Patent Description:
Pressurized breathing gas can be stored and delivered to users in a number of environments. For example, SCUBA divers, firefighters, high-altitude explorers, airplane pilots, and emergency workers may carry and breathe compressed breathing gas stored in tanks. The gas supply is typically metered to the person via a regulator.

With some breathing apparatuses, the user is required to manipulate one or more valves (such as cylinder valves and/or selection valves) when no gas is supplied to the user in order to initiate an emergency supply of gas, e.g. from an emergency tank. This may for example be needed when the gas from a primary supply has been consumed by the user or in the case of a failure, such as a hose rupture. Unfortunately, manipulation of such valves has not been successful in all situations. The user may for example be stressed and/or disoriented due to oxygen starvation and manipulate the valves erroneously.

<CIT> discloses a valve for controlling the flow of fluid from two alternative supplies in such a manner that reduction or cessation of one supply automatically causes the valve to switch to the other supply. The valve may be used in underwater diving applications.

One object of the present disclosure is to provide an arrangement for a breathing apparatus, which arrangement is safe.

A further object of the present disclosure is to provide an arrangement for a breathing apparatus, which arrangement enables a simple use.

A still further object of the present disclosure is to provide an arrangement for a breathing apparatus, which arrangement has a simple design.

A still further object of the present disclosure is to provide an arrangement for a breathing apparatus, which arrangement has a compact design.

A still further object of the present disclosure is to provide an arrangement for a breathing apparatus, which arrangement enables a symmetric design, such as the use of two equally sized containers for gas supply.

A still further object of the present disclosure is to provide an arrangement for a breathing apparatus, which arrangement is well balanced during use under water.

A still further object of the present disclosure is to provide an arrangement for a breathing apparatus, which arrangement solves several or all of the foregoing objects in combination.

A still further object of the present disclosure is to provide a breathing apparatus solving one, several or all of the foregoing objects.

According to one aspect, there is provided an arrangement for a breathing apparatus, the arrangement comprising a breathing device; a primary connection point for fluid communication with a primary container; a secondary connection point for fluid communication with a secondary container; a primary side arranged between the primary connection point and the breathing device; a secondary side arranged between the secondary connection point and the breathing device; a first valve arranged between the primary connection point and the secondary connection point, the first valve being arranged to automatically close a first fluid connection between the primary connection point and the secondary connection point when a secondary pressure in the secondary side decreases below a first pressure threshold; and a second valve arranged on the secondary side, the second valve being arranged to automatically establish a second fluid connection between the secondary connection point and the breathing device when a primary pressure in the primary side decreases below a second pressure threshold, wherein the first pressure threshold is higher than the second pressure threshold.

The arrangement provides full and automatic redundancy all the way from the gas supply to the breathing device. The arrangement can withstand a major damage on either the primary side or the secondary side, such as a hose rupture, and still provide a continuous supply of gas to the user to enable breathing.

For example, in case of a damage on the primary side, the primary pressure may rapidly decrease to an ambient pressure level. This will cause the second valve to automatically open and the gas in a secondary container can be consumed through the secondary side. Conversely, in case of a damage on the secondary side, the secondary pressure may rapidly decrease to an ambient pressure level. This will cause the first valve to automatically close and the gas in the primary container can be consumed through the primary side. In case of a damage on the secondary side, no pressure drop, or substantially no pressure drop, will occur on the primary side. The arrangement can thereby automatically provide a continuous gas supply to the user, and ensure provision of a minimum amount of gas, regardless of where the failure occurs, i.e. upon a major failure on either the primary side or the secondary side. The user is thereby allowed to focus on a safe return or "bail out". During normal use of the arrangement, gas is initially supplied from both the primary container and the secondary container through the primary side. When the pressure in the secondary side, i.e. the pressure supplied by the secondary container, decreases below the first pressure threshold level, the first valve will automatically close the first fluid connection. Gas may then be consumed from only the primary container while a certain minimum amount of gas is saved in the secondary container. When the first fluid connection is closed, gas in the primary container can only be supplied to the breathing device via the primary side and gas in the secondary container can only be supplied to the breathing device via the secondary side. Thus, when the first fluid connection is closed, the gas supplies from the primary container and the secondary container are separated. The minimum amount of gas saved in the secondary container may be set in dependence of regulations and/or intended use of the arrangement, i.e. by setting the first pressure threshold to a certain level.

When the primary pressure eventually decreases below the second pressure threshold, the second valve establishes the second fluid connection between the secondary connection point and the breathing device. The second valve may for example open to establish the second fluid connection.

The primary pressure may be a pressure in the primary side upstream of a primary one-way valve. Alternatively, or in addition, the primary pressure may be a pressure in the primary side between downstream of a primary pressure-reducing valve, e.g. between the primary pressure-reducing valve and the primary one-way valve.

The primary side may alternatively be referred to as a primary system or first system, and the secondary side may be referred to as a secondary system or second system. The first valve and/or the second valve may be a gate valve. The breathing device may be a breathing mask, such as a full face mask (FFM).

The first valve may be arranged to automatically establish the first fluid connection when the secondary pressure increases above the first pressure threshold. The first valve may for example be arranged to open to establish the first fluid connection (and close to close the first fluid connection). Both the primary container and the secondary container can be filled by providing a gas supply to the secondary connection point. For example, a secondary pressure-reducing valve may be detached and replaced with a gas supply connection during filling of the primary container and secondary container.

During initial filling, the secondary pressure may be below the first pressure threshold and the first valve will be closed. Gas is thereby only supplied into the secondary container. Eventually, the secondary pressure will increase above the first pressure threshold and the first valve will open. Gas is then supplied into both the primary container and the secondary container.

The second valve may be arranged to automatically close the second fluid connection when the primary pressure increases above the second pressure threshold. Throughout the present disclosure, the first valve may be referred to as a separation valve and/or the second valve may be referred to as a switching valve.

The arrangement may further comprise a primary container for containing pressurized gas connected to the primary connection point, and a secondary container for containing pressurized gas connected to the secondary connection point. Each of the primary container and the secondary container may be configured to deliver breathing gas under a high pressure. The primary container and the secondary container may be separate. Although being separate, the primary container and the secondary container may be fixed with respect to each other, e.g. in a common container package. Throughout the present disclosure, the primary container may be a primary cylinder and the secondary container may be a secondary cylinder.

The arrangement may further comprise a primary valve between the primary connection point and the primary container. The primary valve may be used to regulate a gas flow from the primary container. The arrangement may further comprise a secondary valve between the secondary connection point and the secondary container. The secondary valve may be used to regulate a gas flow from the secondary container.

A maximum volume of the primary container may differ less than <NUM>%, such as less than <NUM>%, such as less than <NUM>%, from a maximum volume of the secondary container. If the arrangement is used under water, e.g. if the arrangement is used in a self-contained underwater breathing apparatus (SCUBA), the arrangement is very well balanced, at least until the first valve closes the first fluid connection. This is because the amount of gas in the primary container and the secondary container will be equal, or substantially equal, generating equal, or substantially equal buoyancy forces.

The arrangement may thus comprise a container package comprising the primary container and the secondary container. The container package can thereby by symmetric, have a low profile (which reduces the drag coefficient in water) for diving in narrow spaces (e.g. in caves) and improve the balance (pitch and roll) for the diver in the water space. This further increases safety of the arrangement.

The primary side may provide a primary path between the primary container and the breathing device, the secondary side may provide a secondary path between the secondary container and the breathing device, and the primary path and the secondary path may be independent. In this way, an automatic and full redundancy is provided all the way from the gas supply to the breathing device. As long as the breathing device works, the arrangement can withstand a major damage on either the primary side or the secondary side, such as a hose rupture, and still enable the user to breathe. Alternatively, the primary side and the secondary side may be joined upstream of the breathing device in some implementations, e.g. downstream of the second valve and downstream of a second pilot connection point.

The first pressure threshold is higher than the second pressure threshold. The first pressure threshold may for example be set to provide a sufficient gas supply from the secondary container for a safe return, e.g. for a firefighter to return out from a building or for a diver to return to the surface. The first pressure threshold may be between <NUM> bar overpressure and <NUM> bar overpressure, such as between <NUM> bar overpressure and <NUM> bar overpressure, such as between <NUM> bar overpressure and <NUM> bar overpressure, such as <NUM> bar overpressure. As used herein, an overpressure refers to a pressure above the ambient pressure of the arrangement. For example, in case the ambient pressure is <NUM> bar, the absolute value of the first pressure threshold may be <NUM> bar, and in case the ambient pressure is <NUM> bar, the absolute value of the first pressure threshold may be <NUM> bar.

The first pressure threshold may thus be a first threshold value. Alternatively, the first pressure threshold may be a first threshold band. That is, the first valve may open when the secondary pressure increases over an opening pressure within the first threshold band and the first valve may close when the secondary pressure decreases below a closing pressure within the first threshold band, where the opening pressure is higher than the closing pressure. Thus, the first valve may be provided with hysteresis.

Alternatively, or in addition, the second pressure threshold may be between <NUM> bar overpressure and <NUM> bar overpressure, such as between <NUM> bar overpressure and <NUM> bar overpressure, such as <NUM> bar overpressure. The second pressure threshold may thus be a second threshold value. Alternatively, the second pressure threshold may be a second threshold band. That is, the second valve may open when the primary pressure increases over an opening pressure within the second threshold band and the second valve may close when the primary pressure decreases below a closing pressure within the second threshold band, where the opening pressure is higher than the closing pressure. Thus, the second valve may be provided with hysteresis.

The arrangement may further comprise a primary one-way valve arranged on the primary side and a secondary one-way valve arranged on the secondary side. For example, the primary one-way valve and the secondary one-way valve may be arranged in the breathing device. The primary one-way valve may allow a flow to a primary breathing outlet of the breathing device, and block a flow in the opposite direction. The secondary one-way valve may allow a flow to a secondary breathing outlet of the breathing device, and block a flow in the opposite direction. Each of the primary one-way valve and the secondary one-way valve may for example be a check valve.

The arrangement may further comprise an automatic pressure warning device that automatically issues a warning to the user when the pressure in the primary container and/or the pressure in the secondary container decreases below a third pressure threshold. The warning may for example be issued as a blinking light in the breathing device. The third pressure threshold may be lower than the first pressure threshold and/or higher than the second pressure threshold. The third pressure threshold may for example be between <NUM> bar overpressure and <NUM> bar overpressure, such as between <NUM> bar overpressure and <NUM> bar overpressure, such as <NUM> bar overpressure.

Alternatively, or in addition, the arrangement may further comprise a pressure gauge, such as a manometer, associated with each or one of the primary container and the secondary container. For example, in case a diver forgets to read the manometer, is unable to read the manometer due to poor visibility, or upon an error in the manometer, the pressure warning device automatically and independently provides a warning to the user when the pressure decreases below the third pressure threshold. Upon receiving the warning from the pressure warning device, the user should initiate return, e.g. ascend to the surface.

The arrangement may further comprise a primary pressure-reducing valve arranged on the primary side between the primary connection point and the breathing device. In this case, the primary pressure may be a pressure in the primary side downstream of the primary pressure-reducing valve, e.g. between the primary pressure-reducing valve and the breathing device. The primary pressure-reducing valve may be configured to reduce the pressure upstream of the primary pressure-reducing valve to a medium pressure, e.g. between <NUM> bar overpressure and <NUM> bar overpressure.

The arrangement may further comprise a secondary pressure-reducing valve arranged on the secondary side between the secondary connection point and the second valve. In this case, the secondary pressure may be a pressure in the secondary side upstream of the secondary pressure-reducing valve, e.g. between the first valve and the secondary pressure-reducing valve. The secondary pressure-reducing valve may be configured to reduce the secondary pressure to a medium pressure, e.g. between <NUM> bar overpressure and <NUM> bar overpressure.

The arrangement may further comprise a primary high pressure line between the primary connection point and the primary pressure-reducing valve and a secondary high pressure line between the secondary connection point and the secondary pressure-reducing valve. Alternatively, or in addition, the arrangement may further comprise a primary medium pressure line downstream of the primary pressure-reducing valve and a secondary medium pressure line downstream of the secondary pressure-reducing valve.

The second valve may be provided on the secondary medium pressure line. A second pilot connection point, where the primary pressure for the second valve is taken, may be provided on the primary medium pressure line.

The primary side may comprise a primary outlet line, the secondary side may comprise a secondary outlet line, the breathing device may comprise a primary breathing outlet for fluid communication with the primary outlet line; and the breathing device may comprise a secondary breathing outlet for fluid communication with the secondary outlet line.

The primary medium pressure line may transition into the primary outlet line downstream of the second pilot connection point. Alternatively, or in addition, the secondary medium pressure line may transition into the secondary outlet line downstream of the second valve.

According to a further aspect, there is provided a breathing apparatus comprising an arrangement according to the present disclosure. The breathing apparatus may be configured to supply breathing gas to a diver, e.g. for deep diving, or to a firefighter. According to one example, the breathing apparatus is a SCUBA apparatus.

According to a further aspect, there is provided a breathing device for a breathing apparatus, the breathing device comprising a primary connection point, a secondary connection point, a primary breathing outlet for connection to a primary outlet line outside the breathing device via the primary connection point, and a secondary breathing outlet for connection to a secondary outlet line outside the breathing apparatus via the secondary connection point.

The breathing device may further comprise a primary one-way valve arranged between the primary connection point and the primary breathing outlet, and a secondary one-way valve arranged between the secondary connection point and the secondary breathing outlet. Alternatively, or in addition, the breathing device may be a full face breathing mask. The breathing device according to this aspect may be of any type according to the present disclosure.

In the following, an arrangement for a breathing apparatus, and a breathing apparatus comprising such arrangement, will be described. The same or similar reference numerals will be used to denote the same or similar structural features.

<FIG> schematically represents a breathing apparatus <NUM> comprising an arrangement <NUM>. The arrangement <NUM> comprises a primary side <NUM> and a secondary side <NUM>. The arrangement <NUM> further comprises a breathing device <NUM>, here exemplified as a full face breathing mask, a primary connection point <NUM> and a secondary connection point <NUM>. The breathing device <NUM> can be worn by the user (not shown), such that the user breathes through the breathing device <NUM>.

The primary side <NUM> is arranged between the primary connection point <NUM> and the breathing device <NUM>. The secondary side <NUM> is arranged between the secondary connection point <NUM> and the breathing device <NUM>.

The arrangement <NUM> of this example further comprises a primary container <NUM> and a secondary container <NUM>. Each of the primary container <NUM> and the secondary container <NUM> contains pressurized breathing gas, for example air or nitrox. The pressures in the primary container <NUM> and the secondary container <NUM> may be at least <NUM> bar, such as at least <NUM> bar, when filled. The primary container <NUM> and the secondary container <NUM> are rigid and have identic volumes.

The arrangement <NUM> further comprises a primary valve <NUM>, here exemplified as a shut-off valve. The primary container <NUM> is connected to the primary connection point <NUM> via the primary valve <NUM>. The primary valve <NUM> is used to open a gas flow from the primary container <NUM>, such that the primary container <NUM> is in fluid communication with the primary connection point <NUM>.

The arrangement <NUM> further comprises a secondary valve <NUM>, here exemplified as a shut-off valve. The secondary container <NUM> is connected to the secondary connection point <NUM> via the secondary valve <NUM>. The secondary valve <NUM> is used to open a gas flow from the secondary container <NUM>, such that the secondary container <NUM> is in fluid communication with the secondary connection point <NUM>.

The arrangement <NUM> further comprises a first valve <NUM>. The first valve <NUM> is arranged between the primary connection point <NUM> and the secondary connection point <NUM>. The first valve <NUM> is arranged to automatically close to close a first fluid connection between the primary connection point <NUM> and the secondary connection point <NUM> when a secondary pressure in the secondary side <NUM> decreases below a first pressure threshold. The first valve <NUM> of this example is also arranged to automatically open to establish the first fluid connection when the secondary pressure increases above the first pressure threshold. In this example, the first pressure threshold is <NUM> bar overpressure.

The arrangement <NUM> of the example in <FIG> comprises an intermediate line <NUM> between the primary connection point <NUM> and the secondary connection point <NUM>, and the first valve <NUM> is a gate valve arranged on the intermediate line <NUM>. The first valve <NUM> comprises a first pilot line <NUM>. The first pilot line <NUM> is connected to a first pilot connection point <NUM> on the secondary side <NUM>, between the secondary connection point <NUM> and the first valve <NUM>.

The primary side <NUM> of this example comprises a primary high pressure line <NUM>, a primary medium pressure line <NUM> and a primary outlet line <NUM>. Each of the primary high pressure line <NUM>, the primary medium pressure line <NUM> and the primary outlet line <NUM> may be implemented as a flexible hose. Also the intermediate line <NUM> may be implemented as a flexible hose.

The secondary side <NUM> of this example comprises a secondary high pressure line <NUM>, a secondary medium pressure line <NUM> and a secondary outlet line <NUM>. Each of the secondary high pressure line <NUM>, the secondary medium pressure line <NUM> and the secondary outlet line <NUM> may be implemented as a flexible hose.

The arrangement <NUM> further comprises a primary regulator or primary pressure-reducing valve <NUM> and a secondary regulator or secondary pressure-reducing valve <NUM>. The primary pressure-reducing valve <NUM> is provided on the primary side <NUM>, between the primary high pressure line <NUM> and the primary medium pressure line <NUM>. The secondary pressure-reducing valve <NUM> is provided on the secondary side <NUM>, between the secondary high pressure line <NUM> and the secondary medium pressure line <NUM>. Thus, the primary pressure-reducing valve <NUM> is provided downstream of the primary high pressure line <NUM> and the secondary pressure-reducing valve <NUM> is provided downstream of the secondary high pressure line <NUM>.

The primary pressure-reducing valve <NUM> is configured to reduce the pressure in the primary high pressure line <NUM> to a medium pressure, e.g. of <NUM> bar overpressure to <NUM> bar overpressure, in the primary medium pressure line <NUM>. The secondary pressure-reducing valve <NUM> is configured to reduce the pressure in the secondary high pressure line <NUM> to a medium pressure, e.g. of <NUM> bar overpressure to <NUM> bar overpressure, in the secondary medium pressure line <NUM>.

One or more buoyancy control devices (not shown) may be connected to the primary pressure-reducing valve <NUM> and the secondary pressure-reducing valve <NUM>. One example of such buoyancy control device is an inflatable dry suit.

The arrangement <NUM> further comprises a second valve <NUM>. The second valve <NUM> is arranged on the secondary side <NUM>. The second valve <NUM> is arranged to automatically open to establish a second fluid connection between the secondary connection point <NUM> and the breathing device <NUM> when a primary pressure in the primary side <NUM> decreases below a second pressure threshold. The second valve <NUM> of this example is also arranged to automatically close to close the second fluid connection when the primary pressure increases above the second pressure threshold. In this example, the second pressure threshold is <NUM> bar overpressure.

The second valve <NUM> is here exemplified as a gate valve arranged on the secondary medium pressure line <NUM>. The second valve <NUM> comprises a second pilot line <NUM>. The second pilot line <NUM> is connected to a second pilot connection point <NUM> on the primary side <NUM>. In this example, the second pilot connection point <NUM> is provided on the primary medium pressure line <NUM>.

Downstream of the second pilot connection point <NUM>, the primary medium pressure line <NUM> transitions into, or is integrally formed with, the primary outlet line <NUM>. Thus, the primary medium pressure line <NUM> and the primary outlet line <NUM> may be formed by one single hose, or by two connected hoses. The arrangement <NUM> comprises a primary one-way valve <NUM>, here exemplified as a check valve, on the primary outlet line <NUM>. In this example, the primary one-way valve <NUM> is arranged on the primary outlet line <NUM> inside the breathing device <NUM>.

Downstream of the second valve <NUM>, the secondary medium pressure line <NUM> transitions into, or is integrally formed with, the secondary outlet line <NUM>. Thus, the secondary medium pressure line <NUM> and the secondary outlet line <NUM> may be formed by one single hose, or by two connected hoses. The arrangement <NUM> comprises a secondary one-way valve <NUM>, here exemplified as a check valve, on the secondary outlet line <NUM>. In this example, the secondary one-way valve <NUM> is arranged on the secondary outlet line <NUM> inside the breathing device <NUM>.

The breathing device <NUM> of this example comprises a primary breathing outlet <NUM> and a secondary breathing outlet <NUM>. The primary breathing outlet <NUM> comprises a primary breathing valve <NUM> and the secondary breathing outlet <NUM> comprises a secondary breathing valve <NUM>. The primary breathing valve <NUM> is connected to the primary outlet line <NUM> and the secondary breathing valve <NUM> is connected to the secondary outlet line <NUM>.

The primary one-way valve <NUM> allows gas flow in a direction towards the primary breathing outlet <NUM>, and prevents gas flow in an opposite direction. The secondary one-way valve <NUM> allows gas flow in a direction towards the secondary breathing outlet <NUM>, and prevents gas flow in an opposite direction.

As illustrated in <FIG>, the primary outlet line <NUM> and the secondary outlet line <NUM> are connected to separate attachment points (not denoted) on the breathing device <NUM>. Thereby, a primary fluid path is provided from the primary container <NUM>, through the primary side <NUM> and to the primary breathing outlet <NUM> of the breathing device <NUM>, and a secondary fluid path, independent from the primary fluid path, is provided from the secondary container <NUM>, through the secondary side <NUM> and to the secondary breathing outlet <NUM> of the breathing device <NUM>.

In order to fill the primary container <NUM> and the secondary container <NUM> with pressurized gas, the secondary pressure-reducing valve <NUM> may be temporarily disconnected and a source of pressurized gas may be connected to the secondary side <NUM>, i.e. at the position of the secondary pressure-reducing valve <NUM>. During filling, the secondary pressure may initially be lower than the first pressure threshold controlling the operation of the first valve <NUM>. The first valve <NUM> is then consequently closed and the gas is only supplied to the secondary side <NUM> and the secondary container <NUM> to increase the secondary pressure. When the secondary pressure increases above the first pressure threshold, the first valve <NUM> opens. During further filling, pressurized gas is supplied to the primary side <NUM> and the primary container <NUM> until the pressure in the primary container <NUM> reaches the first pressure threshold. During further filling, pressurized gas is supplied to both the primary side <NUM> and the secondary side <NUM> such that the pressure in the primary container <NUM> and the pressure in the secondary container <NUM> each reaches a desired level, e.g. <NUM> bar.

The primary valve <NUM> and the secondary valve <NUM> may be used to perform a precheck, e.g. to check the functionality of the breathing apparatus <NUM> before diving. By means of the primary valve <NUM> and the secondary valve <NUM>, various failure modes can be simulated without consuming much gas. The primary valve <NUM> and the secondary valve <NUM> may then be fully open during use.

When the primary container <NUM> and the secondary container <NUM> have been filled and the user has started to breathe pressurized gas from the breathing device <NUM>, the secondary pressure is initially above <NUM> bar overpressure and the secondary pressure is initially above <NUM> bar overpressure. Thus, the first valve <NUM> is open and the second valve <NUM> is closed. Thereby, pressurized gas is initially supplied to the breathing device <NUM> from both the primary container <NUM> and the secondary container <NUM> via the primary side <NUM>. During normal use of the breathing apparatus <NUM>, each of the primary valve <NUM> and the secondary valve <NUM> is open so that the pressure prevailing in the primary container <NUM> prevails at the primary connection point <NUM> and the pressure prevailing in the secondary container <NUM> prevails at the secondary connection point <NUM>. Eventually, when secondary pressure (e.g. at the secondary connection point <NUM>) decreases below the first pressure threshold, the first valve <NUM> closes.

After closing of the first valve <NUM>, the user only consumes pressurized gas from the primary container <NUM> through the primary side <NUM>. By closing the first valve <NUM>, a certain amount of gas is reserved in the secondary container <NUM>. After further consumption of pressurized gas from the primary container <NUM>, the pressure in the primary container <NUM> will eventually decrease below a third pressure threshold, such as <NUM> bar overpressure. A pressure warning device (not shown) may thereby issue a signal to the user for safe return.

After further consumption of pressurized gas from the primary container <NUM>, the primary pressure (e.g. at the second pilot connection point <NUM>) will eventually decrease below the second pressure threshold. The second valve <NUM> will thereby automatically open to initiate a supply from the secondary container <NUM> to the breathing device <NUM> via the secondary side <NUM> during return by the user.

In case of damage on the primary side <NUM>, e.g. due to a rupture of any of the primary high pressure line <NUM>, the primary medium pressure line <NUM> or the primary outlet line <NUM>, the primary pressure will rapidly decrease to an ambient pressure level. This will cause the pressure warning device to issue a warning signal to the user and the second valve <NUM> to open. Pressurized gas can now be consumed from secondary container <NUM> through the intact secondary side <NUM>.

In case of a damage on the secondary side <NUM>, e.g. due to a rupture of any of the secondary high pressure line <NUM>, the secondary medium pressure line <NUM> or the secondary outlet line <NUM>, the secondary pressure will rapidly decrease to an ambient pressure level. This will cause the first valve <NUM> to automatically close. The pressure in the primary container <NUM> will in this case remain substantially unchanged and gas in the primary container <NUM> can still be consumed through the primary side <NUM>. Eventually, the pressure in the primary container <NUM> will decrease below the third pressure threshold and the automatic warning by the pressure warning device will be issued, so that the user knows he/she has to initiate safe return, if not already initiated upon the damage on the secondary side <NUM>.

Claim 1:
An arrangement (<NUM>) for a breathing apparatus (<NUM>), the arrangement (<NUM>) comprising:
- a breathing device (<NUM>);
- a primary connection point (<NUM>) for fluid communication with a primary container (<NUM>);
- a secondary connection point (<NUM>) for fluid communication with a secondary container (<NUM>);
- a primary side (<NUM>) arranged between the primary connection point (<NUM>) and the breathing device (<NUM>);
- a secondary side (<NUM>) arranged between the secondary connection point (<NUM>) and the breathing device (<NUM>);
- a first valve (<NUM>) arranged between the primary connection point (<NUM>) and the secondary connection point (<NUM>), the first valve (<NUM>) being arranged to automatically close a first fluid connection between the primary connection point (<NUM>) and the secondary connection point (<NUM>) when a secondary pressure in the secondary side (<NUM>) decreases below a first pressure threshold; and
- a second valve (<NUM>) arranged on the secondary side (<NUM>), the second valve (<NUM>) being arranged to automatically establish a second fluid connection between the secondary connection point (<NUM>) and the breathing device (<NUM>) when a primary pressure in the primary side (<NUM>) decreases below a second pressure threshold;
wherein the first pressure threshold is higher than the second pressure threshold.