ISO-4855-1981.pdf
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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
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