SPECIFICATIONProtective, respiratory face masksThis invention relates to protective, respiratory face masks.
Protective, respiratory, face masks enclose the whole face and therefore also protect the eyes. A face mask with one window ensures conditions of visibility which substantially correspond to the natural range of vision. If the face mask contains an inner mask which covers the mouth and nose, a defined air circulation which prevents fog formation on the window is achieved with the mask.
The known mask described in French Patent Specification No. 757280 consists of two masks lying one inside the other. The smaller, inner mask enclose only the mouth and nose, while the outer, larger mask encloses the face.
Both masks are sealed on the face by a sealing lip. The interior of the mask is subdivided into two chambers by this type of construction. Fresh air is introduced into the outer chamber and flow through a check valve in the wall of the inner mask into the inner chamber, while expiratory air flows from the inner chamber through another check valve to the outside. This air circulation prevents moist and warm expiratory air from reaching the window of the mask and causing it to fog.
The structure of this mask is complicated due to the presence of the inner mask. Furthermore, the check valve between the two masks is not easily accessible so that its dismounting for cleaning causes difficulties.
The mask is too expensive for single application only.
The known mask described in German Patent Specification No. 1914224 also has an inner mask for preventing fog formation on the window. Inspiratory air flows first of all to the window and only then to the respiratory organs. On the other hand, expiratory air is kept away from the window. The expiratory air is separated into two portions. On portion passes through an exhaling valve to the outside via a sealing region which is formed by the normal seal of the mask and an additional seal parallel to it. The other portion passes through another exhaling valve, directly to the outside. The outer mask and the inner mask are integral with each other. The inner mask encloses the mouth and nose.
Inspiratory air flows along the window by way of an inhaling valve in the outer mask and then through the gap between the inner maks, without its own seal, and the face, into the inner mask. This mask also is too expensive for once-only use because of its complicated structure, i.e. because of the double seal on the full mask, the additional exhaling valve and the inhaling valve on the filter connector, the latter being necessary because of the lack of a seal in the inner mask.
According to the present invention, there is provided a protective mask comprising (a) an outer mask for enclosing the face of the wearer and including a viewing window, a holder for holding an air filter and a sealing lip which in use bears against the face, (b) an inner mask for enclosing the mouth and nose of the wearer, (c) at least one inhaling valve comprising a valve seat and a valve flap, disposed so as to enable air to flow from the interior of the outer mask to the interior of the inner mask, (d) at least one exhaling valve comprising a valve seat and a valve flap, disposed so as to enable air to flow from the interior of the inner mask to the exterior, and (e) a holding device which fits around the head of the wearer and which holds the protective mask in place; wherein the outer mask including the air filter holder and the sealing rim thereof, the inner mask, the valve seat of the or each inhaling valve and the valve seat of the or each exhaling valve are in the form of an injection-moulded article made of a flexible material.
The advantages achieved with the invention consist in particular in the simple and economic way in which the mask can be manufactured. In view of the present demand for masks, e.g. in the nuclear field, the cost of the manufacture of appropriate injectionmoulding tools is justified. The masks can be used repeatedly. They can be used with air filters or with a source of supply of respiratory air, a suitable connector being used in the latter case in place of the air filter. The masks are easy to clean and disinfect.
Preferably, the injection-moulded article is made of a transparent material.
In one preferred embodiment, the injectionmoulded article is formed around a preformed viewing window. In another preferred embodiment, the viewing window is bonded to the injection-moulded article. In another preferred embodiment, the injection moulded article includes a viewing window formed by injection moulding and, preferably, a stiffening frame, formed by injection moulding, around the viewing window.
For a better understanding of the invention, reference will now be made, by way of example, to the accompanying drawings, in which:Figure 1 is a sectional view of a mask of the invention;Figure 2 shows a modification of part of the mask shown in Fig. 1; andFigure 3 shows another modification of part of the mask shown in Fig. 1.
The protective, respiratory mask 1 shown inFig. 1 consists of (a) an injection-moulded outer mask 2 including a filter holder 3, a viewing window 4 and a sealing lip 5, (b) an inner mask 6 and (c) a holder 7. The mask can also have a connector for a source of respiratory air.
A lip 1 6 seals the inner mask 6 sufficiently tightly on the face of the wearer so that an inhaling valve behind the filter holer 3 is not necessary. Inspiratory air passes through the filter in the filter holder 3, and then flows past the viewing window 4. This air then passes through two inhaling valves 8, each consisting of an injection-moulded valve seat 9 and a valve flap or disc 10, to the respiratory organs, i.e. the mouth and nose, which are enclosed by the inner mask 6. Expiratory air passes from the inner mask 6 through an exhaling valve 11, which is constructed in the same manner as the inhaling valve 8, to the outside.
The outer mask 2 has a circular safety rim 1 2 around the viewing window 4. When a protective suit is worn at the same time as the mask, this rim can be used to fix and seal the suit around the viewing window 4.
The fixing of the mask 1 on the face of the wearer is assisted by a chin pocket 1 3.
The viewing window 4 can alternatively be manufactured as shown in Fig. 2 from rigid material as rigid viewing window 14 or can be stiffened as shown in Fig. 3. As a result, it is easier to put on the protective suit. In the construction shown in Fig. 2, the rigid viewing window 1 4 can be injection-moulded in place during the injection-moulding of the mask or can be bonded in place later into a circular groove provided in the mask. The viewing window 4 shown in Fig. 3, which is formed by injection-moulding, is sufficiently stiffened by a rigid circular frame 1 5 which is also formed by injection-moulding.