1、BRITISH STANDARD AEROSPACE SERIES BS 4N 100-4:1999 Incorporating Amendment No. 1 Aircraft oxygen systems and equipment Part 4: Guide to the physiological factors ICS 49.090 BS 4N 100-4:1999 This British Standard, having been prepared under the direction of the Engineering Sector Committee, was publi
2、shed under the authority of the Standards Committee and comes into effect on 15 October 1999 BSI 18 February 2003 The following BSI references relate to the work on this standard: Committee reference ACE/38 Draft for comment 96/707314 DC ISBN 0 580 29560 5 Committees responsible for this British Sta
3、ndard The preparation of this British Standard was entrusted to Technical Committee ACE/38, Aircraft oxygen equipment, upon which the following bodies were represented: British Airways British Compressed Gases Association Civil Aviation Authority Health and Safety Executive Ministry of Defence Socie
4、ty of British Aerospace Companies Limited South Bank University Amendments issued since publication Amd. No. Date Comments 14191 18 February 2003 Changes to 7.2 and 7.3BS 4N 100-4:1999 BSI 18 February 2003 i Contents Page Committees responsible Inside front cover Foreword ii 1S c o p e 1 2 Normative
5、 references 1 3 Definition 1 4 Physiological effects of altitude 1 5 Relation of oxygen requirements to aircraft operation 2 6 Protection against smoke and noxious gases 2 7 Physiological requirements for aircraft oxygen equipment 2 Bibliography 5 Table 1 Oxygen requirements at altitude 1BS 4N 100-4
6、:1999 ii BSI 18 February 2003 Foreword This Part of BS 4N 100 has been prepared by Technical Committee ACE/38 and provides guidance on the physiological factors to be considered when designing equipment for use with oxygen. It partially supersedes BS 3N 100 which is withdrawn upon publication of all
7、 seven parts. BS 4N 100 consists of the following parts: Part 1: Design and installation; Part 2: Tests for the compatibility of materials in the presence of oxygen; Part 3: Testing of equipment and systems; Part 4: Guide to the physiological factors; Part 5: Guide to fire and explosion hazards asso
8、ciated with oxygen; Part 6: Guidance and recommendations on the selection of materials for use with oxygen; Part 7: Guide to cleaning, labelling and packaging. NOTE The latest revision of an aerospace series standard is indicated by a prefix number. This publication does not purport to include all t
9、he necessary provisions of a contract. Users are responsible for its correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages 1 to 5 and a ba
10、ck cover. The BSI copyright notice displayed in this document indicates when the document was last issued.BS 4N 100-4:1999 BSI 18 February 2003 1 1 Scope This part of BS 4N 100 provides guidance on the physiological factors which should be considered when designing oxygen systems for use within airc
11、raft. 2 Normative references The following normative documents contain provisions which, through reference in this test constitute provisions of this part of this British Standard. For dated references, subsequent amendments to, or revisions of, any of these publications do not apply. For undated re
12、ferences the latest edition of the publication referred to applies. BS 2N 3, Specification for gaseous breathing oxygen supplied for airborne application. 3 Definition For the purposes of this standard the following definition applies: 3.1 hypoxia (oxygen deficiency) any state wherein a physiologica
13、lly inadequate amount of oxygen is available to, or is utilized by, tissue; without respect to cause or degree of inadequacy. 4 Physiological effects of altitude 4.1 The known requirements for oxygen during flight are shown in Table 1. They are based on physiological information and refer to healthy
14、 adults. 4.2 Oxygen supplied for airborne applications shall conform to BS N 3. Table 1 Oxygen requirements at altitude Condition Metres ft (Ref.) Maximum altitude without oxygen at which night vision is not seriously impaired. 1 219 4 000 Maximum altitude without oxygen at which flying efficiency i
15、s not seriously impaired. 2 438 8 000 Altitude below which decompression sickness is highly unlikely. 5 486 18 000 Altitude above which the incidence of decompression sickness increases rapidly with exposures exceeding 10 minutes. 7 620 25 000 Maximum altitude at which sea level physiological condit
16、ions can be maintained by breathing oxygen (94 % minimum) at ambient pressure. 10 058 33 000 Maximum allowable altitude without breathing oxygen (94 % minimum) at a pressure greater than ambient. 12 192 40 000 Maximum altitude from which a rapid descent can be made with the use of a correctly fitted
17、 pressure breathing mask and appropriate oxygen regulating device providing 12 192 m (40 000 ft) is reached within 2 minutes. 15 240 50 000 Altitude above which some form of pressure clothing is essential, the type depending upon the duration of exposure. 15 240 50 000BS 4N 100-4:1999 2 BSI 18 Febru
18、ary 2003 5 Relation of oxygen requirements to aircraft operation 5.1 In order to offset the physiological disturbances referred to in Clause 4, the aircraft cabin should be pressurized to an equivalent altitude of 2 438 m (8 000 ft) or lower when oxygen is not used, or to not higher than 7 620 m (25
19、 000 ft) when added oxygen is breathed. 5.2 Under the emergency conditions which follow the loss of cabin pressure of a pressurized aircraft, some lack of oxygen can be accepted in resting passengers. Thus, unconsciousness is unlikely to occur if the cabin altitude does not exceed 7 620 m (25 000 ft
20、), provided that descent is made to an altitude below 3 962 m (13 000 ft) within 5 minutes. Furthermore, loss of consciousness is unlikely to occur during an exposure of resting individuals at altitudes up to 3 962 m (13 000 ft) lasting several hours, although moderate to severe impairment of the ab
21、ility to perform functional tasks will occur. 5.3 Unless oxygen is administered at high cabin altitudes, unconsciousness and, finally, death will occur. The time of onset of unconsciousness is dependent on the cabin altitude, the rate of decompression and physical activity of the individual. (For ex
22、ample, without added oxygen the “time of useful consciousness” at 7 620 m (25 000 ft) is approximately 3 minutes, and at 12 192 m (40 000 ft) it is 20 seconds.) 5.4 When cabin altitude following failure of the pressure cabin does not exceed 10 668 m (35 000 ft), impairment of consciousness can be av
23、oided by administration of oxygen as the cabin altitude rises above 3 048 m (10 000 ft). If, following a sudden decompression (period of decompression less than 1 minute), the cabin altitude exceeds 10 668 m (35 000 ft), significant hypoxia can only by avoided by breathing an oxygen-enriched air mix
24、ture before the decompression and administration of oxygen (94 % minimum) from the early stages of decompression. If the cabin altitude exceeds 12 192 m (40 000 ft), pressure breathing shall be applied. 6 Protection against smoke and noxious gases The use of oxygen (94 % minimum), together with prec
25、autions against inward mask leakage, provides suitable breathing protection against smoke and noxious gases. NOTE Generally, protection of the eyes will also be required. 7 Physiological requirements for aircraft oxygen equipment 7.1 The primary purpose of aircraft breathing equipment is to maintain
26、 adequate oxygenation of the user on ascent into a rarefied atmosphere while imposing the minimum of interference with breathing and general efficiency. For military aircraft this could be throughout the entire flight envelope; for commercial aircraft (pressurized) this will only be required during
27、an emergency. 7.2 The minimum concentration of oxygen in the gas delivered by the breathing equipment should maintain a partial pressure of oxygen in the inspired gas that is not less than the normal ground level value as specified in Def Stan 00-970, Part 1/2, Section 6.13 (December 1999) (for mili
28、tary applications), or JAR 25.1443 (for commercial applications). This requirement can only be achieved at cabin altitudes below 10 058 m (33 000 ft). The use of high concentrations of oxygen in aircraft is not desirable in circumstances in which the crew may be exposed to prolonged accelerative for
29、ces such as occur in aerobatic manouevres and this may give rise to chest discomfort and coughing due to local lung collapse). In these circumstances, the concentration of oxygen provided by the breathing equipment at a given altitude should not exceed that specified in Def Stan 00-970, Part 1/2, Se
30、ction 6.13 (December 1999). In order to limit impairment of consciousness due to lack of oxygen following sudden decompression (a duration of decompression of less than 1 minute) to a final altitude in excess of 10 668 m (35 000 ft), the minimum concentration of oxygen breathed should be that specif
31、ied by Def Stan 00-970, Part 1/2, Section 6.13 (December 1999) but ideally oxygen (minimum 94 %) should be breathed from the commencement of the decompression. NOTE It is generally accepted that a certain degree of hypoxia can be tolerated by seated passengers in the emergency of exposure to cabin a
32、ltitudes in excess of 3 048 m (10 000 ft). In these circumstances the minimum concentration of oxygen in the gas delivered at the lips should be adequate to maintain a partial pressure of oxygen of 13.3 kPa 1)to 11.2 kPa (inspired gas saturated with water vapour at 37 C) depending on the altitude. (
33、See JAR 25.1443c). 1) kPa =1 kN/m 2= 0.01 bar.BS 4N 100-4:1999 BSI 18 February 2003 3 7.3 The breathing equipment should not impose an undesirable degree of impedance to breathing with the breathing patterns that occur during flight. The form of the breathing pattern is determined principally by the
34、 level of physical activity. It is also modified by emotional disturbances, speech and lack of oxygen. The breathing equipment should be capable of high maximum instantaneous inspiratory and expiratory flows (e.g. up to 3.3 l/s with a maximum rate of change of flow of 20 l/s 2 . (See Def Stan 00-970
35、, Part 1/2, Section 6.13 (December 1999). In many applications, such as passenger supply systems, it may not be necessary to provide a capability as high as 3.3 1/s since, in the case of seated passengers exposed to altitudes greater than 3 048 m (10 000 ft) the respiratory minute volume is unlikely
36、 to exceed 25 1/min and the maximum instantaneous respiratory flow will probably not exceed 1.3 1/s, but in all cases, the impedance should be as low as possible. During a respiratory cycle, total changes of pressure at the lips not exceeding 250 Pa (1 inch water gauge) when the peak inspiratory and
37、 expiratory flows are 0.5 1/s and 1 kPa with the peak at 3.3 1/s represent negligible resistance to breathing (impedance). NOTE Volumes (in litres) are based on ATPD: volume of dry gas at ambient temperature and pressure. 7.4 Various methods of storing oxygen in aircraft may result in the gas leavin
38、g the storage system at a temperature which differs considerably from that of cabin ambient 2) . The temperature of the gas at the lips should be within 5 C of ambient cabin temperature. 2) Liquid oxygen systems may deliver gas from the storage container at a temperature lower than the cabin ambient
39、, while chemical oxygen generators may produce gas at a temperature considerably higher than cabin ambient.4 blankBS 4N 100-4:1999 BSI 18 February 2003 5 Bibliography Def Stan 00-970, Design and airworthiness requirements for service aircraft: Volume 1: Aeroplanes Volume 2: Rotorcraft Jar 25 Joint A
40、viation Requirements JAR 25BS 4N 100-4:1999 BSI 389 Chiswick High Road London W4 4AL BSI British Standards Institution BSI is the independent national body responsible for preparing British Standards. It presents the UK view on standards in Europe and at the international level. It is incorporated b
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