in describing preferred embodiments of the invention , specific terminology is used for the sake of clarity . the invention , however , is not intended to be limited to the specific terms so selected , and it is to be understood that each term so selected includes all technical equivalents that operate similarly . in the practice of the present invention , a powered air purifying respirator is provided that not as unwieldy as supplied air respirators heretofore known in the art . unlike known supplied air respirators , which had hoses of uniform length and which could be too long for smaller users , the present invention furnishes the art with a supplied a respirator that has an adjustable length hose that reduces problems and costs associated with unnecessary hose length . fig1 shows a powered air purifying respirator system 10 that includes an adjustable length hose 12 that has a sleeve 14 disposed over a tube 15 ( fig2 ) through which air passes from a filtering unit 16 to a hood 18 . the filtering unit 16 has a fan 20 that is driven by an electric motor 22 . the fan 20 draws air through a filter element 24 and forces that filtered air into the interior gas space defined by the hood 18 . the fan 20 and the electric motor 22 are typically contained within a housing 26 . an electric switch 28 may be included in the circuit 31 to enable the papr 10 to be turned on and off the filter element is commonly contained within a filter cartridge housing 24 , which housing 24 is usually removably attached to the papr housing 26 . the papr housing 26 is commonly worn about the waist of the user and may be supported by a belt like the one shown in u . s . patent des . d501 , 288 to taylor . examples of a papr systems in which the present invention may be used are shown in u . s . pat . nos . 6 , 796 , 304 to odell et al ., 6 , 666 , 209 to bennett et al ., and 6 , 575 , 165 to cook et al . filter media that could be used to provide the wearer with a source of clean air include particulate filter media such as a webs of electrically charged fibers , particularly electrically charged microfibers — see u . s . pat . nos . 6 , 783 , 574 to angadjivand et al ., 6 , 119 , 691 to angadjivand et al ., and 5 , 472 , 600 to ellefson et al . alternatively , gaseous filters such as activated carbon filters can also be used to filter gaseous contaminants — see u . s . pat . nos . 6 , 344 , 071 b1 to smith et al ., 5 , 078 , 132 to braun et al ., and 4 , 443 , 354 to eian . filter elements that contain combinations of particulate and gaseous filter media may also be used in the filter cartridge ( s ). multiple cartridges 24 also may be attached to the filtering unit 16 . the papr also could be provided with a sensor that tells the user when the flow rate has dropped below a specified level — see u . s . pat . no . 6 , 615 , 828 to petherbridge . in addition , a nonvolatile memory device may be associated with the filter element to keep a record of the filter element &# 39 ; s usage — see u . s . pat . no . 6 , 186 , 130 to hogue . a system of calibrating air flow may also be used — see u . s . pat . no . 6 , 666 , 209 b2 to bennett et al . although the papr shown in fig1 uses a hood 18 as a face piece that provides an interior gas space separate from an exterior gas space , a supplied air system in accordance with the present invention also could use a face mask that fits over wearer &# 39 ; s nose and mouth ( and optionally the eyes ) or it could be a full containment suit — see , for example , u . s . pat . no . 6 , 286 , 144 to henderson et al . fig2 shows a first embodiment of an adjustable length hose 12 in accordance with the present invention . adjustable length hose 12 includes a first sleeve 14 and a tube 15 . the sleeve 14 is disposed over the tube 15 and has first and second ends 30 and 32 , respectively . the first end 30 is elasticated , that is , it can be resiliently stretched to accommodate and snugly grasp the first end 44 of the tube 15 . the sleeve end 30 also can be enlarged so that the tube 15 can be passed therethrough when assembling the device . the elastic nature of end 30 allows the sleeve 14 to fit snugly and tightly about the tube 15 . any other method that permits adequate securement ( physical , mechanical , or chemical ) of the first sleeve end 30 to the first tube end 44 is contemplated under this invention . besides mechanical gripping , the sleeve and could be , for example , adhered ( using an adhesive ) welded ( using similar plastics ) or fastened ( using buttons or snaps ) to the tube end . as fig2 shows , the opposing end 32 of sleeve 14 has a fastener 34 that allows the size of the sleeve opening at end 32 to be adjusted . the fastener 34 may be of the hook and loop type . the tube 15 may be made from a plastic material that is disposed over a spirally wound cord ( see , for example , uk patent 1 , 419 , 841 ). this kind of tube 15 is flexible and tends to exhibit resistance to axial compression . the tube 15 is formed in such a way that displays a tendency to expand in the axial direction if compressed from its naturally extended state . conversely , if the tube is extended axially by exerting tension on it , it has a tendency to compress to return to its naturally extended state . the spirally wound cord provides shape and structural integrity to the tube 15 and allows it to be extended or compressed as needed . alternatively , the tube could be a flexible , molded convoluted hose . the first end 44 of tube 15 can have , for example , a quick release swivel ( q . r . s .) adapter on it so that the hose 12 can be attached to the facepiece 18 . the opposing end 46 of the hose 12 can have a bayonet fitting for being secured to the filtering unit 16 ( fig1 ). other adapters or fittings may be used as desired . a portion of the tube 15 extends out from the interior of sleeve 14 to achieve the desired length . the fastener 34 is tightened around the tube 15 to preclude additional tube 15 from being extended ( or withdrawn ) from within the sleeve 14 . the length of the hose 12 is thus set . because of its spirally - wound or helix , cordlike structure , the tube 15 has a tendency to expand axially to its full unencumbered length . by having the sleeve elastically secured to the tube at end 30 and by having the fastener 34 tightly secured about the tube at end 32 , the natural expansion of the tube 15 to its full - length can be retarded , and thus a desired length can be achieved . although a mechanical fastener has been illustrated in the drawing , any technique for retarding hose expansion is contemplated under this invention . the sleeve 14 , for instance , can be secured to the tube 15 through use of essentially any gripping device such as an elastic fitting , an adhesive tape , a button , etc . or through the techniques mentioned above with respect to the first sleeve end . fig3 shows that the adjustable length hose 12 may include a second sleeve 38 that has first and second ends 40 and 42 . the first end 40 is open and is sized to be sufficiently large to accommodate the first sleeve 14 . the second end 42 is elasticated to fit tightly about the tube 15 ( fig2 ). the second sleeve 38 allows essentially the full length of the tube to be uniform in appearance and fully protected or covered by an outer sleeve member . to assemble the adjustable length hose 12 of the first embodiment of the present invention illustrated in fig2 and 3 , the user starts by inserting the first end 44 of the tube 15 into the second end 32 of the first sleeve 14 . the tube 15 is drawn through the sleeve 14 until the elasticated end 30 fits tightly about the tube 15 and the first end 44 of the tube 15 projects axially from the sleeve 14 . the tube 15 is compressed within the sleeve 14 until the desired length is achieved . the fastener 34 is secured around the tube 15 at the desired length . the second end 46 of the tube 15 is placed in the open end 40 of the second sleeve 38 . the second end 42 of sleeve 38 is secured snugly about the second end 46 of the tube 15 . this can be achieved by making end 42 of tube 38 elasticated or by providing it with an adjustable fastener such as a hook and loop material . the hose 12 is thus adjusted to the desired length to fit the particular user , and the tube 15 is fully covered by the first and second sleeves 14 and 38 . the inventive adjustable length hose thus precludes excessive hose slack from occurring during use of the device by a smaller user . the annoyance and potential hazard that the slack creates is therefore reduced . to further reduce any opportunity for the hose to become inadvertently caught on an adjacent object , hardware could also be provided on the system , which hardware allows the hose to be held closely to the wearer &# 39 ; s body when in use . fig4 shows another method of providing an adjustable length hose 12 ′. in this embodiment , the tube 15 ′ is precluded from achieving its natural expansion through use of a bonding material 36 . alternatively , the tube could be a molded , convoluted tube that expands axially , not naturally , but in response to tension ( or pulling ) by the user in the axial direction . the bonding material 36 may be in the form of a bead that extends as a line along the side of the tube 15 ′. the bonding material may extend along the full length of the side of the tube or along the side a distance sufficient to allow for expansion to accommodate users of various sizes . two or more such bead lines may be disposed on the tube 15 ′ at 180 ° to each other . if desired , four bead lines could be used at 90 ° to each other . to achieve a hose 12 ′ of a desired length , the hose 15 ′ can be secured at one end and pulled at the other to break the bead lines 36 . when the hose 15 ′ has been extended to its desired length , the tension on the hose should cease so that the bead lines 36 are not broken further . the extended hose has two portions , a first compressed portion 35 and a second extended portion 37 . the desired length of the hose 12 ′ is thus achieved . in addition to the adjustment mechanisms illustrated and described above , other approaches are contemplated in connection with the present invention . hose length could , for example , be adjusted using one or more the following techniques : ( i ) molded concertina or corrugations , like in a flexible drinking straw ( see , u . s . pat . nos . 4 , 923 , 083 , 4 , 078 , 692 , and 3 , 346 , 187 ), which corrugations can be extended to a fixed length by pulling on the hose in the axial direction ( ii ) internal frictionally engaging mechanism that holds the internal structure of the hose in a compressed state or desired length via , for example , a ribbed outer edge that engages the internal structure of the tube material ; ( iii ) internal adjustable length wire that extends through the central portion of the hose to connect opposing ends of the hose together ( by varying the length of the wire thus controls the length of the breathing hose ); ( iv ) telescopic device , ( like an antenna ) that can be adjusted by sliding the structured members to the correct length to suit the user ; and ( v ) recoil hose stored under tension in a housing ( the hose can be withdrawn from the housing to the desired length ). additionally , a brace and clip arrangement , which uses a flexible bracing arm , could be fixed on a portion of the compressed flexible hose . the clips would hold the brace in place to engage the hose at a particular corrugation ( s ) and keep the hose from extending between the braced points . fig5 illustrates a scba system 50 that includes a facepiece 18 ′, a hose 52 , and a clean air supply source or tank 54 . the hose 52 is attached at its first end 44 to a fitting 58 that is attached to facepiece 18 ′. the second end of the hose 52 is secured to a fitting that is connected to the tank 54 . the tank 54 contains a pressurized supply of clean air for a wearer of the scba to breathe . the scba can be supported on a wearer &# 39 ; s back through use of a harness 60 that includes straps and 62 and a belt 64 . the facepiece 18 ′ is adapted to fit over the nose , mouth , and eyes of the wearer and includes a harness 66 for supporting the facepiece 18 ′ on the wearer &# 39 ; s head . the facepiece 18 ′ also has a window 68 through which the wearer can see the surrounding environment . the hose 52 can be adjusted in length using any one of the methods or systems described above . although the above discussion describes clean breathable air being supplied by either a papr or scba , it may also be possible for the clean air to be supplied to the user &# 39 ; s facepiece or headtop through an air regulator that supplies clear air to the user from either low or high pressure systems . in such a device , the user typically wears the regulator on a belt , the connection being made between the regulator and the facepiece / headtop by the hose described above . the regulator receives its air supply through a flexible adjustable length hose from either a lower or high pressure supply where low pressure typically comes from an air pump and where high pressure typically comes from an air compressor . a known regulator product has been marketed under the brand flowstream ™ by 3m , and such products have used wide bore hose ( diameter ≧ about 3 cm , typically about 2 to 5 cm ) for the connection between the regulator and the facepiece / headtop . for purposes of this invention , a hose that is connected to a clean air supply source through a regulator or other device is considered to be a hose that “ extends from ” the clean air supply source to the facepiece . hoses that have been used in the past had a fixed length that would accommodate persons of essentially all sizes . this length is referred to in this document as the “ conventional hose length ” or “ chl ”. the present invention is able to provide a variable or desired hose length “ dhl ”, which is equivalent to the chl minus “ x ” where “ x ” is the amount of unneeded hose length , which would have created the extra slack in previously known systems . conventional hose length typically was about 100 centimeters ( cm ). this hose length was provided to accommodate users of about 150 to 190 cm tall . for the smallest users , the minimum dhl is about 60 cm and therefore x = 40 cm . the dhl for each user of the invention thus resides somewhere between the chl of about 100 cm and about 60 cm . thus , the hose of the invention is preferably adjustable from about 60 cm in length to 100 cm in length . the above discussion has for the most part described the hose adjustment apparatus as being a feature associated with or fitted to the hose itself , but this device may , however , also be associated or fitted to the facepiece . this could be accomplished by fashioning the facepiece with a device that allows for entry of the hose into the facepiece . such a device could be particularly suitable for facepieces that are in the form of hoods or headtops ( helmets ). likewise , the adjustment feature could also be associated with or fitted to the clean air supply source . this invention may take on various modifications and alterations without departing from its spirit and scope . this invention , accordingly , is not to be limited to the above described but is to be controlled by the limitations set forth in the following claims and any equivalents thereof . this invention also may be suitably practiced in the absence of any element not specifically disclosed herein . all patents and patent applications cited above , including those in the background section , are incorporated by reference into this document in total .
a supplied air respirator that includes a clean air source , a facepiece , a hose , and a hose adjustment mechanism . the clean air source is designed to be carried by a user of the , and the face piece is sized to fit at least over the user &# 39 ; s nose and mouth . the hose extends from the clean air source to the facepiece . the hose adjustment mechanism enables the hose length to be controlled so that slack is eliminated between the clean air source and the facepiece . the supplied air respirator is beneficial and that it reduces opportunities for the hose to become inadvertently caught on an article located in the work environment .