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1、International Standard 4855 0 * - cool the eye-protector to - 5 f 2 OC, and maintain it at that temperature for 1 h before testing a second time. For eye-protectors intended for use in lower temperatures, ad- ditional treatment shall be carried out by cooling the eye- protector to - 20 -I 2 OC, and
2、maintaining it there for 4 h before testing. The tests shall be conducted within 30 s after completing the temperature treatment. 4 Test for stability at elevated temperature 4.1 Apparatus Oven, capable of maintaining a temperature of 55 + 2 Y 4.2 Procedure Place the eye-protector, in the position c
3、orresponding to nor- mal use, in the oven for 30 min at a temperature of 55 for example, 50 h at 200 mm. 6 Test for ignition 6.1 Industrial protectors 6.1.1 Purpose of test This test is intended to establish whether the test samples ignite or continue to glow, 6.1.2 Number and nature of test samples
4、 Five complete eye-protectors shall be tested. 6.1.3 Apparatus 6.1.3.1 Gas welding rod, made of steel; 300 mm long and 6 mm in diameter, with flat end faces. 6.1.3.2 Heat source. 3 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical
5、 Standards 1/9972545001 Not for Resale, 04/23/2007 23:02:52 MDTNo reproduction or networking permitted without license from IHS -,-,- ISo because of the velocities and distances involved, a timing indicator, recording in multiples of 10 ps, is required. The measurement of velocities should be made a
6、s near as possible to the point of impact and in any case not further than 250 mm from it. The end of the barrel or tube should be protected against ricochets. The area surrounding the test specimen, the head-form and the barrel or tube should be enclosed. 2 The tube length is determined by its abil
7、ity to produce an almost constant velocity of the steel ball in the final stages of its travel, i.e. when it passes through the timing device and is in flight to the item under test. Achievement of this requirement depends not only upon the air pressure or force of the spring but also upon the lengt
8、h of the tube and the fit of the ball inside the tube. Accordingly, each apparatus may have different characteristics and it is impossible to give precise requirements as to the length of the barrel and fit of the ball in the bore. 3 The timing device shall have a degree of accuracy not less than th
9、at specified; the following two methods are recommended : - an electronic timer operated by photoelectric cells through amplifiers; - a cathode ray oscilloscope actuated by detector coils located on the tube. The accuracy of the timing device depends upon the spacing between sensing elements and the
10、 required accuracy for measurements of the ball velocity. Present indications are that the spacing between the sen- sing elements ought not to exceed 150 mm; with this spacing and the highest velocity contemplated, the accuracy of the timing device should be fixed so as to allow for variations of ot
11、her factors while still keeping the velocity within the limits stipulated. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/23/2007 23:02:52 MDTNo reproduction or networking permitted wit
12、hout license from IHS -,-,- Dimensions in millimetres 4 136,5 C Figure 3 - Example of head-form for test for resistance to high-speed particles 9.2 Procedure Place the eye-protector to be tested on the head-form in the position corresponding to normal use and with the tension of the headband adjuste
13、d according to the manufacturer s in- structions. Insert a sheet of carbon paper on top of a sheet of white paper, each sheet being of the appropriate dimensions, between the eye-protector and the head-form. Then position the eye- protector/head-form assembly in front of the propulsion equip- ment,
14、the point of impact being not more than 100 mm from, and in line with, the muzzle of the tube. Project the steel ball at the selected speed on to the centre of each ocular in the case of a two-ocular eye-protector, or, in the case of a one-ocular eye-protector, onto two tests points- 33 mm from the
15、vertical midline of the eye-protector on the horizontal line passing through the centre between the top and bottom of the ocular. The direction of the impact shall be substantially normal to the surface of the eye-protector. 10 Test for non-adherence of molten metal 10.1 Apparatus The test apparatus
16、, shown in figure 4, consists of a spring- loaded piston fitted with an ejector head dished in the centre to take the molten metal. A fixed platform is mounted above the ejector head and has a central opening large enough to permit the charge of molten metal to go through it. The energy of the eject
17、ion spring and the position of the fixed platform shall be such that, on ejection, the metal charge is projected upwards to a nominal distance of 250 mm above the level of the ocular. 10.2 Procedure Place the eye-protector above the opening in such a way that its ocular is immediately above the cent
18、re of the ejector head. Load the ejector head, which shall have been pre-heated to reduce cooling of the molten metal, with a silica crucible con- taining 100 g of grey iron at a temperature of 1 450 f 20 OC. Release the pedal : the spring drives the head vertically up- wards until it strikes the st
19、op platform and the molten metal is projected against the ocular. 5 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/23/2007 23:02:52 MDTNo reproduction or networking permitted without li
20、cense from IHS -,-,- Dimensions in millimetres t 500 c Eye-protector in position Suitable jig to hold eye-protector in position I 580 -I Figure 4 - Apparatus for testing for non-adherence of molten metal -Distance piece Minimum test distance 75. This dimension can be increased, by addition of distan
21、ce pieces, to a maximur of 375 1Ejection head -Ejection cylinder -Ejection spring Release pedal 6 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/23/2007 23:02:52 MDTNo reproduction or n
22、etworking permitted without license from IHS -,-,- IS0 4855-1981 (E) 11 Test for resistance to penetration of hot solids 12 Test for proof against chemical droplets 12.1 Apparatus 11.1 Apparatus The test apparatus, shown in figure 5, consists of a metal cylinder shaped to hold the test material and
23、to take a funnel of heat-insulating material shaped to centre a steel ball on the test specimen. 11.2 Procedure Place the test specimen in the cylinder. Preheat a 6,5 mm diameter steel ball to about 1 030 OC in a furnace, withdraw the ball from the furnace, and drop it as quickly as possible into th
24、e funnel, where it comes into contact with the test specimen at a temperature of about 900 OC. Observe the underside of the cylinder and, if the ball drops, in- dicating complete penetration, record the time it has taken to penetrate. Test 12.1.1 Head-form, as described in 3.2.1 (figure 2). The ocul
25、ar area shall be covered with a double thickness of absor- bent lint the mass per unit area of which is approximately 185 glm2. 12.1.2 Hand atomizer, capable of producing fine droplets (not mist). 12.1.3 Test paper : white blotting paper 180 mm x 100 mm approximately, dipped in a 0,l mol/l solution
26、of sodium car- bonate. This paper shall be placed over the lint. 12.1.4 Detecting solution, prepared by dissolving 5 g of phenolphthalein in 500 ml of methanol and adding 500 ml of water, stirring constantly (filter if a precipitate forms), to obtain 1 litre. Dimensions in millimetres Insulating mat
27、erial Figure 5 - Apparatus for testing resistance to penetration of hot solids Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/23/2007 23:02:52 MDTNo reproduction or networking permitted
28、 without license from IHS -,-,- IS0 485s-1981 it) 12.2 Procedure Mount the eye-protector normally and place in a vertical plane on the head-form, covering the test paper; adjust the headband to the tension recommended by the manufacturer, and spray the assembly with the detector solution. Carry out
29、the spraying at an approximate rate of 20 to 30 ml/min, holding the atomizer about 600 mm from the head-form. The period of spraying shall be about IO s; during this time, spray the head-form from all directions. For safety reasons, it is recommended that the test be carried out under a hood, 12.3 A
30、ssessment of results If the detecting solution penetrates the eye-protectors, a crim- son coloration will instantly develop on the test paper. No ac- count need be taken of crimson colo;ation in the immediate proximity of the edges, provided that it does not develop more than 6 mm inside the eye-pro
31、tector, 13 Test for protection against dust 13.1 Apparatus The test apparatus is shown in figure 6. 13.1.1 Dust-chamber, glass-fronted, with internal dimen- sions 660 mm x 560 mm x 560 mm, with a hopper-shaped bottom and a tightly sealed, hinged lid. To the bottom of the in- verted hopper is connect
32、ed an air-blower capable of delivering approximately 2,8 ms/min at a pressure of 2 255,5 Pa. A suitable agitator, capable of inducing swirling in the air stream from the blower, should be arranged immediately above the air inlet. The dust-chamber outlet is connected to the air blower in- let. 13.12
33、Test dust : 1 000 g of pulverized coal shall be placed inside the dust-chamber; the coal dust shall have the following grain size : Nominal mesh Percentage pass dimension of sieve (IS0 565) (mass/mass) 250 pm 95 125 pm 85 90 Mm 40 13.1.3 Head-form, as described in 3.2.1 (see figure 2). It shall be c
34、overed with a double thickness of absorbent lint the approximate mass per unit area of which is 185 g/m2. This lint shall be covered by a sheet of moist white paper on which have been marked in pencil two circles about 57 mm in diameter, the horizontal distance between centres being 66 mm (represen-
35、 ting the ocular areas). 13.1.4 Photoelectric reflectometer, for the measurement of quantities pertaining to reflection. The apparatus consists of an interference filter for the wavelength 1 = 646 nm, a lens at the focus of which the mercury lamp is placed, and a radiation receiver (for example, pho
36、tovoltaic cell, photodiode). The ex- perimental mounting is shown in figure 7. III -Bars /*Dust collector -Blower Figure 6 - Apparatus for test for protection against dust Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standard
37、s 1/9972545001 Not for Resale, 04/23/2007 23:02:52 MDTNo reproduction or networking permitted without license from IHS -,-,- IS0 4855-1981 (E) Dimensions in millimetres Radiation receiver Interference fitter, X = 546 nm Figure 7 - Photoelectric reflectometer 13.2 Procedure Before placing the eye-pro
38、tector on the head-form, determine the reflectance of the unexposed moist test paper within the two circular areas. For this purpose, place the experimental mounting as shown in figure 7 at a distance of 250 mm from the test paper. Place the assembled eye-protector and head-form in the dust- chamber
39、 and fasten the lid. Operate the blower for 1 min, switch off and keep the chamber closed until the dust has settled. Carefully remove the exposed moist test paper and remeasure the reflectance of the two circular areas. Finally, calculate the ratio of the mean reflectance after exposure to the mean
40、 reflectance before exposure. 14 Test far protection against gas 14.1 Apparatus 14.1.1 Head-form, as described in 3.2.1 (see figure 2). 14.1.2 Gas-chamber : a gas-tight, glass-fronted enclosure, with internal dimensions 560 mm x 560 mm x 560 mm and a tightly sealing, hinged lid. The gas chamber shal
41、l be ventilated by means of a small blower with a capacity of about I,4 cm3/s and a vent pipe leading to a fume chamber or to the outside at- mosphere. Gas supply : any convenient means of generating ammonia gas, for example by blowing air through a washing bottle con- taining a concentrated solutio
42、n of ammonia (Q 0,8% g/ml ap- proximately) or by using a gas cylinder of ammonia. The outlet from the generator or cylinder is connected to the gas chamber. 14.1.3 Test paper : white blotting paper, free from sulphur compounds, 180 mm x 100 mm, dipped in 1 % mercury(l1 nitrate solution at the time o
43、f test. 14.1.4 Mercury(l) nitrate solution, prepared by dissolving 10 g of finely ground mercury(l) nitrate in 100 ml of distilled water to which 1 ml of concentrated nitric acid (Q I,42 g/ml) has been added. 14.2 Procedure Mount the eye-protector on the head-form symmetrically over the test paper,
44、which itself rests on absorbent lint of mass per unit area about 185 g/m2 arranged in a double thickness so as to cover the ocular area. Place the assembly in the gas-chamber with a control strip of test paper placed on the floor of the chamber. Then open the gas generator slightly, the vent being s
45、lightly open, and fill the gas-chamber with ammonia gas at room temperature. Close the vent and leave the test specimen in the gas for 5 min. After the chamber has been cleared of the gas, remove the eye-protector and examine the test paper. 14.3 Assessment of results If any trace of gas has penetra
46、ted the eye-protector, the treated test paper will turn brown. No account need be taken of any darkening in the immediate vicinity of the edges, provided that it does not develop further in than a distance of 6 mm inside the eye-protector. 9 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/23/2007 23:02:52 MDTNo reproduction or networking permitted without license from IHS -,-,-