1、 . .I . -. Vent Innai I I I -+ I (if any) nibs in pdytetrafluoroethylsns Non-metallic container Lower electrode (mercury) ? (PTFE) Figure 1 : Diagram for the electrical conductivity test of the inner tube STD-AECMA PREN 23Li7-ENGL L77b LO12311 0011829 801 DN 6 10 12 16 Minimum inside diameter of 3,3
2、 63 8,6 10,9 the hose assembly (on the end fitting) Page 7 prEN 2347 : 1996 20 25 32 13,9 19,3 23,5 6.3.3 Tensile strength The inner tube of the hose assemblies shall be subjected to the tensile strength test. The rate of application is 50 mm/min. The longitudinal tensile strength shall be 15 MPa at
3、 (25 i 2) OC for all DN. The transverse tensile strength shall be 12 MPa at (25 I 2) “C. Inner tubes with DN 16 shall not be submitted to a transverse tensile strength test. Until a special EN or IS0 Standard for this method has been published, a procedure shall be applied which has been agreed by t
4、he purchaser and approved by the relevant authorities. 6.3.4 Elongation At a temperature of (25 f 2) OC, the elongation shall be 1 200 %. 6.3.5 Specific gravity 6.3.5.1 The apparent specific gravity shall be between 2,125 g/cm3 and 2,155 g/cm3. Apparent specific gravity (to IS0 7258 method BI 6.3.5.
5、2 The relative specific gravity shall not exceed 2,210. Relative specific gravity (to IS0 7258 method Cl 6.4 6.4.1 6.4.1 .I Examination of product Each hose assembly shall be carefully examined to check whether it has been manufactured correctly and is free from defects. Tests on the hose assembly w
6、ith fittings Check on all hose assemblies 6.4.1.2 Dimensions, mass Weigh each hose assembly and carry out the measurements to check that they comply with the relevant standards or, in their absence, with the design document. The inside diameter shall exceed the minimum value given in table 4. 6.4.1.
7、3 Proof pressure The hose assemblies shall show no leak, burst or any other evidence of malfunction when subjected to proof pressure PE which is 2 times P, for a period of 30 s to 5 min. Page 8 prEN 2347 : 1996 DN Volume increase in cm3 for flexible hose assemblies with P, = 21 MPa hose assemblies w
8、ith PN = 28 MPa Volume increase in cm3 for flexible 6.4.2 Tests on samples 6.4.2.1 See annex A. The hose assemblies with two gauge marks at a distance of 250 mm are connected to the test machine with one end free. When the nominal pressure has been applied to them for 5 min: Variation in length and
9、volume - the variation in length between the gauge marks shall not exceed - the increase in volume, under nominal pressure, shall not exceed the values given in table 5 for a length of 250 mm. 2 %; 6 10 12 15 20 25 32 0,65 0,85 1,325 2,175 2,95 7,375 9,85 0,8 1,175 1,675 2,7 3,7 9,25 - Table 5 : Vol
10、ume increase under nominal pressure 6.4.2.2 Effusion test The hose assemblies are subjected to nominal pressure at room temperature for 1 h. During the second half hour, the leakage from the hose assembly is collected and measured. This quantity shall not exceed 26 cm3/m. Air or nitrogen gas r sourc
11、e 7 Inverted graduated Hark Funnel to cover hose plus one-half of each socket / I Water bath-/ without wetting agent Hose assembly under rest Figure 2 : Assembly for effusion test 6.4.2.3 Oil ageing The hose assemblies are immersed for 168 h at (200 f 5) OC in fluid no. 1 or no. 2 in accordance with
12、 table 7 and are then subjected to proof pressure PE which is 2 times PN. 6.4.2.4 Air ageing The hose assemblies are subjected to ageing in air at a temperature of (200 I 5) OC for 168 h and are then subjected to proof pressure PE which is 2 times Phi. STD-AECMA PREN 2397-ENGL 177b LOL23LL UULL82b b
13、B9 6.4.2.5 Pneumatic surge test The hose assembly is installed in a gas system (air or nitrogen) shown in figure 3. The test, conducted at room temperature, consists of 16 times the - nominal pressure is held in the hose assembly for 25 min; Page 9 prEN 2347 : 1996 fitted with rapid action valves as
14、 following cycle: - it is then rapidly reduced to atmospheric pressure and held there for 5 min. After this test, the hose assembly shall withstand proof pressure PE which is 2 times P, and shall be visually examined internally and externally. Any obvious degradation shall form a reason for rejeetio
15、n. Air or nitrogen gas source Hose assembly under test Figure 3 : Pneumatic surge test arrangement 6.4.2.6 Thermal shock test The thermal shock test shall be performed as follows : a) a hose assembly aged in air as described in 6.5.2.4 and a hose assembly not aged in air are subjected for 5 min to p
16、roof pressure PE which is 2 times PN; b) the drained hose assemblies are then assembled in the test assembly for 2 h at a temperature of (- 55 k 2) OC. Test fluid No. 4 in accordance with table 7, at a temperature of 200 OC, at a pressure of 0,35 MPa is then introduced into the hose assemblies. The
17、hose assemblies are then subjected to the proof pressure PE which is 2 times P, within 15 s and for 5 min; c) the pressure is reduced to (033 f 0,171 MPa and the test fluid pressure held for not less than 1 h on the hose assemblies. They are then subjected for 5 min to the proof pressure PE which is
18、 2 times P, ; d) the hose assemblies shall show no sign of leak, blow-off of end fittings from the hose or other defects, at pressure values 3 times PN. 6.4.2.7 Degradation test a) The hose assemblies, filled with fluid no. 4 in accordance with table 7, are placed in a heating chamber at a temperatu
19、re of 200 “C. Care shall be taken that they do not make contact with parts of the heating chamber which are at a higher temperature. The nominal pressure is maintained in the hose assemblies for at least 20 h, then gradually returned to zero. b) The hose assemblies are withdrawn from the heating cha
20、mber and cooled in air to room temperature. c) They are then filled with fluid no. 3 in accordance with table 7 and maintained for at least 2 h at nominal pressure and at room temperature. - STD-AECMA PfCEN 2347-ENGL L97b 3032313 0033827 530 Page 10 prEN 2347 : 1996 d) The above operations al, b) an
21、d c) shall be repeated 3 times. e) The hose assemblies are then drained and rinsed with fluid no. 9 in accordance with table 7 and placed for 1 h in a chamber at (70 k 5) OC. f) Within the next 8 h, the hose assemblies are mounted on equipment similar to that shown in figure 2 for 15 min at nominal
22、pressure. This pressure is maintained for a further period of 5 min and the air escaping from the hose assembly is collected and measured. This quantity shall not exceed 80 cm3/m of hose length per minute. 6.4.2.8 Bending test The hose assemblies are mounted in the assembly in accordance with figure
23、 4, filled with fluid no. 4 in accordance with table 7 and are bent at a frequency of (70 i 10) cycles per min. The temperature of the fluid and the room temperature shall be as shown below. a) The fluid shall act for no less than 1 h at a temperature of (- 55 f 2) OC without pressure on or bending
24、the hose assemblies. b) At the same temperature, the hose assemblies are then subjected for no less than 5 min to the proof pressure PE which is 2 times P,. c) When the pressure is reduced to nominal pressure, bending is applied at a constant temperature of (- 55 * 2) OC for the first 4 O00 cycles.
25、d) The pressure is reduced to zero for the next 1 O00 cycles at the same temperature. e) Still at zero pressure, raise the temperature to 200 “C and complete 1 O00 cycles. f) Then apply the nominal pressure and continue bending until 80 O00 cycles are completed, while the temperature is held at 200
26、OC. g) Operations a), cl, d), e) and fi are repeated five times, .e. a total of 400 O00 cycles. h) Apply the proof pressure PE which is 2 times PN at a temperature of 200 OC for 5 min without bending. The hose assemblies shall show no sign of leak, slipping of the couplings from the hose or other de
27、fects. Dimensions in millimetres Minimum inside bend I L( I Figure 4 : Bending test set-up Page 11 prEN 2347 : 1996 - DN 6 10 12 15 20 25 32 A 185 270 310 355 420 530 650 Minimum inside bend radius 76 127 146 165 197 245 305 6.4.2.9 Leak proof test The hose assemblies are subjected for 5 min to a pr
28、essure of 70 % of minimum burst pressure (PR) at room temperature P, = 4 P, while the rate of pressure increase is 2 MPals 120 bark) to 3 MPa/s (30 bar/s). The pressure is then reduced to zero and raised again to the value at the same rate and for the same period. During this time, the hose assembli
29、es are carefully examined for signs of leak or other defects. 6.4.2.10 Impulse test a) The hose assemblies are connected to the manifold tube and bent to a cemi-circle to the minimum bend radius specified in table 6. The nominal dimension 32 of pressure class IV and nominal dimensions 25 and 32 of p
30、ressure class V shall be subjected to the test in a straight position, their end left free. b) The hose assemblies are filled with fluid no. 1 in accordance with table 7. The temperature of the fluid and of the air shall be maintained at (200 k 5) OC. The amplitude of the pulses is indicated in the
31、diagram of figure 5 which also gives the shape of the cycle. The frequency is from 35 to 70 cycles per min. At least 80 % of the impulses shall be applied at 200 OC. The minimum number of cycles is 250 O00 for hose assemblies of pressure class IV, 100 O00 for hose assemblies of pressure class V up t
32、o nominal dimension 20, and 45 O00 for nominal dimensions 25 and 32. The impulses shall be measured using electronic measuring instruments. Any sign of leakage, as well as blow-off of end fittings before the end of the impulse test shall be cause for rejection. Peak oressure : 150% Minimum increase
33、of the pressura 1 225 MPels (1 2 250 bark 150 125 110 i00 95 z 75 s -0 1; 25 50 75 lO Cycle duration Figure 5 : Impulse diagram Page 12 prEN 2347 : 1996 The curve shows the pressure variation during the impulse test. The comparison of results is adequate when the pressure/time curve is confined to t
34、he shaded area. In order to calculate the rate of pressure increase, the slope of the curve shall be determined by a straight line on the y-axes between 10 and 90 % of peak pressure. The rate of pressure increase is calculated according to : 10 (0.9 P- 0.1 P) Where : P is the peak pressure, in pasca
35、ls; T, is the time at 10 % P, in seconds; T2 is the time at 90 % P, in seconds. Other impulse tests, such as e.g. pressure peak at 125 % of P, and 600 O00 cycles, may be used to quaiify the flexible hose assemblies intended for a specific aircraft provided that authorisation is granted by the qualif
36、ication authority in the light of the other technical specifications concerning this specific aircraft. 6.4.2.1 1 Corrosion test The hose assemblies subjected to nominal pressure are installed vertically and immersed for 5 min in fluid no. 5 in accordance with table 7. They are then dried in air at
37、a temperature of 60 “C for 25 min. This cycle is repeated for 172 h. Then, one of the hose assemblies shall be subjected to the room temperature burst test and the other to the high temperature burst test. Any sign of leak or malfunctioning below the relevant burst pressure, any trace of rust or abn
38、ormal corrosion which might adversely affect the life of the hose assembly are a cause for rejection. 6.4.2.12 Burst test 6.4.2.12.1 Burst test at room temperature The hose assemblies are left straight, the end opposite to the pressure source being free. With the appropriate fluid, apply pressure by
39、 increasing it continuously and evenly at a rate varying between 2 MPa/s (20 bar/s) and 3 MPa/s (30 bar/s) until bursting of the hose assembly. Bursting shall occur at a pressure above or equal to the burst pressure at room temperature PR = 4 P,. 6.4.2.1 2.2 Burst test at high temperature The hose a
40、ssemblies filled with fluid without pressure are raised and then held for 1 h at a temperature of (200I5) OC. After this time, the pressure is raised to nominal pressure PN for 5 min, and the pressure is then increased continuously and evenly at the rate of 2 MPa/s (20 bark) to 3 MPa/s (30 bark) unt
41、il bursting of the hose assembly. Bursting shall occur at a pressure above or equal to the burst pressure at high temperature PR = 3 PN. 6.4.2.1 3 Electrical conductivity test a) The specimen consists of a length of hose with metal braid and fitted with an end fitting at one end. The internal wall o
42、f the inner tube is first cleaned with an appropriate solvent and then with fluid no. 9 in accordance with table 7, and then carefully dried at room temperature. The metal braid is peeled as shown in figure 6 to avoid contact with the end of the inner tube. An end fitting used as lower electrode and
43、 insulated against earth is screwed into the end fitting of the hose length; fluid no. 5 or no. 8 in accordance with table 7 is used as upper electrode. I STD.AECMA PREN 23Li7-ENGL 1976 I LOL23LL DOLL830 005 m Page 13 prEN 2347 : 1996 b) The specimen is then installed as shown in figure 6 at room te
44、mperature at an air humidity 70 %, the upper electrode and the lower electrode are then subjected to a voltage of 1 O00 V d.c.; c) The current is measured with an amperemeter of a sensitivity of at least 1 pA. For hose assemblies of nominal dimensions from 5 to 12, the current shall be 6 pA or more,
45、 and 2 12 pA for hose assemblies of larger nominal dimensions. Dimensions in Conauc:or inreaded inlo nng Flare raitsi/spiral Upoe. eiec:rode Non-meiallic ring Inner tube in polytetrafluoroethylene (PTFE) Venr iaiternativei linsuiaie eiectrode from ground1 millimeti Figure 6 : Electrical conductivity
46、 test of the hose assembly 6.4.2.14 Fire resistance test The hose assemblies for which fire resistance qualification is required shall be subjected to the tests specified in IS0 2685, when specified on the order. 7 Acceptance conditions 7.1 Application The acceptance tests are conducted on the tube
47、before braiding and on the hose assemblies supplied against an order, to check that the main properties of the hose assembly are maintained. They concern only the types and DN of hose assemblies which have cleared the qualification tests. STD-AECMA PREN 2347-ENGL L77b = LOL231L OOLLB31 TL1L Page 14
48、prEN 2347 : 1996 7.2 Conformance certificate A conformance certificate shall be attached to each delivery to confirm that the hoses or hose assemblies have been : - manufactured to the same standard as the sample presented with : - the same materials; - the same process; - according to this standard
49、; - checked and accepted by an entitled controller. The purchaser shall refuse any delivery to which a conformance certificate is not attached. 7.3 Batching a) Inner tube: a batch is made up of a tube extruded in one go and sintered in one go, and taken from preforms produced in one go and from one single batch of PTFE powder. b) Hose: a batch is made up of a maximum of 7 O00 m of hose of the same type and same DN. c) Hose assemblies: a batch is made up of hose assemblies of the same type and same DN manufactured in similar conditions and of which the number shall not exceed 3 0
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