Patent Publication Number: US-6338340-B1

Title: Filter mask

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention broadly concerns a mask which is to be worn in conditions of fire and smoke to filter harmful particulates and gases. More particularly, it is concerned with a mask which includes a lightweight and disposable filter element which includes a carrier element and a coating of aloe gel for removing smoke particulates and toxic gas during breathing to permit temporary work and escape. 
     2. Description of the Prior Art 
     The danger to persons attendant to fire has long been recognized to include death and injury attributable to smoke inhalation. In addition to injuries attributable to burns, one of the major causes of death and injury during fire is smoke inhalation. In many fire and smoke environments, there is sufficient oxygen available to permit escape, but the individual is overcome by smoke inhalation or toxic gas. Devices which are directed to filtering smoke particulates include U.S. Pat. Nos. 4,402,317 and 4,854,314. While the devices shown therein are useful in filtering smoke particulates during escape of occupants from a structure, they do not address the need for uses in other applications nor for the filtering of toxic gases such as hydrogen cyanide generated during building fires. 
     Firefighters also need temporary protection from smoke and fire. Firefighters, and especially those encountering brush fires and forest fires, may need to carry a substantial amount of equipment which may not include respirators. They may also suddenly encounter a dangerous situation such as the reversal of direction of a fire which may expose them to unexpected smoke and fire hazards. While masks have been developed for use in these environments, such as shown in U.S. Pat. No. 5,628,308, they have been uncomfortable to wear and expensive. Moreover, they have failed to address the need for a lightweight, temporary filter to remove toxic gas such as hydrogen cyanide from the air breathed by the wearer. 
     As a result, there has developed a need for a lightweight, easily storable filter mask which, in various constructions, can be stored in a home or office for emergency use, or used by firefighters or in industrial applications to augment available respirators. 
     SUMMARY OF THE INVENTION 
     The present invention satisfies the need for a lightweight, portable, and inexpensive mask capable of filtering both smoke particulates and hazardous chemicals which can be adapted to different needs. In its simplest form, the present invention includes a filter element and a retainer. The filter element has a container having a permeable fabric cover and a filling of shiftable bodies covered with a coating including a quantity of aloe vera gel. The retainer includes a support strap connected to the cover. Surprisingly, the coating primarily of aloe vera gel having an elevated pH as used in the present invention is not only non-toxic and gentle to the wearer if it contacts the skin, but traps smoke particulates and neutralizes toxic gases which would be harmful to the wearer. The aloe vera gel is preferably combined with a base to elevate the pH of the coating to an alkaline pH level of about 9.25 to 10. As a result, a high degree of neutralization of toxic gases such as hydrogen cyanide which come in contact with the aloe vera gel. The beads are preferably of a lightweight, non-absorbent material such as polystyrene of mixed sizes in the range of 0.01 inch to 0.5 inch in diameter. The simple filter mask described above may be worn to aid in the removal of smoke particulates and toxic gases during the escape of individuals from homes and other buildings in which smoke and fire is encountered. 
     In a second embodiment, the basic filter element, as described above without the strap, is provided as a disposable element within a retainer or mask. The filter element is removably attached to the inside of the facial portion of the mask to be in direct contact with and conform around the nose and mouth of the wearer, thus causing the inhaled air to be drawn therethrough and filtered. The facial portion of the retainer mask preferably has an outer, fire resistant fabric layer and includes a pocket for receiving the filter element therein, and straps for holding the facial portion in place. The retainer mask may also include a collar portion which is attached to a lower edge of the facial portion and hang downwardly therefrom to protect the neck and upper chest area of the wearer from heat and sparks. Additionally, the facial portion may be provided with an attachment member, such as a snap or hook and loop fastener, to connect to a firefighters goggles to provide additional resistance to slippage of the filter element away from the nose and mouth of the wearer. 
     In a third embodiment of the mask of the present invention, the filter element as described with reference to the second embodiment is attached to the inside of a retainer including shell which includes a substantially impermeable barrier except for at least one-way valve and an inlet for ensuring air entering the shell passes through the filter element. Straps are connected to the shell for holding it in place on the face of the wearer. The one-way valve is preferably an exhalation-only valve, with the filter element covering the inside of the inlet. 
     A fourth embodiment of the present invention is similar to the third embodiment, but wherein the filter element is provided as an external component to the mask. The filter element then preferably includes a rigid or semi-rigid container carrying the filling, which may be further augmented by carbon monoxide handling material. The bodies are covered with the modified aloe vera gel as described above either before insertion into the container or preferably thereafter, whereby the uncoated bodies may be stored in their containers until required for use. Mesh or other air-permeable screen-type material permits inhalation through the removable filter element, while a one-way valve permits exhalation. The filter element may be removed from a flexible gasket-type mount in the shell without the need for removing the mask. This may be helpful in some fire situations where removal of the mask would require removal of goggles or helmet and thereby expose the wearer to additional risks. 
     The resulting filter mask of any of the aforementioned embodiments presents significant improvements over the prior art. Further benefits will be readily appreciated by those skilled in the art with reference to the drawings and the written description of the preferred embodiments set forth below. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a front perspective view of a first embodiment of the filter mask of the present invention showing the a part of the cover broken away to show the coated beads therein, and straps for holding the cover in position over the nose and mouth of the wearer; 
     FIG. 2 is an exploded front perspective view of a second embodiment of the present invention for use by firefighters, showing the filter element, facial portion and collar portion; 
     FIG. 3 is a left side elevational view of the filter mask shown in FIG. 2, with portions of the filter element, facial portion and collar portion broken away; 
     FIG. 4 is a rear elevational view of the collar portion of the filter mask of FIG. 2, with a portion of the lining material broken away to show the fire resistant outside layer; 
     FIG. 5 is a left side elevational view of the facial portion of the filter mask of FIG. 2, with the filter element shown in phantom; 
     FIG. 6 is a rear perspective view of the facial portion of the filter mask of FIG. 2, with the filter element removed to show the pocket and attachment members into which the filter element is received; 
     FIG. 7 is an exploded view of a modified form of the embodiment of FIG. 2, showing a firefighters goggles and a releasable fastener for connecting the facial portion of the mask to the goggles; 
     FIG. 8 is a side elevational view of the embodiment of FIG. 7, with the goggles and filter mask in place on the face of a wearer; 
     FIG. 9 is a lower front perspective view of a third embodiment of the filter mask of the present invention, showing the cover with the one-way exhalation valve and straps for holding the mask in position; 
     FIG. 10 is a lower rear perspective view of the filter mask of FIG. 9, showing the rear of the one-way valve, with the filter element shown in phantom; 
     FIG. 11 is a lower rear perspective view of a fourth embodiment of the filter mask of the present invention, similar to the filter mask of FIG. 9 except that an exterior filter cannister is provided instead of the removable filter element; 
     FIG. 12 is an exploded front perspective view of a fifth embodiment of the present invention, showing the filter element of the embodiment of FIGS. 2 through 10 held by a facial protector; and 
     FIG. 13 is a rear perspective view of the facial protector of FIG.  12 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     As shown in FIG. 1, the filter mask  10  of the present invention in its simplest form includes a filter element  12  and a retainer  14  for holding the filter element  12  in position over the nose and mouth of the wearer  16 . The filter element  12  includes a container  18  having a cover  20  of flexible, air permeable material which is preferably soft and non-irritating to the skin of the wearer. Polyester is one such material which is suitable because of its non-absorbent properties. The cover  20  as shown in FIG. 1 is bag-like and preferably about 5 and ½ to 6 and ½ inches across, between about 4 and 6 inches vertically, and about ½ inch to 1 inch in thickness when laying flat to adequately cover the nose and mouth of a wearer. Of course, the cover could be of a greater dimension as desired to provide greater thickness or span across the face of the wearer. Preferably, to permit the use of small polystyrene beads therewithin and provide good breathability, the pores or interstices of the fabric cover are no more than about {fraction (1/64)} inch. 
     The filter element  12  includes a filling  22  of lightweight, discrete, shiftable, substantially dust-free bodies  24  which are resistant to absorption of liquids. Such beads and suitable shape and size assortments thereof are shown, for example, in U.S. Pat. No. 4,854,314 to Martin, the disclosure of which is incorporated by reference. For the container size set forth above, a preferably quantity of bodies of polystyrene beads is approximately 164 to 173 grams. The beads are covered with a coating  26  derived from a flowable gel-like extract of the mucilaginous jelly from the parenchyma cells of the aloe vera plant referred to as aloe vera gel. Aloe vera is a succulent, fibrous plant, of the family Liliaceae, with basal leaves, having toothed or fibrous margins. The aloe vera gel is a well known emollient derived from the mucilaginous cells and is about 98.5% by weight water. More than 60% of the total solid is made up of polysacchiarides of carbohydrate origin. Organic acids and inorganic compounds, especially calcium oxalate, account for the remainder of the solid. Aloe vera gel ordinarily has a pH of about 4.5 to 5. The aloe vera gel is modified to improve its flowability in the present invention by adding moisture in the form of raw aloe vera extract or water to yield a viscosity of about 1.25 poise to 1.75 poise to provide suitable flowability, particulate capture, and retention of the gel on the bodies  24 . The gel is then modified to increase the pH to an alkaline condition in order to neutralize toxic gases such as hydrogen cyanide, hydrogen chloride and acrilyne prior to inhalation through the filter element  12 . The bodies  24  are preferably completely covered with the coating by immersion, massaging or other means such as spraying with the coating  26  after filling in the container, and typically between about ¼ and one ounce of coating material will be sufficient to thoroughly coat the bodies  24  in the amounts used in the filter elements  12  hereof. The amount of filling provided into the container  18  is sufficient to create a thickness of the bodies of about ¼ inch or more when in use, but will also permit some shifting of the beads within the container  18  in order that the filter element  12  is able to conform around the nose and mouth of the wearer. 
     The coating includes an extract from the aloe vera plant, a preservative, a base, and a modifier to maintain the desired viscosity and gel-like qualities of the coating. Aloe vera gel is particularly beneficial in the present invention because it is non-toxic, resistant to rapid loss of moisture, is soothing to the skin and effectively buffers the base, stores well, and provides good smoke particulate capture. Methyl paraben is a good preservative because it is non-toxic and helps resist the growth of mold. Sodium hydroxide is a satisfactory base, and sodium sesquicarbonate helps to maintain the viscosity and coating capability of the aloe vera and is slightly alkaline to help elevate or maintain the pH of the coating  26 . 
     In accordance with a preferred embodiment of the invention, the coating  26  begins with aloe vera gel which is diluted, preferably by aloe vera juice but alternatively by water added to the aloe vera gel until the desired viscosity is achieved to yield a start-up mixture. Aloe vera gel is a commercially available product which is gel or jelly-like in consistency, while aloe vera juice is the liquid extracted directly from the leaf of the aloe vera plant and is liquid. The amount of aloe vera juice which may be added to the aloe vera gel may range between 20% and 50% of the aloe vera gel by volume, with 35% of the mixture being aloe vera juice being most preferred to provide the start-up mixture. One gallon of aloe vera start-up mixture is combined with five grams of methyl parabens (N.F.) and the resulting product is then stirred until thoroughly mixed. To this product, 75 grams of Carbapol 981 (N.F.) polymer is added and stirred until mixing is complete, typically for a period of 3-4 hours. Carbapol 981 is a carboxyvinyl polymer available from BF Goodrich Performance Materials of Cleveland, Ohio. This product is then mixed at slow speed in a Hobart 60 Quart power mixer with a sufficient quantity of 10% sodium hydroxide solution to raise the pH to 6.5 to 7.0. Thereafter a 10% solution of 10% sodium sesquicarbonate (50% sodium carbonate −50% sodium Bicarbonate) is added during mixing until the desired thickness and viscosity is achieved to provide coating for the bodies. The amount of sodium sesquicarbonate which is added will typically be up to about 0.22 pounds per gallon of the mixture. Additional 10% sodium hydroxide is added then added during mixing to bring the coating to a final desired pH level. The preferred pH level for the coating  26  is above 7.0, and most preferably in the range of 9.25 to 10. Optimal performance for the coating  26  is obtained with a pH of 9.80. The preferred viscosity is in excess of about 1.25 poise at 20° C. and the preferred kinematic viscosity of the coating  26  is between about SAE viscosity nos. 135 and 150. 
     As shown in FIG. 1, the retainer  14  includes a pair of elastic straps  28  and  30  provided respectively with a clasp  32  and receiver  34  at the distal ends  36  and  38  thereof. The proximal ends  40  and  42  of the straps  28  and  30  are stitched or otherwise secured to the filter element  12  so that upon placement of the filter element  12  over the nose and mouth of the wearer and securing the clasp  32  within the receiver  34 , the filter element  12  will conform to the wearer&#39;s face and inhalation and exhalation will be through the filling  26  and cover  20 . 
     FIGS. 2-6 illustrate a second embodiment  10 A of the filter mask hereof. In the filter mask  10 A, the filter element  12 A is provided as a removable and disposable element for attachment within the retainer  14 A so as to be positioned between the retainer  14 A and the wearer  16 . The retainer  14 A includes a facial portion  50  which overlies the filter element  12 A. Additionally, the filter mask  10 A includes a collar  44  adapted to connect to the bottom of the retainer  14 A and provide additional protection against heat and sparks. 
     In greater detail, the filter element  12 A includes a container  46  a coupling member  48  for releasably connecting the container  46  to a facial portion  50  of the retainer  14 A, and a filling  22  as described above. The container  46  is preferably a cover  52  of a polyester fabric material which is breathable through pores or interstices between the fibers which are desirably not more than about {fraction (1/64)} inch in size. The container is preferably at least about 5 and ½ inch across, at least about 4 inches top to bottom, and at least about ½ inch in thickness when filled with the bodies  24 . A typical filter element  12 A will contain about 164 to 173 grams of the polystyrene bead bodies  24  as described herein above, which after securement within the flexible cover  52  are then coated with the coating  26 . Coating may be accomplished by immersion of the container in a bath of the coating  26  and then allowing the excess coating to drip free, or by taking about one-quarter to about I ounce by volume of the coating  26  (for the weight of polystyrene bodies referenced above) and massaging it into the container  46  to coat the bodies  24 . The coupling member  48  may be of hook and loop fabric as shown, but alternate couplers such as snaps, buttons, hook and eyelet, zippers or other conventional fastening means which permit ready detachment may be used. As shown, the hook fabric component  48 ′ is sewn in three positions to the portion of the cover facing the facial portion  50  to maintain the filter element  12 A in a spread position, properly located to cover the wearer&#39;s nose and mouth. 
     The facial portion  50  is preferably provided with an outer fire resistant layer  54  of Nomex® Defender 600 RS or other fire-resistant fabric on the normally outwardly facing surface  56 , and a liner  58  sewn thereto of soft fabric material such as cotton or polyester on the normally inside surface  60 . Polyester is especially beneficial as a lining material as it has been found to wick away moisture from the wearer&#39;s face. The facial portion includes an upper margin  62 , a lower margin  64 , and first and second flaps  66  and  68  terminating in respective first and second ends  70  and  72 . As shown in FIGS. 2,  3   5  and  6 , the flaps  66  and  68  extend sufficiently in length to permit wrapping around the neck of the wearer. The flaps are maintained in tension by elastic material such as Spandex® sewn between the layer  54  and the liner  58  to form gathers  74 , and patches  76  and  78  of hook and loop fabric are sewn to the outwardly facing surface  56  of one flap and the normally inside surface  60  of the other flap adjacent the respective ends  70  and  72  to permit easy and adjustable fastening of the flaps  66  and  68 , thereby holding the facial portion  50  in position. Reflective strips  80  such as, for example, 3M or G-SIL#9485 reflective tape, may be sewn or glued to the outwardly facing surface  56 . Nomex® binding material may be used as an edge finish to resist raveling of the cloth. 
     A pocket  82  is formed in the facial portion  50  approximately midway between the ends  70  and  72  so as to be positioned over the wearer&#39;s mouth and nose and receive the filter element  12 A therein. The loop fabric portion  48 ″ of the coupling member  48  is sewn or glued to the inside surface  60  of the facial portion in complemental facing locations to the hook portion  48 ′ to permit the filter element  12 A to be removably mounted thereto. A central mesh portion provides a window  84  of breathable fire-retardant cloth such as Nomex® Hood Material is sewn over central opening  86  defined in the outer layer  54 , which provides an air inlet so that inhaled air passes through the mesh portion  84  rather than through the outer fire resistant layer  54 , and thus through the filter clement  12 A. A connector  88  is provided to removably couple the collar  44  to the facial portion  50 , the connector  88  being shown as hook material  90  positioned on the outwardly facing surface  56  adjacent the lower margin  64  in three locations  92 ,  94  and  96 . Other suitable connectors  88  would include snaps, buttons, zippers, hooks and eyes, or other fasteners. 
     The collar  44  shown in FIGS. 2,  3  and  4  includes an facing layer  98  of Nomex® Defender 600 RS or other fire-resistant material on an outer surface  100  and an inner layer  102  of a soft cloth material such a cotton or polyester backing on an inner surface  103 . Two arms  104  and  106  extend normally rearwardly around the back of the neck of the wearer, each ending in a respective tail  108 ,  110 . A closure  112  of hook and loop fabric material is provided and sewn to the outer surface  100  of one arm and the inner surface  103  of the other arm adjacent the respective tails  108 ,  110  to retain the collar around the neck of the wearer. Nomex® binding material may be sewn around the perimeter of the collar  44  to prevent raveling. A clip or length of binding material may be sewn to one or both of the tails to aid a firefighter in retaining the collar  44  on a tool belt when not in use. The collar has an upper edge  113 , with the loop material  114  of the connector  88  being sewn or glued in three complemental locations on the outer surface  100  adjacent the upper edge  113 , whereby the collar  44  may hang from the lower margin of the facial portion  50 . An enlarged bib  115  is located midway between the tails  108 ,  110  to provide enhanced protection in the frontal region over the wearer&#39;s chin, throat and upper chest. 
     A modification of filter mask  10 A′ is shown in FIGS. 7 and 8. The filter mask  10 A′ is in all respects similar to filter mask  10 A, except that it is especially adapted to include goggles  116  in combination therewith. To that end, a coupler  118  is provided to connect the goggles  116  to the facial portion  50  adjacent the upper margin  62  thereof. As shown in FIGS. 7 and 8, the goggles  116  include a nose bridge portion  120  and the coupler  118  includes a loop fabric portion  122  glued or otherwise secured to the inner side of the nose bridge portion  120 , while a complemental hook fabric portion  124  is sewn or glued to the outwardly facing surface  56  adjacent the upper margin  62 . The goggles  116  thereby aid in holding the upper margin  62  over the nose of the wearer  16  to both support the filter mask  10 A′ in position but also to provide greater resistance to burns over the nose region. 
     A further embodiment of the filter mask  10 B is shown in FIGS. 9 and 10. Filter mask  10 B utilizes the same filter element  12 A as referenced above. However, the retainer  14 B has a facial portion  126  which is provided as a semi-conical shell  128 . The shell  128  is provided of substantially impermeable foam, such as, for example, 1.2 lb. density {fraction (5/8+L )} inch thickness polyurethane foam. The shell is sized to substantially cover the cheeks, nose and chin of the wearer  16  but to have an upper margin  130  which is below the eye sockets to permit vision. A one-way check valve  132  is centrally located, the check valve  132  oriented for permitting exhalation but not inhalation therethrough. Two polyester or Nomex® cloth filter screens  134  and  136  are secured by gluing or sewing on the inside of openings in the shell  128  and located so that during inhalation, the air is drawn through the filter element  12 A, shown in phantom in FIG. 10, before entering either the wearer&#39;s nose or mouth. Elastic straps  138  and  140  are sewn or otherwise affixed to the exterior side of the shell  128  so as to be located for extending around the back of the wearer&#39;s head and tensioning the shell adjacent the wearer&#39;s face. Coupling member  48  also includes the loop fabric  48 ″ on positioned on the interior side of the shell  128  for holding the filter element  12 A in proper position. The filter mask  10 B is designed to provide egress from an indoor fire where adequate oxygen is present. 
     A fourth embodiment of the filter mask  10 C is shown in FIG.  11 . It is similar to the embodiment shown in FIGS. 9 and 10, except that the filter element  12 B is provided with a container in the form of an externally mounted cannister  142 , and the screens  134  and  136  are replaced by a mounting gasket  144  of rubber or synthetic rubber such as Neoprene which elastically grips the cannister  142 . The cannister is provided with a modified filling  22 C which includes the coated bodies  24  of polystyrene as described above occupying about 50% to 90% of the volume therein, with the remaining volume of the cannister  142  being provided of Carulite particles by Carus Chemical of Peru, Ill. A typical amount of Carulite used in the cannister  142  is about 70 grams, the Carulite being used to capture carbon monoxide passing therethrough. Polyester woven covers  20 C are positioned at each end of the cannister, which has a cylindrical wall  146  of aluminum. Aluminum or other moisture barrier caps may be provided over each cover  20 C during storage and until the time for use. Air is inhaled by the user through the cannister  142  and exhaled through the one-way check valve  132 . This filter mask  10 C provides additional capture of carbon monoxide gases. 
     A fifth embodiment of the filter mask  10 D is shown in FIGS. 12 and 13. The filter element  12 A is as described herein above, with a modified retainer  14 D. The retainer  14 D includes an outer fabric layer  148  of fire-resistant material such as Nomex® Defender 600 RS and having an inner side  150  and an outer side  152 . The inner side is provided with loop fabric  48 ″ of coupling member  48  for attachment of the filter element  12 A thereto. The retainer  14 D further includes an elastic strap  154  connected by metal loops adjacent the side edges  158  and  160  of the facial portion  162 . The facial portion of the retainer  14 D further forms a pocket  164  for receiving the filter element against the wearers face as described above. The inner side  150  also includes side flaps  165  and  166  which aid in restraining the filter element  12 A against excessive lateral shifting within the pocket  164 . This version of the filter mask  10 D is useful for firefighters experiencing only limited close contact with the fire environment. 
     Surprisingly, the use of the coating  26  on the bodies  24  provides excellent short-term removal of not only smoke particulates of at least about 90%, but also toxic gases, e.g. hydrogen cyanide removal of at least about 80%. Testing under situations approximating the normal breathing flow of a human (approximately 22 liters per minute) revealed that uses of the filter element  12 A resulted in a reduction of hydrogen cyanide gas from about 365 parts per million to about 23 parts per million. Similar testing revealed a capture of about 94.7% of hydrogen chloride passing through the filter element  12 A and a capture of about 99.1% of acrolein. The filter element also retains an excellent ability to capture smoke particulates, with a reduction from 90 to 95% of the smoke particulates passing therethrough. The ability of the aloe vera based coating resists irritation to the wearer&#39;s face while maintaining an alkaline pH, with a pH between 9.25 and 10 being especially beneficial for treating toxic gases while remaining non-irritating to the wearer&#39;s skin. In addition, the aloe vera based coating resists drying to maintain the ability to capture smoke particulates and capture toxic gases over a period of up to eight hours, depending on the severity of the smoke particulates and gases. Beneficially, the filter elements are easily replaceable, lightweight, may be stored in sealed bags for extended periods without degradation, are non-toxic, and require no special training prior to use. The filter masks hereof may be used in any temperature within the limits of survival. 
     Although preferred forms of the invention have been described above, it is to be recognized that such disclosure is by way of illustration only, and should not be utilized in a limiting sense in interpreting the scope of the present invention. Obvious modifications to the exemplary embodiments, as herein above set forth, could be readily made by those skilled in the art without departing from the spirit of the present invention. 
     The inventors hereby states their intent to rely on the doctrine of equivalents to determine and assess the reasonably fair scope of their invention as pertains to any apparatus not materially departing from but outside the literal scope of the invention as set out in the following claims.