Closed-circuit breathing apparatus and procedures for checking the operational readiness of a closed-circuit breathing apparatus

Abstract

Method (100) for checking the operational readiness of a closed-circuit breathing apparatus (1) in a step sequence for carrying out the check with the steps: - Continuous metrological acquisition (104, 104') and recording of pressure measurement signals P L a low-pressure sensor (41) arranged in or on a low-pressure system (77) of the closed-circuit breathing apparatus (1), - Identification based on the pressure measurement signal P L (81) of the low-pressure sensor (41) whether there is currently a situation in which an inflow of quantities of gas into the low-pressure system (77) has begun, - Storage of a first pressure measurement signal P1 (109) at a first time t1 (108), which indicates the identified pressure situation immediately after the start of the inflow of gas quantities into the low-pressure system (77) with a breathing bag (3), - Storage of a second pressure measurement signal P2 (114), which indicates a pressure situation at the end of the inflow of gas quantities into the low-pressure system (77) at a second time t2 (113), - Formation (115) of a difference value ΔP (ΔP = P2 - P1) (116) between the first pressure signal P, (109) and the second pressure signal P2 (114), - Performing a comparison (117) between the difference value ΔP (116) with a difference threshold value P C (118) - Determining a result (94, 95) of the verification of the functionality of the closed-circuit breathing apparatus based on the comparison (117), - Provision of an output signal (88) which indicates the result (94, 95) of the check.

Description

[0001] The invention relates to a method for checking the operational readiness of a closed-circuit breathing apparatus and a closed-circuit breathing apparatus with a breathing gas circuit. Closed-circuit breathing apparatuses are often also referred to as closed-circuit respirators, LDBAs (Long Duration Breathing Apparatus), or SCBAs (Self-Contained Breathing Apparatus). According to the invention, the closed-circuit breathing apparatus is designed to perform an operational readiness check exclusively using means that are arranged as components in or on the closed-circuit breathing apparatus within an insert. The means that enable the check include, as essential components, a control unit and sensors, in particular pressure sensors.

[0002] The method according to the invention enables the functional readiness of a closed-circuit breathing apparatus to be checked using only components of the breathing apparatus. In closed-circuit breathing apparatus, particularly in closed-circuit breathing devices, breathing is performed in a closed loop to reduce weight and increase operating time, and only the oxygen consumed is replaced from a pressurized gas supply and fed back into the circuit. An accumulation of exhaled carbon dioxide (CO2) in the circuit to physiologically problematic levels must be avoided. For this purpose, a CO2 absorber with an absorbent is present in the circuit, which removes the CO2 from the breathing circuit. The amounts of oxygen consumed by the breathing and metabolism of the wearer – and exhaled as carbon dioxide and removed from the exhaled gas by the CO2 absorber – must be replaced by fresh oxygen.This is achieved by replenishing oxygen from the pressurized gas supply. This replenishment is carried out by metering oxygen through a valve into a breathing bag within the closed-circuit breathing apparatus. The breathing bag is a flexible bag into which the air exhaled by the user, after CO2 removal by the CO2 absorber, is collected and returned to the circulatory system. The metering into the breathing bag is typically controlled by a valve assembly. This valve assembly meteres the oxygen into the breathing bag, or into the breathing circuit, in such a way that the breathing bag remains constantly filled. The metering process replenishes the amount of oxygen required by the user's breathing.To prevent any possibility of harmful gases entering the breathing apparatus's circuit and thus reaching the user, the closed-circuit breathing apparatus is operated in such a way that the circuit maintains positive pressure relative to the ambient environment. This means that any loss of gas in the circuit necessitates the addition of oxygen through metering. To accommodate varying levels of user respiration, as well as any leaks, the metering into the breathing bag or the breathing circuit can, according to current technology, be achieved using two different operating principles: constant metering or demand metering. These two principles can be implemented in various ways in closed-circuit breathing apparatus designs, either as independent operating modes or in combination.A first dosing device can be used, for example, to continuously dose oxygen from the pressurized gas supply into the breathing bag or the breathing circuit at a substantially constant flow rate, such as 1 l / min to 2 l / min. A second dosing device can then be used to supplement this by adding an additional amount of oxygen on demand, specifically when the breathing bag is nearly empty. The breathing bag is equipped with a lever mechanism connected to the second dosing device, so that the second device is linked to the movement of the breathing bag and releases an additional amount of oxygen into the bag whenever it is nearly empty.Such a secondary metering device is also known as a minimum flow valve and is usually opened by means of a lever mechanism attached to the breathing bag once the bag has largely collapsed, meaning only a small volume of breathing gas remains. This allows an additional amount of oxygen to be metered and supplied to the circulatory system, in addition to the continuously metered, essentially constant flow rate. In commonly used devices, a pressure gauge provides continuous pressure measurement and display, thus keeping the user constantly informed about the available breathing gas supply. A warning device indicates when the breathing gas supply is running low. These pressure gauges and warning devices can be mechanical / pneumatic or electronic, utilizing electronic components and sensors.

[0003] DE 10 2014 017 634 B4 discloses a closed-circuit breathing apparatus with a measuring device for determining gas quantities. The closed-circuit breathing apparatus is designed with a circuit for breathing gas and a measuring device for determining gas quantities. The measuring device has at least one measuring element and an evaluation unit to detect movements of the breathing bag as measured variables and to determine the tidal volume.

[0004] US Patent 4,364,384A discloses a pressurized oxygen rebreather with positive pressure in the breathing circuit, which has a valve. This valve is designed with an additional function in its mechanical lever mechanism: when the breathing bag is completely empty, the valve closes and the delivery stops. This ensures that in the event of a major leak, the pressurized gas supply is not completely depleted.

[0005] German patent application DE 82 01 997 U1 discloses a breathing apparatus with a closed-loop air supply. Air and oxygen from a compressed air cylinder and an oxygen cylinder are fed into the breathing bag by means of a self-regulating compensating gas supply valve and a changeover valve.

[0006] German patent DE 34 29 345 C2 discloses a closed-circuit breathing apparatus that can be operated under positive pressure, whereby movements of the breathing bag via a compressed gas line and an auxiliary device cause a pressure increase in the breathing circuit. A measuring circuit is also provided to detect breathing phases, so that during the exhalation phase the auxiliary device causes the pressure increase in the breathing bag.

[0007] US Patent 10,252,089 B2 discloses a monitoring device for monitoring a wearer of a respiratory protective device, wherein the monitoring device is configured to determine whether breathing has begun using the respiratory protective device and to activate the metering of quantities of breathing gas if the wearer has begun breathing.

[0008] US 10,183,184 B2 discloses a method for operating a closed-circuit breathing apparatus, wherein a pressure measurement within the breathing circuit is used to determine whether sufficient quantities of breathing gases are supplied to the breathing circuit, and a warning is issued based on the pressure measurement if insufficient quantities of breathing gases are supplied to the breathing circuit.

[0009] Further state-of-the-art information on closed-circuit breathing apparatus can be found in US 4,879,996 A, US 5,048,517 A, and US 4,266,539 A. Various systems are known for cooling the breathing air. One common method is cooling with ice, as described, for example, in DE 33 45 584 C1. Alternative methods for cooling breathing gases include zeolite-water coolers, evaporative coolers, and wax coolers.

[0010] Reliable operational readiness and functionality of closed-circuit breathing apparatus (CCBA) is of paramount importance to the wearer. The wearer must be certain that the CCBA intended for use is fully functional. In typical operational situations, the devices are cleaned, inspected, and prepared for the next use by a designated maintenance technician after each use. This involves checking the control unit and internal sensors for leaks in the high-pressure and / or low-pressure systems, as well as verifying the correct configuration of internal components such as pneumatic or electrical connections, breathing bags, gas coolers, CO2 absorbers, valves, compressed gas cylinder, control unit, display unit (or combined control and display unit), energy storage, and the sensors themselves within the housing.Furthermore, an external testing device can be used to verify whether the breathing detection function, via sensors and a control unit, is functioning correctly for the wearer. This breathing detection function is essential for the use of a closed-circuit breathing apparatus, as it allows the wearer to be alerted or receive an alarm if they have started breathing while the compressed gas cylinder is either not open or already empty. Therefore, in addition to the leak tests already mentioned, it is crucial for the equipment technician to verify this function during equipment maintenance and preparation. The external testing device can simulate breathing while using the closed-circuit breathing apparatus. A disadvantage of using such an external testing device is that it is not always readily available.The present invention therefore addresses the question of providing a way to verify the functionality of breathability detection without an external testing device. A constraint for a successful solution to this problem, which is also reflected in the design of the solution according to the invention, is the fact that a deterministic methodology for breathability detection implemented in the control unit does not itself need to be verified; rather, it is only necessary to ensure that the measurement signals or data from the low-pressure sensor are available without errors for the application of the methodology.Since cleaning and reconditioning of a closed-circuit breathing apparatus requires checking, possibly replacing, and depending on their condition, rerouting or reconnecting pneumatic lines between the low-pressure sensor and the pressure measurement point in the low-pressure system, as well as electrical lines between the low-pressure sensor and electronics with signal acquisition and processing in the control unit, the object of the present invention is extended to ensure the correct configuration and proper assembly of the closed-circuit breathing apparatus after maintenance work has been completed, even without the need for an external testing device. In connection with checking pneumatic lines, correct connection of plugs / couplings must also be guaranteed, especially when self-locking pneumatic plugs are used.

[0011] The object of the present invention is therefore to provide a method for checking the operational readiness of a closed-circuit breathing apparatus.

[0012] Another object of the present invention is to provide a computer program or a computer program product which enables a check of the operational readiness of a closed-circuit breathing apparatus.

[0013] Another object of the present invention is to provide a closed-circuit breathing apparatus whose operational readiness can be verified internally.

[0014] The problem of providing a method for testing a closed-circuit breathing apparatus is solved by a method with the features of claim 1.

[0015] The tasks of providing a computer program or a computer program product for testing a closed-circuit breathing apparatus are solved by a computer program or a computer program product having the features of claim 8.

[0016] The problem of a closed-circuit breathing apparatus with internal verification of operational readiness is solved with a device having the features of claim 9 and with a closed-circuit breathing apparatus having the features of claim 10.

[0017] The method according to the invention enables the operational readiness of the closed-circuit breathing apparatus to be checked without an external test device. The closed-circuit breathing apparatus according to the invention is designed to enable the operational readiness of the closed-circuit breathing apparatus to be checked without an external test device by means of a control unit and internal sensors suitable for pressure measurement.

[0018] Advantageous embodiments of the invention are set forth in the dependent claims and are explained in more detail in the following description with partial reference to the figures. Features and details described in connection with the closed-circuit breathing apparatus naturally also apply in connection with the inventive method for checking the operational readiness of the closed-circuit breathing apparatus, and vice versa, so that the disclosure regarding the individual aspects of the invention is always, or can always be, mutually referenced.

[0019] A closed-circuit breathing apparatus with a breathing circuit has the following essential components: - Hose system with a mouthpiece for supplying quantities of breathing gases as inhalation gas to a device wearer and for conveying quantities of exhaled breathing gases from the device wearer out of the breathing circuit, - a pressurized gas cylinder filled with oxygen, operating under a high pressure above 100 hPa, as a pressurized gas supply, - a pressure reducer to reduce the high pressure to a low pressure in the range slightly above the pressure of the operating environment of the device carrier, - a CO2 absorber, which serves to chemically bind CO2 in the breathing gas and represents a heat source due to the heat of reaction generated during the chemical binding of CO2, - a breathing bag for buffering quantities of respiratory gases in the respiratory circuit, - an optional breathing gas cooler functioning as a heat sink, which is arranged in the direction of circulation in the breathing circuit behind the heat source and in front of the mouthpiece to cool heated quantities of breathing gases during operation, - a valve arrangement with at least one metering valve for metering quantities of oxygen from the pressurized gas supply into the breathing circuit or breathing bag by means of the pressure reducer, - internal sensors, in particular pressure sensors and a control unit for monitoring during operation and for checking the functions of the closed-circuit breathing apparatus, - at least one display unit for providing information and alerts to the device operator and guidance to the device operator when performing test or verification routines, - at least one control unit for operating functions of the closed-circuit breathing apparatus, for carrying out test or check routines as well as for acknowledging messages and / or alarms, - at least one energy storage device to supply the control unit, sensors, operating unit and display unit with electrical energy, - in addition, in standard designs a housing shell to accommodate the aforementioned components as well as - a carrying frame connected to the housing shell with a strap system for use of the closed-circuit breathing apparatus by the wearer in operation.

[0020] The control unit and display unit can also be combined into a single control and display unit. First, some of the terminology used in this patent application, as well as the basic principle of a closed-circuit breathing apparatus, will be explained in more detail. For the purposes of this invention, high pressure is defined as a pressure range of 100 hPa to 300 hPa. Low pressure, for the purposes of this invention, is defined as a pressure range with a difference of more than 1 hPa and less than 10 hPa above the pressure in the operating environment of the device.

[0021] The high-pressure system of the closed-circuit breathing apparatus consists of a pressurized gas cylinder filled with oxygen under high pressure, a manual cylinder valve for opening the cylinder, a pressure regulator designed to reduce the high pressure to a low pressure within the range of ambient pressure, high-pressure lines connecting the cylinder valve and the pressure regulator, and a pressure sensor – hereinafter referred to as the high-pressure sensor – located on the high-pressure system. This sensor is designed and configured to detect the pressure level within the high-pressure system. The high-pressure sensor is configured to transmit signals or data indicating the pressure level in the high-pressure system to the control unit via data transmission.

[0022] A low-pressure system of the closed-circuit breathing apparatus comprises the hose system with the mouthpiece for connection to the user's breathing mask, the breathing bag, the valve assembly, the CO2 absorber, the optional breathing gas cooler, low-pressure lines connecting the pressure reducer, breathing bag, CO2 absorber, breathing gas cooler, valve assembly, and a pressure sensor located on the low-pressure system – hereinafter referred to as the low-pressure sensor – which is designed and configured to detect the pressure level within the low-pressure system, as is the breathing mask itself if it is connected to the mouthpiece. The low-pressure sensor is designed to transmit signals or data indicating a pressure level within the low-pressure system to the control unit via data transmission. The low-pressure sensor can be located at various points within the breathing circuit or on components of the low-pressure system.Examples of suitable measurement locations include the breathing bag, the CO2 absorber, the breathing gas cooler, or the valve assembly. The choice of measurement location for the low-pressure sensor in the breathing circuit, as determined by the technical implementation of closed-circuit breathing apparatus, is based on criteria such as maintainability, available space and accessibility within the device, signal quality, and minimal susceptibility to errors and malfunctions. From the perspective of good maintainability, coupling the low-pressure sensor to the breathing gas cooler is advantageous, and coupling it to the CO2 absorber is particularly beneficial.

[0023] Optional versions of the closed-circuit breathing apparatus may also include a pre-purge system. This system, activated by opening the cylinder valve of the compressed gas cylinder when the breathing apparatus is switched on, ensures a continuous flow of oxygen for a predetermined period, so that the breathing bag is filled with a defined volume of oxygen before breathing begins. Such a pre-purge system is particularly important in closed-circuit breathing apparatus without a constant metering function, ensuring that the wearer is supplied with oxygen immediately at the start of breathing and thus preventing the wearer from re-inhaling significant amounts of previously exhaled gas.

[0024] In certain versions or configurations of the closed-circuit breathing apparatus, an optional manual metering element (bypass element) may be incorporated into the low-pressure system. Such a manual metering element (bypass element) – usually designed as a control knob for manual activation – allows the wearer to add an additional amount of oxygen to the low-pressure system, and thus directly into the breathing circuit, as needed. This can improve the wearer's comfort in situations involving very high physical exertion. Furthermore, the manual metering element (bypass element) can be used to vent the high-pressure system when the cylinder valve is closed.

[0025] The control unit is designed to coordinate the operation and / or routines for checking the functions of the closed-circuit breathing apparatus. The control unit is designed to receive the data or signals from the high-pressure and low-pressure sensors, process them using signal processing (A / D conversion) and / or signal amplification (op-amps) and / or signal filtering, process them using a computing unit, and perform evaluations with the processed data. The computing unit can, for example, be a processor unit (microprocessor, microcontroller) with associated data memory (RAM, ROM). Thus, the computing unit—and therefore also the control unit—can, for example, be configured and programmed using program code to evaluate the data or signals from the low-pressure sensor to determine whether the wearer has begun breathing.

[0026] The control unit or processing unit can, for example, be configured or programmed to evaluate data or signals from the high-pressure sensor to determine whether the pressure in the high-pressure system is sufficient for the upcoming use of the closed-circuit breathing apparatus on the wearer. A lower threshold value of, for example, 150 Pa can be used by the control unit to indicate sufficient filling of the compressed gas supply. The valve arrangement comprises at least one metering valve, preferably a metering valve for constant metering, a minimum pressure valve that can be activated by movement of the breathing bag, and a pressure relief valve for relieving pressure in the breathing bag, for example, in the event of a malfunction in the compressed gas supply.To enable the breathing bag to fill and empty itself with a cyclical movement of inhaled and exhaled air, the closed-circuit breathing apparatus includes a base plate, a spring bridge, a breathing bag plate, and a spring assembly as additional components. The base plate and the spring bridge, acting as a kind of support bracket, are positioned at a predetermined distance from each other within the breathing apparatus. The breathing bag is held to the base plate on one side (underside), while the breathing bag plate is attached to the opposite side (top) of the breathing bag.The spring assembly is positioned between the breathing bag plate and the spring bridge with a predetermined spring tension. By supporting the spring assembly against the spring bridge, a force is exerted on the breathing bag plate and thus on the breathing bag itself. This predetermined spring tension creates a specific pressure on the breathing bag. This pressure results in an overpressure within the breathing bag, ranging from 1 hPa to 10 hPa relative to the ambient pressure. In operation, the closed-circuit breathing apparatus is used by the user. Through the hose system and mouthpiece, which connects to a mask, the required amount of breathing gas is drawn from the breathing bag of the rebreather via the inhalation valve. This gas passes through an optional gas cooler during inhalation, and is then exhaled back into the breathing bag via the exhalation valve.The inflow of gas into the breathing bag and the outflow from the breathing bag are thus achieved through the user's breathing.

[0027] This process cyclically circulates a volume of air within the breathing bag, removing carbon dioxide from the system via the CO2 absorber. Sufficient oxygen is then added from the pressurized gas supply through at least one metering valve, thus compensating for the removed carbon dioxide and ensuring a supply of fresh breathing gas in the bag. The positive pressure within the breathing bag ensures that this pressure is maintained in the mask worn by the user, preventing any leaks from allowing ambient air to enter the mask. This is particularly important because ambient air can contain pollutants that could pose a health risk to the user if inhaled.

[0028] In a method according to the invention for checking the operational readiness of a closed-circuit breathing apparatus, the following steps are carried out in a sequence 1 - 8: 1. Continuous metrological acquisition and recording of pressure measurement signals P L a low-pressure sensor arranged in or on a low-pressure system of the closed-circuit breathing apparatus, 2. Identification based on the pressure measurement signal P L of the low-pressure sensor, whether there is currently a situation in which a flow of gas into the low-pressure system with a breathing bag has begun, 3. Storage of a first pressure measurement signal P1 at a first time t1, which indicates the identified pressure situation immediately after the start of the inflow of gas quantities into the low-pressure system, 4. Storage of a second pressure measurement signal P2, which indicates a pressure situation at the end of the gas flow into the low-pressure system at a second time t2, 5. Calculation of a difference value ΔP (ΔP = P2 - P1) between the first pressure signal P1 and the second pressure signal P2, 6. Performing a comparison between the difference value ΔP and a difference threshold value P C , 7. Determining a result of the functional test of the closed-circuit breathing apparatus based on comparison, 8. Provision of an output signal that indicates the result of the check.

[0029] The aforementioned sequence of steps in the procedure can, for example, be carried out by the control unit previously described in the description of the present invention for checking the operational readiness of a closed-circuit breathing apparatus. A closed-circuit breathing apparatus can be equipped with such a control unit, which is designed and intended to coordinate and / or monitor the operation of the closed-circuit breathing apparatus during use and also to perform a check of the closed-circuit breathing apparatus.

[0030] This allows changes in the values ​​of the continuously recorded measured values ​​P LFor the low-pressure sensor to function correctly, a situation must exist within the closed-circuit breathing apparatus where breathing gas is currently flowing into the low-pressure system, particularly into the breathing bag. Such a situation can arise, for example, from the opening of the cylinder valve of the closed-circuit breathing apparatus's compressed gas supply. When performing the comparison between the difference value ΔP and the difference threshold value P C The control unit determines whether there is a difference ΔP in the pressure level of the low-pressure system between the start and end of the inflow into the breathing bag. The differential threshold value P CFor example, a predetermined value in the range of 0.75 hPa to 1.5 hPa, preferably a value of 1.0 hPa, can be selected. If – despite filling the breathing bag – no difference ΔP in the pressure level of the low-pressure system can be determined by the control unit, a situation may arise in which the low-pressure sensor was unable to correctly measure the pressure level in the low-pressure system, at least during the execution of the check at the first and / or second time point t1, t2.Such a situation can, for example, indicate a defect in the low-pressure sensor or be an indication that there is no correct fluidic-pneumatic coupling of the low-pressure sensor to the low-pressure system, such as to the breathing bag or the CO2 absorber, which can be caused, for example, by a pressure measuring line - for example by means of a pneumatic connector - not being correctly connected to the CO2 absorber and thus the low-pressure sensor cannot measure pressure values ​​that indicate a pressure level of the low-pressure system.

[0031] Provided that the pressure difference ΔP exceeds the difference threshold P C If the value exceeds the limit, the low-pressure sensor is functioning correctly. In such a case, a positive test result (pass) can be displayed, for example, on an operating and display unit.

[0032] Provided that the pressure difference ΔP exceeds the difference threshold P C If the limit is not exceeded, a negative verification result (Fail) is provided, e.g. as an output on the operating and display unit.

[0033] In a preferred embodiment, a first low-pressure comparison of the measured values ​​P can be performed at the first time t1 – for example, by means of implementation through the control unit. L of the low-pressure sensor with a first lower low-pressure threshold P A This will be done. The first lower threshold P A For example, a predetermined value in the range of 1.8 hPa to 2.2 hPa, preferably a value of 2.0 hPa, can be selected. Provided that the measured value P is at the first time t1 L of the low-pressure sensor the first lower low-pressure threshold P AIf the measured value P exceeds this, a situation exists in the closed-circuit breathing apparatus where quantities of breathing gas are currently flowing into the low-pressure system, particularly into the breathing bag. This allows further testing of the closed-circuit breathing apparatus to continue. In such a case, a positive test result (passport) can also be generated, for example, on a control and display unit. Provided the measured value P L of the low-pressure sensor the lower low-pressure threshold P AIf the pressure does not exceed the set limit, there is no situation in the closed-circuit breathing apparatus where any amount of breathing gas can currently flow into the low-pressure system, particularly into the breathing bag. In such a case, a negative test result (Fail) can be displayed, for example, on a control and display unit. After troubleshooting the closed-circuit breathing apparatus by maintenance personnel, the functional test of the breathing apparatus is then usually repeated.

[0034] In a further preferred embodiment of the method, a second low-pressure comparison of the measured values ​​P can be carried out at the second time t2 – for example, by means of implementation through the control unit. L of the low-pressure sensor with a second lower low-pressure threshold P B This will occur. As the second lower threshold P B For example, a predetermined value can be set above the pressure level of the first lower threshold P.A , preferably a value of 2.5 hPa should be chosen. Provided that the measured value P is at the second time t2. L of the low-pressure sensor the second lower low-pressure threshold P B If the measured value P exceeds the specified value, the breathing bag is sufficiently filled with breathing gases. The second low-pressure value, P2, indicates a pressure level in the low-pressure system at the end of the filling process with a sufficient amount of breathing gas to begin inhalation. This allows further testing of the closed-circuit breathing apparatus to continue and a positive test result (passport) to be generated, for example, on a control and display unit. Provided the measured value P L of the low-pressure sensor the second lower low-pressure threshold P BIf the pressure does not exceed the specified limit, the breathing bag is not sufficiently inflated to initiate ventilation. In such a case, a negative test result (Fail) may be displayed, for example, on a control and display unit. After troubleshooting the closed-circuit breathing apparatus by maintenance personnel, the functional test of the breathing apparatus is then usually repeated.

[0035] In a further preferred embodiment of the method, a third low-pressure comparison of the measured values ​​P can be carried out at a third time t3 – for example, by means of implementation via the control unit – to check a relief valve and / or drainage valve arranged at an outlet of the breathing bag. L of the low-pressure sensor with an upper low-pressure threshold P EThis involves checking a pressure relief valve located in or on the breathing bag, which in typical designs opens at a pressure level P. L The system checks whether the pressure in the breathing bag exceeds 8 hPa, allowing excess breathing gas to escape. Conversely, a drainage valve located in or on the low-pressure system is tested to drain accumulated fluid from the breathing bag, typically operating at a pressure level P. L In the breathing bag, excess fluid drains out in a range above 15 hPa to 20 hPa. The upper threshold value is P. E For example, a predetermined value in a range of 7 hPa to 20 hPa, preferably a value of 16 hPa, can be selected.

[0036] Provided that at the third time t3 the measured value P L of the low-pressure sensor the upper low-pressure threshold P EIf the pressure does not exceed a certain value, the correct function of the relief valve on the breathing bag and / or the drainage valve is ensured. In such a case, a positive verification result (passport) can be provided, for example, on a control and display unit.

[0037] Provided that at the third time t3 the measured value P L of the low-pressure sensor the upper low-pressure threshold P E If the pressure exceeds the specified value, the correct function of the relief valve on the breathing bag and / or the drainage valve is confirmed. In such a case, a negative test result (Fail) can be displayed, for example, on an operating and display unit.

[0038] In a further preferred embodiment of the method, the procedure for checking the operational readiness of the closed-circuit breathing apparatus can also include checking a manual metering element (bypass element) arranged in the low-pressure system. This can be done, for example, by means of a check carried out by the control unit by comparing the current low-pressure level in the low-pressure system P. L This occurs if, upon activation of the manual dosing element, the pressure level in the low-pressure system rises by a predetermined pressure difference P. E If the error is identified, the verification of the manual dosing element (bypass element) is successfully completed, and a positive verification result (pass) can be provided, for example, on an operating and display unit.

[0039] Provided that, upon activation of the manual dosing element, there is no increase in the pressure level in the low-pressure system by the predetermined pressure difference P E If a fault is identified, a negative verification result exists with regard to the manual dosing element (bypass element). A negative verification result (Fail) can be displayed, for example, on an operating and display unit.

[0040] In a further preferred embodiment, the method for checking the operational readiness of the closed-circuit breathing apparatus can also include a check of the high-pressure system. In a first variant of the high-pressure system check, the filling pressure of the compressed gas supply can be checked with the cylinder valve of the compressed gas supply open. For this purpose, a high-pressure sensor is arranged on the compressed gas supply or in the high-pressure system. For example, by means of a connection to the control unit, a check can be performed by comparing the currently detected high-pressure level in the high-pressure system P. H with a lower high-pressure threshold. Such a lower high-pressure threshold can, for example, be a value P. D be defined within a pressure range of 150 Pa to 180 Pa.

[0041] Provided that the pressure level of the high-pressure system is above the upper high-pressure threshold P DIf this is the case, the test is successfully completed, meaning that a sufficient pressure level for the use of the closed-circuit breathing apparatus is present in the compressed gas supply, and a positive test result (passport) can be issued, optionally including an indication of the current high pressure P. H in the compressed gas supply, for example on an operating and display unit.

[0042] Provided that the pressure level of the high-pressure system is below the high-pressure threshold value P D If a negative verification result exists regarding the filling of the compressed gas supply, a negative verification result (Fail) can be provided, for example, on an operating and display unit.

[0043] A second method for checking the high-pressure system involves verifying its leak tightness. This can be achieved, for example, by monitoring pressure changes within the high-pressure system using the control unit, based on an upper pressure change threshold value ΔP. D This is carried out. In typical configurations, such a leak test is performed after the high-pressure system has been filled with a pressure below a certain level (P) – caused by opening the cylinder valve on the oxygen cylinder. H stationary quantities of breathing gas with the resulting transfer of air under a low pressure P L Monitoring of pressure changes over a period of time t by means of the pressure reducer allows for the introduction of standing quantities of breathing gas into the low-pressure system with the cylinder valve of the oxygen cylinder closed. w It will be over the period t wA check was carried out to ensure there was no deviation from the current readings of the high-pressure sensor P. H above the upper high-pressure change threshold ΔP D is given. Such an upper high-pressure change threshold ΔP D can be, for example, a value P D be defined within a pressure range of 0.5 Pa to 1.5 Pa, preferably at 1.0 Pa. Provided that over the period t w no changes in the pressure level of the high-pressure system above the upper high-pressure change threshold ΔP D If the conditions are met, the inspection is successfully completed; no significant leaks were identified in the high-pressure system. Therefore, further testing of the closed-circuit breathing apparatus can continue, and a positive inspection result (passport) can be displayed, for example, on an operating and display unit. Provided that over the period t wsignificant changes in the pressure level of the high-pressure system above the high-pressure change threshold ΔP D If the above conditions are met, a negative test result regarding the tightness of the high-pressure system is present, and a negative test result (Fail) can be provided, for example, on an operating and display unit.

[0044] In a specific embodiment, a check of the high-pressure system according to the first variant of the high-pressure system check with regard to the sufficient filling pressure of the compressed gas supply can be carried out as a prerequisite before carrying out the second variant, whereby a comparison of the current high-pressure level P HThe high-pressure system is operated at a lower high-pressure threshold within a pressure range of 140 Pa to 180 Pa, preferably 150 Pa. This can be designed, for example, such that the control unit only initiates the leak test of the high-pressure system if the first method of checking the high-pressure system indicates a sufficiently high filling pressure of at least 150 Pa in the compressed gas supply (oxygen cylinder).

[0045] Based on the previously described embodiments of the low-pressure system and high-pressure system checks, further preferred embodiments of low-pressure system checks can be described using measured values ​​P1, P2 of the low-pressure sensor in comparison to associated pressure threshold values ​​P A , P B or to the difference threshold P Cin a combination or in a joint process with checks of the high-pressure system based on measured values ​​P H of the high-pressure sensor in comparison to high-pressure threshold values ​​to associated pressure threshold values ​​P D or to the difference threshold ΔP D can be designed. This allows for the creation of testing sequences with high-pressure and low-pressure systems, in which the step sequence for testing the low-pressure system is combined or nested in a common sequence with steps for testing the high-pressure system, as well as in which the step sequence for testing the high-pressure system is combined or nested in a common sequence with steps for testing the low-pressure system.

[0046] A closed-circuit breathing apparatus is equipped with a control unit. The control unit is designed and configured according to the invention and is intended to perform the variants and embodiments described in connection with the method according to the invention for checking the operational readiness of a closed-circuit breathing apparatus.

[0047] The rebreathing apparatus can be configured as a closed-circuit breathing apparatus or as a closed-circuit diving apparatus. In any configuration, the rebreathing apparatus, closed-circuit breathing apparatus, or closed-circuit diving apparatus must have at least the following components: - a control unit, - a low-pressure system with breathing bag, low-pressure sensor, valve assembly, hose system, breathing circuit, mouthpiece, CO2 absorber, - a high-pressure system with compressed gas reservoir, pressure reducer, high-pressure sensor.

[0048] Optionally, the closed-circuit breathing apparatus can also have a breathing gas cooler, a relief valve, a drainage valve, and a manual metering element (bypass element).

[0049] In a preferred embodiment, the closed-circuit breathing apparatus can have an output unit arranged in or on the breathing apparatus or in or on the control unit, which is connected to the control unit via a data link and is configured to provide measurement signals, status data of the closed-circuit breathing apparatus, and / or results of functional tests of the closed-circuit breathing apparatus. For this purpose, in a preferred configuration of an operating and output unit, the output unit can have a user interface, for example, configured as a display unit for outputting audible alarm tones and / or for visual representations of instructions and / or alarms in the form of monochrome or multicolored characters, numbers, texts, or symbols for the device wearer or user.Alternatively or additionally, the output unit can have an interface, for example, a wired or wireless interface, for providing information and / or alerts to an external evaluation unit, user, incident commander, or equipment maintenance personnel. The operating and output unit can also be configured to guide the user, whether the wearer or maintenance personnel, through the routines for checking the functionality of the closed-circuit breathing apparatus. This might involve, for example, performing actions in specific situations within the previously described procedures for checking the functionality of the closed-circuit breathing apparatus, such as opening or closing the valve of the high-pressure gas cylinder or attaching or removing a sealing plug from the mouthpiece, as well as performing operating steps on the operating and output unit itself.

[0050] A significant advantage of the invention is that no additional, external testing device is required to check the functionality of the respiratory detection of a device wearer in the low-pressure system.

[0051] Checking the low-pressure sensor with means that are permanently located in the closed-circuit breathing apparatus itself allows a high degree of flexibility regarding the time and place of carrying out the functional readiness check, be it during routine equipment maintenance, after use or at the deployment site before the start of the operation.

[0052] The following will be based on Fig. 1, Fig. 2 to Fig. Three exemplary embodiments of the invention are explained in more detail without limiting the scope of the inventive concept. The Fig. Figure 1 schematically shows a basic structure of a closed-circuit breathing apparatus. The Fig. Figure 2 shows a schematic representation of the basic procedure for checking the operational readiness of a closed-circuit breathing apparatus. The Fig. Figure 3 shows one variant of the process according to the Fig. 2.

[0053] The Fig. Figure 1 shows a closed-circuit breathing apparatus 1 with a breathing circuit 15, a control unit 10 for determining gas volumes, a breathing bag 3, a pressurized gas reservoir 5, a valve assembly 7, a CO2 absorber 13, and an optional breathing gas cooler 12. The closed-circuit breathing apparatus 1 can be connected via a hose system 17 with an inspiratory branch 21 and an expiratory branch 23 and a mouthpiece 19 to a connection element 24 of a breathing mask 25 of a user. The breathing mask 25 is shown here only schematically with connection element 24, a visor 20, and a strap 22. An electronics unit 11 with a control unit 10 and a low-pressure sensor 41 is indicated by a dashed line as an element of the closed-circuit breathing apparatus 1. A high-pressure sensor 43 is also associated with the electronics unit 11. The electronics 11 also includes means for data acquisition (A / D converter), signal amplification and signal filtering.The control unit 10 comprises a processing unit, for example designed as a microcontroller (µC) or microprocessor (µP), and an associated data memory (RAM, ROM). Program code can be stored in the data memory, which the control unit 10, in conjunction with electronics 11 and sensors 41, 43, can execute for operation and / or routines for checking the functions of the closed-circuit breathing apparatus 1. The electronics 11 also includes an energy storage device 87 (battery). Furthermore, an operating and display unit 50 is coupled to the electronics 11 or control unit 10. In the configuration according to this... Fig. 1. Operating and display elements are combined as a single operating and display unit; embodiments with separately designed operating and display units are also possible within the scope of the present invention. The operating and display unit 50 comprises, on the one hand, means suitable for outputting instructions and alarms. These include means for visual or acoustic output, such as for displaying visual representations of instructions and / or alarms in the form of monochrome or multicolored characters, numbers, texts, or symbols as suitable display means, as well as acoustic output means, such as horns, loudspeakers, or piezoelectric sound elements. On the other hand, the operating and display unit 50 also comprises means for input and operation, such as pushbuttons or switches. The operating and display unit 50 can also be designed as a graphical user interface (UI, GUI). In an embodiment according to this Fig. Figure 1 shows the energy storage device 87 and the low-pressure sensor 41 as exemplary components of the electronics 11. The high-pressure sensor 43 is shown in an embodiment located outside the electronics 11. The present invention also includes embodiments in which at least one of the two pressure sensors 41, 43 is arranged within the electronics 11, as well as embodiments in which at least one of the two pressure sensors 41, 43 is arranged outside the electronics 11. Furthermore, the control unit 10 and / or the power supply 87 can be arranged, in whole, predominantly, or partially, as components of the electronics 11 as well as components of the operating and display unit 50.The operating and display unit 50 is designed to allow the user to perform certain operating steps or settings on the closed-circuit breathing apparatus 1, for example, configurations as well as acknowledgments of messages or alarms generated by the control unit 10 and provided to the operating and display unit 50. The closed-circuit breathing apparatus 1 has a - in this schematic representation according to the . Fig. Figure 1 shows a construction consisting of a base plate 27 and a spring bridge 29, over which the breathing bag 3 is arranged in the closed-circuit breathing apparatus 1 by means of a spring assembly 31 and a breathing bag plate 33 such that the gas in the breathing bag 3 is maintained at a pressure level above the ambient pressure. The wearer breathes fresh breathing gas from the breathing bag 3 and through the optional breathing gas cooler 12 via the inspiratory branch 21 of the hose system 17 and back into the breathing bag 3 and thus into the breathing circuit 15 via the expiratory branch 23 of the hose system 17 and the CO2 absorber 13. The valve arrangement 7 includes, as a means of pressure adjustment from the pressurized gas supply 5 to a pressure level 25 breathable for the user, a pressure reducer 34 and a first metering valve 71 for continuous - usually designed as a time-pulsed - constant metering into the low-pressure system 77 and a second, by - in this Fig. 1. For the sake of clarity, the coupling to the deflections of the breathing bag 3 activates a metering valve 72 – usually referred to as a minimum valve – for a demand-controlled supply of quantities of breathing gases into the breathing bag 3, i.e., dependent on the depth of breathing by the wearer. A pressure relief valve 75 allows pressure to be released to the environment in the event of overpressure in the breathing bag 3, which can occur, for example, in the case of malfunctions in the pressure reducer 34. An optional manual metering element (bypass element) 14 allows the wearer to directly activate the addition of gas quantities to the breathing circuit 15. Fig. Figure 1 shows an exemplary feed point at the breathing gas cooler 12. Other feed points into the breathing circuit 15 or into a low-pressure system 77, such as into the breathing bag 3, are also technically possible. Pneumatic low-pressure lines 73 and a connection block 35 on the pressure reducer 34 pneumatically connect the components 3, 7, 12, 13, 18, 71, 72, 75, 76, 41 to each other and, together with the components, form the low-pressure system 77. The compressed gas supply 5, designed as an oxygen cylinder with a filling pressure above 200 hPa, forms a high-pressure system 79 together with a cylinder valve 74, which can be operated by means of a handwheel 80, high-pressure lines 78, the pressure reducer 34, the high-pressure sensor 43, and pneumatic high-pressure lines 78. The control unit 10 is connected to the low pressure sensor 41 and the high pressure sensor 43 by means of electrical signal lines 81, 83.The control unit 10 is electrically connected to other components of the electronics 11, such as the energy storage device (battery) 87 and / or the operating and display unit 50, by means of electrical connecting lines 88. In this . Fig. Figure 1 shows, in dashed lines, a housing shell 2 in which the previously described components are arranged, and a carrying system 28 for transporting the closed-circuit breathing apparatus 1 on the back of a wearer during use. To perform a functional test of the closed-circuit breathing apparatus 1, the mouthpiece 19 of the hose system 17 can be sealed using a sealing plug 16. In this way, the closed-circuit breathing apparatus 1 can be tested – for example, after maintenance – without a pneumatic connection to the wearer. Thus, for example, leak tests in the high-pressure system 79 or the low-pressure system 77 can be carried out with the breathing circuit 15 sealed at the mouthpiece 19.

[0054] The Fig. Figure 2 shows in schematic form a basic sequence 100 of a procedure for checking the operational readiness of a closed-circuit breathing apparatus 1 according to the Fig. 1.

[0055] In order to perform this functional readiness check with the subsequent process 100, the following boundary conditions are required: - The mouthpiece 19 ( Fig. 1) on the hose system 17 ( Fig. 1) must be sealed by a sealing plug 26 ( Fig. 1) be sealed. - The low-pressure system 77 ( Fig. 1) must be vented, the pressure in the low-pressure system 77 ( Fig. 1) therefore corresponds to the ambient pressure.

[0056] The sequence 100 begins with a start 101, the start of the closed-circuit breathing apparatus 1 ( Fig. 1) is initiated by the application of electrical energy 103. With the application of electrical energy 103, a routine with continuous data acquisition 104 of measured values ​​P starts in a continuous loop 91. L of the low-pressure sensor 41. Simultaneously with the data acquisition 104, a low-pressure comparison 105 of the measured values ​​P is continuously carried out.L 41 with a first lower low-pressure threshold P A 106. Provided the measured value P L of the low-pressure sensor 41 the lower low-pressure threshold P A If the value exceeds 106, data 107 of the measured value P is stored at a first time point t1 108. L 43 as a first low-pressure value P1 109. Thus, the measured value P L of the low-pressure sensor 41 the first lower low-pressure threshold value P A To reach 106, it must be in the closed-circuit breathing apparatus 1 ( Fig. 1) a situation exists in which quantities of breathing gas are currently entering the low-pressure system 77 ( Fig. 1), especially into the breathing bag 3 ( Fig. 1) flow in. Such a situation can occur, for example, through the opening of the bottle valve 74 ( Fig. 1) result. The first low-pressure value P1 109 indicates a pressure level in the low-pressure system 77 ( Fig. 1) at the start of the closed-circuit breathing apparatus 1 ( Fig. 1) The process 100 is carried out immediately after the low-pressure comparison 105 or also during the low-pressure comparison 105 with continuous data acquisition 104' of measured values ​​P L the low-pressure sensor 41 continued. In an optional embodiment of the process 100, the continuous data acquisition 104' can be limited to a predetermined time duration t. w 92 in a time loop 93. Subsequently, a second low-pressure comparison 110 is performed during the continuous data acquisition 104 of the recorded measured value P. L of the low-pressure sensor 41 with a second lower low-pressure threshold P3 111. Provided the measured value P L of the low-pressure sensor 41 the second lower low-pressure threshold P B If the value exceeds 111, a further data storage of the measured value P takes place at a second time point t2 113. L43 as a second low-pressure value P2 114. The second low-pressure value P2 114 indicates a pressure level in the low-pressure system 77 ( Fig. 1) at the end of the filling of the low-pressure system 77 ( Fig. 1), in particular the breathing bag 3 ( Fig. 1) with a quantity of breathing gas. Provided the measured value P L of the low-pressure sensor 41 the second lower low-pressure threshold P B If the value does not exceed 111, a negative verification result 94 (Fail) is displayed on an operating and display unit 50 ( Fig. 1), and the process 100 is terminated 300 (STOP). Provided the measured value P L of the low-pressure sensor 41 the second lower low-pressure threshold P BIf the value exceeds 111, a difference calculation 115 is performed based on the first low-pressure value P1 109 and the second low-pressure value P2 114, with the resulting pressure difference ΔP 116. Subsequently, a difference comparison 117 of the pressure difference ΔP 116 is made with a difference threshold value P. C 118. Provided that the pressure difference ΔP 116 exceeds the difference threshold P C If the value does not exceed 118, a negative verification result 94 (Fail) is displayed on the operating and display unit 50 ( Fig. 1) Provided that the pressure difference ΔP 116 exceeds the difference threshold P C If the value exceeds 118, a positive verification result 95 (passport) is displayed on the operating and display unit 50 ( Fig. 1) This completes procedure 100 for checking the operational readiness of a closed-circuit breathing apparatus 1 ( Fig. 1) terminates 300 (STOP) and, if the verification result 95 is positive, a transition 301 to regular device operation or device provision can take place, or, if the verification result 94 is negative, troubleshooting and, if necessary, further checks on the closed-circuit breathing apparatus 1 ( Fig. 1) be carried out by maintenance personnel until all required verification routines have been completed with positive results 95, 99 ( Fig. 3), 97 ( Fig. 3) have passed.

[0057] The Fig. Figure 3 shows in schematic form a variant 200 of the process 100 according to the Fig. 2 to an extended check of the operational readiness of a closed-circuit breathing apparatus 1 after the Fig. 1. Sequence 200 includes a check of the low-pressure sensor 41 and a check of the high-pressure sensor 43. Sequence 200 and the start of the closed-circuit breathing apparatus 1 ( Fig. 1) starts in the same way as before Fig. 2 described with the start 201 of the closed-circuit breathing apparatus 1 ( Fig. 1) by adding 102 of electrical energy 103. Also the to Fig. The two boundary conditions mentioned must be addressed in the same way as for the Fig. 2 described above must be given in order to perform the alternative procedure 200 for an extended check of operational readiness. After the first data acquisition 104 of the low-pressure sensor P L 41 and the subsequent first low-pressure comparison 105 with the first low-pressure threshold 106 as to the Fig. 2 described, in addition to checking the low-pressure system 77 ( Fig. 1) a check of the high-pressure system 79 ( Fig. 1) For this purpose, continuous data acquisition 204 of measured values ​​P takes place in a time loop 93. H of the high-pressure sensor 43 ( Fig. 1) for a predetermined time period 92. After the predetermined time period 92 has elapsed, the low-pressure system 77 is checked ( Fig. 1) as in process 100 with the ones belonging to the Fig. The action elements 107, 104', 112, 115, 300, comparison elements 110, 117 with threshold values ​​111, 118, data storage 108, 109, 113, 114, 116 and an output of the verification results 94, 95 are described. In addition, after the predetermined time period 92 has elapsed, a high-pressure comparison 220 is carried out on a measured value P recorded at the end of the time period 92. H of the high-pressure sensor 43 with a high-pressure threshold value of 219. Provided that the measured value P H of the high-pressure sensor 43 the lower high-pressure threshold value P D If the value is not exceeded, a negative verification result 96 (Fail) is displayed on an operating and display unit 50 ( Fig. 1) Provided the measured value P H of the high-pressure sensor 43 the lower high-pressure threshold value PD If this value is exceeded, a positive verification result 97 (passport) is displayed on an operating and display unit 50 ( Fig. 1) In this Fig. Figure 3 is an exemplary, schematic and symbolic representation of a type of provision 93 of the verification results 93, 94, 95, 96, 97, 98, 99 as shown on an operating and display unit 50 ( Fig. 1) can be implemented with graphical output options. In this Fig. Figure 3 shows, as an example of further checks, a check of the energy supply, for example a battery charge level directly after the start 201 of the process 200; the check results 98, 99 are then supplied to provision 93 in this exemplary configuration, for example as a situation of a battery storage system 87 ( Fig. 1) with a good charge level 99 or too low a charge level 98. The steps following provision 93 also in this Fig. 3 can, for example, be like the Fig. 2 described with a termination 300 ( Fig. 2) of the process 100 ( Fig. 1) or the process 200. In this Fig. 3 is added for the sake of graphic clarity. Fig. 3 - only a transition 301 is indicated, which can be designed as a transition 301 to regular device operation, to device provision, or as a transition to further tests. Interactions with a user, for example, details of the electrical commissioning 102, 103 of the closed-circuit breathing apparatus 1 ( Fig. 1) or opening or closing the bottle valve 74 ( Fig. 1) by means of a handwheel 80 ( Fig. 1) during the process of 200 of the low-pressure system check 79 ( Fig. 1), if necessary, 200 user actions or acknowledgments at the display and control unit 50 (UI, GUI) during the process ( Fig. 1) are included in the diagram for the sake of clarity. Fig. 3 and Fig. 3 not shown. REFERENCE MARK LIST 1. Closed-circuit breathing apparatus, closed-circuit breathing apparatus, closed-circuit diving apparatus 2 Housing shell 3 breathing bags, counterlung 5. Compressed gas supply, oxygen pressurized gas cylinder 7 Valve arrangement 10 Control unit 11 Electronics, electronics module 12 breathing gas coolers 13 CO2 absorbers, soda lime containers 15 Respiratory circuit (respiratory circuit in the low-pressure system) 16 Control element (button) for bypass element 17 Hose system (inhalation and exhalation hose) 18 manual dosing element, bypass element (O2 supplementary dosing) 19 Mouthpiece on the hose system 20 visor of the breathing mask 21 inspiratory branch (inhalation tube) 22 Straps of the breathing mask 23 expiratory branch (exhalation tube) 24 Connection element on the breathing mask 25 Respiratory masks, users 26 sealing plugs for mouthpiece on hose system 27 Base plate 28 Carrying system (strap, belt system) 29 Spring bridge assembly (base plate, spring assembly) 31 Spring arrangement, spring pack 33 Breathing bag plate 34 Pressure reducers (device for pressure reduction) 35 Connection block (low-pressure distribution) 41 Low pressure sensor P L 43 High-pressure sensor P H 50 Display and control unit (UI, GUI) 71 first metering valve (constant metering) 72 second metering valve, minimum valve (demand-based metering) 73 Low-pressure lines in the low-pressure system 74 Bottle valve (shut-off valve) 75 Pressure relief valve (relief valve) 76 pneumatic connecting elements (plug / coupling) 77 Low-pressure system 78 high-pressure lines in the high-pressure system 79 High-pressure system 80 Handwheel (rotary wheel) 81 electrical signal line (low pressure sensor) 83 electrical signal line (high pressure sensor) 87 Energy storage (battery) 88 electrical connecting lines 91 continuous loop 92 predetermined time duration t w 93 Time Loop 93 Provision of review results, output or presentation 94 negative test result low pressure test 95 positive test results Low-pressure test 96 negative test result high pressure test 97 positive test results, high-pressure test 98 Negative test result: Energy supply (low charge level) 99 positive test result energy supply (charge status good) 100 Expiry ( Fig. 2, Fig. 3) the review 101 Start (Start of low-pressure check) 102 Switching on, switching operation 103 Electrical energy, energy storage (battery) 104, 104' Data acquisition P L , low pressure 105 First low-pressure comparison, comparison 106 first lower low-pressure threshold P A 107 Data storage Low pressure P1 108 first time point t1 109 first low pressure value P1 110 second low-pressure comparison, comparison 111 second lower low-pressure threshold P B 112 Data storage low pressure P2 113 second time point t2 114 first low-pressure value P1 115 Differential calculation Low pressure 116 Pressure difference low pressure ΔP 117 Difference comparison low pressure 118 Differential threshold low pressure P C 200 alternative procedures ( Fig. 3) the review 201 Start (Start of the combined low-pressure / high-pressure check) 202 Checking the power supply (battery charge level) 204 Data collection P H , high pressure 219 lower high-pressure threshold P D 220 High pressure comparison, comparison 300 STOP (End of check) 301 Transition

Claims

[1] Method (100) for checking the operational readiness of a closed-circuit breathing apparatus (1) in a sequence of steps for carrying out the check comprising the steps: - Continuous metrological acquisition (104, 104') and recording of pressure measurement signals P L a low-pressure sensor (41) arranged in or on a low-pressure system (77) of the closed-circuit breathing apparatus (1), - Identification based on the pressure measurement signal P L (81) of the low-pressure sensor (41) whether there is currently a situation in which an inflow of quantities of gas into the low-pressure system (77) has begun, - Storage of a first pressure measurement signal P1 (109) at a first time t1 (108), which indicates the identified pressure situation immediately after the start of the inflow of gas quantities into the low-pressure system (77) with a breathing bag (3), - Storage of a second pressure measurement signal P2 (114), which indicates a pressure situation at the end of the inflow of gas quantities into the low-pressure system (77) at a second time t2 (113), - Formation (115) of a difference value ΔP (ΔP = P2 - P1) (116) between the first pressure signal P, (109) and the second pressure signal P2 (114), - Performing a comparison (117) between the difference value ΔP (116) with a difference threshold value P C (118) - Determining a result (94, 95) of the verification of the functionality of the closed-circuit breathing apparatus based on the comparison (117), - Provision of an output signal (88) which indicates the result (94, 95) of the check. [2] Method (100) according to claim 1, wherein at the first time t1 (108) a first low-pressure comparison (105) of the measured values ​​P L (81) of the low pressure sensor (41) with a first lower low pressure threshold P A(106) is done. [3] Method (100) according to claim 1 or according to claim 2, wherein at the second time t2 (113) a second low-pressure comparison (110) of the measured values ​​P L (81) of the low pressure sensor (41) with a second lower low pressure threshold P3 (111). [4] Method (100) according to any one of claims 1 to 3, wherein at a third time t3 a third low-pressure comparison of the measured values ​​P L of the low-pressure sensor (41) with a third lower low-pressure threshold P E This has been done. [5] Method (100, 200) according to one of claims 1 to 4, wherein a continuous, metrological acquisition (204) and recording of pressure measurement signals P H a high-pressure sensor (43) arranged in or on a high-pressure system (79). [6] Method (100, 200) according to claim 5, wherein at the first time t1 a high-pressure comparison (220) of measured values ​​P Hof the high-pressure sensor (43) with a lower high-pressure threshold P D This has been done. [7] Method (100, 200) according to claim 5, wherein the high-pressure comparison (220) is configured to determine a pressure level in the high-pressure system (79) or to determine a tightness in the high-pressure system (79). [8] Computer program (100, 200) or computer program product (100, 200) for carrying out one of the methods (100, 200) according to one of claims 1 to 7. [9] Device (1) for carrying out one of the methods (100, 200) according to one of claims 1 to 7. [10] Device (1) according to claim 9, wherein the device is designed as a closed-circuit breathing apparatus (1), closed-circuit breathing apparatus or closed-circuit diving apparatus, which in a configuration has at least the following components: - a control unit (10), - a low-pressure system (77) with a breathing bag (3), the low-pressure sensor (41), a valve assembly 7, a hose system 17, a breathing circuit (15), a mouthpiece 19, a CO2 absorber (13), - a high-pressure system (79) with a compressed gas reservoir (5), a pressure reducer (34), the high-pressure sensor (43).

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