EP0489815A1

EP0489815A1 - Improvements in or relating to safety helmets

Info

Publication number: EP0489815A1
Application number: EP90913277A
Authority: EP
Inventors: Robert Lowrie
Original assignee: Aran Fire & Safety (uk) Ltd
Current assignee: Aran Fire & Safety (uk) Ltd
Priority date: 1989-09-01
Filing date: 1990-08-28
Publication date: 1992-06-17
Also published as: HU9200681D0; JPH05500017A; FI920872A0; AU637825B2; WO1991003279A1; KR920703153A; HUT64244A; GB8919825D0; CA2065300A1; AU6345090A

Abstract

Casque de protection (11) pouvant être utilisé avec ou sans appareil de respiration. Selon un mode de réalisation, un casque de protection "totale" (11) doté d'une ouverture transparente (12) comprend des dispositifs à déclenchements rapides agencés pour serrer sélectivement l'un ou l'autre de deux ensembles structurels (27) fermés rigides, se trouvant à l'intérieur dudit casque (11). Chacun des ensembles (27) comprend un joint d'étanchéité annulaire souple (26) dont une extrémité circonférentielle est fixée à la structure (27) et dont l'autre extrémité est destinée à venir en contact avec la face de l'utilisateur. Lorsqu'un desdits ensembles est serré dans ledit casque (11), le volume situé devant la face de l'utilisateur est exposé à l'atmosphère par l'intermédiaire de l'ouverture transparente ouverte (12). Lorsque l'autre ensemble (27) est serré dans ledit casque (11), un panneau transparent (24) ferme l'ouverture (12) se trouvant dans ledit casque (11) et des vannes ainsi que des conduits d'air supportés par ladite structure (27) acheminent de l'air respirable dans le volume défini à l'intérieur du joint d'étanchéité annulaire (26).Protective helmet (11) which can be used with or without a breathing apparatus. According to one embodiment, a "total" protective helmet (11) provided with a transparent opening (12) comprises quick-release devices arranged to selectively tighten one or the other of two structural assemblies (27) closed. rigid, located inside said helmet (11). Each of the assemblies (27) comprises a flexible annular seal (26), one circumferential end of which is fixed to the structure (27) and the other end of which is intended to come into contact with the face of the user. When one of said assemblies is clamped in said helmet (11), the volume located in front of the user's face is exposed to the atmosphere through the open transparent opening (12). When the other assembly (27) is clamped in said helmet (11), a transparent panel (24) closes the opening (12) in said helmet (11) and valves as well as air ducts supported by. said structure (27) conveys breathable air in the volume defined inside the annular seal (26).

Description

"IMPROVEMENTS IN OR RELATING TO SAFETY HELMETS"

This invention relates to safety helmets and, more specifically, to safety helmets for use in combination with breathing apparatus. Virtually all conventional safety helmets are capable of being used with conventional mask-type breathing apparatus and wherein the breathing apparatus includes a flexible mask held to the forward regions of the wearer's face by a network of straps or bands which pass over and around the head of the wearer. The mask defines a breathable volume forward of the breathing apertures of the wearer and the apparatus includes a valve arrangement for controlling the air supply to the mask. The air supply duct is connected to those regions of the mask most remote from the face of the wearer and with such a breathing apparatus fitted the wearer can readily don a conventional safety helmet. The valve arrangements for conventional breathing apparatus are relatively large and, for such breathing apparatus as is intended to afford protection against a hazardous environment, the mask extends to the upper regions of the wearer's face and includes an aperture, closed by a see- through panel. Because of the limited size of the mask the see-through panel is relatively small and restricts the wearer's vision.

A serious problem with helmet/conventional breathing mask arrangements as defined above resides in the fact that the helmet is completely independent of the breathing apparatus and the helmet is ill-fitting and uncomfortable on the straps supporting the breathing mask. Further, with the forward regions of the mask supporting the valve arrangement and air supply duct, the forward mask parts project forward of the brim of the helmet and the helmet affords little, if any, protection for the said forward parts of the breathing apparatus.

Further, as the mask is essentially flexible, the forwardly projecting valve arrangement and air connections to the mask are susceptible to dislodgement, particularly in poor visibility and crowded conditions, and if dislodged the hazardous atmosphere can enter the breathable volume of the mask, to the detriment of the wearer.

In more recent years so called "total" protective helmets incorporating breathing apparatus have been proposed and which helmets protect the whole of the head of the wearer down to the neck level.

Such helmets, generally made from a plastics material, conveniently include a large aperture, closed by a see-through panel, with a flexible seal extending from the periphery of the see-through panel inwardly of the helmet to define a seal with the face of the wearer. Thus, the whole of the face of the wearer is open to the enclosed volume defined by the seal, the see-through panel and the face of the wearer. Valve arrangements, often attached externally to the helmet, duct breathable atmosphere to the said volume and some such helmets may include an exhalation valve, generally passing through the see-through panel, and through which valve exhaled air is exhausted.

An inherent disadvantage of with the prior art "total" protection helmets is that whilst the helmet is being worn the wearer is totally dependant upon a breathable air supply to the said enclosed volume and, when the air supply comprises a tank or reservoir carried by the wearer, the time period for which the helmet can be worn is severely limited. Further, as the helmet must be fitted before the wearer enters a hazardous environment and must not be removed until after the wearer has left the hazardous environment the actual amount of time the wearer can be exposed to the hazardous environment is restricted. A further disadvantage of such helmet and integral breathing apparatus combinations is that they are extremely expensive.

In many rescue and/or fire fighting applications personnel may be designated to areas of operation which do not include a hazardous atmosphere and, therefore, such personnel do not require a breathing apparatus. In other areas of operation of operation personnel will be expected to enter a hazardous environment, in which cases they will require a breathing apparatus. In most rescue operations, and again in particular in fire fighting, the conditions of the environment in which personnel are to work may not be determined until arrival at the site.

The present invention seeks to provide a safety helmet capable of being selectively used with or without a breathing apparatus.

According to the present invention there is provided a safety helmet, characterised by quick-release means for selectively attaching a breathing apparatus to said helmet.

Preferably the said helmet is adapted to totally encase the head of the wearer and includes a see-through aperture through its forward regions. - -. -

Preferably the helmet is used in combination -with a rigid, closed frame, said frame being located within the helmet, concentric with the said aperture.

Preferably the said closed frame supports an annular seal having one continuous end in sealed relationship with the frame and concentric therewith.

Preferably the continuous end of said seal remote from the said frame is arranged to engage the face of the wearer across the forehead, down the cheeks and across the chin. Preferably the helmet includes a harness comprising straps for supporting the helmet on the head of the wearer and a padding engageable with the rear of the head of the wearer.

Preferably the said annular seal is resilient and the said straps of said harness are adjustable to allow the front to rear position of said padding to be adjusted relative to the said annular seal.

It will now be appreciated that with the helmet arrangement described thus far the face of the wearer is, when the harness straps are tensioning the padding against the rear of the head of the wearer, forced into pressure contact with the annular seal and the helmet is, thereby, effectively located fore and aft with respect to the wearer's head.

In one mode of use the said see-through aperture in the helmet is totally closed by a see-through panel. In a preferred embodiment in accordance with the invention an exhalation valve is supported by the said see- through panel.

Preferably a nose cone extends from the said see- through panel to engage the face of the wearer with a continuous seal surrounding the breathing ducts of the wearer, said exhalation valve is arranged to exhaust from the volume defined by said nose cone and said nose cone includes valve means for allowing air flow from the said volume defined by the said annular seal, the see-through panel and the face of the wearer into said nose cone.

Preferably when used in such mode the helmet includes

SUBSTITUTE SHSET with valve means and air ducts, arranged to supply pressure air from an air source externally of the helmet to the volume forward of the wearer's face and defined by the said annular seal, the see-through panel and the face of the wearer bounded by the said annular seal.

In one embodiment in accordance with the invention said rigid closed frame is detachably retained within the helmet by said quick-release devices and said annular seal, said see-through panel, said valve means and said air ducts are supported by said rigid closed frame to be detachable therewith.

With such an embodiment the helmet preferably includes an internal cavity below the aperture and said valve means and air ducts are attached to the lower regions of said rigid closed frame and are housed in said internal cavity when the closed frame is fitted to the helmet.

In another embodiment the volume forward of the wearer's face and bounded by the annular seal is open to the surrounding environment through the opening in the frame and the aperture in the helmet.

Preferably said rigid closed frame is detachably retained within the helmet by said quick release devices and said annular seal is supported by said rig:Ld closed frame to be detachable therewith. Preferably said quick-release means comprise rotatable devices adjacent the aperture through the helmet and arranged in one rotational position for each device to securely clamp the said closed frame with the helmet and in another rotational position for each device to release the said closed frame from the helmet.

Thus, in one embodiment for a helmet proposed by the present invention a rigid closed frame having only the annular seal secured thereto is rapidly and readily interchangeable with a rigid closed frame supporting a see- hrough panel closing the annular seal and a breathing apparatus.

In another embodiment in accordance with the invention a duct connects the volume defined by the annular seal to the atmosphere externally of the helmet.

Preferably the said duct comprises a flexible connection between the volume within the annular seal and an aperture through the helmet.

Preferably said duct is selectably closable by an air supply assembly.

In a preferred embodiment said air supply assembly comprises an air supply valve arrangement contained in a housing and an air supply from a air reservoir to said air supply valve arrangement and said quick- release mean comprise means for selectively connecting or disconecting the air outlet from said housing to said duct.

Preferably said quick-release means comprise interrupted screw means presented by said housing and said duct.

The invention will now be described further by way of example with reference to the accompanying drawings in which,

Fig. 1 shows a cross section, on the central plane passing front to rear of a helmet, with a breathing apparatus attachment.

Fig. 2 shows, diagranmatically, a view of the forward lower regions of the mask, from the inside, with breathing apparatus contained therein,

Fig. 3 shows a cross section in the same plane as that for

Fig. 1, of an open front helmet attachment for use with the helmet illustrated in Fig. 1,

Fig. 4 shows a plan view of a quick-release device in accordance with the invention, Fig. 5 shows a side view of the quick-release device shown in Fig. 4,

Fig. 6 shows an underneath view of the quick-release device shown in Fig. 4 and 5.

Fig. 7 shows one end view of the quick-release shown in

Figs. 4, 5 and 6 and,

Fig. 8 shows, in perspective view, a fragment of the rigid closed frame and annular seal with an integral lug engageable by the quick-release device.

Fig. 9 shows, a left side view of the lower forward region of a safety helmet incoporating means for selectively connecting a further embodiment breathing apparatus to the helmet,

Fig. 10 shows a cross-section through the left side of the helmet on the line II II in Fig. 9,

Fig. 11 shows a side view of a breathing apparatus connecting means for use with the helmet shown in Figs. 9 and 10, and

Fig. 12 shows a view of the breathing apparatus connecting means in the direction of the arrow A.

The helmet illustrated in Fig. 1 conveniently comprises a one piece helmet 11, made from a plastics material conventionally by a moulding process, with an aperture 12 in the forward regions thereof. The helmet 11 is of thickened material, indicated at 11a, around the neck aperture to ensure a safety edge therefore.

The helmet 11 includes an internal harness comprising a top pad 13, supported on each side by resilient straps

- δ -

14, with each strap 14 passing through a slot in an anchor plate 15 secured by a screw 16 engaged in a nut (not shown) moulded into the helmet shell.

The pad 13 is intended to contact the head of the wearer, thus to support the top of the helmet in spaced relationship with the head of the wearer.

The harness also includes a back pad 17, pivotably connected at its upper regions to the rearmost regions of the pad 13, and pad 17 is further supported on each side by a resilient strap 18, which passes through a slot in an anchor plate 19 secured to the helmet by a screw 20 engaged in a nut (not shown) moulded into the helmet shell.

The pad 17 had its lower regions 17a extending adjacent to, and preferably projecting from, the neck opening of the helmet 11 -whereupon the wearer can manually displace the lower regions of the pad 17 towards the rear of the helmet 11 to assist in donning and removing the helmet 11.

The pad 17 also includes side straps 21, attached one to each side of the pad 17 near its lowermost regions, each strap 21 include a row of stud fastener sockets 22a, 22b, 22 , 22rl and 22e_^ selectively engageable with the cooperating part of a stud fastener (not shown) secured to the helmet and, in the .present example, located in the region of the fastener 22_b as illustrated. The helmet also includes a peak member 23, made from a transparent material, secured to the shell immediately above the aperture 12 and projecting downwardly to partially close the aperture 12 and forwardly of the helmet to divert small falling solids or liquids away from the aperture 12. In the example illustrated in Fig. 1 the helmet is provided with a breathing apparatus attachment comprising a see-through panel 24 which closes the aperture 12, with a resilient sealing element 25 interposed between the peripheral regions of the see-through panel 24 and the helmet surface adjacent the aperture 12. An annular seal 26 has one continuous or radial end region 26a splayed outwardly and contacting the peripheral regions of the inner surface of the see-through panel 24 and the assembly is retained by a rigid closed frame 27. The elements 24, 25, 26, and 27 are concentric with the aperture 12 and preferably the elements 25, 24, 26ji and 27 are bonded together as, for example, by an adhesive so as to form a composite assembly.

As will be seen from Fig. 1 the lower forward regions of the helmet 11, that part of the helmet 11 below aperture 12, is formed to provide enlarged internal cavity, generally indicated by reference llb_, and the frame 27 includes an extension 27a extending into said cavity to support an air supply and control valve arrangement 28 for a breathing apparatus. The valve arrangement 28 is provided with pressure air via a duct 29 which extends from the valve arrangement 28 through the neck aperture in the helmet, conveniently to one side of the neck aperture, and said duct 29 extends to a pressure air reservoir (not shown) such as a cylinder carried by the wearer of the helmet 11 as a back pack.

The valve arrangement 28 includes a sensor duct 30, which projects through the frame 27 and the seal 26 so as to be open to the atmosphere within the annular seal 26. The duct 30 is open to a manifold 31 which is open to a sensing port in the valve arrangement 28 whereupon, on sensing a pressure below a predetermined pressure via the sensor duct 30, the valve 28 is arranged to open to allow air flow from the duct 29 through the valve arrangement 28 to a manifold 32 from which the air flows via an outlet 33 into the volume within the bore of seal 26.

The valve arrangement 28 may also include a manual over-ride, generally indicated at reference 34, and which can be nanually actuated by the wearer, or any other person in the vicinity, pushing a finger up the neck aperture of the helmet to press the over-ride button 34, thus allowing air flow into the volume within seal 26, if the wearer should experience breathing difficulties.

The breathing assembly further includes an exhalation valve 35 which passes through the see-through panel 24 and supports, at its inner end, a nose cone, generally indicated by numeral 36, and which includes two one-way valves 37 one on each of its sides. The nose cone 36 may be forwardly and rearwardly displaceable by adjusting means, well known in the art, included in the exhalation valve assembly.

The frame 27 further includes, at each of its opposite side edge regions, an integral lug 27b with an arcuate recess 21 c_ in its peripheral edge region, as shown in Fig. 8.

The sealing element 25, the see-through panel 24, the annular seal 26, the valve arrangement 28, the manifolds 31 and 32 and the ducts 30, 33 and 29, are all supported by the rigid closed frame 27 and the frame 27 and all the elements supported by said frame 27 comprise an assembly detachable from the helmet 11.

One form of quick-release device suitable for supporting the rigid frame 27 and its supported assembly with the helmet illustrated in Figs. 1 and 2 is shown in Figs. 4, 5, 6 and 7 and wherein the quick-release device comprises a solid body, generally indicated by numeral 40, with an aperture 41 therethrough by which the body 40 is pivotably attached to the helmet_' via a pivot screw 42, secured in a nut (not shown) embedded in the helmet 11. The aperture 41 is counter-bored, as at 41a_, to receive the head of the screw 42 therein.

The body 40 includes, at its end regions most remote from the aperture 41, a cylindrical element 43, having its axis parallel to the axis of the aperture 41, and a roof-like projection part 44 above the cylindrical element 43 extends radially and terminates forwardly of the said element 43.

When two such quick-release devices 40 to 44 are fitted to the helmet 11, one adjacent each side edge region of the aperture 12, and with the pivot screws 41 secured in their respective nuts, the said quick-release devices are pivotable about their respective pivotable screws 42.

When a breathing apparatus assembly comprising a rigid frame 27 and its supported assembly 24, 25, 26 and 28 to 37 is to be fitted, the quick-release devices 40 to 44 are pivoted to positions where their ends presenting the cylindrical elements

43 are most remote from the aperture 12, whereupon the breathing apparatus assembly 24 to 37 can be entered into the helmet 11 and located therein with the resilient sealing element 25 in pressure contact with the helmet surface surrounding the aperture 12. The quick release devices 40 to

44 are then pivoted so that their roof like projection parts 44 engage over the free side 27d of the adjacent lug 27b and the cylindrical element 43 of each quick release device 40 to 44 engages in the adjacent arcuate recess 27c in the adjacent lug 27b.

The quick-release devices 40 to 44 are in pressure contact with their respective arcuate recesses 27 'c_ in the frame 27 and thus, with pressure contact on its side edge regions, the frame 27 compresses the sealing element 25 between the helmet surface and see-through panel 24, thereby effectively sealing the opening 12 from the surrounding environment. To remove the breathing apparatus assembly 24 to 37 it is only necessary to rotate the quick release devices away from their adjacent lugs 27b, whereupon the breathing apparatus assembly is released from its locking contact with the helmet 11 and can be readily removed through the neck opening of the helmet.

To use the helmet 11 with the breathing apparatus assembly 24 to 37 fitted it is only necessary for a person to release the straps 21 from engagement with their respective press stud fasteners, manually displace the rear pad 17 towards the rear of the helmet and the helmet can be donned. The wearer will retain the rear pad 17 rearwardly until the free edge regions of the seal 26 are in a comfortable sealing engagement with the face of the wearer and the rear pad 17, can then be released to advance forwardly, via the resilient straps 18. The wearer can then make final adjustments to the fitting of the helmet 11, by holding the helmet 11 between the hands and pushing back with the head against the rear pad 17 to ensure a comfortable sealing fit with the seal 26, and the helmet is then secured by pulling the straps 21 forwardly and securing the appropriate press stud fitting 21a to 21e_ to the respective press stud fastener.

With the helmet 11 firmly, but comfortably, fitted to the wearer the seal 26 is in sealing contact with the wearer's face across the forehead, down the cheeks and across the chin and the volume defined by the panel 24, annular seal 26 and the face of the wearer, hereinafter called "the first volume" is being continuously sensed by the sensor duct 30. When the sensor duct 30 detects a pressure fall in the said volume, below a predetermined pressure which is preferably slightly above atmosphere, the valve arrangement 28 is actuated to supply air via manifold 32 and duct 33 to said first volume. When the pressure in the said first volume rises above the said predetermined pressure the elevated pressure is sensed by the duct 30 and the air supply though valve 28 is terminated.

The breathing ducts of the wearer open to the volume within the nose cone 37, hereinafter called "the second volume," and on inhaling air flows from the said first volume to the second volume via the one way valves 37 and, on exhaling, the valves 37 close and the exhaled air is exhausted from the second volume via the exhalation valve 35. To remove the helmet it is only necessary to release the straps 21, push the rear pad 17 towards the rear of the helmet using the fingers or simply pushing the helmet forward on the head so that the head deflects the rear pad 17 rearwardly, to release the face from sealing contact with the seal 26, and the helmet can be readily removed.

Fig. 3 shows an alternative attachment for the helmet 11 when the breathing apparatus assembly 24 to 37 had been removed from the helmet 11.

The attachment illustrated in Fig. 3 comprises a resilient sealing element 51, intended to contact the internal surface of the helmet 11 surrounding the aperture 12, an annular seal 52, which may be identical with the annular seal 26 illustrated in Fig. 1 and which includes an outwardly turned flange region 52a in contact with the sealing element 51, and a rigid closed frame 53, identical to the rigid frame 27 and which includes lugs 53b, identical with the lugs 27b of the frame 27 shown in Fig. 1. The sealing element 51, the flanged part 52a_ of the seal 52 and the frame 53 are secured together, conveniently by an adhesive, to form a composite assembly. The attachment 51 to 53 is fitted to the helmet in identical manner to the breathing apparatus assembly 24 to 37, in that the sealing element 51 is located against the internal surface of the helmet 11 surrounding the aperture 12 and the quick-release devices 40 to 44 are rotated until each roof- like elements 44 engage with the free surface 57d of the associated lug 53a_ and the cylindrical element 43 is located in the recess 53c of the adjacent lug 53b.

It should be noted that the sealing element 51 in the attachment 51 to 53 is at least as thick as the combined thickness of the sealing element 25 and the panel 24 in the Fig. 1 embodiment so that the roof-like parts 44 of the quick- release devices are in pressure contact with the free surface 53d_ on- their respective lugs 53b and the cylindrical elements 43 are in pressure contact with their respective arcuate recesses 53c, whereupon the rigid frame 53 causes the resilient sealing element 51 to be in compression, thus to retain the assembly 51 to 53 securely with the helmet 11.

With the attachment 51 to 53 secured within the helmet 11 the helmet 11 is donned in identical manner to that described above with reference to the Figs. 1 and 2 embodiment, the free edge of the seal 52 makes the same seal with the face of the wearer as described for the Fig. 1 embodiment but, in this case, the volume forward of the wearer's face exposed within the seal 52 is open to atmosphere. Thus, the seal 52, in combination with the rear pad

17, firmly locate the user's head front to rear with respect to the helmet to ensure the greatest protection for the wearer's head.

The helmet arrangement described above, in combination with the breathing apparatus attachment 24 to 37 and with the inter-changeable attachment 51 to 53 available, is particularly advantageous for fire fighting applications where, on route for a fire, all the fire fighting personnel may fit the breathing apparatus attachment 24 to 37, to the helmet and cement the air supply duct 29 to an air supply tank carried as a back pack.

On arrival at the site those personnel to work in a hazardous environment, or a potentially hazardous environment, can simply fit the helmet, shoulder the back pack and move immediately into action. In the event there is not hazardous environment, or for those selective personnel who are not to work in the hazardous environment, it is a simple matter to release the breathing apparatus assembly 24 to 37 from the helmet, fit the second attachment 51 to 53 to the helmet and the firemen can then move immediately away from the vehicle, leaving the back¬ pack with the breathing assembly 24 to 37 attached thereto.

In the embodiment illustrated in Fig. 9 a helmet 51 is substantially identical to the helmet 11 illustrated in Fig. 1, with the exception that the see-through panel 24, the annular seal 26 and the rigid closed frame 27 are permanently secured in the helmet 11 and the helmet shell includes an aperture 52 adjacent the left side edge of the see-through panel 24.

A sleeve 53 is located in the aperture 52 and said sleeve 53 defines a cylindrical section 54 adjacent one end region 53, a radial flange 55 and a threaded section 56 on that side of the flange 55 remote from the cylindrical part 54.

The sleeve 53 has a through bore 57 with an interrupted screw thread 58 in that end of said bore radially aligned with the threaded section 56. The sleeve 53 is secured in the aperture 52 by passing the threaded section 56 from the inside of the helmet through said aperture 52 so that said threaded 56 projects externally of the helmet and the sleeve 53 is secured by a nut 59 engaged on said threaded part 56.

The nut 59 is firmly secured on the thread 56, whereupon the helmet shell 51 surrounding the aperture 52 is firmly trapped between the flange 55 and the nut 59 and the sleeve 53 is securely held against rotation.

A flexible tubular element 60 presents a cylindrical section 61 into which the cylindrical section 54 of the C sleeve 53 is entered and secured, as by an adhesive, or by a jubilee clip surrounding the cylindrical section 61. The mid- region 62 of the tubular element 60 is of concertina form and the end region 63 remote from section 61 is cylindrical and includes a radial flange 64 on its outer end. The flange 63 5 and the end region 63 enter through an aperture 65 in the seal 26 and the annular flange 64 is bonded to the seal 26 to define a gas tight seal therewith.

It will now be seen that with the embodiment described thus far the volume defined by the annular seal, the see- o through panel and the face of the wearer is in open communication with the surrounding atmosphere via the open bore of tubular element 60 and the bore 57 in the sleeve 53.

The breathing apparatus attachment for the helmet comprises a valve housing 70 of generally cylindrical form 5 with a concentric boss 71.

The boss 71 includes an interrupted screw thread, defined by elements 72 and a duct 73 from an air supply source (not shown) ducts air to the valve housing 70.

The external diameter of the screw thread elements 72 0 is such that with the screw thread elements 58 and 72 out of alignment the boss 71 can enter into the bore 57 of the sleeve 53.

The housing 70 includes a conventional breathing apparatus demand valve, arranged to supply air to the bore 57 5 of sleeve 53, and via bore of the tubular element 60 to the volume defined by the annular seal 26, the see-through panel and the face of the wearer, when the pressure in said volume falls below a predetermined level.

Such breathing apparatus supply valves are well known in the art in many forms and no further description of the

_- valve arrangement or the principal of operation is required herein.

The valve arrangement may also include a manually actuable by-pass actuator button 75 arranged to by-pass the demand valve, to supply air directly through the valve

_*._Q arrangement when required.

To fit the housing 70-71 with its internal valve arrangement it is only necessary to enter the boss 71 into the bore 57 of the sleeve 53, with the interrupted screw threads 58 and 72 out of register, and then to rotate the housing 70-71

^ through ninety degrees to engage the interrupted threads 58,

72, and whereupon the housing 70-71 is locked with the helmet.

A resilient seal 74 is provided on the radial face of the housing 70 and surrounding the boss 71 and said member 74 is compressed between the nut 59 and the radial face of the

_2C housing 70 when the housing 70-71 is locked with the sleeve 53.

The radial position of the sleeve 53 is so selected that when the housing 70-71 is locked with the sleeve 53 the duct 73 is lying in its natural unstressed position to extend

25 to the air reservoir, so that the duct 73 is not circumferentially loading the housing 70-71 towards an unlocked position or to an over-locked position, but in the event, housing 70-71 may include a latch mechanism (not shown) engageable with the sleeve 53, nut 59 or the helmet casing 51

~_Q to retain the housing 70-71 locked with the helmet when in use.

It will now be seen that with the housing 70-71 disconnected from the helmet 51 the wearer is breathing atmospheric air via the bore 57 and the bore in the element 60. _j5 When it is desired to attach the breathing apparatus it is only necessary to insert the boss 71 into the bore 57, rotate the housing 70-71 through ninety degrees to lock the housing 70-71 in the bore 57, and the bore of the tubular element and the volume forward of the wearer's face bounded by the seal 26 and see-through panel 21 are isolated from the surrounding atmosphere and air can be supplied to the wearer via duct 73 and the housing 70-71

To disconnect the breathing apparatus it is only necessary to release any latch mechanism retaining the housing 70-71 with the helmet, rotate the housing 70-71 through ninety degrees and the housing 70-71 can be disconnected from the helmet 51, again to connect the volume forward of the wearer's face with the surrounding atmosphere.

Claims

1. A safety helmet, characterised by quick-release means for selectively attaching a breathing apparatus to said helmet.

2. A safety helmet according to claim 1, characterised in that said helmet is adapted to totally encase the head of the wearer and includes a see-through aperture through its forward regions.

3. A safety helmet according to claim 2, in combination with a rigid closed frame, said frame being located within the helmet, concentric with the said aperture.

4. A safety helmet according to claim 3, characterised in that said closed frame supports an annular seal, having one continuous end in sealed relationship with the frame and concentric therewith.

5. A safety helmet according to claim 4, characterised in that the continuous end of said seal remote from the said frame is arranged to engage the face of the wearer across the forehead, down the cheeks and across the chin.

6. A safety helmet according tc claim any one of the preceding claims, characterised in that the helmet includes a harness comprising straps for supporting the helmet on the head of the wearer and a padding engageable with the rear of the head of the wearer.

7. A safety helmet according to claim 6, when dependant upon claim 5, characterised in that said annular seal is resilient and the said straps of said harness are adjustable to allow the front to rear position of said padding to be adjusted relative to the said annular seal.

8. A safety helmet according to any one of claims 2 to 7 inclusive, characterised in that the see-through aperture in the helmet is totally closed by a see-through panel.

9. A safety helmet according to claim 8, characterised in that an exhalation valve is supported by the said see- through panel.

10. A safety helmet according to claim 9, characterised in that a nose cone extends from the said see-through panel to engage the face of the wearer with a continuous seal _O surrounding the breathing ducts of the wearer, said exhalation valve is arranged to exhaust from the volume defined by said nose cone and said nose cone includes valve means for allowing air flow from the said volume defined by the said annular seal, the see-through panel and the face of the wearer, into said

*>c nose cone.

11. A safety helmet according to claim 8, 9,or 10, when dependent on any one of claims 4, 5, 6 or 7, in combination with valve means and air ducts, arranged to supply pressure air from an air source externally of the helmet to the volume ₀ forward. of the wearer's face and defined by the said annular seal, the see-through panel and the face of the wearer bounded by the said annular seal.

12. A safety helmet according to any one of claims 3 to 11 inclusive, characterised in that said rigid closed frame is detachably retained within the helmet by said quick-release devices and said annular seal, said see-through panel, said valve means and said air ducts are supported by said rigid closed frame to be detachable therewith.

13. A safety helmet according to claim 12 characterized in that the helmet includes an internal cavity below the aperture and said valve means and air ducts are attached to the lower regions of said rigid closed frame and are housed in said internal cavity when the closed frame is fitted to the helmet.

14. A safety helmet according to any one of claims 2 to 7 inclusive characterised in that the volume forward of the wearer's face and bounded by the annular seal is open to the surrounding environment through the opening in the frame and 0 the aperture in the helmet.

15. A safety helmet according to claim 14, when dependant on any one of claims 4 to 7 inclusive, characterised in that said rigid closed frame is detachably retained within the helmet by said quick release devices and said annular seal is 5 supported by said rigid closed frame to be detachable therewith.

16. A safety helmet according to any one of claims 3 to 15 inclusive, characterised in that said quick-release means comprise rotatable devices adjacent the aperture through the 0 helmet and arranged in one rotational position for each device to securely clamp the said closed frame with the helmet and in another rotational position for each device to release the said closed frame from the helmet.

17. A safety helmet according to any one of claims 4 to 10 ^C inclusive, characterised by a duct connecting the volume defined by the annular seal to the atmosphere externally of the helmet.

18. A safety helmet according to claim 17, characterised in that said duct comprises a flexible connection between the

^0 volume within the annular seal and an aperture through the helmet.

19. A safety helmet according to claims 17 or 18, characterised in that said duct is selectably closable by an air supply assembly.

20. A safety helmet according to claim 19, characterised in that said air supply assembly comprises an air supply valve arrangement contained in a housing and an air supply from a air reservoir to said air supply valve arrangement and said quick- release mean comprise means for selectively connecting or disconecting the air outlet from said housing to said duct.

21. A safety helmet according to claim 20, characterised in that said quick-release means comprise interrupted screw means presented by said housing and said duct.