GB2202151A - Heat- and smoke- protective hood - Google Patents

Abstract

A heat- and smoke-protective hood (1) suitable for use by the general public in fire emergencies and comprising a bag-like head-covering (2) and two close-fitting annular substantially gas-impermeable diaphragms (4, 7) which isolate the nose and throat from the remainder of the hood (1) thus enabling the dead-space of the hood (1) to be reduced and the hood (1) to be donnable in any direction. The hood (1) preferably has a single annular filter pad (9), which is preferably soft to aid compact packing of the hood and which extends around the entire circumference of the hood (1) between the two diaphragms (4, 7).

Description

HEAT- AND SMOKE- PROTECTIVE HOOD This invention relates to a heat- and smokeprotective hood which is suitable for use by the general public in fire emergencies.

There have been a number of proposals for the design of hoods and face masks which can be worn to protect the wearer at least temporarily from the effects of heat, smoke and other toxic and noxious fumes in case of an emergency, such as an aircraft crash or a hotel fire.

It is important to realise that the general public involved in such incidents, in the main, have no training or experience of fire emergencies and may of course include elderly people, children and other persons who are physically and/or mentally handicapped. Additionally, the emotional effects of such emergencies tend to inhibit logical thought even in people who would, in other circumstances, be considered to be highly intelligent. Accordingly it is imperative that the wearing of escape masks or hoods must involve the assimilation of only the most simple of instructions, and the amount of adjustment required to be made by the person wearing this apparel must be miffimal. Ideally the donning of the mask or hood should involve only a single, self-evident and rapid action which when carried out results in the mask or hood fitting perfectly and comfortably.

In practice, however, such perfection is difficult to achieve particularly when other requirements have to be met. Thus, for example, it is highly desirable that the hood or mask can be folded flat, so that it can be conveniently stored and transported.

The previous attempts to meet the problems involved can be conveniently divided into those involving the use of masks, i.e. devices which cover the whole or part of the face, and in particular the nose and mouth; and those involving hoods, i.e.

devices which cover the whole head.

Face masks, known as the "oronasal" type which cover just the nose and the mouth, or the so-called 'half-mask' type, which also covers the chin, are potentially very efficient in that in theory the amount of dead space in which gases can accumulate is reduced to a minimum. However, in practice it is impossible to achieve a good universal fit because of the wide disparity in the critical dimensions of the human face. Moreover, if a good fit is not achieved the mask may of course be dangerous in that it may not in fact keep out the smoke and noxious or poisonous fumes. Face masks also have the disadvantage that they do not protect the whole head from heat. In the latter regard hoods have an advantage over masks. However, hoods have an inherent disadvantage in that they usually involve a considerable dead space which gives opportunity for gases to accumulate inside the hood.An attempt has been made to reduce this disadvantage by the incorporation of dfaw strings which can be pulled to bring the fabric of the hood close to the surface of the head. However, this procedure is not entirely effective, and moreover involves an additional operation which complicates rather than simplifies the wearing of the hood, which, as explained above, as a general principle, is to be avoided.

It should be mentioned that types of hoods have been prepared which incorporate an oronasal mask, and a neck seal. However, such hoods can be said to possess some of the disadvantages of both hoods and masks. Thus, the hood gives a large dead-space in which gases can accumulate, and it is difficult, if not impossible to arrange for the mask part to fit all persons properly. Moreover, this type of hood requires separate actions in order to be correctly donned, namely, firstly putting the hood over the head, and secondly adjusting the position and fitting of the mask back against the face. The latter operation can also prove to be particularly difficult since the neck seal is in the way and the mask cannot readily be reached with the hands to adjust its position.

Also, most hoods and all masks can be said to have unidirectional features, that is they have to be donned with a particular orientation, otherwise, for example, there is a .possibility of their being put on 'back-to-front'. Such a possibility gives rise to risk of delay and malfunction, and if possible should be avoided.

According to the present invention there is provided a heat- and smoke- protective hood suitable for use by the general public in fire emergencies, said hood comprising a bag-like head-covering of a transparent heat-resistant substantially gas-impermeable sheet material which is adapted to fit loosely over the head and down to the shoulders; an upper flexible, substantially gas-impermeable diaphragm which is secured continuously around the inside of the hood-covering and is adapted to fit snugly around the head, over the nose and under the ears; a lower flexible substantially gas-impermeable diaphragm which is also secured continuously around the inside of the head-covering but which is adapted to fit snugly around the neck; a porous flexible material which when the hood is in use is substantially cylindrical or frusto.conical in shape and which serves to maintain an appropriate distance between the two diaphragms, said porous flexible material being secured continuously at each of its two annular peripheries to the respective diaphragms; at least one filter means adapted to filter noxious ingredients from air or gases inhaled by the wearer into the space between the two diaphragms; and at least one exhaust valve adapted to permit exhaled air or gases to escape from the said space to the environment and to prevent ingress of air or gases from the environment, the hood being capable of being placed over the head, and worn, in any orientation.

Preferably the transparent sheet material of the head-covering is a polyimide film having adequate heat-radiation resistance and chemical resistance, for example the film material known as "KAPTON". "KAPTON" is a Registered Trade Mark of Du Pont de Nemours International S.A., and "Kapton" film can be obtained through this Company at its PP and R Films Division, CH-1211 Geneva, Switzerland. The film may be about one thousandth of an inch in thickness (.025mm). The transparent sheet material is preferably not a thermoplastic material, in view of the obvious danger which such a material would present. It may also be spattered with a metal, or combination of metals, such as gold and/or nickel to increase the heat reflectivity of the film.

The material of the flexible diaphragms may be rubber or any other suitable elastic substantially gas impermeable sheet material. It should be noted that such materials may be more prone to damage by heat or chemicals than the material of the head-covering, and the head-covering material, reaching down to the shoulders serves the purpose of not only protecting these dead-space limiting diaphragms, but also protecting the neck and upper shoulder areas of the wearer from heat and flames.

It is an important characteristic of the present invention that1 not only is the dead-space reduced, as compared with previously proposed hoods, but the hood may also be put on in any direction and does not require directional adjustment after it has been put on. This is because the space through which the wearer breathes extends in annular manner completely around the inside of the hood. In conjunction with this annular space arrangement, although the filter or filters used may be positioned at discretelpositions around this space, it is a particularly preferred feature of this invention that the filter extends continuously around the hood.

This arrangement of the filter has several advantages. In particular it causes a large area of filter to be exposed to the incoming air so that the filter can act very efficiently. Moreover, as parts of the filter may become blocked during continued use other parts of the filter remain free to perform their function.

Specific embodiments of the present invention will now be described with reference to the accompanying drawings in which: Figure 1 is a general view from the front of a heat- and smoke- protective hood of the invention when in use; Figure 2 is a view from the side showing the same hood; Figure 3 is a section of part of the hood of Figures 2 and 3 shown diagrammatically; Figure 4 is a section of a different part of the hood of Figures 2 and 3; and Figure 5 is a perspective view from above of the hood of the Figures 1 and 2, but without the head of the wearer and without the two diaphragms, so that features of the interior of the hood can be seen.

Referring firstly to Figures 1 and 2 a protective hood in accord with invention comprises a bag-like head covering 1 of "KAPTON" film which fits loosely over the head 2 of the wearer and down to the shoulders at 3.

An upper rubber diaphragm 4 is secured continuously around the inside of the head-covering and is adapted to fit snugly around the head, over the nose 5 and under the ears at 6.

A lower rubber diaphragm 7 is secured continuously around the inside of the head-covering and is adapted to fit snugly around the neck at 8.

In this embodiment of the invention a particularly preferred feature is that filter pack 9 which is made in accord with that described in my Patent No. GB 2 129 670B extends in annular fashion completely around the outside of the hood. The filter part is soft and this enhances the foldability of the hood, which is important in that it enables the hood to be packed relatively flatly and compactly, unlike hoods and face masks which use cannister filters. The unitary nature of the filter pack also results in the air inflow being equalised through the inlets; and, if present, the catalyst pads. The size of the filter pad also enables a large volume of air to be admitted at a lower pressure drop, and certainly in excess of the breathing requirements of any human being.

Also provided are two exhalation valves 10, 11 of the duckbill type.

Referring in more detail to the hood shown in Figures 1 and 2 it will be clearly seen that there are two separate seals: a) There is an elasticated, impermeable diaphragm with a central hole which stretches over the nose, under the ears and around the back of the head and is joined on its outer edge to the top of the filter pack.

b) The bottom seal is also a diaphragm with a central hole which, when stretched, will seal around the neck. Its outer edge is sealed to the bottom edge of the filter pack.

It will be noted that the mask can be put on in any direction. It will also be noted that the two seals effectively enclose the respiratory organs and the dead space is thereby dramatically reduced by comparison with previous hoods.

Figure 3 shows in section a view of the "KAPTON" or similar material hood, the soft filter pad 9 as described in Patent No. GB 2 129 670B; or changed to include more layers of, for example, activated charcoal, and/or chemical protectors for removing such noxious agents as e.g. sulphur compounds, hydrogen chloride and hydrogen fluoride, which tend to poison the catalyst; an expandable material 12, a catalyst pad 13 which may or may not be fitted, the upper and lower diaphragms, 4, 7, all held in position by sealing tapes 16, 17, 18, 19, (other methods of sealing may, of course, be used) as well as an expandable, knitted material 14 joining the two diaphragms together as shown. The latter is important as it maintains the distance between the two diaphragms 4, 7. It is expandable over its circumference but not its height.This allows the wearer to pull the hood over the head, pulling on the bottom diaphragm which will also exert at the same time, a pulling force on the top diaphragm, thereby simplifying the ease of donning the mask, and locating the top diaphragm in its correct position, over the nose.

Figure 4 is a similar view in section but it will be noted that there is no break in the "KAPTON" film to allow air to pass into the mask, unlike the position shown in Figure 3. This is more clearly understood when it is realised that air must pass through the soft filter pack into the space between the inside of the soft filter pack and the outside "KAPTON" surface until it reaches the aperture 15 shown in Figure 3, which may or may not incorporate a catalyst pad 13. There must be one opening, but in the case of this specific embodiment there are two such openings in the mask, as is shown in Figure 5, which also shows the two exhalation valves 10, 11.

It will be apparent that there could be more than two openings in which case they could perhaps be of smaller dimensions. In this view the totally surrounding filter 9 is shown, with the two inlet apertures 20, 21 which may or may not incorporate catalyst pads over them, through which the inhaled air must pass. The majority of the exhaled air will pass through the two exhalation vales 10, 11, but a small percentage will pass through the catalyst pads if fitted, which will help to reduce the surface temperature, and thereby reduce the temperature of incoming air at the next inhalation stroke. The exhalation valves may instead be located in the same position as, and on the outside of the catalyst pads so that all exhaled air passes through the catalyst pads, or there may be one or more openings with or without catalyst pads.A possible arrangement is to have one or more openings containing catalyst pads which allow exhaled air to be passed out of the hood through the catalyst pad and corresponding openings arranged in the filter pad.

Referring again to Figures 3 and 4, it is also possible to incorporate an upper and/or lower tubular sachet 22 made from air-permeable material filled with soda, lime, zeolite or similar material which will absorb carbon dioxide. Also, in Figure 4 the expandable material shown between the inside surface of the soft filter pad and the outside surface of the "KAPTON", may be a material such as reticulated foam or glass wool or springy wire wool which, when the mask is unpacked, will spring open and create a space between the two surfaces, thereby easing the passage of air to the two apertures in the "KAPTON", but which will still allow the mask to be packed flat due to its compressibility.The positions of the two apertures and the two exhalation valves are important and they will preferably be positioned so that the mask, when folded, will allow the catalyst pads in particular, to lie side by side and not on top of each other, so as to reduce the overall thickness of the packed mask. Preferably also one or more layers of CO2- absorbant material are incorporated in the soft filter pack, or one or more layers are lcoated in front of or between the catalyst pads and incorporated with them.

It will be understood that the invention is not limited to the specific details of the embodiment of the heat- and smoke- protective hood specifically-described above. Thus for example, the hood may incorporate an electric light, a whistle, a miniature radio beacon, or other means to enable the wearer of the hood to be located in a fire emergency, in which of course all artifical lighting in the building, aircraft, vessel, or other environment in which the emergency has occurred, may have been extinguished as a direct or indirect result of the emergency, and in which smoke and fumes may in any case cause diminished visibility.

Claims (5)

1. A heat- and smoke- protective hood suitable for use by the general public in fire emergencies, said hood comprising a bag-like head-covering of a transparent heat-resistant substantially gas-impermeable sheet material which is adapted to fit loosely over the head and down to the shoulders; an upper flexible, substantially gas-impermeable diaphragm which is secured continuously around the inside of the hood-covering and is adapted to fit snugly around the head, over the nose and under the ears; a lower flexible substantially gas-impermeable disphragm which is also secured continuously around the inside of the head-covering but which is adapted to fit snugly around the neck; a porous flexible material which when the hood is in use is substantially cylindrical or frusto.conical in shape and which serves to maintain ah appropriate distance between the two diaphragms, said porous flexible material being secured continuously at each of its two annular peripheries to the respective diaphragms; at least one filter means adapted to filter noxious ingredients from air or gases inhaled by the wearer into the space between the two diaphragms; and at least one exhaust valve adapted to permit exhaled air or gases to escape from the said space to the environment and to prevent ingress of air or gases from the environment, the hood being capable of being placed over the head, and worn, in any orientation.

2. A hood as claimed in claim 1 wherein a single filter is provided which extends substantially completely around the hood between the said upper and lower diaphragms.

3. A hood as claimed in claim 2 wherein said single filter is soft in construction to enable the hood to be folded compactly.

4. A hood as claimed in any one of the preceding claims and also comprising any feature or combination of features as herein described.

5. A hood as claimed in claim 1 and substantially as herein described with reference to and as illustrated in Figures 1 to 5 of the accompanying drawings.