WO1992019322A1

WO1992019322A1 - Protective respirator's air guidance system and protective respirator

Info

Publication number: WO1992019322A1
Application number: PCT/FI1992/000137
Authority: WO
Inventors: Hannu Inkinen
Original assignee: Air-Ace Oy
Priority date: 1991-05-02
Filing date: 1992-04-30
Publication date: 1992-11-12
Also published as: DE69215868D1; AU1655992A; ATE146089T1; EP0582612B1; FI912138A0; FI912138A; JPH06506845A; CA2102296C; JP3438073B2; CA2102296A1; DE69215868T2; FI87047B; FI87047C; EP0582612A1

Abstract

The object of this invention is a valve arrangement of a protective respirator intended for protecting the wearer against dust or gases. The invention sets out how the exhalation air is guided as soon as possible out of the face section (7) and further how te air can be caused to pass through an air enclosure (11) in between the face section (7) and the frame section (3).

Description

PROTECTIVE RESPIRATOR'S AIR GUIDANCE SYSTEM AND PROTECTIVE RESPIRATOR

This invention concerns an air guidance system for a protec- tive respirator and a protective respirator.

Protective respirators have conventionally been used mainly in industrial work and agricultural work in order to protect the user against harmful dust and gases. Protective respira- tors are being used increasingly in the home as well; e.g. in order to avoid pollen allergy. The following is a description of some alternative solutions concerning the valve arrange¬ ment of protective respirators.

In accordance with FI patent application 833006, the exhala¬ tion valve of a filter bridge type of a half mask is located at an angle in the upper part of the mask's visor to enable the exhaled air to exit. In accordance with EP patent appli¬ cation 258508, the exhalation valve and the inhalation valve have been located concentrically in the face section of the respirator's fore part. The exhalation air is conveyed di¬ rectly into the surrounding air from the face section.

One of the major problems with protective respirators is the formation of condensated water on the sealing surface of the face section. The excess moisture causes powerful bacterial growth on the surfaces in contact with the skin and thus leads to skin infections and hypersensitiveness. Further, the mask is extremely unhygienic should more than one person take turns in wearing it. The formation of condensated water is caused by the air temperature outside the face section of the device being lower than inside the face section. The warm and moist exhalation air condensates on the surfaces of the face section when the temperature of these surfaces falls below what is referred to as the dewpoint temperature.

.Another significant problem is encountered when breathing in cold inhalation air in sub-zero temperatures. Since breathing through the protective respirator always causes some degree of breathing resistance, the person using the respirator is generally forced to breath in the air using such a breathing technique as will cause the cold air to pass (especially when working reasonably hard) directly into the person's respira¬ tory organs. Person's afflicted by asthma run a definite health risk in such a situation.

Often, sub-zero temperatures also lead to the formation of ice in the exhalation valve. When this happens, non-filtered air may leak via the exhalation valve in the wrong direction into the face section.

A common shortcoming in protective respirators is that the exhalation air leaves the respirator too close to the inhala¬ tion inlet. This leads to the risk that the carbon dioxide concentration of the air breathed in may rise to an excessive level. High carbon dioxide levels causes headache, fatigue, and even loss of consciousness in extreme cases. According to the authorities, a carbon dioxide concentration limit of ca. 1 % is still safe when breathing in.

A shortcoming in several currently available masks that redu- ces work safety and wearing comfort is that the user's spec¬ tacles and protective goggles tend to fog up because of the warm and moist exhalation air. This is generally due to the exhalation air having the possibility of being guided unobst¬ ructed from the exhalation valve directly onto the user's spectacles or goggles.

Since the exhalation valve on conventional protective respi¬ rators is on the outside of the mask in the immediate vi¬ cinity of the surrounding non-filtered air, a leak in the exhalation valve may result in the unfiltered air outside the valve and in its immediate vicinity being admitted in small amounts along with the inhalation air because of the suction produced during the inhalation stage.

The air guidance system of the respirator in accordance with the invention brings about a decisive improvement to the above shortcomings. In order to implement these .improvements, the air guidance system of the respirator of the protective breathing apparatus type in accordance with the invention is characterised by what is stated in cla.im 1 and the respirator is characterised by what is stated in claim 7.

The foremost advantage of the invention may be seen in that the formation of condensated water on the sealing surfaces of the face section is markedly reduced. This is accompanied by the warming up of the inhalation air and the respirator is safe to use even in sub-zero temperatures. Further, the mixing up of exhalation air into the inhalation air is mini¬ mised.

In the arrangements in accordance with the invention, due to the location of the exhalation valve, the air leaked by the exhalation valve is noticeably cleaner than the air surroun¬ ding the respirator, because the unclean surrounding air is not in the immediate vicinity of the exhalation valve, the leaked air has, in the main, composed of air that has been filtered once and then exhaled. As an example, air containing particles as impurities is cleaner between the frame and face sealing section than on the outer surface of the mask, becau¬ se the exhaled air stays around the exhalation valve in between the user's breaths and the pressure of the exhaled air forces unclean air away through the valve opening.

In the following, the invention is explained in detail with references being made to the appended drawings.

Figure 1 is an exploded presentation of the protective respi¬ rator. Figure 2 shows the protective respirator from above and par¬ tially as a sectional presentation.

Figure 3 shows a side view of the protective respirator and partly as a sectional view along the line C-C in fig. 2.

Figures 4a and 4b show two different implementations of the heat exchange surfaces.

Figure 5 is an isometric assembly drawing of a respirator in accordance with the invention.

Fig. 1 is a schematic exploded presentation of a protective respirator in accordance with the invention. The respirator is composed of a lattice section 1 protecting the filter, a filter 2, a frame section 3 made up of supporting ribbing with a hole for the inhalation air, a valve frame 4 onto which the inhalation and exhalation valves are mounted, and a face sealing section 7 that is connected to a valve frame 4 by means of the respirator's mounting straps, these straps not being shown in fig. 1. The top of the respirator's frame section 3 houses an air guidance plate 8.

Fig. 2 shows the protective respirator as seen from above and partially as a sectional view of it. The mounting straps 3 are indicated by dashed lines in the drawing.

Fig. 3 shows the assembled mask placed over the user's face: The presentation is a side view partially as a sectional presentation along the line C-C shown in fig. 2. The drawing shows how the warm exhalation air is guided through the exha¬ lation valve 6 through the frame section 3 and into the air enclosure 11 of the face sealing section 7. Due to convec- tional force, the warm exhalation air rises upward in the air enclosure 11 until it meets the air guidance plate 8. The air guidance plate 8 guides most of the warm air to the rear and up toward the ears of the person wearing the protective respirator. This being the case, a flow of warm air is gene¬ rated in the air enclosure formed between the protective respirator's frame section and the face sealing section, the said flow of warm air keeping the temperature in the said air 5 enclosure essentially higher than that of the outside air. The number 16 indicates a removable protective visor.

The warm exhalation air in the air enclosure maintains the temperature of the face sealing section's outside surface 10 above the dewpoint temperature and thereby the formation of condensated water on the inner surfaces of the face sealing section is significantly reduced.

The warm exhalation air in the air enclosure also warms up 15 the heat exchange surface 12 forming the rear surface of the frame section 3. Heat is transmitted by conduction from the heat exchange surface to the supporting ribbing 13. On being warmed up, the supporting ribbing releases heat into the filtered inhalation air flowing between the ribbing. Thus, 20 the temperature of the inhalation air is not dangerously cold even for persons afflicted by asthma.

Since the exhalation air rich in carbon dioxide flows in its own air enclosure and exits essentially via the ends of the 25 respirator, there is little chance of it finding its way back to be breathed in once again. This enhances the respirator's operational safety.

Due to the guiding plate 8 the warm air is prevented from 30 causing fogging up of spectacles or goggles.

Figs. 4a and 4b shows another possible solution for the structure of the heat exchange surface 12. The ribbing 13 is thus formed that the frame section 3 is essentially of the 35 same thickness at the points of the ribs as it is next to the transfer channels 10. The said construction facilitates a more efficient exchange of heat because of the greater surfa- ce area and more even thickness of the frame section.

Fig. 5 shows a fastening stud 15 by means of which the latti¬ ce section 1 is fastened onto the frame section. The pressure equalising apertures 14 can be executed, for example, into the section of the lattice 1 curving underneath the respira¬ tor. When this is done, the said pressure equalising apertu¬ res converge with the apertures made into the corresponding parts of the frame section 3 when the respirator is assem- bled.

It should be noted that the respirator in accordance with the invention has been described with reference having been made to only one of its advantageous implementation examples. This is in no way intended to restrict the invention to only this one example. Instead, all modifications of the inventive idea within the scope defined in the patent claims are, naturally, possible.

Claims

1. An air guidance system for a respirator protecting the user against air impurities, the said respirator being formed of a face sealing section (7) made of a rubber type substan¬ ce, of inhalation and exhalation valves (5, 6) connected onto a frame section (3) and a valve frame (4) , of a filter (2) , through which air is breathed into the face section (7) , characterized in that the air that passes through the exhala- tion valve (6) is guided into an enclosure (11) between the frame and face sealing sections (3, 7) .

2. An air guidance system as cla ed in claim 1, characte¬ rized in that the top part of the respirator's frame section (3) contains an air guidance plate (8) that adapts itself to the contours of the face of the wearer and is oriented essen¬ tially from the respirator's frame section (3) toward the face of the wearer of the respirator.

3. An air guidance system as claimed in claim 1, characte¬ rized in that the exhalation air warms up the heat exchange surface (12) of the frame section (3) and the heat exchange ribbing (13) from which the heat is released into the inhala¬ tion air.

4. An air guidance system as claimed in claijn 1, characte¬ rized in that the exhalation air warms up the outer surface of the face sealing section (7) keeping its inner temperature above the dewpoint and thus preventing the formation of con- densated water inside the face sealing section (7).

5. An air guidance system as claimed in claim 1, characte¬ rized in that grooves or cavities following the orientation of the heat exchange ribbing (13) have been formed into the ribbing.

6. An air guidance system as claimed in claim 1, characte- rized in that the exhalation air exits the respirator the respirator essentially in the direction of the filter surface with the heat exchange surface (12) of the frame section (3) and the guidance plate (8) guiding the flow of the exhalation 5 air.

7. A protective respirator for the purpose of protecting the wearer against air impurities, the said respirator being formed of a face sealing section (7) made of a rubber-like

10 substance, of inhalation and exhalation valves (5, 6) connec¬ ted onto a frame section (3) and a valve frame (4), of a filter (2), through which air is breathed into the face section (7), characterized in that the air that the outlet aperture of the exhalation valve (6) is between the frame and

15 face sealing sections (3, 7) and the inlet aperture of the inhalation valve (5) is in the frame section (3) underneath the filter surface.

8. A protective respirator as claimed in claim 7, characte- 20 rized in that the heat exchange surface (12) forming the other wall of the enclosure (11) is connected to heat ex¬ change ribbing (13) forming a contiguous piece.

9. A protective respirator as claimed in claim 8, characte- 25 rized in that the heat exchange surface's (12) side facing the enclosure (11) is comprised of longitudinal grooves and/or cavities advantageously opening toward the enclosure (11).

30 10. A protective respirator as claimed in claim 8, characte¬ rized in that pressure equalising apertures (14) have been executed into the frame section (3) and lattice (1) outside and/or underneath the exhalation valve (6) .