1、BRITISH STANDARD AEROSPACE SERIES BS C22:1995 ISO9475:1994 Test methods for aircraft inner tube and tubeless tyre valves Cores and capsBSC22:1995 This BritishStandard, having been prepared under the directionof the Engineering SectorBoard (E/-), was publishedunder the authorityofthe Standards Board
2、and comes into effect on 15 April1995 BSI01-2000 The following BSI references relate to the work on this standard: Committee reference ACE/59 Draft for comment93/710105DC ISBN 0 580 24046 0 Committees responsible for this BritishStandard The preparation of this BritishStandard was entrusted to Techn
3、ical Committee ACE/59, Aircraft tyres, rims and associated equipment, upon which the following bodies were represented: British Airways British Rubber Manufacturers Association Ltd. Civil Aviation Authority (Airworthiness Division) Ministry of Defence Retread Manufacturers Association Society of Bri
4、tish Aerospace Companies Ltd. Amendments issued since publication Amd. No. Date CommentsBSC22:1995 BSI 01-2000 i Contents Page Committees responsible Inside front cover National foreword ii 1 Scope 1 2 Normative references 1 3 General 1 4 Valve cores 1 5 Tyre valve caps 3 Figure 1 Manifold 2 Table 1
5、 3 Table 2 3 List of references Inside back coverBSC22:1995 ii BSI 01-2000 National foreword This BritishStandard has been prepared by Technical Committee ACE/59. It is identical with ISO9475:1994, Aircraft inner tube and tubeless tyre valves Cores and caps Test methods, published by the Internation
6、al Organization for Standardization (ISO). The Technical Committee has reviewed the provisions of ISO37:1994 and ISO48:1994, to which normative reference is made in the text, and has decided that they are acceptable for use in conjunction with this standard. A British Standard does not purport to in
7、clude all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Cross-references International Standard Corresponding BritishStandard ISO815:1991
8、BS903 Physical testing of rubber Part A6:1992 Method for determination of compression set at ambient, elevated or low temperatures (Identical) ISO868:1985 BS2782 Methods of testing plastics Part3 Mechanical properties Method365 B:1992 Determination of indentation hardness by means of a durometer (Sh
9、ore hardness) Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, pages1 to4, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on
10、 the inside front cover.BSC22:1995 BSI 01-2000 1 1 Scope This International Standard specifies the test methods used for valve cores and caps for aircraft tyres, with or without inner tubes, and minimum airtightness standards. It constitutes a detailed method allowing products to be evaluated on the
11、 same basis, and results to be compared. 2 Normative references The following standards contain provisions which, through reference in this text, constitute provisions of this International Standard. At the time of publication, the editions indicated were valid. All standards are subject to revision
12、, and parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. Members of IEC and ISO maintain registers of currently valid International Standards. ISO37:1994, Rubber, vulcanized o
13、r thermoplastic Determination of tensile stress-strain properties. ISO48:1994, Rubber, vulcanized or thermoplastic Determination of hardness (hardness between10 IRHD and100 IRHD). ISO815:1991, Rubber, vulcanized or thermoplastic Determination of compression set at ambient, elevated or low temperatur
14、es. ISO868:1985, Plastics and ebonite Determination of indentation hardness by means of a durometer (Shore hardness). 3 General For the test methods, the requirements laid down under the test conditions are obligatory. The procedure and certain additional performance requirements shall be fixed by a
15、greement between the valve manufacturer and the client, with an obligation to meet the minimum airtightness requirements defined in this International Standard. 4 Valve cores 4.1 Types of tests Aircraft tyre valve cores shall be submitted to the following tests: a) tightening torque test(4.4.1); b)
16、washout test(4.4.2); c) blowout test(4.4.3); d) pressurized pulse test(4.4.4); e) environmental tests at low temperature(4.4.5); f) environmental tests at constant high temperature(4.4.6); g) environmental tests at peak high temperature(4.4.7). 4.2 Minimum airtightness requirements Valve cores shall
17、 be rejected if the leakage rate during tests is greater than0,2cm 3 /min. 4.3 General test conditions Unless otherwise specified, all tests shall be conducted under the following conditions: a) ambient temperature and pressure; b) valve cores shall be installed in a six-position manifold as shown i
18、n Figure 1; c) tightening torques for cores with elastomeric valve seats shall be between0,17Nm and0,34Nm; d) tightening torques for cores with metal (orelastomeric plus metal stop) valve seats shall be between0,34Nm and0,54Nm; e) the pressure inside the manifold shall be3800kPa; f) airtightness sha
19、ll be verified by immersing the core in water, acetone or alcohol. 4.4 Test methods 4.4.1 Tightening torque test 4.4.1.1 Test conditions a) Carry out the test on six cores installed in a manifold in accordance with Figure 1. b) Tighten the cores to the minimum torque specified in4.3. c) The test pre
20、ssure is200kPa to3800kPa. 4.4.1.2 Performance requirement The core leak-rate shall not be greater than the value set in4.2 throughout the pressure range. Checks shall be made at least at the minimum and maximum pressures. 4.4.2 Washout test This test simulates rapid deflation at high pressure. 4.4.2
21、.1 Test conditions a) Carry out this test on cores which have successfully passed the tightening torque test(4.4.1). b) Set the manifold pressure to3800kPa. c) Carry out10 test cycles, defined as follows, on each valve core: 1) open each core manually and keep it open for at least3s to allow the pre
22、ssurized air to escape at high speed across the valve seal; 2) allow the core to close freely.BSC22:1995 2 BSI 01-2000 4.4.2.2 Performance requirement The leak-rate, measured after10 cycles, shall not be greater than the value specified in4.2. 4.4.3 Blowout test This test simulates rapid inflation a
23、t high pressure. 4.4.3.1 Test conditions a) Carry out this test on the cores that have passed the tightening torque test(4.4.1) and the washout test(4.4.2). b) Carry out10 test cycles, defined as follows, on each valve core: 1) reduce the manifold pressure to0kPa; 2) attach a standard connector to a
24、3800kPa compressed air system; 3) keep each core open for at least3s to allow the pressurized external air to enter the manifold at high speed across the valve seal; 4) after3s, remove the inflation connector and let the core close freely. 4.4.3.2 Performance requirement The leak-rate, measured afte
25、r10 cycles, shall not be greater than the value specified in4.2. 4.4.4 Pressurized pulse test 4.4.4.1 Test conditions a) Carry out this test on six new cores installed in a manifold in accordance with Figure 1. b) Carry out the pulse tests on the valve cores in accordance with Table 1. 4.4.4.2 Perfo
26、rmance requirement Throughout the test, the leak-rate shall not be greater than the value set in4.2. It shall be noted after every1000 cycles. 4.4.5 Environmental test at low temperature 4.4.5.1 Test conditions a) Carry out this test on six new cores installed in a test manifold in accordance with F
27、igure 1. b) Hold the cores at a temperature of54 C for24h. c) Check the airtightness in acetone or alcohol cooled to54 C, with air cooled to54 C at a pressure of3800kPa. d) After cooling, check the airtightness at each of the following stages, in the order indicated: 1) at3800kPa; if the core leaks,
28、 retighten to the maximum torque defined in4.3; 2) washout test(4.4.2); 3) blowout test(4.4.3); 4) at200kPa; 5) at620kPa; 6) at1380kPa; 7) at3800kPa. Perform seven test cycles at each pressure. Figure 1 ManifoldBSC22:1995 BSI 01-2000 3 Table 1 4.4.5.2 Performance requirement Under each test conditio
29、n, the leak-rate shall not be greater than the value set in4.2. 4.4.6 Environmental test at constant high temperature 4.4.6.1 Test conditions a) Carry out this test on the same cores as passed the low-temperature test(4.4.5). b) Place them in an oven and increase the temperature to+93 C. Hold this f
30、or24h. c) Cool the samples to+52 C and check the airtightness in water at+52 C with air at+52 C at a pressure of3800kPa. d) Then follow the test procedure in4.4.5.1 d). 4.4.6.2 Performance requirement Under each test condition, the leak-rate shall not be greater than the value set in4.2. 4.4.7 Envir
31、onmental test at peak temperature 4.4.7.1 Test conditions a) Carry out this test on the same cores as passed the low-temperature test(4.4.5) and constant high-temperature test(4.4.6). b) Place them in an oven and increase the temperature to+120 C. Hold this for20min. c) Cool the samples to+52 C and
32、check the airtightness in water at+52 C with air at+52 C at a pressure of3800kPa. d) Then follow the test procedure in4.4.5.1 d),10times. 4.4.7.2 Performance requirement Under each test condition, the leak-rate shall not be greater than the value set in4.2. 5 Tyre valve caps 5.1 Test types Aircraft
33、tyre valve caps shall be submitted to the following tests: a) determination of mechanical properties of seal material(5.3.1); b) temperature resistance test(5.3.2); c) ageing test(5.3.3); d) screwing/unscrewing test(5.3.4). 5.2 Minimum airtightness requirement No leakage is acceptable during the var
34、ious airtightness checks. Leaking caps shall be rejected. 5.3 Test methods 5.3.1 Mechanical properties of gasket materials 5.3.1.1 Test conditions a) Determine the following initial properties of the gasket material as indicated: breaking strength, in accordance with ISO37; elongation in accordance
35、with ISO37; hardness in accordance with ISO48 or ISO868; compression set in accordance with ISO815. b) Determine the properties of the seal again after oven-ageing at+93 C for7 days. 5.3.1.2 Performance requirements Variations in tensile strength, elongation and hardness characteristics determined a
36、fter oven-heating shall not differ from initial characteristics by more than the maximum variation values given in Table 2. Table 2 5.3.2 Temperature resistance test 5.3.2.1 Test conditions a) Carry out this test on six valve caps. b) The service temperature range is54 C to+93 C with a24-h holding p
37、eriod at each of these two temperatures. Operation Pressure kPa Cycles per minute Total cycle in this condition min. a max. High-pressure cycle 1380 3800 35 1000 Normal cycle 620 1380 35 1000 Low-pressure cycle 200 620 5 1000 a Never let the pressure fall below the indicated minimum pressures. Chara
38、cteristic Increase max. Decrease max. Tensile strength 20% Elongation 30% or40% (to be specified) Shore A hardness 10% BSC22:1995 4 BSI 01-2000 c) The cap tightening torque is between0,56Nm and0,79Nm. d) The test pressure is up to3800kPa. 5.3.2.2 Performance requirements The requirement in5.2 shall
39、be met within the temperature and torque tightening range for pressures of up to3800kPa. 5.3.3 Ageing test 5.3.3.1 Test conditions a) Carry out this test on six valve caps. b) Place the caps in an oven and increase the temperature to+93 C. Hold this for7 days. 5.3.3.2 Performance requirements After
40、oven heating, the requirement in5.2 shall be met. 5.3.4 Screwing/unscrewing test 5.3.4.1 Test conditions a) Carry out this test on three new caps and three caps aged in accordance with5.3.3. b) Screw the caps down with a torque of0,56Nm10 times, unscrewing them each time, ensuring that the seals bre
41、ak contact with the valve mouth. Carry out at least five of the screwing/unscrewing cycles at54 C on caps which have been held at this temperature for a minimum of72h. The caps shall not be screwed onto the valve body during this72-h hold period at54 C. c) Screw the caps which have undergone10 screw
42、ing/unscrewing cycles back onto the valve body and torque them to between0,56Nm and0,79Nm. d) Apply a pressure of70kPa and hold it for1h. e) Apply a pressure of3800kPa and hold it for1h. f) With the caps still tightened onto the valve body with the same torque, cool them to54 C and hold this tempera
43、ture for24h, applying an internal pressure to the cap of at least3800kPa. 5.3.4.2 Performance requirements The requirement in5.2 shall be met during stages5.3.4.1 d),5.3.4.1 e) and5.3.4.1 f). In addition, after this test, the seal shall rotate freely within the cap without becoming unseated.BSC22:19
44、95 BSI 01-2000 List of references See national foreword.BS C22:1995 ISO9475:1994 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInstitution BSI is the independent national body responsible for preparing BritishStandards. It presents the UK view on standards in Europe and at the internat
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