GB2182568A

GB2182568A - Improvements in or relating to breathing apparatus

Info

Publication number: GB2182568A
Application number: GB08622167A
Authority: GB
Inventors: Robert Edwin Lowrie; Adrian Leonard Scott
Original assignee: Total Inert Maintenance & Engi
Current assignee: Total Inert Maintenance & Engi
Priority date: 1985-09-13
Filing date: 1986-09-15
Publication date: 1987-05-20
Also published as: GB8622167D0; GB2182568B

Abstract

The invention relates to breathing apparatus comprising a two-piece helmet 11 with a see-through panel 19 in its forward regions. Two flexible resilient seals 20,26 extend from the see-through panel 19 into pressure contact with the wearer's face to define two isolated volumes V1 and V2. The wearer's nostrils and mouth open only into volume V2 and volume V1 surrounds volume V2. Air is supplied to volume V1 via a primary air supply system and a secondary air supply system to maintain volume V1 at a predetermined pressure. A one-way valve 27 in the flexible seal 26 allows air to flow from volume V1 to volume V2 only when the pressure in volume V2 falls below that of V1, and volume V2 exhausts via an exhalation valve 23 to the atmosphere surrounding the helmet 11. The helmet 11 preferably includes a microphone 33 and earphone 34 attached to a two-way radio and the system may include a cooler for cooling the air supplied to the helmet. <IMAGE>

Description

SPECIFICATION Improvements in or relating to breathing apparatus This invention relates to breathing apparatus and, more particularly, to breathing apparatus intended to be used with a protective helmet.

The so-called "gas mask" is one well known breathing apparatus and comprises a soft mask, intended to be secured to the wearer's face by straps which pass overthe head of the wearer, with afilter adapted to filter our chemically treat air drawn into the maskfrom the surrounding atmosphere. Such breathing apparatus is frequently used by firemen and the like rescue personnel in combination with a convention safety helmet.

A disadvantage with such soft mask breathing apparatus is that the mask can be dislodged and there are a numberof reported cases each year of personnel who have suffered from such accidental dislodgement.

One further disadvantage of the conventional filter type breathing apparatus is that it can only be used when the surrounding atmosphere is air and the air contaminate or contaminates can be filtered out be foretheair passes into the breathing volume in the mask; For atmospheres which do not contain certain sufficient air orwherein the contaminant(s) cannot be filtered out it is the practise to supply the mask with airfrom a reservoir carried by the wearer. In such cases accidental dislodgement ofthe mask could prove fatal.

With the ever increasing manufacture of materials capable of rendering an atmosphere unbreathable the pressure on personnel to use breathing apparatus is increasing. Further, as many industries, such as the chemical industry, use processes which require an unbreathable atmosphere and there is a growing requirement for personnel, such as maintainance personnel, to work in such atmospheres, there is a vital need for a new order of protective breathing apparatus.

In one recent development it has been proposed that a protective helmet, totally enclosing the wearer's head and provided with a see-through panel of glass or plastics material in its forward regions, befitted with a continuous seal, surrounding said panel and extending therefrom to the wearer's face, whereupon the said seal and panel define a volume forward of the wearer's face totally isolated from the remainder of the helmet. The said volume is supplied with air via a tube from a pressure reservoir which may be carried by the wearer or be remote from the wearer and an exhalation valve allows airto be vented from said volume.A headband passing behind the wearer's head within said helmet, or re silientpads between the wearer's head and the rear ofthe helmet, maintain thewearer'sface in pressure contact with the seal so that the breathing volume cannot be displaced relative to the wearer's face.

Such a helmet, hereinafter called a "helmet ofthe type defined", affords the wearerfull protection for the head and a breathing apparatus which cannot be accidentally dislodged.

Difficulties with helmets of the type defined proposed to date arise from the seals and the breathing arrangements.

The seal, which is in the form of a closed frame, has its continuous surface contacting the helmet secured by screws or rivets and in orderto accommodate this securement and to ensure an effective seal against the wearer's face the seals have been made relatively rigid, too rigid to accommodate the normal facial var- iations between adults. It has therefore become the practise to "tailor" a seal and thereby a helmetfor use by an individual. This greatly increases the costs of such helmets and affords only limited interchange between personnel.

The breathing arrangement also generates problems because, with the exhalation valve venting from the totally enclosed volume, an increase in the CO2 content of the atmosphere in said volume occurs, to the detriment ofthe wearer, and fu rther, water vapour exhaled by the wearer condenses on the viewing panel, greatly reducing the efficiency of the wearer.

The present invention seeks to provide a helmet of the type defined which doesnotsufferfromthe above recited disadvantages.

According to one aspect of the present invention there is provided a helmet of the type defined and wherein the said seal extending from the helmetto the face ofthe wearer comprises a flexible resilient material and said seal is so supported as to beflex ible and resilient over the greater part of its direction between the helmet and the wearer's face.

As stated hereinbefore the said seal is in the form of a closed-frame and the seal proposed bythe invention preferably includes a flange clamped between the helmet and a mounting member, whereupon the seal isflexible and resilientforthe whole of its direction from said flange to the wearer's face.

Preferably the seal comprises a flexible resilient material, such as rubber, rubber substitute or a flexible, resilient plastics material, made by a moulding process or formed from a blank cut from a sheet material.

In one preferred embodiment said seal is formed from a blank cut from a sheet of Neoprene, the blank is folded over about its centre line so that two opposing edges are broughttogether, and the said edges are secured together by an adhesive. The blank is then folded to the desired "closed frame" form and the ends secured together, again using an adhesive.

When mounting the seal a relatively flat, closed frame mounting member is placed on the seal such thatthetwo edges protrude through the opening in the mounting member and the adhered edge portions are then flexed outwardly to be securely clamped between the mounting member and the helmet.

According to another aspect ofthe invention the helmetincludes a second seal, extending from the see-through panel to the wearer's face within the volume defined bythefirstseal to define a second isolated volume within said first isolated volume.

Preferably the said second seal contacts the wearer's face to include at least the nostrils and mouth ofthewearer.

Preferably the helmet includes an exhaltion valve which passes through the see-thrnugh panel and communicates with the said second volume.

With such an arrangement the air supply from the reservoir is supplied to thefirstvolume and the second seal includesa onewayvalveallowing airto flowfrom said firstvolumeto said second volume onlywhenthe pressure in said second volume falls belowthatofthefirstvolume.Thus,asthewearer inhales,the pressure in the second volumefallsand airflowsfrom the firstvolumeto the second volume.

When the wearer exhales there is a pressure increase in the second volume and atmosphere is exhausted from the second volume via the exhalation valve so that an adverse build up of CO2 is avoided and the water vapour exhaled is isolated from the seethrough panel and is discharged via the exhalation valve.

The invention will now be described further byway of example with reference to the accompanying drawings in which Figure 1 shows a side view of a helmet ofthetype defined according to the present invention Figure2 shows a cross section through the helmet shown in Figure 1 Figure 3 shows an enlarged detailed view ofthe cross section circled in Figure 2.

In the illustrated example a helmet, generally indicated by numeral 11, comprises a front part 12 and a rear part 13, connected to part 12 bya hinge 14.

The rear partl3can besecuredtothefrontpartl2 by latches 15, there being a latch 15 on each side of the helmet 11, and when the helmet 11 is closed onto the head of wearerthe neck opening 16 is too small to allow the helmet 11 to be removed from the wearer. Thus, when the helmet 11 is fitted to a wearer the helmet cannot be removed except by opening the latches 15 and the helmet 11 is thereby secured against accidental removal.

The front part 12 includes an aperture 17, surrounded bya lip 18, within which a see-through panel, conveniently a glass panel 19, is located.

Afirstseal 20 within the helmet 11 is made byfolding a blankcutfrom a sheet of Neoprene along its longitudinal centre line until the two opposing edge regions 20a and 20b are in contact and can be secured togetherwith an adhesive. The blank is then bent longitudinally and its two ends secured together, again with an adhesive, to form a closed frame the circumferential length of which is slightly smaller than the peripheral length ofthe see-through panel 19.

Amounting member 21, intheform of closed frame, has its peripheral configuration substantially identical with that ofthe see-through panel 19 and is of substantially uniform radial thickness.

Tosecurethesee-through panel 19,theseal 20 and the mounting member 21 to the helmet 11 the member 21 is first slipped overthe seal 20 until the end regions 20a and 20b protrude through the member21 byanamountsubstantiallyequaltothe radial thickness ofthe member 21 and said end regions are then splayed outwardly and secured to the adjacent radial face of the member 21 with an adhesive. The panel 19, seal 20 and member 21 are then secured to the helmet by rivets 22 such thatthe panel 19 seats in the recess defined by lip 18to close the aperture 17.

It will be seen that with this construction a first isolated volume V1 forward of the wearer's face will be defined wholly by the see-through panel 19, the seal 20 and the wearer's face and the seal 20 is supported so as to be flexible and resilient overthe whole of its direction from said panel 19 to the wearer's face whereby the degree offlexible resilience allows the seal to readily conform with the facial configurations of most adults.

A resilient seal (not shown) may be inserted between the periphery of panel 19 and the lip 18 but as any leakage of atmosphere between lip 18 and panel 19 cannot contaminate the first isolated volume such a seal is not important to the breathing arrangement.

The see-through panel 19 has an aperture 19a therethrough and an exhalation valve 23 has a threaded cylindrical portion 24 which passes through the aperture 19a and has a nut 25 threaded thereon inside the heimet. A "nose-cone" seal 26, of a flexible resilient material, conveniently made by a moulding process, has an aperture 26a through its narrow end through which the threaded cylindrical portion 24 passes before entering the nut 25. Thus, the nut 25 clamps the nose-cone seal 26 to the panel 19 and locates the exhalation valve 23 for the release of atmosphere from the volume V2 within the nose cone seal 26.

The nose cone seal 26 includes a periphery 26b which is intended to make pressure contact with the wearer's face such that the breathing passages, the wearer's nostrils and mouth, open into the volume V2 defined by the nose-cone seal 26.

It will be appreciated that with the embodiment as illustrated the flexible resilient seal 20 can accommodate mostfacialvariations in adults to obtain an effective seal between the seal 20 and the wearer'sface but thereby, having established the wearer's face a predetermined distance from the see-through panel 19, difficulty could be experienced in obtaining an effective seal between the nose-cone seal 26 and the wearer's face. To overcome this problem the helmet may be provided with interchangeable nose-cones 26, of different axial lengths or a resilient spacer or spacers (not shown) may be inserted between the see-through panel 19 and the nose-cone 26.Thus, by providing a means for adjusting the spacing of periphery 26afrom the see-through panel 19 the nosecone 26 can be readily adjusted to meet the needs of any individual adultand an effective seal obtained between the nose-cone 26 and the wearer's face.

With the nose-cone seal 26 adjusted to make pressure contact with the face of the wearerthe wearer can only inhale from and exhale to the volume V2 defined by the nose-cone seal 26. The nose-cone seal 26 includes a one-way demand valve 27 let into its side wall to allowairto flowonlyfrom volume V1 to volumeV2 and onlywhenthe pressure in volumeV2 falls below that ofvolumeVl.

Air is supplied to the helmet 11 from a pressure reservoir (not shown) via a flexible pipe (also not shown) which connects to the tubular inlet 28 of a one-way demand valve 29 secured to the helmet 11.

The air is ducted from valve 29 via a tube 30 to the first isolated volume V1 the tube 30 passing through the seal 20 as shown in Figure 2, and, as stated here inbefore,aircanflowfromvolumeV1 tovolumeV2 via the one-way demand valve 27 in nose-cone seal 26.

Itwill be notedthatthe helmetincludesa one-way demand valve 29 on each side and each valve 29 has its supply tube 30 to the first isolated volume V1 and itstubular inlet 28for receiving a flexible pipe (not shown) from an air reservoir. Thus, there are two in dependent airsupply systems to volume V1 and one of said two valves 29 is set to open at a slightly higher pressure than the other. By this means the valve 29 opening at the lower pressure, and the air supply ducts associated with said valve, constitute the primary airsupplytothevolumeV1 and the other valve,opening atthe higherpressure,and itsassoc- iated air supply ducts constitute a secondary air supplyto volume V, and the secondary air supplyoperates automatically should any failure ofthe primary air supply system occur.

The helmet also includes padding 31, conveniently flexible resilient padding, to cushion the wearer's head within the helmet 11 and an additional resilient padding 32 in the rear portion 13, the purpose of which will become apparent hereinafter.

In use, the helmet 11 is fitted to the wearer, the latches 15 are closed to secure rear part 1 to front part 12 ofthe helmet and the resilient padding 32forces the wearer's head forwardly within the helmet 11 and thereby forces the wearer's face into pressure contact with the resilient seals 20 and 26. Air from the reservoir is supplied to the primary demand valve 29 at a suitable pressure and the primary demand valve 29 operates to allow the air in volume V1 to be retained art a constant pressure.

AsthewearerinhalesthepressureinvolumeV2 falls and valve 27 opens to allowairtoflowfrom volume to volumeV2. When the wearer exhales valve 27 closesto isolate volume V1 from volume V2 and the rise in pressure in volume V2 causes atmos phereinvolumeV2to be exhausted through exhalation valve 23.

When the wearer next inhales the pressure in volume V2 again falls, valve 23 closes, valve 27 opens and again airflows into volume V2.

Thus, with the breathing arrangement proposed by the present invention, all the exhaled air is exhausted through the exhalation valve 23, there is no leakage of exhaled airto volume V1 andasthe volume V2 is small relative to the volume of air exhaled per breath by the wearer, there is no danger of an adverse build-up of CO2 in the apparatus. Further, as the air exhaled from the wearer is isolated from the see-through panel there is no way in which exhaledwatervapourcan fog the said panel.

The helmet also includes a microphone 33 conveniently supported in the upper regions of seal 20, and earphones 34 which may also act as ear muffs.

The microphone 33 and earmuffs 34 are connected by lines (not shown) to a two-way radio (not shown) carried by the wearer whereupon the wearer can be in constant two-way communication with a remote monitoring station. In certain environments the wearer, and/or the flexible pipes connecting the helmetto its air reservoir, may be exposed to elevated temperatures whereupon the air supplied to the first isolated volume V1 may be heated to the discomfort of the wearer. To overcome this problem the air supply to the helmet may be cooled.

In one preferred embodiment the secondary air supply may at some location pass through a cooler, conveniently an insulated dry ice heat exchanger, carried by the wearer, and the primary air supply may include a shut-off valve operable by the wearer. By this means, in the event that the air suppled by the primaryairsupplyshould become uncomfortably hot, the wearer can close the shut-offvalve to there minate the primary air supply, the secondary air supply will then become effective and the air supplied by the secondary air supply will be cooled by flowthrough the cooler.

Claims

1. A helmet ofthe type defined in which the said seal extending from the helmet to the face of the wearerto define the isolated volume comprises a flexible resilient material and said seal is so supported as to be flexible and resilient over the greater part of its direction between the helmet and the wearer's face.

2. Ahelmetasclaimed inclaim 1 inwhichtheseal is in the form of a closed frame.

3. A helmet as claimed in claim 1 or2 in which the seal includes a flange which is clamped between the helmet and a mounting member.

4. Ahelmetasclaimed inclaim 1,20r3inwhich the seal comprises a rubber, rubber substitute or a flexible resilient plastics material

5. A helmet as claimed in any preceding claim in which the seal is made from a blank cut from a sheet material.

6. A helmet as claimed in claim 5 in which the blank is folded over about its centre-line so that two opposite edges are brnught together and secured to one another and the two ends of the folded blank are brought together and secured to form a closed frame.

7. A helmet as claimed in any preceding claim in which a second volume is defined within the first isolated volume and said second volume is defined by a seal which extends substantiallyfrom the seethrough panel to that region of the wearer's face surrounding the nostrils and mouth of the wearer.

8. A helmet as claimed in claim 7 in which an exhalation valve passing through the see-through panel opens into the said second volume.

9. A helmet as claimed in claim 7 or 8 in which at least the greater part of said seal defining the said second volume comprises a flexible resilient material.

10. A helmet as claimed in claim 7,8 and 9 in which the said seal defining said second volume is displaceable towards and away from said seethrough panel.

11. Ahelmet as claimed in claim 7,8,9 or 10 in which said seal defining said second volume includes at least one one-wayvalve arranged to allow air flowtherethrough from said first isolated volume to said second volume.

12. A helmetas claimed in any preceeding claim in which a one-way valve allows airto flow into said first isolated volume.

13. A helmet as claimed in claim 12 in which said one-way valve is supported by the heimet, a duct in side the helmet supplies air from said valve to said first isolated volume and said valve includes a connection externally ofthe helmetfor receiving aflex ible pipe supplying airtosaidvalvefrom an airreservoir.

14. A helmet as claimed in claim 13 in combina- tion with an air reservoir carried by the wearer and wherein said flexible pipe extends from said air reservoirto the external connection of said one-way valve.

15. A helmet as claimed in claim 12,13 or 14 in which a second one-way valve is supported by the helmet, a duct inside said helmet supplies air from said valveto said first isolated volume and said valve includes a connection externally ofthe helmetfor receiving a flexible pipe supplying air to said second one-way valve from an air reservoir.

16. A helmetas claimed in claim 140r 15 in com- bination with an air reservoir carried by the wearer and wherein said flexible pipe extends from said air reservoir to the external connection of said second one-way valve

17. A helmet as claimed in claim 15 or 16 in which said second one-way valve is set to open, to allow air4lowtherethrough to the saidfirstisolated volume, at a higher pressure than said first one-way valve whereupon the first one-way valve and its associated air supply ducts constitute the primary air supply to the first isolated volume and said second one-way valve and its associated air supply ducts constitutes a secondary air supplyto said first isolated volume.

18. A helmet as claimed in anyone of claims 13, 14,15,16 or 17 in combination with an air cooling device carried by the wearer and wherein at least part of the air supplied to said helmet has passed through said cooling device.

19. A helmet as claimed in any proceeding claim in which a microphone is supported within the helmet connectable by a line to a transmitter externally ofthe helmet.

20. Ahelmetas claimed in claim 19 in whichthe microphone is located in the seal defining the said first isolated volume.

21. Ahelmetasclaimed in any proceeding claim including earphones mounted within the helmet and connectable to receiver externally ofthe helmet.

22. Ahelmetasclaimed in any proceeding claim including meanswithinthehelmetforurgingand maintaining the wearer's face in pressure contact with said seal defining the first isolated volume.

23. A helmet, substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.