displacement for the span, bulges outwardly. The shut-off valve is configured and arranged such that when the actuator is depressed, the seal is translated toward an interior wall of the mask body, ultimately blocking the opening when the shut-off valve is in the closed position. The span, when viewed in cross-section in the plane that is parallel with the direction of displacement for the span, exhibits varying thickness so that the actuator buckles producing an oil canning in response to the force placed onto the actuator when operated from the open position to the closed position, thereby providing a tactile feedback in response to an applied force placed on the actuator.

0006The above summary is not intended to describe each disclosed embodiment or every implementation. The Figures and the Detailed Description, which follow, more particularly exemplify illustrative embodiments.

BRIEF DESCRIPTION OF DRAWINGS

0007The disclosure may be further explained with reference to the appended Figures, wherein like structure is referred to by like numerals throughout the several views, and wherein: <ul id="ul0001" list-style="none" compact="compact"><li><figref idref="f0001">Figure 1a</figref> is a front perspective view of an exemplary respiratory protection device not according to the claimed invention.</li><li><figref idref="f0001">Figure 1b</figref> is a partial cross-sectional view of an exemplary respiratory protection device not according to the claimed invention.</li><li><figref idref="f0002">Figure 1c</figref> is a partial cross-sectional perspective view of an exemplary respiratory protection device not according to the claimed invention showing a shut-off valve in an open position.</li><li><figref idref="f0002">Figure 1d</figref> is a partial cross-sectional perspective view of an exemplary respiratory protection device not according to the claimed invention showing a shut-off valve in a closed position.</li><li><figref idref="f0003">Figure 2a</figref> is a partial cross-sectional perspective view of an exemplary respiratory protection device not according to the claimed invention showing a shut-off valve in an open position.</li><li><figref idref="f0003">Figure 2b</figref> is a partial cross-sectional perspective view of an exemplary respiratory protection device not according to the claimed invention showing a shut-off valve in a closed position.</li><li><figref idref="f0004">Figure 3a</figref> is a partial perspective view of an exemplary respiratory protection device not according to the claimed invention showing a shut-off valve in an open position.</li><li><figref idref="f0004">Figure 3b</figref> is a partial perspective view of an exemplary respiratory protection device not according to the claimed invention showing a shut-off valve in a closed position.</li><li><figref idref="f0005">Figure 4a</figref> is a partial perspective view of an exemplary respiratory protection device not according to the claimed invention showing a shut-off valve in an open position.</li><li><figref idref="f0005">Figure 4b</figref> is a partial perspective view of an exemplary respiratory protection device not according to the claimed invention showing a shut-off valve in a closed position.</li><li><figref idref="f0006">Figure 5a</figref> is a front perspective view of an exemplary respiratory protection device not according to the claimed invention.</li><li><figref idref="f0006">Figure 5b</figref> is a partial perspective view of an exemplary respiratory protection device not according to the claimed invention showing a shut-off valve in an open position.</li><li><figref idref="f0006">Figure 5c</figref> is a partial perspective view of an exemplary respiratory protection device not according to the claimed invention showing a shut-off valve in a closed position.</li><li><figref idref="f0007">Figure 6a</figref> is a partial perspective view of an exemplary respiratory protection device according to the present disclosure.</li><li><figref idref="f0008">Figure 6b</figref> is an exploded view of an exemplary respiratory protection device according to the present disclosure.</li><li><figref idref="f0007">Figure 6c</figref> is an exploded view of an exemplary respiratory protection device according to the present disclosure.</li><li><figref idref="f0009">Figure 7</figref> is a graph showing a force response curve for an actuator used in an exemplary respiratory protection device according to the present disclosure.</li><li><figref idref="f0010">Figure 8a</figref> is a sectional view of an exemplary actuator in an open position for a respiratory protection device according to the present disclosure.</li><li><figref idref="f0011">Figure 8b</figref> is a sectional view of an exemplary actuator in an intermediate position for a respiratory protection device according to the present disclosure.</li><li><figref idref="f0012">Figure 8c</figref> is a sectional view of an exemplary actuator in a closed position for a respiratory protection device according to the present disclosure.</li><li><figref idref="f0013">Figure 9a</figref> is a sectional view of an exemplary actuator for a respiratory protection device according to the present disclosure.</li><li><figref idref="f0013">Figure 9b</figref> is a sectional view of an exemplary actuator for a respiratory protection device according to the present disclosure.</li><li><figref idref="f0014">Figure 9c</figref> is a sectional view of an exemplary actuator for a respiratory protection device according to the present disclosure.</li><li><figref idref="f0014">Figure 9d</figref> is a sectional view of an exemplary actuator for a respiratory protection device according to the present disclosure.</li><li><figref idref="f0015">Figure 10a</figref> is a sectional view of an exemplary actuator in an open position for a respiratory protection device not according to the claimed invention.</li><li><figref idref="f0015">Figure 10b</figref> is a sectional view of an exemplary actuator in an intermediate position for a respiratory protection device not according to the claimed invention.</li><li><figref idref="f0016">Figure 10c</figref> is a sectional view of an exemplary actuator in a closed position for a respiratory protection device not according to the claimed invention.</li></ul>

0008While the above-identified figures, in particular <figref idref="f0007 f0008 f0009 f0010 f0011 f0012 f0013 f0014">Figures 6a to 9d</figref>, set forth various embodiments of the disclosed subject matter, other embodiments are also contemplated. In all cases, this disclosure presents the disclosed subject matter by way of representation and not limitation. It should be understood that numerous other modifications can be devised by those skilled in the art which fall within the scope of this disclosure.

DETAILED DESCRIPTION

0009The present disclosure provides a respiratory protection device including a mask body defining a breathable air zone for a wearer and having one or more inlet ports configured to receive one or more breathing air source components. A shut-off valve operable between a closed position and an open position is provided to allow a wearer to easily perform a negative pressure fit test. In a closed position, the shut-off valve prevents fluid communication between each of the one or more inlet ports and the breathable air zone. Inhalation by a wearer results in a negative internal pressure within the mask if the respiratory protection device is appropriately fitted and an adequate seal is achieved.

0010<figref idref="f0001 f0002">Figures 1a through 1d</figref> illustrate an exemplary respiratory protection device 100 - not according to the claimed invention - that may cover the nose and mouth and provide breathable air to a wearer. The respiratory protection device 100 includes a mask body 120 including one or more inlet ports, such as a first inlet port 103, and/or a second inlet port 104. One or more breathing air source components may be positioned at the one or more inlet ports of mask body 120. In the exemplary device, first and second breathing air source components 101, 102 are provided and include filter cartridges configured to be attached at first and second inlet ports 103 and 104. Filter cartridges 101, 102 filter air received from the external environment before the air passes into interior space within the mask body for delivery to a wearer.

0011The mask body 120 may include a rigid or semi-rigid portion 120a and a compliant face contacting portion 120b. The compliant face contacting portion of the mask body is compliantly fashioned for allowing the mask body to be comfortably supported over a person's nose and mouth and/or for providing an adequate seal with the face of a wearer to limit undesirable ingress of air into an interior of mask body 120, for example. The face contacting member 120b may have an inturned cuff so that the mask can fit comfortably and snugly over the wearer's nose and against the wearer's cheeks. The rigid or semi-rigid portion 120a provides structural integrity to mask body 120 so that it can properly support breathing air source components, such as filter cartridges 101, 102, for example. Mask body portions 120a and 120b may be provided integrally or as separately formed portions that are subsequently joined together in permanent or removable fashion.

0012An exhalation port 130 allows air to be purged from an interior space within the mask body during exhalation by a wearer. In the exemplary device, exhalation port 130 is located centrally on mask body 120. An exhalation valve is fitted at the exhalation port to allow air to exit due to positive pressure created within mask body 120 upon exhalation, but prevent ingress of external air. In some exemplary devices, exhalation port 130 is positioned at a lower position on mask body 120, for example below the nose and mouth of a wearer.

0013A harness or other support (not shown) may be provided to support the mask in position about the nose and mouth of a wearer. In an exemplary case, a harness is provided that includes one or more straps that pass behind a wearer's head. In some cases, straps may be attached to a crown member supported on a wearer's head, a suspension for a hard hat, or another head covering.

0014The one or more inlet ports of mask body 120 are configured to receive one or more breathing air source components. In exemplary devices including two or more breathing air source components, as shown in <figref idref="f0001">Figure 1a</figref>, mask body 120 includes first and second inlet ports 103, 104 on either side of mask body 120, and may be proximate cheek portions of mask body 120. First and second inlet ports 103, 104 include complementary mating features (not shown) such that first and second breathing air source components 101, 102 may be securely attached to mask body 120. Other suitable connections may be provided as known in the art. The mating features may result in a removable connection such that the breathing air source components 101, 102 may be removed and replaced at the end of service life of the breathing air source component or if use of a different breathing air source component is desired. Alternatively, the connection may be permanent such that the breathing air source components cannot be removed without damage to the breathing air source component, for example.

0015Respiratory protection device 100 includes a shut-off valve 150 for closing a fluid intake communication component. Typically, shut-off valve 150 is operable between a closed position and an open position. In a closed position, shut-off valve 150 prevents fluid communication between each of one or more breathing air source components, such as filter cartridge 101 and/or 102, and a breathable air zone of mask body 120.

0016Shut-off valve 150 allows a wearer to perform a negative pressure fit check to provide an indication of the presence of leaks around a periphery of the mask body. When shut-off valve 150 is in a closed position, air is prevented from entering a breathable air zone of mask body 120. Inhalation by a wearer while the shut-off valve is in a closed position will result in a negative pressure within the mask, and in an exemplary situation may cause greater difficulty for a wearer to inhale or cause a compliant face contacting member to deflect inward, if an adequate seal has been achieved between the mask body and the wearer's face. If an adequate seal is not achieved, inhalation may result in air from the external environment entering the breathable air zone between the periphery of the mask body and the face of the wearer. In this way, a negative pressure fit check can be easily performed by a wearer wearing respiratory protection device 100 to determine if an adequate seal is achieved between the respiratory protection device 100 and the face and/or head of the wearer.

0017<figref idref="f0001">Figure 1b</figref> shows a representative cross-sectional view of an exemplary mask body 120 through a middle portion of mask body 120. Exemplary mask body 120 includes a first chamber 121 and a second chamber 122. A breathable air zone is defined by second chamber 122. In some cases, first and second breathing air source components 101,102, such as filter cartridges, may be attached to first and second inlet ports 103, 104. First and second inlet ports 103, 104 are in fluid communication with first chamber 121. Accordingly, air entering mask body 120 through first inlet port 103 after passing through first breathing air source component 101 is in communication with air entering mask body 120 through second inlet port 104 after passing through second breathing air source component 102. Air from first and second breathing air sources 101, 102 is thus allowed to mix in first chamber 121 before being delivered to the breathable air zone defined by second chamber 122 of mask body 120.

0018In an exemplary case, first and second chambers 121, 122 are separated by an inner wall 124 having a fluid intake communication component 140. Fluid intake communication component 140 comprises one or more openings to provide fluid communication between first and second chambers 121, 122. Fluid intake communication component 140 may include an inhalation valve for selectively allowing fluid communication between first and second chambers 121, 122, as described in greater detail below.

0019First chamber 121 is defined by one or more walls of mask body 120 and may exhibit any desired shape. In an exemplary case, first chamber 121 is defined in part by an outer wall 123 that is an outer wall of mask body 120, and an inner wall 124. First chamber 121 is substantially sealed from the external environment with the exception of one or more inlet ports, such as first and second inlet ports 103, 104 extending through outer wall 123.

0020A chamber defined, at least in part, by the walls of mask body 120 and integrally formed with mask body 120, or rigid or semi-rigid portion 120a, provides a chamber within the structure of mask body 120 that may be configured to minimize extra bulk or weight that can be associated with a chamber separate from a mask body. Further, a chamber can be provided in close proximity to the head of a wearer such that the profile of the respiratory protection device is not greatly increased, minimizing a large moment of inertia away from the head of a wearer that could be perceived to cause neck pain or other discomfort for a wearer.

0021Second chamber 122 is similarly defined by one or more walls of mask body 120 and may exhibit any suitable shape defining a breathable air zone about the nose and mouth of a wearer. In an exemplary case, second chamber 122 is defined in part by inner wall 124, a portion of outer wall 123, and, when respiratory protection device 100 is positioned for use on a wearer, a portion of a wearer's face and/or head. In various cases, inner wall 124 separates an interior space defined by outer wall 123 into first chamber 121 and second chamber 122, including a portion of outer wall 123 in front of inner wall 124 partially defining the first chamber 121, and a portion of outer wall 123 nearer to the face of a wearer partially defining the second chamber 122.

0022In an exemplary cases, first chamber 121 may function as a duct to direct air from one or more inlet ports, such as first and/or second inlet ports 103, 104, for example, to a different location in mask body 120. While many traditional respiratory masks deliver clean air from a cartridge through an inlet port and into the mask body at the location of the inlet port, first chamber 121 allows one or more inlet ports 103, 104 to be positioned generally independent of fluid intake communication component 140. In an exemplary device, inlet ports 103, 104 are positioned near cheek portions of mask body 120, and fluid intake communication component 140 is positioned centrally. For example, fluid intake communication component is positioned proximate a central axis extending through the mask and dividing mask body 120 into imaginary left and right halves, such as axis 190. Such a component may be said to be centrally positioned if some portions of the component are positioned on each side of axis 190. A configuration in which one or more inlet ports 103, 104 are positioned near cheek portions while a fluid intake communication component 140 is centrally located may allow a breathing air source component to be received in a desirable position and/or orientation, for example extending rearwardly along the face of a wearer so as to minimize obstruction to the field of view or maintain the center of mass of the cartridge in close proximity to the mask body 120 and/or face of the wearer. Fluid intake communication component 140, however, may still be positioned centrally so as to deliver clean air in close proximity to the nose and mouth of a wearer, and in an exemplary device is provided at an upper central location. Thus, first chamber 121 allows first and second breathing air source components to be positioned to provide desired ergonomic characteristics, and allows fluid intake communication component 140 to be positioned to provide desirable airflow to the wearer, for example. Further, first chamber 121 allows first and second inlet ports to be in fluid communication with a single fluid intake communication component. A respiratory protection device having two or more breathable air source components and a single fluid intake communication component can reduce manufacturing costs and provide a more robust respiratory protection device. Costly fluid intake communication components can be minimized, and the use of relatively fragile diaphragms or flaps may be reduced.

0023<figref idref="f0002">Figures 1c and 1d</figref> provide partial cross-sectional views showing an exemplary shut-off valve 150 of respiratory protection device 100. As described above, mask body 120 includes first and second chambers 121 and 122 separated by inner wall 124. In an exemplary device, inner wall 124 includes a fluid intake communication component 140 including an inhalation port 141 to allow fluid communication between first chamber 121 and second chamber 122. Fluid intake communication component 140 allows air to be drawn into second chamber 122 from the first chamber 121 during inhalation but prohibits air from passing from second chamber 122 into first chamber 121. In an exemplary device, fluid intake communication component 140 includes a diaphragm or flap 143. The diaphragm or flap 143 may be secured at a central location 144 by one or more central pins or flanges, for example, or at a peripheral edge or another suitable location as known in the art. In the absence of negative pressure within second chamber 122 of mask body 120, such as when a wearer is exhaling for example, the diaphragm is biased towards a surface of fluid intake communication component, such as sealing ring 145. During inhalation by a wearer, negative pressure within second chamber 122, i.e. a pressure lower than the pressure of the external atmosphere, may result in diaphragm or flap 143 being in an open position to allow air to enter second chamber 122 from first chamber 121. That is, diaphragm or flap 143 flexes or moves away from sealing ring 145 such that air may pass into second chamber 122 to be inhaled by a wearer. In various exemplary devices, fluid intake communication component 140 may include multiple inhalation ports and/or two or more diaphragms or flaps 143 to selectively allow fluid communication from first chamber 121 to second chamber 122 when pressure in second chamber 122 is negative.

0024In an exemplary device, shut-off valve 150 of mask body 120 includes an actuator 151 and sealing pad 152. In a closed position, sealing pad 152 contacts inner wall 124 to block inhalation port 141 to prevent fluid communication between the two or more breathing air sources and the breathable air zone defined by second chamber 122. When shut-off valve 150 is in a closed position, air from breathing air source components 101, 102 is in fluid communication with first chamber 121 but is prevented from entering the breathable air zone defined by second chamber 122 through fluid intake communication component 140. In an exemplary device, sealing pad 152 contacts a sealing surface 146 surrounding inhalation port 141. Sealing surface 146 may be in the form of a ridge or projection extending outwardly from inner wall 124 to allow an adequate seal to be achieved around a periphery of inhalation port 141.

0025Sealing pad 152 may be formed of a soft or resilient material such that sealing pad may flex upon contacting sealing surface 146. In an exemplary device, sealing pad 152 includes seating features, such as angled or flanged lips (not shown), to facilitate an adequate seal with sealing surface 146. All or a portion of sealing pad 152 may also articulate or rotate when contacting sealing surface 146. A sealing pad that may flex and/or articulate or rotate may facilitate formation of an adequate seal around inhalation port 141.

0026In an exemplary device, a shaft 154 guides sealing pad 152 and maintains sealing pad 152 in proper alignment with inhalation port 141 as sealing pad 152 moves linearly between open and closed positions. Sealing pad 152 may include a boss, flange, or other projection 153 that further serves to prevent rotation or misalignment of sealing pad 152. Shaft 154 extends from inner wall 124, such as from a central portion of fluid intake communication component 140. In various other exemplary devices, shaft 154 may extend from other portions of mask body 120, for example.

0027Shut-off valve 150 may be operated to switch between an open position (<figref idref="f0002">Figure 1c</figref>) and a closed position (<figref idref="f0002">Figure 1d</figref>). In an exemplary device, actuator 151 is a button, such as an over-molded elastomeric push-button, slideable button, or the like, that may be pressed inward linearly to cause sealing pad 152 to move towards fluid intake communication component 140 until sealing pad 152 contacts sealing surface 146. In an open position shown in <figref idref="f0002">Figure 1c</figref>, air may pass through inhalation port 141 into the breathable air zone defined by second chamber 122 if allowed by diaphragm or flap 143. In a closed position shown in <figref idref="f0002">Figure 1d</figref>, sealing pad 152 is in sealing engagement with sealing surface 146 to prevent air from passing through inhalation port 141. When actuator 151 is released by a wearer, actuator 151 returns to an open position due to a resilient member that biases sealing pad 152 away from sealing engagement with sealing surface 146.

0028In an exemplary device, an actuator 151 in the form of an elastomeric button acts as a resilient member that biases sealing pad towards an open position away from sealing engagement with sealing surface 146 in the absence of an applied force, for example. Actuator 151 may include a flexible web 156 attached to outer wall 123 (<figref idref="f0001">Figs. 1a, 1b</figref>) of mask body 120 to support actuator 151 and/or bias shut-off valve 150 to an open position. The web is formed of a flexible or compliant material that is able to elastically deform when actuator 151 is pressed inwardly by a wearer, as shown in <figref idref="f0002">Figure 1d</figref>, for example. In a closed position, flexible web 156 is flexed and/or deformed allowing sealing pad 152 to travel towards sealing surface 146. Flexure and/or deformation of flexible web 156 is desirably limited to the elastic regime such that flexible web 156 is able to repeatedly return to an original configuration in which shut-off valve 150 is in an open position.

0029Other resilient members may be provided in place of or in addition to a flexible web. In various exemplary cases, a coil spring, leaf spring, elastomeric band or other suitable resilient member as known in the art may be provided to bias actuator 151 and/or sealing pad 152 to an open position. Alternatively or in addition, a spring loaded member may be provided on a surface of sealing pad 152 to bias actuator 151, and shut-off valve 150, away from sealing surface 146 and towards an open position. In some exemplary cases, a coil spring 159 is provided around shaft 154 to bias actuator 151 and sealing pad 152 away from sealing surface 146 and into an open position. A coil spring may provide a force to bias actuator 151 and sealing pad 152 in place of or in addition to one or more additional resilient members, such as the elastomeric web described above.

0030In an exemplary device, actuator 151 is attached to mask body 120 such that a seal is formed between actuator 151 and mask body 120, for example by over-molding the actuator on mask body 120. Other suitable seals may be provided using gaskets, flanges, adhesive, interference fits, molding techniques, sonic welding, and other suitable techniques as known in the art to provide an adequate seal such that air and contaminants from the external environment are unable to enter mask body 120 proximate actuator 151. The presence of an adequate seal preventing ingress of air and contaminants from the external environment is desirable because the volume surrounding the portions of shut-off valve 150 internal to mask body 120 is in fluid communication with breathable air zone 122. A sufficient seal proximate actuator 151 thus protects the breathability of air in breathable air zone 122 when shut-off valve 150 is in an open, closed, or intermediate position.

0031Fluid intake communication component 140 and shut-off valve 150 are configured to minimize a negative effect on pressure drop that could interfere with a wearer's ability to breathe freely. In various exemplary cases, sealing pad 152 is positioned between approximately 8 mm and 1 mm, approximately 6 mm and 2 mm, or approximately 3 mm from sealing surface 146 when shut-off valve 150 is in an open position. That is, sealing pad 152 travels between approximately 8 mm and 1 mm, or approximately 6 mm and 2 mm, or approximately 3 mm from an open position to a closed position. Such a distance provides a shut-off valve that may be relatively compact while providing sufficient space for air to pass through when in an open position.

0032In various exemplary cases, shut-off valve 150 may remain in a closed position due to a negative pressure within the mask. That is, while performing a negative pressure fit check, a wearer may move actuator 151 to a closed position by pressing inward on actuator 151, inhale, and then release actuator 151. After a wearer releases actuator 151, the resilient member may not overcome the negative pressure within second chamber 122 applied on sealing pad 152. Shut-off valve 150 may thus remain in a closed position until the wearer exhales or the pressure within second chamber 122 is no longer sufficient to overcome the force of the resilient member. A resilient member that allows shut-off valve 150 to remain in a closed position even after actuator 151 is released by a wearer may allow for a more accurate fit check because the wearer is not applying a force on actuator 151 that could affect the seal between mask body 120 and the wearer's face. However, even while the resilient member allows shut-off valve 150 to remain in a closed position due to negative pressure within a breathable air zone of mask body 120, the shut-off valve may automatically return to an open position without further input to actuator 151 by the wearer. An increase in pressure within the mask body, resulting from exhalation of the wearer, for example, may result in the shut-off valve 150 returning to an open position in which the wearer may breathe freely. Such a feature allows a wearer to safely breathe without further input to actuator 151 to return shut-off valve 150 to an open position.

0033In other exemplary cases, shut-off valve 150 may remain in a closed position regardless of pressure within second chamber 122 and may return to an open position upon further input by a wearer.

0034<figref idref="f0003">Figures 2a and 2b</figref> illustrate an exemplary configuration of a shut-off valve 250 - not according to the claimed invention - having a self-aligning sealing pad. In an exemplary configuration, shut-off valve 250 includes an actuator 251 and sealing pad 252. In a closed position, sealing pad 252 contacts inner wall 224 to block inhalation port 241 to prevent fluid communication between the two or more breathing air sources and the breathable air zone defined by second chamber 222. When shut-off valve 250 is in a closed position, air from breathing air source components 201, 202 (not shown) is in fluid communication with first chamber 221 but is prevented from entering the breathable air zone defined by second chamber 222 through fluid intake communication component 240. In an exemplary case, sealing pad 252 contacts a sealing surface 246 surrounding inhalation port 241. Sealing surface 246 may be in the form of a ridge or projection extending outwardly from inner wall 224 to allow an adequate seal to be achieved around a periphery of inhalation port 241. In an exemplary case, sealing surface 246 includes a first sealing surface portion 246a surrounding an outer periphery of inhalation port 241 and a second sealing surface portion 246b surrounding an inner periphery of inhalation port 241.

0035Sealing pad 252 may be formed of a soft or resilient material such that sealing pad 252 may flex upon contacting sealing surface 246. In an exemplary case, sealing pad 252 includes seating features 255, such as angled or flanged lips, to facilitate an adequate seal with sealing surface 246. All or a portion of sealing pad 252 may also articulate or rotate when contacting sealing surface 246. A sealing pad that may flex and/or articulate or rotate may facilitate formation of an adequate seal around inhalation port 241.

0036In an exemplary case, sealing pad 252 is attached to and supported by actuator 251. Rather than traveling on a shaft projecting from fluid intake communication component 240, for example, sealing pad 252 is guided by actuator 251. In some exemplary cases, sealing pad 252 and actuator 251 may be integrally formed as a unitary component. Seating features 245 facilitate an appropriate alignment and/or adequate seal with sealing surface 246. In some cases, seating features 245 may include complementary features to align sealing pad 252 with sealing surface 246.

0037Shut-off valve 250 may be operated to switch between an open position (<figref idref="f0003">Figure 2a</figref>) and a closed position (<figref idref="f0003">Figure 2b</figref>). In an exemplary case, actuator 251 is a button, such as an over-molded elastomeric push-button, slideable button, or the like, that may be pressed inward by a wearer to cause sealing pad 252 to move towards fluid intake communication component 240 until sealing pad 252 contacts sealing surface 246. In an open position shown in <figref idref="f0003">Figure 2a</figref>, air may pass through inhalation port 241 into the breathable air zone defined by second chamber 222 if allowed by diaphragm or flap 243. In a closed position shown in <figref idref="f0003">Figure 2b</figref>, sealing pad 252 is in sealing engagement with sealing surface 246 to prevent air from passing through inhalation port 241. At least a portion of sealing pad 252 is flexed and/or compressed due to the force applied to actuator 251, and such flexure and/or compression may facilitate an adequate seal. When actuator 251 is released by a wearer, actuator 251 may return to an open position due to a resilient member that biases sealing pad 252 away from sealing engagement with sealing surface 246. In some exemplary situations, as described above with respect to shut-off valve 150 for example, shut-off valve 250 may remain in a closed position due to a negative pressure within the mask until the wearer exhales or the pressure within second chamber 222 is no longer greater than the force of the resilient member.

0038In an exemplary case, an actuator 251 in the form of an elastomeric button acts as a resilient member that biases sealing pad 252 towards an open position away from sealing engagement with sealing surface 246. Actuator 251 may include a flexible web 256 attached to outer wall 223 of mask body 220 to support actuator 251 and/or bias shut-off valve 250 to an open position. Flexible web 256 is formed of a flexible or compliant material that is able to elastically deform when actuator 251 is pressed inwardly by a wearer. In a closed position, flexible web 256 is flexed and/or deformed allowing sealing pad 252 to travel towards sealing surface 246. Flexure and/or deformation of flexible web 256 is desirably limited to the elastic regime such that flexible web 256 is able to repeatedly return to an original configuration in which the shut-off valve is in an open position.

0039Other resilient members may be provided in place of or in addition to flexible web 256. In various exemplary cases, a coil spring, leaf spring, elastomeric band, or other suitable resilient member as known in the art may be provided to bias actuator 251 and sealing pad 252, to an open position. Alternatively or in addition, a spring loaded member may be provided on a surface of sealing pad 252 to bias actuator 251, and shut-off valve 250, away from sealing surface 246 and into an open position.

0040<figref idref="f0004">Figures 3a and 3b</figref> illustrate an exemplary configuration of a shut-off valve 350 - not according to the claimed invention - having a pivoting sealing pad. In an exemplary configuration, shut-off valve 350 includes an actuator 351 and sealing pad 352. Similar to respiratory protection device 100 described above with reference to <figref idref="f0001 f0002">Figures 1a through 1d</figref>, shut-off valve 350 may be incorporated in a respiratory protection device including a first chamber 321 and a breathable air zone defined by a second chamber 322, for example. In an exemplary case, first and second chambers 321, 322 are separated by an inner wall 324 including a fluid intake communication component 340. Fluid intake communication component 340 comprises one or more openings to provide fluid communication between first and second chambers 321, 322. Fluid intake communication component 340 may include an inhalation valve for selectively allowing fluid communication between first and second chambers 321, 322. In an exemplary case, fluid intake communication component 340 includes a diaphragm or flap (not shown) such that air may be drawn into the second chamber from the first chamber during inhalation but prohibits air from passing from the second chamber into the first chamber, as described above with reference to fluid intake communication component 140 for example.

0041In an exemplary case, shut-off valve 350 includes an actuator 351 and sealing pad 352. In a closed position, sealing pad 352 contacts inner wall 324 to block inhalation port 341 to prevent fluid communication between the two or more breathing air sources and the breathable air zone defined by second chamber 322. When shut-off valve 350 is in a closed position, air from breathing air source components (not shown) is in fluid communication with first chamber 321 but is prevented from entering the breathable air zone defined by second chamber 322 through fluid intake communication component 340. In an exemplary case, sealing pad 352 contacts a sealing surface 346 surrounding inhalation port 341. Sealing surface 346 may be in the form of a ridge or projection extending outwardly from inner wall 324 to allow an adequate seal to be achieved around a periphery of inhalation port 341.

0042Shut-off valve 350 may be operated to switch between an open position (<figref idref="f0004">Figure 3a</figref>) and a closed position (<figref idref="f0004">Figure 3b</figref>). In an exemplary case, actuator 351 is a button, such as an over-molded elastomeric push-button, slideable button, or the like, that may be pressed inward by a wearer to cause sealing pad 352 to pivot at pivot location 359 until sealing pad 352 contacts sealing surface 346. In an open position shown in <figref idref="f0004">Figure 3a</figref>, air may pass through inhalation port 341 into the breathable air zone defined by second chamber 322 if allowed by a diaphragm or flap, for example. In a closed position shown in <figref idref="f0004">Figure 3b</figref>, sealing pad 352 is in sealing engagement with sealing surface 346 to prevent air from passing through inhalation port 341. At least a portion of sealing pad 352 may be flexed and/or compressed due to the force applied to actuator 351, and such flexure and/or compression facilitates an adequate seal. When actuator 351 is released by a wearer, actuator 351 may return to an open position due to a resilient member that biases actuator 351 to an open position. In some exemplary situations, as described above with respect to shut-off valve 150 for example, shut-off valve 350 may remain in a closed position due to a negative pressure within the mask until the wearer exhales or the pressure within second chamber 322 is no longer greater than the force of the resilient member.

0043In an exemplary configuration, an actuator 351 in the form of an elastomeric button acts as a resilient member that biases sealing pad 352 towards an open position away from sealing engagement with sealing surface 346. Actuator 351 may include a flexible web 356 attached to an outer wall (not shown) of mask body 320 to support actuator 351 and/or bias shut-off valve 350 to an open position. Web 356 is formed of a flexible or compliant material that is able to elastically deform when actuator 351 is pressed inwardly by a wearer, as shown in <figref idref="f0004">Figure 3b</figref>, for example. In some exemplary cases, actuator 351 is not attached to sealing pad 352. A resilient member such as flexible web 356 biases actuator 351 to an open position and one or more additional members, such as spring member 357 biases sealing pad 352 to an open position. Spring member 357 may comprise any suitable spring to bias sealing pad 352 to an open position including a coil spring, leaf spring, elastomeric band, or suitable resilient member as known in the art. In other exemplary cases, actuator 351 is attached to sealing pad 352 and a resilient member such as a flexible web and/or spring member 357 bias both actuator 351 and sealing pad 352 towards an open position.

0044Sealing pad 352 may include at least a portion of soft or resilient material such that at least a portion of sealing pad 352 may flex or compress upon contacting sealing surface 346. At least a portion of sealing pad 352 may be rigid or semi-rigid such that force from actuator 351 may be transmitted to the entire portion of sealing pad 352 that contacts sealing surface 346. Excessive flexure of sealing pad 352 when actuator 351 moves sealing pad 352 into a closed position could result in gaps between sealing pad 352 and sealing surface 346 that could allow ingress of air inhibiting performance of an accurate negative pressure fit check.

0045<figref idref="f0005">Figures 4a and 4b</figref> illustrate an exemplary configuration of a shut-off valve 450 - not according to the claimed invention - having a pivoting sealing pad and a rotatable actuator. Similar to respiratory protection device 100 described above with reference to <figref idref="f0001 f0002">Figures 1a through 1d</figref>, shut-off valve 450 may be incorporated in a respiratory protection device including a first chamber 421 and a breathable air zone defined by a second chamber 422, for example. In an exemplary configuration, first and second chambers 421, 422 are separated by an inner wall 424 including a fluid intake communication component 440. Fluid intake communication component 440 comprises one or more openings to provide fluid communication between first and second chambers 421, 422. Fluid intake communication component 440 may include an inhalation valve for selectively allowing fluid communication between first and second chambers 421, 422. In an exemplary case, fluid intake communication component 440 includes a diaphragm or flap (not shown) such that air may be drawn into the second chamber from the first chamber during inhalation but prohibits air from passing from the second chamber into the first chamber, as described above with reference to fluid intake communication component 140 for example.

0046In an exemplary configuration, shut-off valve 450 includes a rotatable actuator 451 and sealing pad 452. In a closed position, sealing pad 452 contacts inner wall 424 to block inhalation port 441 to prevent fluid communication between the two or more breathing air sources and the breathable air zone defined by second chamber 422. When shut-off valve 450 is in a closed position, air from breathing air source components (not shown) is in fluid communication with first chamber 421 but is prevented from entering the breathable air zone defined by second chamber 422 through fluid intake communication component 440. In an exemplary case, sealing pad 452 contacts a sealing surface 446 surrounding inhalation port 441. Sealing surface 446 may be in the form of a ridge or projection extending outwardly from inner wall 424 to allow an adequate seal to be achieved around a periphery of inhalation port 441.

0047Shut-off valve 450 may be operated to switch between an open position (<figref idref="f0005">Figure 4a</figref>) and a closed position (<figref idref="f0005">Figure 4b</figref>). In an exemplary case, actuator 451 is a rotatable actuator that may be rotated between a first position and a second position. When rotatable actuator 451 is in a first position, shut-off valve 450 is in an open position, and when rotatable actuator 451 is in a second position, shut-off valve 450 is in a closed position. In an exemplary case, rotatable actuator 451 is rotated 90 degrees between an open position and a closed position. In other exemplary cases rotatable actuator 451 is rotated 45 degrees, 180 degrees, or other suitable angle, between an open position and a closed position. Rotatable actuator 451 includes a cam 458. Rotation of rotatable actuator 451 causes cam 458 to push sealing pad 452 towards sealing surface 446 and pivot at pivot location 459 until sealing pad 452 contacts sealing surface 446. In a closed position shown in <figref idref="f0005">Figure 4b</figref>, sealing pad 452 is in sealing engagement with sealing surface 446 to prevent air from passing through inhalation port 441. At least a portion of sealing pad 452 may be flexed and/or compressed due to the force applied to actuator 451, and such flexure and/or compression facilitates an adequate seal. In an exemplary configuration, rotatable actuator 451 returns to an open position due to a resilient member (not shown) when rotatable actuator is released by a wearer. Resilient member may be a torsion spring, for example, or other suitable resilient member as known in the art. In other exemplary configurations, rotatable actuator 451 returns to an open position only upon further input by a wearer and remains in the second position, such that shut-off valve 450 is in a closed position, until the wearer rotates actuator 451 to the first position for example. A spring member 457 biases sealing pad 452 to an open position. Spring member 457 may comprise any suitable spring to bias sealing pad 452 to an open position including a coil spring, leaf spring, elastomeric band or suitable resilient member as known in the art.

0048Sealing pad 452 may include at least a portion of soft or resilient material such that at least a portion of sealing pad 452 may flex or compress upon contacting sealing surface 446. At least a portion of sealing pad 452 may be rigid or semi-rigid such that force from actuator 451 may be transmitted to the entire portion of sealing pad 452 that contacts sealing surface 446. A rotatable actuator 451 able to rotate through a predetermined angle between an open and closed position and having a cam 458 that causes sealing pad 452 to move to a closed position results in a uniform force transmitted to sealing pad 452 each time sealing pad 452 is moved to a closed position. Thus, an appropriate force to create a desired seal is easily and consistently achieved.

0049A rotatable actuator is believed to provide several advantages including ease of use and less effect on the fit of a mask body during performance of a negative pressure fit check. Rotation of a rotatable actuator does not require force in a direction towards the face of a wearer and thus may not alter the natural contact between a mask body and a wearer's face. Accordingly, an accurate negative pressure fit check may be achieved.

0050<figref idref="f0006">Figures 5a through 5c</figref> illustrate an exemplary respiratory protection device 500 - not according to the claimed invention that may cover the nose and mouth and provide breathable air to a wearer. The respiratory protection device 500 includes a mask body 520 including first and second inlet ports 503 and 504. First and second breathing air source components (not shown) may be positioned on opposing sides of mask body 520. In an exemplary device, first and second breathing air source components are filter cartridges configured to be attached at first and second inlet ports 503 and 504. The filter cartridges filter air received from the external environment before the air passes into interior space within the mask body for delivery to a wearer.

0051The mask body 520 may include a rigid or semi-rigid portion 520a and a compliant face contacting portion 520b. The compliant face contacting portion of the mask body is compliantly fashioned for allowing the mask body to be comfortably supported over a person's nose and mouth and/or for providing an adequate seal with the face of a wearer to limit undesirable ingress of air into an interior of mask body 520, for example. The face contacting member 520b may have an inturned cuff so that the mask can fit comfortably and snugly over the wearer's nose and against the wearer's cheeks. The rigid or semi-rigid portion 520a provides structural integrity to mask body 520 so that it can properly support breathing air source components, such as filter cartridges, for example. In various exemplary devices, mask body portions 520a and 520b may be provided integrally or as separately formed portions that are subsequently joined together in permanent or removable fashion.

0052An exhalation port 530 allows air to be purged from an interior space within the mask body during exhalation by a wearer. In an exemplary configuration , exhalation port 530 is located centrally on mask body 520. An exhalation valve is fitted at the exhalation port to allow air to exit due to positive pressure created within mask body 520 upon exhalation, but prevent ingress of external air.

0053First and second inlet ports 503, 504 are configured to receive first and second breathing air source components. In an exemplary device shown in <figref idref="f0006">Figure 5a</figref>, mask body 520 includes first and second inlet ports 503, 504 on either side of mask body 520, and may be proximate cheek portions of mask body 520. First and second inlet ports 503, 504 include complementary mating features such that first and second breathing air source components (not shown) may be securely attached to mask body 520. Other suitable connections may be provided as known in the art. The mating features may result in a removable connection such that the breathing air source components may be removed and replaced at the end of service life of the breathing air source component or if use of a different breathing air source component is desired. Alternatively, the connection may be permanent such that the breathing air source components cannot be removed without damage to the breathing air source component, for example.

0054Respiratory protection device 500 includes a shut-off valve 550 for closing multiple fluid intake communication components. In an exemplary device, shut-off valve 550 is operable between a closed position and an open position. In a closed position, shut-off valve 550 prevents fluid communication between both of breathing air source components at inlet ports 503 and 504 and a breathable air zone of mask body 520.

0055Shut-off valve 550 allows a wearer to perform a negative pressure fit check to provide an indication of the presence of leaks around a periphery of the mask body. When shut-off valve 550 is in a closed position, air is prevented from entering a breathable air zone of mask body 520. Inhalation by a wearer while the shut-off valve is in a closed position will result in a negative pressure within the mask, and in some exemplary situations may cause a compliant face contacting member to deflect inward, if an adequate seal has been achieved between the mask body and the wearer's face. If an adequate seal is not achieved, inhalation may result in air from the external environment entering the breathable air zone between the periphery of the mask body and the face of the wearer. In this way, a negative pressure fit check can be easily performed by a wearer wearing respiratory protection device 500 to determine if an adequate seal is achieved between the respiratory protection device 500 and the face and/or head of the wearer.

0056First and second breathing air source components, such as filter cartridges, may be attached to first and second inlet ports 503, 504. Accordingly, air entering mask body 520 through first inlet port 503 after passing through a first breathing air source component may enter breathable are zone 522 through first fluid intake communication component 540a, and air entering mask body 520 through second inlet port 504 after passing through a second breathing air source component may enter breathable are zone 522 through second fluid intake communication component 540b. Air from first and second breathing air sources 501, 502 thus enter breathable air zone 522 through distinct fluid intake communication components 540a, 540b. Each of the first and second fluid intake communication components 540a, 540b comprise one or more openings to provide fluid communication between first and second inlet ports 503, 504 and breathable air zone 522. First and second fluid intake communication components 540a, 540b may each include an inhalation valve for selectively allowing fluid communication between first and second inlet ports 503, 504 and breathable air zone 522.

0057In an exemplary device, shut-off valve 550 includes an actuator 551 and first and second sealing pads 552a, 552b. When the actuator is depressed, first and second sealing pads 552a, 552b block the first and second inhalation ports to prevent fluid communication between the two or more breathing air sources and the breathable air zone 522. In an exemplary case, first and second sealing pads 552a, 552b include actuation surfaces 547a, 547b contacted by actuator 551 to cause sealing pads 552a, 552b to block first and second inhalation ports. In an exemplary case, sealing pads 552a, 552b contact first and second sealing surfaces 546a, 546b surrounding first and second inhalation ports 541a, 541b, respectively. Sealing surfaces 546a, 546b may be in the form of a ridge or projection extending outwardly from an inner surface of mask body 520 or first and second fluid intake communication components 540a, 540b to allow an adequate seal to be achieved around a periphery of inhalation ports 541a and 541b.

0058Shut-off valve 550 may be operated to switch between an open position (<figref idref="f0006">Figure 5b</figref>) and a closed position (<figref idref="f0006">Figure 5c</figref>). In an exemplary case, actuator 551 is a button, such as an over-molded elastomeric push-button, slideable button, or the like, that may be pressed inward by a wearer to cause first and second sealing pads 552a, 552b to pivot about pivot locations 559a, 559b (not shown) until first and second sealing pads 552a, 552b contact sealing surfaces 546a, 546b of first and second fluid intake communication components 540a, 540b. In an open position shown in <figref idref="f0006">Figure 5b</figref>, air may pass through inhalation ports 541a, 541b into the breathable air zone 522 if allowed by a diaphragm or flap (not shown). In a closed position shown in <figref idref="f0006">Figure 5c</figref>, sealing pad 552a is in sealing engagement with sealing surface 546a to prevent air from passing through inhalation port 541a. When actuator 551 is released by a wearer, actuator 551 returns to an open position due to a resilient member that biases actuator 551 to an open position. In some exemplary embodiments, as described above with respect to shut-off valve 150 for example, shut-off valve 550 may remain in a closed position due to a negative pressure within the mask until the wearer exhales or the pressure within breathable air zone 522 is no longer greater than the force of the resilient member.

0059In an exemplary case, actuator 551 in the form of an elastomeric button acts as a resilient member that biases actuator 551 towards an open position. Actuator 551 may include a flexible web 556 attached to an outer wall 523 of mask body 520 to support actuator 551 and/or bias shut-off valve 550 to an open position. Flexible web 556 is formed of a flexible or compliant material that is able to elastically deform when actuator 551 is pressed inwardly by a wearer, as shown in <figref idref="f0006">Figure 5c</figref>, for example. In a closed position, flexible web 556 is flexed and/or deformed causing sealing pads 552a, 552b to pivot by contacting actuation tabs 547a, 547b, for example. Flexure and/or deformation of elastomeric web is desirably limited to the elastic regime such that elastomeric web is able to repeatedly return to an original configuration in which the shut-off valve is in an open position.

0060In an exemplary case, actuator 551 is attached to mask body 520 such that a seal is formed between actuator 551 and mask body 520. For example, a portion of actuator 551 may be joined to mask body 520 to provide an adequate seal, for example by over-molding. Other suitable seal may be provided using gaskets, flanges, adhesive, interference fits, molding techniques, sonic welding, and other suitable techniques as known in the art. A sufficient seal proximate actuator 551 prevents ingress of unfiltered air from the external environment when shut-off valve 550 is in an open, closed, or intermediate position.

0061Other resilient members may be provided in place of or in addition to a flexible web of actuator 551. In some exemplary cases, actuator 551 is not attached to sealing pads 552a, 552b. A resilient member such as flexible web 556 biases actuator 551 to an open position and one or more additional members, such as spring members 558a, 558b bias sealing pads 552a, 552b to an open position. Spring members 558a, 558b may comprise any suitable spring to bias sealing pads 552a, 552b to an open position including a coil spring, leaf spring, elastomeric band or suitable resilient member as known in the art. In some exemplary embodiments, actuator 551 is attached to sealing pads 552a, 552b and a resilient member such as a flexible web and/or one or more spring members 558a, 558b bias both actuator 551 and sealing pads 552a, 552b towards an open position.

0062<figref idref="f0007">Figures 6a through 6c</figref> illustrate an exemplary respiratory protection device 600 that may cover the nose and mouth and provide breathable air to a wearer. The respiratory protection device 600 includes a mask body 620 including first and second inlet ports 603 and 604. First and second breathing air source components (not shown) may be positioned on opposing sides of mask body 620. In an exemplary embodiment, first and second breathing air source components are filter cartridges configured to be attached at first and second inlet ports 603 and 604. The filter cartridges filter air received from the external environment before the air passes into interior space within the mask body for delivery to a wearer.

0063The mask body 620 may include a rigid or semi-rigid portion 620a and a compliant face contacting portion (not shown). The compliant face contacting portion of the mask body is compliantly fashioned for allowing the mask body to be comfortably supported over a person's nose and mouth and/or for providing an adequate seal with the face of a wearer to limit undesirable ingress of air into an interior of mask body 620, for example. The face contacting member may have an inturned cuff so that the mask can fit comfortably and snugly over the wearer's nose and against the wearer's cheeks. The rigid or semi-rigid portion 620a provides structural integrity to mask body 620 so that it can properly support breathing air source components, such as filter cartridges, for example. In various exemplary embodiments, mask body portion 620a and the compliant face contacting portion may be provided integrally or as separately formed portions that are subsequently joined together in permanent or removable fashion.

0064First and second inlet ports 603, 604 are configured to receive first and second breathing air source components. In an exemplary embodiment shown in <figref idref="f0007">Figure 6a</figref>, mask body 620 includes first and second inlet ports 603, 604 on either side of mask body 620, and may be proximate cheek portions of mask body 620. First and second inlet ports 603, 604 include complementary mating features such that first and second breathing air source components (not shown) may be securely attached to mask body 620. Other suitable connections may be provided as known in the art. The mating features may result in a removable connection such that the breathing air source components may be removed and replaced at the end of service life of the breathing air source component or if use of a different breathing air source component is desired. Alternatively, the connection may be permanent such that the breathing air source components cannot be removed without damage to the breathing air source component, for example.

0065<figref idref="f0007">Figure 6c</figref> shows a representative cross-sectional view of the mask body 620 through a middle portion of mask body 620. Mask body 620 includes a first chamber 621 and a second chamber 622 separated by an interior wall 623. A breathable air zone is defined by second chamber 622. First and second inlet ports 603, 604 are in fluid communication with first chamber 621. Accordingly, air entering mask body 620 through first inlet port 603 after passing through a first breathing air source component is in communication with air entering mask body 620 through second inlet port 604 after passing through a second breathing air source component. Air from first and second inlet ports 603, 604 is thus allowed to mix in first chamber 621 before being delivered to the breathable air zone defined by second chamber 622 of mask body 620. To this end, interior wall 623 includes or defines an opening 624 that allows fluid communication between the first chamber 621 and the second chamber 622. In one embodiment, opening 624 may be fitted with a suitable inhalation valve 625. The inhalation valve 625 is fitted at the opening 624 to allow air to enter second chamber 622 due to negative pressure created within mask body 620 upon inhalation, but prevent exhaled air from entering first chamber 622 upon exhalation.

0066An exhalation port 630 allows air to be purged from an interior space within the mask body during exhalation by a wearer. In an exemplary embodiment, exhalation port 630 is located centrally on mask body 620. An exhalation valve is fitted at the exhalation port to allow air to exit due to positive pressure created within mask body 620 upon exhalation, but prevent ingress of external air. In the illustrated embodiment, a secondary exhalation port 631 in a lower portion of the mask body 620 is provided that further allows air to exit second chamber 622 due to positive pressure created within mask body 620 upon exhalation. Each of the exhalation port 630 and secondary exhalation port 631 can be equipped with suitable check valves that allow air to exit second chamber 622, but prevent ingress of external air.

0067Respiratory protection device 600 includes a shut-off valve 650 for preventing fluid communication between first chamber 621 and second chamber 622. The shut-off valve 650 is operable between a closed position and an open position. In a closed position, shut-off valve 650 prevents fluid communication between first chamber 621 (i.e., fluid from both of breathing air source components at inlet ports 603 and 604) and the second chamber 622 of mask body 620. In an open position, shut-off valve 650 allows fluid communication between the first chamber 621 and second chamber 622.

0068Shut-off valve 650 allows a wearer to perform a negative pressure fit check to provide an indication of the presence of leaks around a periphery of the mask body. When shut-off valve 650 is in a closed position, air is prevented from entering a breathable air zone defined by second chamber 622 of mask body 620. Inhalation by a wearer while the shut-off valve is in a closed position will result in a negative pressure within the mask, and in some exemplary embodiments may cause a compliant face contacting member to deflect inward, if an adequate seal has been achieved between the mask body and the wearer's face. If an adequate seal is not achieved, inhalation may result in air from the external environment entering the breathable air zone between the periphery of the mask body and the face of the wearer. In this way, a negative pressure fit check can be easily performed by a wearer wearing respiratory protection device 600 to determine if an adequate seal is achieved between the respiratory protection device 600 and the face and/or head of the wearer.

0069First and second breathing air source components, such as filter cartridges, may be attached to first and second inlet ports 603, 604. From first and second inlet ports 603 and 604, air entering mask body 620 through first inlet port 603 after passing through a first breathing air source component may enter first chamber 621 through first fluid intake communication component 640a, and air entering mask body 620 through second inlet port 604 after passing through a second breathing air source component may enter first chamber 621 through second fluid intake communication component 640b. In particular, air from first and second inlet ports 603, 604 thus enter first chamber 621 through distinct fluid intake communication components 640a, 640b. Each of the first and second fluid intake communication components 640a, 640b comprise one or more openings to provide fluid communication between first and second inlet ports 603, 604 and first chamber 621.

0070The shut-off valve 650 includes an actuator 651, a seal 652, and a retainer 653. Actuator 651 and seal 652 are coupled together through a suitable connection. Retainer 653 is positioned between the actuator 651 and seal 652 and secures the actuator 651 to the mask body 620. When the actuator 651 is depressed, seal 652 is actuated toward the interior wall 623, ultimately blocking the opening 624 to prevent fluid communication between the first chamber 621 and the second chamber 622. In an exemplary embodiment, the seal 652 defines a contact sealing surface 654. In an exemplary embodiment, the sealing surface 654 surrounds the opening 624. As illustrated, seal surface 654 includes an outer ridge or projection extending outwardly toward interior wall 623. Upon movement of the shut-off valve 650 to the closed position, this projection deflects, allowing an improved seal between the sealing surface 654 around a periphery of opening 624.

0071As discussed in more detail below, shut-off valve 650 may be operated to switch between an open position and a closed position. In an exemplary embodiment, actuator 651 is a button, such as an elastomeric push-button, that may be pressed inward by a wearer to cause sealing surface 654 to contact sealing surfaces interior wall 623 and seal opening 624. When transitioning from an open position to a closed position, the actuator 651 produces tactile feedback that may be sensed by an operator. For example, the actuator 651 can be formed of a flexible body that may buckle or distort in response to an applied force. In the open position, air may pass through opening 624, if allowed by inhalation valve 625. In the closed position, sealing surface 654 is in sealing engagement with interior wall 623 to prevent air from passing through opening 624. When actuator 651 is released by a wearer, actuator 651 returns to an open position due to a resilient structure that biases actuator 651 to an open position. Seal 652 may also be formed of an elastomeric material as desired to assist in forming preventing fluid communication between first chamber 621 and second chamber 622.

0072The actuator 651 is attached to mask body 520 such that a seal is formed between actuator 651 and mask body 620. For example, actuator 651 includes an outwardly extending flange 660 that is positioned between a projection 662 of the mask body 620 and retainer 653. In this exemplary embodiment, flange 660 is U-shaped, although other shapes can be used. Other suitable seal may be provided using gaskets, flanges, adhesive, interference fits, molding techniques, sonic welding, and other suitable techniques as known in the art. A sufficient seal proximate actuator 651 prevents ingress of unfiltered air from the external environment when shut-off valve 650 is in an open, closed, or intermediate position. Cooperation between retainer 653 and projection 662 provides a region 664 (mostly, if not all of the flange 660) of the actuator 651 that is fixed during movement of the actuator 651 from an open position to a closed position. Pressing the actuator 651 at an outer surface 665 of the actuator causes the outer surface 665 to move toward the interior wall 623 while area 664 remains fixed relative to the mask body 620 and interior wall 623.

0073Actuator 651 provides tactile feedback to an operator so as to indicate that a seal check is being implemented. Resiliency of the actuator 651 is such that, absent an applied force to outer surface 665, actuator 651 returns to an open position. In order to provide tactile feedback, in one embodiment, actuator 651, in response to an applied force to outer surface 665, exhibits a force response similar to that schematically illustrated in a graph 700 of <figref idref="f0009">Figure 7</figref>. In particular, actuator 651 travels (i.e., is displaced) along a linear path from an open position to a closed position. Depending on a position of the actuator 651, a corresponding response force is provided. Graph 700 includes a vertical axis 702 indicating force and a horizontal axis 704 indicating displacement of actuator 651. A loading path or curve 706 is indicative of a minimum force placed on outer surface 665 to displace the outer surface 665 toward the interior wall 623.

0074Initially, the loading curve 706 begins at an initial position 708. At position 708, no force is applied to the actuator 651 and as such a response force of the actuator is zero. As the actuator 651 is depressed, the loading curve 706 exhibits a positive slope until reaching a first intermediate position 710. At the first intermediate position 710, the actuator 651 buckles or distorts, producing a "pop" or "click" (also referred to as "oil canning") that provides tactile feedback to an operator. A portion of the loading curve 706 from the initial position 708 to the first intermediate position can be referred to as a first transition of the actuator 651, exhibiting an increasing response force. As indicated by the loading curve 706, the response force decreases after the intermediate position 710 until reaching a second intermediate position 712. This portion of the loading curve can be referred to as a second transition, exhibiting a decreasing response force. After reaching second intermediate position 712, the loading curve 706 increases, indicating contact between the seal surface 654 and interior wall 623. The loading curve 706 will increase as a seal is formed between the seal surface 654 and the interior wall 623 (i.e., due to deflection of the seal surface 654) until reaching a stop position 714, indicating that the seal between the surface 654 and the interior wall 623 is complete. This portion of the loading path 706 can be referred to as a third transition, exhibiting an increasing response force. Upon release of the actuator 651, a return curve or path 716 returns to the initial position 708, wherein the response force is zero, indicating that no force is being applied to the actuator 651. The return curve 716 is similar to the loading curve 706, exhibiting a slightly less response force as the actuator 651 travels from a closed position to an open position.

0075With the above understanding of the loading curve 706 and return curve 716 in mind, <figref idref="f0010 f0011 f0012">Figs. 8a to 8c</figref> illustrate actuator 651 in an open position (<figref idref="f0010">Figure 8a</figref>), an intermediate position (<figref idref="f0011">Figure 8b</figref>) and a closed position (<figref idref="f0012">Figure 8c</figref>). For frame of reference, actuator 651 is formed of a flexible web or body embodied in <figref idref="f0010 f0011 f0012">Figs. 8a to 8c</figref> as an elastomeric push button, wherein outer surface 665 forms a dome-like structure that at least partially extends above an outer surface of mask body 620 for interface with an operator's finger. In alternative embodiment, the outer surface 665 may be formed entirely below the outer surface of the mask body 620. In any event, the actuator 651 includes or defines a span 720 extending inwardly from the flange 660. While actuator 651 is depressed, span 720 moves toward the interior wall 623 while the flange 660 more or less remains fixed. Extending from span 720 is a projection 722 that cooperates with an opening 724 of seal 652 to secure the actuator 651 to the seal 652. Due to this connection, span 720 and seal 652 translate in concert with one another in response to an applied force to outer surface 665.

0076Retainer 653 defines a rim 730 that terminates at a surface 732 that faces an outer periphery of the span 720. The surface 732 defines a plane 734. In one example embodiment, during operation of the actuator 651, at least a portion of the span 720 (excluding the projection 722) passes through plane 734. In one particular embodiment, a portion 736 (e.g., a tip) of outer surface 665 passes through the plane 734 upon actuator 651 reaching the closed position illustrated in <figref idref="f0012">Figure 8c</figref>. Stated another way, at least a portion of the span 720, when the actuator is in the open position of <figref idref="f0010">Figure 8a</figref>, is on a first side of the plane 734. In the closed position, the portion is positioned on a second side of the plane 734, opposite the first side. The portion can be disposed on an outer surface 665 of the actuator 651 or internal from the outer surface 665.

0077Actuator 651 may include structural features to exhibit desired properties. Example properties include low required force to displace the actuator 651, automatic return to an open position absent an applied force, providing meaningful tactile feedback to an operator, low profile with respect to mask body 620, providing an adequate seal with the mask body 620, providing an aggressive drop in force and others. In one example, a force required to displace the actuator 651 may be in a range from about 0.14 joule to 6.8 joules (0.1 pound-foot to 5.0 pound-foot). In a more particular range, the force is in a range from approximately 0.34 joule to 1.02 joules (0.25 pound-foot to 0.75 pound-foot) and in a specific embodiment around 0.68 joule (0.5 pound-foot). In a further example, the actuator 651 can be formed of a material that exhibits varying thickness at different positions. In a further example, different materials can be selected for actuator 651, such as elastomeric materials including silicone, ethylene propylene diene monomer rubber, natural rubber, a thermoplastic elastomer and linear low density polyethylene. In various exemplary embodiments, a material of actuator 651 is selected to provide a low surface energy surface. Actuator 651 may be made of a low surface energy silicone such that dirt and contaminants in an environment of use may be repelled or otherwise not build up on actuator 651 or otherwise interfere with actuation of actuator 651. In one specific embodiment, the silicone is polydimethylsiloxane. A range of surface energy values for the actuator 651 may be from about 10 to 30 milliJoules per square meter and may be in a more specific range of 15 to 25 milliJoules per square meter.

0078Span 720 exhibits varying thickness. In one embodiment, span 720, when viewed in cross-section in a plane that is parallel with a direction of displacement for span 720, includes two or more sections that exhibit different thicknesses. The different thickness can be achieved in a tapering manner or in a more discrete fashion as desired. With specific reference to span 720, span 720 includes a first, middle section 740, a second, intermediate section 742 and a third, outer section 744. The first section 740 includes a first thickness 750 (selected at a position along a width of the section 740). In a similar manner, the second section 742 includes a second thickness 752 (selected at a position along a width of the section 742) and the third section includes a third thickness 754 (selected at a position along a width of the section 744).

0079In one embodiment, the first thickness 750 is selected as a maximum thickness in section 740, the second thickness 752 is selected as a minimum thickness in section 742 and the third thickness is selected as a maximum thickness in section 744. Other thicknesses can be selected as desired, as variation in thickness across the span 720 is intended to herein be disclosed. Regardless of the position of thickness, one example includes the first thickness 750 and the third thickness 754 being greater than the second thickness 752. In this embodiment, strain exhibited by the actuator 651 is concentrated in the second section 742.

0080The second section 742 can be formed by forming a cut-out in the actuator 651. In one embodiment, the second section 742 is annular in shape, whereas other embodiments include the second section 742 including distinct portions of reduced thickness. In various embodiments, the second section 742 is formed as a semi-circle in cross-section, defined by a diameter in an exemplary range from about 1.5 mm to 3.5 mm. In any event, the second section 742, when actuator 651 is in the closed position illustrated in <figref idref="f0012">Figure 8c</figref>, will exhibit a higher strain than either the first section 740 or the third section 742 and further has a reduced stiffness compared to the first section 740 or the third section 742.

0081In one embodiment, the third section 744 forms a rib or projection 760 extending from the span 720 toward the surface 732 of rim 730. While the rib 760 is optional, rib 760 deforms during operation of the actuator 651, resulting in a sharper drop in force during the second transition identified above (from first intermediate position 710 to second intermediate position 712), thus providing increased tactile feedback. In an alternative embodiment, a plurality of ribs can be utilized to increase tactile feedback, as desired.

0082As will be appreciated by those skilled in the art, changes can be made to actuator 651 in various ways so as to exhibit desired properties. For example, positioning of the second section 742 (and thus a minimum thickness 752) may be selected to exhibit various properties. Other variables that can alter a response for actuator 651 may include a diameter of actuator 651 (e.g., an outer dimension of flange 660 and/or an outer diameter of span 720), a shape of outer surface 665 of actuator 651 (e.g., dome, flat, inverted dome), a height of an arc of outer surface 665 (when utilizing a dome shape, a height from a point of connection between span 720 and flange 660 to tip 736 in a direction of actuation for the actuator 651), displacement of the actuator 651 from an open position to a closed position, selection of a ratio of cut-out diameter of section 742 to a maximum thickness of span 720 and others. It may further be desirable to minimize separation between the actuator 651 and the outer surface of the mask body 62. Gaps or crevices between the actuator 651 and the outer surface of the mask body 620 may undesirably trap contaminants and/or debris. Thus, a dome shape similar to outer surface 665 can be advantageous so as to minimize separation between the outer surface 665 and the outer surface of the mask body 620. In particular, the outer surface 665 is placed in compression upon operation of the actuator 651. By limiting displacement of the actuator 651 to be less than twice a height of the arc of outer surface 665 as identified above, separation of outer surface 665 from the outer surface of mask body 620 is minimized. Selection of a ratio for cut-out diameter of reduced thickness section 742 to a maximum thickness of actuator 651 may be in a range of about 1.50 to 0.33. Stated in a specific example, if a cut-out diameter for section 742 is selected to be 2 mm, then a maximum thickness of actuator 651 may be in a range from 3.00 mm to 0.67 mm.

0083<figref idref="f0013 f0014">Figs. 9a to 9d</figref> illustrate four different embodiments of actuators for use with a respiratory protection device such as device 600 discussed above. <figref idref="f0013">Figure 9a</figref> illustrates an actuator 800 similar in structure to actuator 651. In actuator 800, a reduced thickness section 802 is provided within a span 804 of the actuator 800. The section 802, as compared to second section 742 in <figref idref="f0010">Figure 8a</figref>, extends deeper into span 804, thus having a smaller thickness than the second section 742. Additionally, the section 802 has a smaller width when compared to a width of second section 742. In <figref idref="f0013">Figure 9b</figref>, an actuator 810 includes a reduced thickness section 812 positioned within a span 814 proximate a projection 816 of the actuator 810. When compared with section 742 of actuator 651, the section 812 is positioned closer to a center of actuator 810 than section 742. In <figref idref="f0014">Figure 9c</figref>, an actuator 820 includes a first, inner section 822 of reduced thickness and a second, outer section 824 of reduced thickness. The inner section 822 is located proximate a projection 826 of the actuator 820, whereas outer section 824 is spaced apart from inner section 822 and positioned closer to a flange 828 of the actuator 820. In <figref idref="f0014">Figure 9d</figref>, an actuator 830 includes a reduced thickness section 832 extending from a central section 834 to a flange 836 positioned at a periphery of the actuator 830. In this embodiment, the reduced thickness section is of uniform thickness along its length.

0084Another respiratory protection device 600 - not according to the claimed invention - is illustrated in <figref idref="f0015 f0016">Figs. 10a to 10c</figref>. In particular, <figref idref="f0015">Figure 10a</figref> illustrates actuator 900 in a first, open position, <figref idref="f0013">Figure 9b</figref> illustrates actuator 900 in a second, intermediate position and <figref idref="f0014">Figure 9c</figref> illustrates actuator 900 in a third, closed position. Actuator 900 includes a span 902 defining an outer surface 903 coupled with a flange 904. When coupled with a mask body, flange 904 is secured to the mask body at an outer rim 906. From the rim 906, the flange 904 extends downwardly in a first section 908 and upwardly in a second section 910 to couple with span 902. A lower U-shaped section 912 connects the first section 908 with the second section 910. A seal 914 is coupled with the span 902 and cooperates with an interior wall 916 in order to prevent fluid communication from reaching a chamber 918.

0085During operation, in response to an applied force to outer surface 903, the seal 914 moves toward the interior wall 916, as illustrated in <figref idref="f0015">Figure 10b</figref>. As the seal 914 moves toward wall 916, stress begins to be placed on the flange 904. In particular, the flange 904 begins to unfold, forming a larger angle between first section 908 and second section 910. In <figref idref="f0016">Figure 10c</figref>, the actuator 900 is in a closed position, wherein seal 914 contacts interior wall 916, preventing fluid flow to the chamber 918. Although actuator 900 may be effective for use in allowing a wearer to perform a negative pressure fit test, an opening 920 is created between an edge of the span 902 and the rim 906. Debris and other contaminants may easily enter through opening 920 and become lodged between the first section 908 and the second section 910 of the flange 904. In applications with a high amount of debris and/or contaminants, this arrangement can be undesirable.

0086A respiratory mask according to the present disclosure provides several advantages. A shut-off valve operable between a closed position and an open position allows a wearer to easily perform a negative pressure fit test. A shut-off valve that closes inlet ports, for example, is believed to provide a more effective and reproducible fit check to verify the presence of an appropriate seal between a periphery of the mask and a user's face as compared to prior positive pressure fit devices. A respiratory mask according to the present disclosure thus may provide a solution to closing inlet valves that were inaccessible and not easily closed in many prior devices, for example. Respiratory masks as described above allow a negative pressure fit test to be performed by closing a single valve even if the mask may include more than one breathing air source components or more inlet ports, and does not require a wearer to engage multiple actuators or perform individual tests for each inlet port or breathing air source components, for example. A shut-off valve as described herein may be suitable for half-face respirators, full-face respirators, powered or positive pressure respirators, and other suitable respiratory protection devices.

0087The foregoing detailed description and examples have been given for clarity of understanding only. No unnecessary limitations are to be understood there from. Thus, the scope of the present disclosure should not be limited to the exact details and structures described herein, but rather by the structures described by the language of the claims.