Compressed Air Breathing Apparatus

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] None.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[0002] Not applicable.

REFERENCE TO A MICROFICHE APPENDIX [0003] Not applicable.

BACKGROUND

[0004] Traditionally, a self-contained breathing apparatus (or SCBA) may use a demand valve to control the air flow from one or more cylinders into a mask for the user to breathe. A demand valve may be controlled by the pressure from the breathing of a user, allowing air flow when a user breathes in and stopping air flow when a user breathes out. In some instances, a user may wish to breathe ambient air when able, such as when the user is in a waiting area or has exited a hazardous environment, in order to preserve the air stored in the cylinders of the SCBA. However, it may be difficult or time intensive to disconnect the demand valve or remove the mask of the SCBA. Applicants have found that the use of an intermediate device may provide the user with the ability to temporarily disconnect and/or deactivate the demand valve, while wearing the mask. Applicants have developed a fresh-air port apparatus operable to allow a user to alternate between the demand valve and ambient air.

SUMMARY

[0005] Aspects of the disclosure may include embodiments of a self-contained breathing apparatus comprising: one or more air cylinders; a pressure reducer; a mask having an exhalation valve; a demand valve operable to attach to the mask, wherein a user inhales air through the demand valve and exhales air through the exhalation valve; a medium-pressure hose from the pressure reducer to the demand valve, wherein the pressure reducer is in fluid communication with the demand valve; a combined pressure gauge and warning whistle; and a fresh-air port assembly coupled to the demand valve such that the fresh-air port assembly is positioned between the demand valve and the mask, wherein the fresh-air port assembly is operable to rotate and open and close one or more port to ambient air. In some embodiments, the fresh-air port assembly comprises: a cam knob operable to house one or more driving balls; a cam collar comprising at least one pathway operable to accept and guide the driving balls; an adapter operable to attach the fresh-air port assembly to the mask; and a spring positioned between the cam collar and the adapter operable to bias the cam collar away from the adapter. In some embodiments, the cam knob comprises a first protrusion operable to interact with the exhalation valve to hold the exhalation valve open when the one or more port is open to ambient air. In some embodiments, the cam knob comprises a second protrusion operable to indicate the position of the cam assembly to the user of the apparatus, wherein the second protrusion is in the line-of-sight of the user when the port is open to ambient air. In some embodiments, the at least one pathway of the cam collar comprises: a first section operable to provide control feel resistance when initiating the turning operation; a second section operable to move the cam collar in a linear motion perpendicular to the face of the mask; a third section operable to lock the cam collar in an open position; and a forth section operable to allow assembly of the cam assembly. In some embodiments, the fresh-air port assembly further comprises a front cover attached to the cam collar. In some embodiments, the demand valve attaches to the fresh-air port assembly via the demand valve adapter. In some embodiments, the apparatus may further comprise a mask cover assembly operable to cover at least a portion of the mask and exhalation valve.

[0006] Other aspects of the disclosure may include a rotating assembly for use with a respirator comprising a mask and a demand valve, the assembly comprising: one or more driving balls; a cam knob operable to house the one or more driving balls; a cam collar coupled to the cam knob comprising at least one pathway on the exterior surface of the collar operable to receive the driving balls; an adapter operable to attach the cam assembly to the mask of the respirator; and a spring positioned between the cam collar and the adapter operable to bias the cam collar away from the adapter, wherein: the rotating assembly is coupled to the mask such that the assembly is positioned between the demand valve and the mask, and the rotating assembly is operable to open and close one or more port to ambient air. In some embodiments, the cam knob comprises a first protrusion operable to interact with the exhalation valve to hold the exhalation valve open. In some embodiments, the cam knob comprises a second protrusion operable to indicate the position of the cam assembly to the user of the apparatus, wherein the second protrusion is in the line-of-sight of the user when the port is open to ambient air. In some embodiments, the cam knob rotates with respect to the mask and the cam collar moves linearly perpendicular to the face of the mask. In some embodiments, the at least one pathway of the cam collar comprises: a first section operable to provide control feel resistance when initiating the turning operation; a second section operable to move the cam collar in a linear motion perpendicular to the face of the mask; a third section operable to lock the cam collar in an open position; and a forth section operable to allow assembly of the cam assembly. In some embodiments, the cam collar comprises two matching pathways. In some embodiments, the assembly may further comprise a front cover attached to the cam collar with screws. In some embodiments, the adapter interacts with a push rod of the demand valve to activate or deactivate the demand valve. In some embodiments, the port to ambient air opens between the demand valve and the adapter, while the demand valve remains coupled to the rotating assembly.

[0007] Additional aspects of the disclosure may include a method of retrofitting or upgrading a self-contained breathing apparatus having a mask and a demand valve, the method comprising: providing a fresh-air port assembly; attaching the fresh-air port assembly to the mask; and attaching the demand valve to the fresh-air port assembly. In some embodiments, attaching the fresh-air port assembly to the mask comprises attaching an adapter of the assembly to the mask via threads. In some embodiments, attaching the demand valve to the fresh-air port assembly comprises attaching the demand valve to a cam collar of the assembly.

[0008] These and other features will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] For a more complete understanding of the present disclosure, reference is now made to the following brief description, taken in connection with the accompanying drawings and detailed description, wherein like reference numerals represent like parts.

[0010] FIG. 1 is an illustration of an exemplary embodiment of a self-contained breathing apparatus system;

[0011] FIGS. 2A-2B illustrate an exemplary embodiment of a demand valve;

[0012] FIGS. 3A-3B illustrate an exemplary embodiment of a fresh-air port assembly coupled to a mask and demand valve of a self-contained breathing apparatus;

[0013] FIG. 4 is an exploded view of an exemplary embodiment of a fresh-air port assembly;

[0014] FIGS. 5A-5D illustrate detailed views of an embodiment of a cam collar;

[0015] FIG. 6 illustrates an embodiment of a pathway of the cam collar;

[0016] FIGS. 7A-7E illustrate detailed views of an embodiment of a cam knob;

[0017] FIGS. 8A-8D illustrate detailed views of an embodiment of a demand valve adapter;

[0018] FIGS. 9A-9B illustrate detailed views of an embodiment of a front cover comprising screws;

[0019] FIGS. lOA-lOC illustrate detailed views of an embodiment of an exhalation valve assembly;

[0020] FIGS. 1 lA-1 ID illustrate detailed views of an embodiment of a mask cover assembly;

[0021] FIGS. 12A-12D illustrate detailed views of an embodiment of a demand valve;

[0022] FIGS. 13A-13B illustrate an exemplary embodiment of a fresh-air port assembly when the fresh-air port is closed; [0023] FIGS. 14A-14B illustrate an exemplary embodiment of a fresh-air port assembly when the fresh-air port is being opened; and

[0024] FIGS. 15A-15B illustrate an exemplary embodiment of a fresh-air port assembly when the fresh-air port is open.

DETAILED DESCRIPTION

[0025] It should be understood at the outset that although illustrative implementations of one or more embodiments are illustrated below, the disclosed systems and methods may be implemented using any number of techniques, whether currently known or not yet in existence. The disclosure should in no way be limited to the illustrative implementations, drawings, and techniques illustrated below, but may be modified within the scope of the appended claims along with their full scope of equivalents.

[0026] Generally, Applicants have found that incorporation of a fresh-air port assembly into the mask of a self-contained breathing apparatus (SCBA) may be beneficial to enabling the user to breathe ambient air when purified air is not required. For example, a user may be in a waiting area and may wish to conserve the air in the cylinders of the SCBA, so they may wish to temporarily switch to ambient air. A fresh-air port assembly positioned between the demand valve and mask of an SCBA may be operable to disconnect and/or disable the demand valve to allow ambient air into the mask, as well as to control the exhalation valve of the mask so that a user may easily breathe ambient air. This may also allow a user to quickly switch to purified air when necessary. The fresh-air port assembly may comprise a cam knob operable to rotate with respect to the mask, a cam collar operable to move linearly perpendicular to the face of the mask, and a demand valve adapter operable to attach the assembly to the mask and/or the demand valve.

[0027] FIG. 1 illustrates a SCBA system 100 comprising a mask 102, a demand valve 104 operable to be connected to the mask 102, one or more air cylinders 110, a medium-pressure hose 106 providing fluid communication between the air cylinder(s) 110 and the mask 102 via the demand valve 104 (which may also be known as a second stage reducer), and a pressure reducer 124, operable to reduce the pressure of the air from the cylinders 110, providing fluid communication between the air cylinders 110 and the medium-pressure hose 106. In some embodiments, the cylinders 110 may comprise high-pressure air at approximately 4500 psi, for example. The pressure reducer 124 may reduce the high-pressure air from the cylinders 110 to medium-pressure air of approximately 100 psi, for example. In some embodiments, the demand valve 104 may be operable to reduce the medium-pressure air to approximately atmospheric pressure before delivering the air into the mask 102.

[0028] Additionally, the SCBA system 100 may comprise a harness comprising shoulder straps 108, a belt strap 112, and/or a cylinder strap 122. In some embodiments, the SCBA may also comprise a pressure gauge 118 and whistle 119, wherein the pressure gauge 118 and whistle 119 may be in fluid communication with the air cylinder(s) 110 via a high-pressure hose 120. In some embodiments, the high-pressure hose 120 may be coupled to the cylinders 110 via the pressure reducer 124. For example, in some embodiments the pressure reducer 124 may comprise a high-pressure pathway, for the high-pressure hose 120 to provide high-pressure air to the high-pressure gauge 118), a first medium-pressure pathway for the medium-pressure hose 106, and a second medium-pressure pathway (to provide medium-pressure air to the whistle). Thus, the pressure reducer 124 of FIG. 1 may be operable to reduce the high-pressure air of the air cylinder(s) 110 to medium pressure air, and to transmit (via coupling of the appropriate hoses) high pressure air to the pressure gauge 118, medium pressure to the demand valve 104, and medium pressure air to the whistle 119. Typically, the high-pressure hose 120 comprises a high- pressure pathway and a medium-pressure pathway, and couples to the pressure reducer 124 so that both high-pressure air and medium-pressure air may be transmitted to the combined high- pressure gauge 118 and whistle 119. In FIG. 1, the pressure reducer 124 has only one high- pressure pathway/port (for attachment of the high-pressure hose 120). In some embodiments, the pressure gauge 118 and whistle 119 may be operable to monitor the pressure of the air in the cylinders 110 as well as alert a user of the SCBA if the pressure drops below a pre-set or defined limit.

[0029] Turning now to FIGS. 2A-2B, an exemplary embodiment of the mask 102 and the demand valve 104 is shown. The mask 102 may comprise an exhalation valve 202. The demand valve 104 may be operable to control air flow 206 into the mask 102, wherein the air may flow into the mask from the medium-pressure hose 106 through the demand valve 104 and out of the mask through the exhalation valve 202. In FIG. 2 A, a user may be breathing in, causing the demand valve 104 to open and allow air flow 206 into the mask 102. In FIG. 2B, a user may be breathing out, causing the demand valve 104 to close and the exhalation valve 202 to open and allow air flow 206 out of the mask 102. In some embodiments, both the demand valve 104 and the exhalation valve 202 may be controlled by springs. In the embodiment shown in FIGS. 2A- 2B, the demand valve 104 may be attached to the mask 102 via threads 208 on the mask 102 and threads 210 on the demand valve 104. In some embodiments, the demand valve 104 may couple to the medium-pressure hose 106 at a connector 204.

[0030] Turning now to FIGS. 3A-3B, an exemplary embodiment of the mask 102 and demand valve 104 is shown, wherein the assembly further comprises a fresh-air port assembly 300 coupled to both the mask 102 and the demand valve 104. In some embodiments, the fresh- air port assembly 300 may be positioned between the mask 102 and the demand valve 104. The fresh-air port may be operable to rotate in the direction shown by arrow 302, wherein FIG. 3A illustrates the fresh-air port assembly 300 in a first position, and FIG. 3B illustrates the fresh-air port assembly 300 in a second position. In some embodiments, the fresh-air port assembly 300 may be considered "closed" in the first position and "open" in the second position. As described further herein, the open and closed positions of the fresh-air port assembly 300 may control engagement of one or more air passages through the assembly 300, wherein the air passages may provide air from the cylinders 110 of the SCBA and/or ambient air. [0031] Turning now to FIG. 4, an exploded view of the fresh-air port assembly 300, mask 102 and demand valve 104 is shown. Although, in some embodiments, the assembly 300 may comprise the specific components described herein, different components may also be used to accomplish similar functionality. The fresh-air port assembly 300 may comprise a cam collar 402, a cam knob 404, driving balls 405, a load spring 410, a demand valve adapter 412, and front cover 414. In some embodiments, the cam collar 402 may comprise pathways 406 operable to receive the driving balls 405. The cam knob 404 may be operable to fit over the cam collar 402, wherein the cam knob 404 may comprise indentions 407 operable to hold the driving balls 405. In some embodiments, the demand valve adapter 412 may be operable to fit through the cam collar 402 and cam knob 404. In some embodiments, the demand valve adapter 412 may be operable to attach to the mask 102, wherein the demand valve adapter 412 may comprise threads 411 operable to fit with threads 208 of the mask 102. In some embodiments, the assembly 300 may comprise a load spring 410 that may fit between the cam collar 402 and the demand valve adapter 412, wherein the load spring 410 may bias the cam collar 402 away from the demand valve adapter 412. In some embodiments, the front cover 414 may attach to the cam collar 402 with screws 416 and may be operable to hold the demand valve adapter 412 and spring 410 in place.

[0032] In some embodiments, the mask 102 may attach to a mask cover assembly 430, which may comprise an exhalation valve cover 432 and a nozzle cover 434. Additionally, the exhalation valve 202 may be coupled to a hold clip 436. In some embodiments, the demand valve 104 may be operable to attach to the demand valve adapter 412.

[0033] Turning now to FIGS. 5A-5D, the cam collar 402 is shown in detail. The cam collar may comprise at least one pathway 406, wherein the embodiment shown in FIGS. 5A-5D comprises two pathways 406. In some embodiments, the cam collar 402 may comprise a lip 502 around the circumference of the cam collar 402 and protruding into the center of the cam collar 402 operable to contact the load spring 410. Additionally, the cam collar 402 may comprise one or more openings 504 operable to receive screws 416 and hold the front cover 414 in place against the cam collar 402. In some embodiments, the pathways 406 may be located on the outer surface of the cam collar 402, and they may be located on opposite sides of the cam collar 406. In some embodiments, the pathways 406 may be matching. In other embodiments, the cam collar 402 may comprise any number of pathways 406 wherein the pathways 406 may each be operable to receive and direct a driving ball 405.

[0034] Turning now to FIG. 6, outer surface of the cam collar 402 is shown as a rectangle comprising the two pathways 406. FIG. 6 is a special view of the exterior surface of the cam collar 402 that has been cut and flattened out, such that the far left and far right sides of the rectangle shown would be connected. The pathways 406 may comprise four sections, a first section 601, a second section 602, a third section 603, and a fourth section 604. In some embodiments, when the driving ball 405 is in the first section 601 of the pathway, the fresh-air port assembly may be considered closed. The shape of the first section 601 is designed to demand the user to positively control and turn the cam knob 404. When the driving ball 405 is in the second section 602 of the pathway 406, a user may be opening the fresh-air port assembly 300. In some embodiments, the second section 602 may be angled such that, if a user releases, or loses their hold on, the assembly 300 while the driving ball 405 is in the second section 602, the assembly 300 may be biased closed, or back to the first section 601, by the load spring 410. The user must deliberately turn the cam knob 404 past the second section 602 into the third section 603 to open, and must deliberately turn the cam knob 404 back past the third section 603 into the second section 602 to close. When the driving ball 405 is in the third section 603, the assembly 300 may be locked in an open position, or biased open, by the load spring 410. In some embodiments, the third section 603 may be angled such that, if a user releases, or loses their hold on, the assembly 300 while the driving ball 405 is in the third section 602, or if the assembly 300 is bumped or moved, the assembly 300 may be biased open, or back to the third section 603, by the load spring 410. The fourth section 604 may only be used when assembling the fresh-air port assembly 300. In some embodiments, the first section may be operable to provide control feel resistance when initiating the turning operation; the second section may be operable to move the cam collar in a linear motion perpendicular to the face of the mask; the third section may be operable to lock the cam collar in an open position; and the forth section may be operable to allow assembly of the cam assembly.

[0035] Turning now to FIGS. 7A-7E, the cam knob 404 is shown in detail. The cam knob 404 may comprise indentions 702 on the interior surface operable to receive the driving balls 405. The driving balls 405 may interact with the pathways 406 of the cam collar 402 and may follow the pathways 406 if the cam knob 404 is turned in either a clockwise or counter-clockwise direction. Additionally, the cam knob 404 may comprise an indicator 704 , wherein the indicator 704 may align with the line of sight of a user whenever the assembly 300 is turned to the second (or open) position. This may allow a user to notice if the fresh-air port assembly is open or closed before entering a hazardous environment, for example. The indicator 704 may also be considered a protrusion from the cam knob 404. In some embodiments, the indicator 704 may comprise a color, particularly a bright or noticeable color. In some embodiments, the indicator 704 may comprise further indication, such as a light, for example. Also, the cam knob 404 may comprise a protrusion 706 operable to engage with at least a portion of the exhalation valve 202, wherein when the cam knob is in the second (open) position, the exhalation valve 202 may be held open by the protrusion 706. In some embodiments, the protrusion 706 may slope away from the side of the cam knob 404, so that it may slidingly engage with the exhalation valve 202. In some embodiments, the protrusion 706 and the indicator 704 may be aligned on opposite sides of the cam knob 404, such that when the indicator 204 is in the line of sight of a user, the protrusion 706 is holding the exhalation valve 202 open. The cam knob 404 may also comprise a lip 710 about the circumference of the cam knob 404 and protruding in toward the center of the cam knob 404, operable to contact the cam collar 402. Additionally, the cam knob 404 may comprise ridges 708 on the outer surface, wherein the ridges 708 may allow for gripping to assist turning of the cam knob 404.

[0036] Turning now to FIGS. 8A-8D, the demand valve adapter 412 is shown in detail. The demand valve adapter 412 may comprise threads 411 operable to connect the demand valve adapter 412 to the mask 102. In some embodiments, the demand valve adapter 412 may comprise a first sealing ring 802, wherein the sealing ring 802 may be operable to seal against a portion of the demand valve 104. The sealing ring 802 may be operable to create an air-tight seal between the demand valve 104 and the demand valve adapter 412. In some embodiments, the demand valve adapter 412 may comprise a second sealing ring 804 operable to seal with at least a portion of the mask 102. The second sealing ring 804 may be operable to create an air-tight seal between the mask 102 and the demand valve adapter 412.

[0037] Turning now to FIGS. 9A-9B, the front cover 414 is shown in detail. The front cover 414 may comprise openings 902 operable to receive screws 416. The screws 416 may attach the front cover 414 to the cam collar 402. In some embodiments, the front cover 414 may comprise any number of openings 902 and screws 416, wherein in the embodiment shown in FIGS. 9A-9B, the front cover 414 may comprise 6 openings 902 equally spaced around the circumference of the front cover 414.

[0038] Turning now to FIGS. 1 OA- IOC, the exhalation valve 202 is shown in detail. The exhalation valve 202 may be coupled to a hold clip 436, wherein the hold clip 436 may be attached to one or more rods 1006. In some embodiments, the exhalation valve 202 may comprise a membrane 1004 operable to seal the exhalation valve 202 closed against at least a portion of the mask 102. In some embodiments, the rods 1006 may be attached to a pin 1010. Additionally, the rods 1006 may be coupled to the membrane 1004, such that if the rods 1006 are moved, the membrane 1004 is also moved. In some embodiments, the exhalation valve 202 may comprise a spring 1002 operable to bias the membrane 1004 against the mask 102. In other words, the spring 1002 may be operable to bias the exhalation valve 202 closed. In some embodiments, the hold clip 436 and/or rods 1006 may be operable to interact with the protrusion 706 of the cam knob 404. In some embodiments, the protrusion 706 of the cam knob 404 may be operable to move the hold clip 436, and therefore the rods 1006, in a lateral direction. In other words, when the cam knob 404 is in the second (open) position, the protrusion 706 may be holding the exhalation valve 202 open, such that if the fresh-air port assembly 300 is open, the exhalation valve 202 is also held open. In the embodiment shown in FIG. 10B, the membrane 1004 may be in a first position, held against the mask 102 by the spring 1002, and the exhalation valve 202 may be considered closed. In the embodiment shown in FIG. 10A, the membrane 1004 may be in a second position, pulled away from the mask 102 by the hold clip 436 and/or rods 1006, and the exhalation valve 202 may be considered open. In some embodiments, the membrane 1004 may move a distance 1008 between the first and second positions.

[0039] Turning now to FIGS. 1 lA-1 ID, the mask cover assembly 430 is shown in detail. In some embodiments, the mask cover assembly 430 may comprise an exhalation valve cover 432 and a nozzle cover 434. In some embodiments, the nozzle cover 434 may fit over at least a portion of the mask 102. The nozzle cover 434 may comprise vents 1102 to allow air flow from the exhalation valve 202. In some embodiments, the exhalation valve cover 432 may cover at least a portion of the exhalation valve 202. In some embodiments, the exhalation valve cover 432 may fit against, or snap to, the nozzle cover 434. In some embodiments, the rods 1006 of the exhalation valve 202 may fit through the vents 1102 of the nozzle cover 434, wherein the hold clip 436, coupled to the rods 1006, may be located on the exterior of the nozzle cover 434, while the exhalation valve 202 may be covered by the nozzle cover 434. In some embodiments, the hold clip 436 may be covered by the exhalation valve cover 432.

[0040] Turning now to FIGS. 12A-12D, the demand valve 104 is shown in detail. The demand valve 104 may comprise a push rod 1202, wherein the push rod 1202 may be a trigger operable to open up and/or close down the demand valve 104. For example, when the push rod 1202 is pushed down, as shown in FIG. 12D, the demand valve 104 may be activated or opened, such as when the demand valve 104 is attached to the mask 102 and/or the demand valve adapter 412. Additionally, when the push rod 1202 is extended, as shown in FIG. 12C, the demand valve 104 may be deactivated or closed, such as when the demand valve 104 is removed from the mask 102 and/or the demand valve adapter 412. In some embodiments, the push rod 1202 may be spring loaded, such that the push rod 1202 is biased to an extended position, shown in FIG. 12C. In some embodiments, the demand valve 104 may comprise a portion 1204, wherein the portion 1204 of the demand valve 104 may be operable to seal with the demand valve adapter 412.

[0041] Turning now to FIGS. 13A-13B, the fresh-air port assembly 300 is shown assembled and coupled to the demand valve 104 and mask 102, wherein the assembly 300 may be positioned between the demand valve 104 and the mask 102. In the embodiment shown in FIGS. 13A-13B, the assembly 300 may be in a first (or closed) position. The driving ball 405 may be in the first section 601 of the pathway 406 on the cam collar 402. The assembly 300 may be considered closed when the demand valve 104 is positioned against a sealing ring 802 located within the demand valve adapter 412. As shown in FIG. 5B, at least a portion of the demand valve 104 may be positioned against the demand valve adapter 412, wherein the sealing ring 802 may be in contact with the portion 1204 of the demand valve 104. In the embodiment shown in FIGS. 5A-5B, the air flow 206 may flow through the demand valve 104, through the demand valve adapter 412, and into the mask 102 when a user is breathing in, and then out through the exhalation valve 202 when a user is breathing out (similar to FIGS. 2A-2B). In the embodiment shown in FIGS. 13A-13B, the demand valve 104 may be activated, wherein the push rod 1202 may be pushed down by the demand valve adapter 412.

[0042] Turning now to FIGS. 14A-14B, the fresh-air port assembly 330 is shown, wherein the driving ball 405 may be in the second section 602 of the pathway 406. The cam knob 404 may be turned, moving the driving ball(s) 405 into the second section 602. As shown in FIG. 14B, cam collar 402 may be pushed against the load spring 410 by the movement of the driving ball(s) 405, pushing the demand valve 104 outward (or away from the mask 102). This may release the seal between the sealing ring 802 and the portion 1204 of the demand valve 104. In some embodiments, a port 1402 may be opened between the portion 1204 of the demand valve 104 and the demand valve adapter 412. Additionally, as the demand valve 104 is pushed away from the mask 102 (and therefore the demand valve adapter 412), the push rod 1202 may begin to extend, deactivating the demand valve 104. Additionally, as the cam knob 404 is turned, the protrusion 706 may be moving the hold clip 436 outward, or away from the mask 102, causing the exhalation valve 202 to be opened. In some embodiments, the position of the fresh-air port assembly 300 shown in FIGS. 14A-14B may be considered a transition stage between closing and opening the assembly 300. In this transition stage, if the user were to stop turning the cam knob 404, the load spring 410 may be operable to push the cam collar 402 and driving ball(s) 405 back to the first (closed) position. This may serve as a safety mechanism to prevent from opening the fresh air port 1402 accidentally, since it may be dangerous in a contaminated environment.

[0043] Turning now to FIGS. 15A-15B, the fresh-air port assembly 300 is shown in an open position. The cam knob 404 may be turned further, causing the driving ball(s) 405 to enter the third section 603 of the pathway(s) 406 on the cam collar 402. As shown in FIG. 15B, the cam collar 402 may be further pushed against the load spring 410, pushing the demand valve 104 outward (or away from the mask 102). The port 1402 may be further opened as the demand valve 104 is pushed away from the demand valve adapter 412. In some embodiments, the port 1402 may extend around the circumference of the demand valve adapter 412, wherein a portion of the circumference may be blocked by the push rod 1202. In other words, the space created between the portion 1204 of the demand valve 104 and the demand valve adapter 412 may extend around the circumference of both the portion 1204 and the demand valve adapter 412. Additionally, the demand valve 104 may comprise ports or spaces 1504 to allow air flow through at least a portion of the demand valve 104. In some embodiments, the exhalation valve 202 may also be held open by the protrusion 706 interacting with the hold clip 436. In the embodiment shown, air flow 206 may flow through the port 1402 around the demand valve adapter 412 as well as through the exhalation valve 202. In some embodiments, the direction of the air flow may be directed into the mask through the fresh-air port assembly 300 and out of the mask through the exhalation valve 202. As shown in FIGS. 15A-15B, the push rod 1202 of the demand valve 104 may be extended, deactivating the demand valve 104.

[0044] Some embodiments of the disclosure may include methods of using the fresh-air port assembly 300 described above. In some embodiments, a user may wish to deactivate the demand valve 104 and breathe atmospheric air while wearing a mask 102, such as on a SCBA 100. The method may comprise rotating a cam knob 404 of the fresh-air port assembly 300 from a first position to a second position, causing the demand valve 104 to be deactivated and opening one or more ports 1402 through the fresh-air port assembly 300, allowing atmospheric air into the mask 102. In some embodiments, rotating the cam knob 404 may also open the exhalation valve 202 of the mask 102, allow a user to breathe out of the mask 102 without the pressure gradient typically required to open the exhalation valve 202. The method may further comprise rotating the cam knob 404 in the opposite direction from the second position to the first position, causing the demand valve 104 to be activated and closing the one or more ports 1402 through the fresh- air port assembly 300. In some embodiments, rotating the cam knob 404 back to the first position may release the exhalation valve 202, wherein the exhalation valve 202 may then operate based on the pressure in the mask 102 from a user's breathing.

[0045] Other embodiments of the disclosure may include methods of retrofitting a fresh-air port assembly to an SCBA 100. The method may comprise removing the demand valve 104 from the mask 102 of the SCBA 100, attaching the fresh-air port assembly 300 to the mask 102, and attaching the demand valve 104 to the fresh-air port assembly 300. In some embodiments, the fresh-air port assembly 300 may attach to the mask 102 via the demand valve adapter 412. In some embodiments, the fresh-air port assembly 300 may attach to the demand valve via the cam collar 402 and/or front cover 414 of the fresh-air port assembly 300. [0046] The figures discussed above provide examples of various exemplary devices, systems, and techniques and ways to make and use such devices. These illustrations are merely exemplary. The scope of the present disclosure extends beyond the specific examples set forth above, capturing the full range of the inventive concept (and including all equivalents).

[0047] While various embodiments in accordance with the principles disclosed herein have been shown and described above, modifications thereof may be made by one skilled in the art without departing from the spirit and the teachings of the disclosure. Alternative embodiments that result from combining, integrating, and/or omitting features of the disclosed embodiments are also within the scope of this disclosure. The embodiments described herein are representative only and are not intended to be limiting. Many variations, combinations, and modifications are possible and are within the scope of the disclosure. Accordingly, the scope of protection is not limited by the description set out above, but is defined by the claims which follow, that scope including all equivalents of the subject matter of the claims. Furthermore, any advantages and features described above may relate to specific embodiments but shall not limit the application of such issued claims to processes and structures accomplishing any or all of the above advantages or having any or all of the above features.

[0048] Additionally, the section headings used herein are provided for consistency with the suggestions under 37 C.F.R. 1.77 or to otherwise provide organizational cues. These headings shall not limit or characterize the invention(s) set out in any claims that may issue from this disclosure. Specifically and by way of example, although the headings refer to a "Field of the Invention," the claims should not be limited by the language chosen under this heading to describe the so-called field. Further, a description of a technology in the "Background" is not to be construed as an admission that certain technology is prior art to any invention(s) in this disclosure. Neither is the "Summary" to be considered as a limiting characterization of the invention(s) set forth in issued claims. Furthermore, any reference in this disclosure to "invention" in the singular should not be used to argue that there is only a single point of novelty in this disclosure. Multiple inventions may be set forth according to the limitations of the multiple claims issuing from this disclosure, and such claims accordingly define the invention(s), and their equivalents, that are protected thereby. The term "comprising" as used herein is to be construed broadly to mean including but not limited to, and in accordance with its typical usage in the patent context, is indicative of inclusion rather than limitation (such that other elements may also be present). In all instances, the scope of the claims shall be considered on their own merits in light of this disclosure, but should not be constrained by the headings set forth herein.