GB2132900A - A respiratory apparatus - Google Patents

Abstract

A chemical cartridge (1) in a closed respiratory apparatus or, in the case of protective respiratory apparatus housed in a container, the container, bears an outlet valve (7) which opens in the case of external low pressure and an inlet valve (8) which opens in the case of external excess pressure. Excessive loads on component parts of the apparatus are avoided as the pressure difference across the valves (7, 8) is determined by valve springs (9) and is always the same. <IMAGE>

Description

SPECIFICATION A respiratory apparatus This invention relates to a respiratory apparatus.

Protective respiratory apparatus for example those which are carried as escape apparatus, may be exposed to an ambient pressure which varies considerably. Such apparatus are used, for example, in diving chambers, in mining and even in aeroplanes.

The varying external pressure causes a stress to be applied to the closed protective respiratory apparatus. If is it packed in a container, then the container is subject to stress or if it is a closed unpackaged apparatus, then a respiratory hose thereof, for example, is stressed.

A known oxygen generator, disclosed in U.S.

Patent Specification No. 3,580,250, has an excess pressure valve in the bottom of its container. The purpose of this valve is to reduce the resulting pressure difference when the apparatus is used in an environment having reduced pressure. Air flows off thereby from the inside outwards. An ordinary simple valve, which opens in the case of excess pressure, is used.

This generator has the disadvantage that pressure compensation is only possible with an excess pressure prevailing in the generator with respect to the ambient environment.

In accordance with the present invention there is provided a respiratory apparatus including an oxygen-generating cartridge, the apparatus being provided with a first valve responsive to a low external pressure, relative to the pressure prevailing in the cartridge, to allow gas to flow from the apparatus, and a second valve responsive to a high external pressure relative to the pressure prevailing in the cartridge to allow gas to flow into the apparatus.

The valves may be provided on the cartridge or, if the apparatus is housed in a container, on the container.

In one embodiment of the present invention the cartridge bears at its lower region the first valve which opens in the case of external low pressure and the second valve which opens in the case of external excess pressure. The valves can be arranged to open when there is approximately ten times the usual resistance to respiration obtained in protective respiratory apparatus, that is at a pressure of, for example, between 50-100 mbar.

An apparatus in accordance with the present invention enables pressure compensation to be achieved in the case of both high and low external pressure by the use of simple valves, which may be identical and which are installed in opposition. Thus, pressure differences between inside and outside a protective respiratory apparatus, which differences are too large and which might result in excessive loads on component parts, are prevented. The component parts must be constructed so that they are light and it is important that the flexible portions, such as, for example, the respiratory hose, do not bear any loads which are too great.

In the present specification the term "oxygenqenerating cartridge" is used to define a replaceable container of any suitable material containing an oxygen-generating chemical.

For a better understanding of the present invention, and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings which shows diagrammatically a partial section through an apparatus in accordance with an embodiment of the present invention.

A protective respiratory apparatus is constructed in the usual way and includes a chemical cartridge 1 which removes carbon dioxide from expiratory air and produces oxygen. The cartridge 1 is connected to a mouth piece 3 by way of a pleated hose 2, the mouth piece 3 to be worn by a wearer. In an inoperative state the mouth piece 3 is sealed by means of a sealing plug 4 and the chemical cartridge 1 is sealed by means of a bottom seal 5. When the sealing plug 4 and the bottom seal 5 have been removed, closed circuit artificial respiration occurs.

The bottom 6 of the chemical cartridge 1 bears an exit or A-valve 7 which opens in the case of external low pressure and also an intake or E-valve 8 which opens in the case of external excess pressure. The pressure required to the two valves 7,8 are determined by respective springs shown at 9 in valve 7, and correspond approximately to ten times the usual resistance to respiration. They are thus so tight that under normal conditions ambient air cannot penetrate.

It will be appreciated that if the respiratory apparatus is housed in a carrying container, the container may be provided with E- and A-valves such as 7 and 8 in preference to the cartridge 1 being provided therewith.

1. A respiratory apparatus including an oxygengenerating cartridge, the apparatus being provided with a first valve responsive to a low external pressure, relative to the pressure prevailing in the cartridge, to allow gas to flow from the apparatus, and second valve responsive to a high external pressure relative to the pressure prevailing in the cartridge to allow gas to flow into the apparatus.

2. A respiratory apparatus as claimed in claim 1, wherein the valves are provided on the cartridge.

3. A respiratory apparatus as claimed in claim 1, wherein the apparatus is housed in a housing, the housing being provided with the valves.

4. A respiratory apparatus as claimed in claim 1, 2 or 3 wherein each valve allows gas to flow therethrough when a predetermined pressure difference is obtained between the external pressure and the pressure prevailing in the cartridge, the predetermined pressure difference being dependent on the resilience of biasing means controlling the movement of a closure member of each valve relative to a valve seat thereof.

5. A respiratory apparatus substantially as hereinbefore described with reference to, and as shown in, the accompanying drawing.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (5)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION A respiratory apparatus This invention relates to a respiratory apparatus. Protective respiratory apparatus for example those which are carried as escape apparatus, may be exposed to an ambient pressure which varies considerably. Such apparatus are used, for example, in diving chambers, in mining and even in aeroplanes. The varying external pressure causes a stress to be applied to the closed protective respiratory apparatus. If is it packed in a container, then the container is subject to stress or if it is a closed unpackaged apparatus, then a respiratory hose thereof, for example, is stressed. A known oxygen generator, disclosed in U.S. Patent Specification No. 3,580,250, has an excess pressure valve in the bottom of its container. The purpose of this valve is to reduce the resulting pressure difference when the apparatus is used in an environment having reduced pressure. Air flows off thereby from the inside outwards. An ordinary simple valve, which opens in the case of excess pressure, is used. This generator has the disadvantage that pressure compensation is only possible with an excess pressure prevailing in the generator with respect to the ambient environment. In accordance with the present invention there is provided a respiratory apparatus including an oxygen-generating cartridge, the apparatus being provided with a first valve responsive to a low external pressure, relative to the pressure prevailing in the cartridge, to allow gas to flow from the apparatus, and a second valve responsive to a high external pressure relative to the pressure prevailing in the cartridge to allow gas to flow into the apparatus. The valves may be provided on the cartridge or, if the apparatus is housed in a container, on the container. In one embodiment of the present invention the cartridge bears at its lower region the first valve which opens in the case of external low pressure and the second valve which opens in the case of external excess pressure. The valves can be arranged to open when there is approximately ten times the usual resistance to respiration obtained in protective respiratory apparatus, that is at a pressure of, for example, between 50-100 mbar. An apparatus in accordance with the present invention enables pressure compensation to be achieved in the case of both high and low external pressure by the use of simple valves, which may be identical and which are installed in opposition. Thus, pressure differences between inside and outside a protective respiratory apparatus, which differences are too large and which might result in excessive loads on component parts, are prevented. The component parts must be constructed so that they are light and it is important that the flexible portions, such as, for example, the respiratory hose, do not bear any loads which are too great. In the present specification the term "oxygenqenerating cartridge" is used to define a replaceable container of any suitable material containing an oxygen-generating chemical. For a better understanding of the present invention, and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings which shows diagrammatically a partial section through an apparatus in accordance with an embodiment of the present invention. A protective respiratory apparatus is constructed in the usual way and includes a chemical cartridge 1 which removes carbon dioxide from expiratory air and produces oxygen. The cartridge 1 is connected to a mouth piece 3 by way of a pleated hose 2, the mouth piece 3 to be worn by a wearer. In an inoperative state the mouth piece 3 is sealed by means of a sealing plug 4 and the chemical cartridge 1 is sealed by means of a bottom seal 5. When the sealing plug 4 and the bottom seal 5 have been removed, closed circuit artificial respiration occurs. The bottom 6 of the chemical cartridge 1 bears an exit or A-valve 7 which opens in the case of external low pressure and also an intake or E-valve 8 which opens in the case of external excess pressure. The pressure required to the two valves 7,8 are determined by respective springs shown at 9 in valve 7, and correspond approximately to ten times the usual resistance to respiration. They are thus so tight that under normal conditions ambient air cannot penetrate. It will be appreciated that if the respiratory apparatus is housed in a carrying container, the container may be provided with E- and A-valves such as 7 and 8 in preference to the cartridge 1 being provided therewith. CLAIMS

1. A respiratory apparatus including an oxygengenerating cartridge, the apparatus being provided with a first valve responsive to a low external pressure, relative to the pressure prevailing in the cartridge, to allow gas to flow from the apparatus, and second valve responsive to a high external pressure relative to the pressure prevailing in the cartridge to allow gas to flow into the apparatus.

2. A respiratory apparatus as claimed in claim 1, wherein the valves are provided on the cartridge.

3. A respiratory apparatus as claimed in claim 1, wherein the apparatus is housed in a housing, the housing being provided with the valves.

4. A respiratory apparatus as claimed in claim 1, 2 or 3 wherein each valve allows gas to flow therethrough when a predetermined pressure difference is obtained between the external pressure and the pressure prevailing in the cartridge, the predetermined pressure difference being dependent on the resilience of biasing means controlling the movement of a closure member of each valve relative to a valve seat thereof.

5. A respiratory apparatus substantially as hereinbefore described with reference to, and as shown in, the accompanying drawing.