AU2006226722A1

AU2006226722A1 - Method and arrangement for determination of the residual capacity of breathable air for an oxygen-generating breathing apparatus operated in circuit

Info

Publication number: AU2006226722A1
Application number: AU2006226722A
Authority: AU
Inventors: Karl-Heinz Feldner; Frank Kruger
Original assignee: MSA Auer GmbH
Current assignee: MSA Europe GmbH
Priority date: 2005-03-25
Filing date: 2006-03-23
Publication date: 2006-09-28
Anticipated expiration: 2026-03-23
Also published as: WO2006099863A1; ATE404253T1; ES2313628T3; EP1861173B1; CN101180100A; AU2006226722B2; EP1861173A1; DE102005015275B3; CN101180100B; DE502006001335D1

Abstract

The residual capacity of breathable air remaining at any point for an oxygen-generating breathing apparatus operated in circuit is determined by measurement of the number of breathing cycles and the pressure and temperature of the inspired air in sequential periods by means of a pressure and temperature sensor. The current breathed air usage is calculated for each time period and subtracted from the total air capacity. The residual capacity of breathable air at a given reading point is displayed on a display.

Description

CERTIFICATION OF TRANSLATION METHOD AND ARRANGEMENT FOR THE DETERMINATION OF THE RESIDUAL CAPACITY OF BREATHABLE AIR FOR AN OXYGEN-GENERATING BREATHING APPARATUS OPERATED IN CIRCUIT I, Geoffrey Brownbill, c/o Technical Translation Agency GmbH, Fasangarten 8, A-2136 Laa/Thaya, Austria, am the translator of the documents attached and certify that the following is a true translation to the best of my knowledge and belief. Signature of translator dated this 3 rd day of August 2007 WO 2006/099863 Al METHOD AND ARRANGEMENT FOR THE DETERMINATION OF THE RESIDUAL CAPACITY OF BREATHABLE AIR FOR AN OXYGEN GENERATING BREATHING APPARATUS OPERATED IN CIRCUIT DESCRIPTION The invention relates to a method for the determination of the residual capacity of breathable air for an oxygen generating breathing apparatus operated in circuit, with at least one chemical canister which is connected to an exhalation bag with an integrated blower and to an inhalation bag with an inhalation tube, as well as an arrangement for performing the method. Such a breathing apparatus operated in circuit with a consumption display for the breathable air volume still remaining during the time of use is known for example from DE 44 11 560. An exhalation valve is followed by an exhalation bag, in which a blower is housed. The exhalation air is pressed with the aid of the blower through two chemical canisters arranged in parallel. The respiratory resistance to be overcome by the user during exhalation on account of the chemical canisters disposed downstream is reduced considerably with the aid of the blower. The chemical contained as a granulate in the chemical canisters binds a part of the carbon dioxide contained in the exhaled air and converts the latter into oxygen in an exothermic reaction. The air enriched with oxygen passes via a particle filter into the inhalation bag and via an inhalation valve to the user. The oxygen generating breathing apparatus operated as an isolating device can be used - for example in deployments of the fire brigade or mine rescue teams - for a much longer period than conventional compressed air breathing apparatuses. For example, operating times of four hours are conceivable, based on a specific - average - respiratory volume, of 301/min. Since the stated operating time on the basis of 2 an assumed average value of the respiratory volume of the user per minute (respiratory minute volume) is very imprecise, a consumption display coupled to the blower has already been proposed in DE 44 11 560. On the basis of the measured blower parameters, the supply of usable respiratory gas still available is determined with the aid of an evaluation unit. The consumption display determined with the aid of the blower parameters in the known devices, however, is imprecise, since the consumption of the chemical, i.e. the respiratory gas consumption, or the respiratory volume per minute, on the one hand differs in the case of different users and on the other hand is essentially dependent on the burden on the user, i.e. the operational and respiratory conditions, and the temperature determines the actually breathed volume. The consumption display determined on the basis of the blower parameters has to be recalibrated after each application during maintenance. The maintenance, moreover, cannot take place immediately, but only at a temperature of the blower lying below 30 0 C. The problem underlying the invention, therefore, is to design a method and an arrangement for the determination of the residual capacity of breathable air for an oxygen generating breathing apparatus operated in circuit, in such a way that, during use under the prevailing conditions, exact individual values are displayed in respect of the respiratory air still available at the given point in time. According to the invention, this problem is solved with a method according to the features of claim 1 and an arrangement for performing the method according to the features of claim 7. Advantageous developments of the invention are stated in the sub-claims.

3 The essence of the invention consists in the determination of the pressure characteristic and the temperature of the inhalation air during inhalation by the user, whereby the pressure and the number of respiratory cycles are each ascertained at constant preset time intervals and the actually breathable air volume in the given time interval is calculated therefrom taking account of the temperature and, proceeding from the original capacity, the still remaining respiratory air capacity of the chemical canisters of the breathing apparatus is subtracted from the preceding value after each time interval. The still remaining residual capacity of breathable air is displayed - preferably as a percentage - at each point in time during the use of the breathing apparatus on the basis of the air actually consumed by the user and thus offers the latter a high degree of safety. The consumption display is independent of device-related changes in the breathing apparatus and can be prepared immediately for a subsequent application without calibration and independent of temperature and can then be used. The duration of a time interval preferably amounts to twenty seconds. In the case of non-respiration or extremely low respiration, a fixed value of 201/min is used for the calculation. The arrangement according to the invention for performing the method comprises a sensor unit integrated into the inhalation tube of the breathing apparatus, with a pressure sensor for determining the pressure characteristic and a temperature sensor for measuring the temperature of the inhalation air which is markedly influenced by the exothermic reaction in the chemical canisters. The sensor unit is connected via a distributor unit to an evaluation and display unit. In the evaluation and display unit, the air volume corresponding to the given temperature for the given time interval is determined with the ascertained 4 number of respiratory cycles and their respective pressure characteristic. This value is subtracted in the evaluation and display unit from the start capacity or from the residual capacity remaining after the preceding time interval. The evaluation and display unit displays the residual capacity ascertained at the given time on a display. Incorporated in the evaluation and display unit is a dead man warning and also a fault display, which concerns the energy source, electrical connections, the blower or the starter, and a signal transmitter for generating a signal when certain residual capacities are reached. An example of embodiment of the invention is explained in greater detail with the aid of the drawing, in the individual figures whereof an oxygen-generating breathing apparatus is represented schematically with a consumption display for long-time use. The breathing apparatus comprises two chemical canisters 1 arranged in a parallel circuit, said chemical canisters being connected via an air distributor 2 to an exhalation bag 3 with blower 4 housed in the latter. An excess valve 5 is integrated into the wall of exhalation bag 3. An exhalation tube 6 with an exhalation valve 7 is connected to exhalation bag 3. Chemical canisters 1 are provided with a cooling jacket 8 and filled with a potassium hyperoxide granulate (KO 2 ) 21. A connection tube 9 connects the outlets of the two chemical canisters 1 via a particle filter 10 to an inhalation bag 11. Emerging into inhalation bag 11 is an inhalation tube 12 with an inhalation valve 13. Exhalation valve 7 and inhalation valve 13 are connected to a valve control (not shown). The exhalation air enriched with carbon dioxide flows via opened exhalation valve 7 (with closed inhalation valve 13) 5 into exhalation bag 3 and is pressed with the aid of blower 4 via air distributor 2 through chemical canisters 1 filled with KO 2 granulate 21. Carbon dioxide contained in the exhalation air is converted into oxygen in an exothermic reaction with the potassium hyperoxide. The air enriched with oxygen thus prepared passes via connection tube 9 and particle filter 10, in which fine particles entrained from the chemical are retained, into inhalation bag 11 and from their via now opened inhalation valve 13 and inhalation tube 12 to the user. The breathing apparatus also comprises an energy source 14 and a distributor unit 15 connected to the latter. Apart from an automatic starting mechanism 16 with quick starters 17 as well as blower 4 and a charging socket 18, a sensor unit 19 and an evaluation and display unit 20 are also connected to distributor unit 15. Sensor unit 19, which is assigned to inhalation tube 12, has a pressure sensor and a temperature sensor (in each case not shown). On the basis of an assumed respiratory minute volume of 301/min, the operating time of the above-described oxygen generating breathing apparatus, with the size of the two chemical canisters 1 used here which can deliver a total of 7200 litres of breathable air, amounts to four hours. The operating time can actually be much longer or also much shorter, since it depends to a considerable extent on the given conditions of use and the physical condition of the user concerned, i.e. the nature of the respiration. The inhalation resistance in the form of the pressure characteristic is measured in inhalation tube 12 by means of the pressure sensor, and the respiratory resistance in the form of the maximum height of the respiratory cycles is measured in intervals of, in each case, 20 seconds and their number is determined. Since the temperature of the inhalation gas changes on account of the exothermic reaction taking place in chemical canisters 1 and the 6 volume also depends on the temperature according to the relationship p.V/T = const., the temperature of the inhalation gas is also measured continuously with the temperature sensor provided in sensor unit 19. The data pressure level, number of respiratory cycles and temperature - ascertained by sensor unit 19 in each case in a 20 second interval are sent via distributor unit 15 to an evaluation and display unit, in which the inhalation gas inhaled - consumed - by the user in the time interval is calculated using these data and this inhalation volume per unit of time - proceeding from the original capacity of 7200 litres - is repeatedly deducted from the respiratory air capacity still remaining in chemical canisters 1. The residual capacity at a given time is calculated as a percentage and is presented in this way on the display of evaluation and display unit 20. At each point in time of his deployment, the user thus obtains information concerning the respiratory volume actually consumed by him under the prevailing conditions, i.e. the breathable air volume still remaining at the given point in time. The residual capacity can also be presented in the form of a pictorial representation of a "bottle filling" on the display. If a specific residual capacity is reached or fallen below, evaluation and display unit 20 generates an optical and/or acoustic signal by means of a signal transmitter.

7 List of reference numbers 1 chemical canister 2 air distributor 3 exhalation bag 4 blower 5 excess valve 6 exhalation tube 7 exhalation valve 8 cooling jacket 9 connection tube 10 particle filter 11 inhalation bag 12 inhalation tube 13 inhalation valve 14 energy source 15 distributor unit 16 automatic starting mechanism 17 quick starter 18 charging socket 19 sensor unit 20 evaluation and display unit 21 potassium hyperoxide (KO 2 ) granulate, chemical

Claims

1. A method for the determination of the residual capacity of breathable air in an oxygen-generating breathing apparatus operated in circuit, with at least one chemical canister which is connected to an exhalation bag with an integrated blower and to an inhalation bag with an inhalation tube, characterised in that the pressure characteristic and the temperature of the inhalation air during inhalation by the user as well as the pressure and the number of respiratory cycles are individually ascertained in preset time intervals during the deployment and the breathable air volume in the given time interval is calculated therefrom taking account of the temperature and successively subtracted from the initial respiratory volume of the chemical canisters.

2. The method according to claim 1, characterised in that the residual capacity is calculated and displayed as a percentage.

3. The method according to claim 1, characterised in that the residual capacity is represented pictorially in the form of the degree of filling of a bottle.

4. The method according to claim 1, characterised in that a warning signal is generated when a specific residual capacity is reached.

5. The method according to claim 1, characterised in that the duration of a time interval amounts to 20 seconds.

6. The method according to claim 1, characterised in that, in the case of extremely low respiration or non respiration, a respiratory volume of 201/min is fixed in order to determine the residual capacity. 2

7. An arrangement for performing the method according to claim 1, for an oxygen-generating breathing apparatus operated in circuit, with at least one chemical canister which is connected to an exhalation bag with a blower integrated therein and to an inhalation bag with an inhalation tube, characterised by a sensor unit (19) assigned to the inhalation tube (12), with a pressure sensor for determining the pressure characteristic during inhalation and a temperature sensor for measuring the temperature of the inhalation air, as well as an evaluation and display unit (20) connected via a distributor unit (15) to the sensor unit (19), said evaluation and display unit being used to ascertain the number of respiratory cycles in preset time intervals, the maximum pressures of the respiratory cycles and the temperature of the inhalation air, as well as to calculate the air volume inhaled by the given user in the unit of time and the residual capacity of breathable air volume still available at the given point in time.

8. The arrangement according to claim 7, characterised in that the evaluation and display unit (20) has a display for the percentage or pictorial indication of the residual capacity of breathable air volume.

9. The arrangement according to claim 8, characterised in that the evaluation and display unit (20) has a signal transmitter for the optical and/or acoustic signalling of specific residual capacities.

10. The arrangement according to claim 7, characterised in that an energy source (12) and a charging socket (18), as well as an automatic starting mechanism (16), quick starters (17) and the blower (4) are connected to the distributor unit (15). 3

11. The arrangement according to claim 7, characterised in that a dead-man warning is integrated into the evaluation and display unit (20).

12. The arrangement according to claim 7, characterised in that the evaluation and display unit (20) has a fault display in respect of the capacity of the energy source (14), absent or defective connections and absent or spent quick starters (17).