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1、INTERNATIONAL STANDARD ISO 9022-5 First edition 1994-07-15 Optics and Optical instruments - Environmental test methods - Part 5: Combined cold, low air pressure Op tique et ins trumen ts d optique - M6thodes d essais d environnemen t - Partie 5: Essais combin b) number of specimens to be tested; c)
2、conditioning method 50: time of first hoarfrost formation and method of generation; d) location of the temperature Sensors on the speci- men; e) preconditioning; 0 ISO ISO 9o22-5:1994(E) type and scope of initial test; period of Operation for state of Operation 2; type and scope of intermediate test
3、 for state of i) recovefy; j) type and scope of final test; k) criteria for evaluation; Operation 2; 1) type and scope of test report. Table 1 - Degrees of severity for conditioning methods 50 and 51: Combined cold, low air pressure Degree of severity I 01 I 02 I 03 f 04 I 05 l 06 I 07 I 08 Test cha
4、mber tempera- ture oc -25f3 -4Of3 -25f3 -4Of3 -65f3 -25f3 -4Of3 -650 kPa 60 i: 3 8,s k 1 1 * 0,5 Air pressure Equivalent al- titudel) 3 500 m 16 000 31 000 Time needed for air pressure reduction or air min max. 5 max. 20 max. 40 pressure rise Mean temperature Change rate during heating or K/min In t
5、he range from 0,2 to 2 cooling respectively Exposure time h State of Operation 1) The data are based on bad weather conditions. 3 ISO 9022-5: W%(E) Annex A (informative) Explanatory notes Al General This part of ISO 9022 describes two methods of ex- posure characterized by different environmental in
6、flu- ences. Both methods employ cold and low air pressure as acting factors. Whereas conditioning method 51 requires only low temperature and low air pressure, conditioning method 50 also includes ex- posure to hoatfrost and condensed moisture. Conditioning method 51 simulates the Operation and tran
7、sport of Optical instruments in high mountainous areas where temperature and humidity Change slowly without noticeably affecting the instrument. Similar conditions are encountered in unheated internal com- partments of aircraft where there is little or no press- ure balance e.g. in cargo space. Hoar
8、frost and moisture condensation may be excluded in such sur- roundings. However, Optical instruments, or Parts of them that are externally mounted on aircraft, are ex- posed not only to cold and low air pressure but also to air humidity in the form of condensed moisture or hoarfrost. Condensation or
9、 freezing of moisture on instrument surfaces, or even within leaky instruments, occurs when descending aircraft or missiles penetrate re- gions where, with rising temperature and pressure, humid air or rain are encountered, the temperature of which exceeds the temperature of the instrument surfaces.
10、 The melting hoarfrost or the condensed moisture is likely to penetrate into externally mounted instruments or components. As a consequence of leakages or inadequately ventilated Parts, condensed moisture may accumulate within the instrument and Cause malfunctions. Exposure conditions as required fo
11、r conditioning method 51 may be simulated in Standard low air pressure cabinets or chambers providing means of cooling and air circulation. If, for conditioning method 50, the formation of hoatfrost in the low air pressure range is additionally required, the test apparatus should include a device fo
12、r injecting, at low tempera- ture and low air pressure, water vapour and Spray into the chamber; the injection inlet should be located near the specimen. One of several methods of performing the test in accordance with conditioning method 50, using chamber as described above, is given in A.2. A.2 Ex
13、ample of conditioning method 50 At the end of the exposure time and while heating up is in process, adjust the test chamber temperature to between - 20 “C and - 10 “C. Let specimen tem- peratures stabilize within this temperature range. Adjust the pressure within the test chamber to be- tween 40 kPa
14、 and 60 kPa. Inject, in the immediate neighbourhood of the specimen, water vapour or Spray through a weil-insulated hose and funnel into the chamber until hoarfrost becomes clearly visible on the specimen. Then, as rapidly as possible, raise the chamber temperature to approximately 2 “C, at constant
15、 pressure, and dwell at this temperature until the wet bulb indicates a positive temperature value. This dwell time, which depends upon the type of humidifier used in the test chamber, is required be- Cause, normally, the humidity control will not work until the mantle humidifier installed within th
16、e test chamber has defrosted. The relative humidity within the test chamber is to be maintained at a level of more than 95 % in Order to prevent the condensed moisture from drying while heating up continues. As soon as the mositure control has started working and the relative humidity has reached a
17、level of more than 95 %, adjust the test chamber temperature, as rapidly as possible, and at constant pressure and constant relative humidity, to ambient atmospheric conditions until the hoarfrost on the specimen has completely changed into condensed moisture. After ambient atmospheric conditions ha
18、ve been reached, gradually adjust the test chamber air press- ure to ambient air pressure. The relative humidity within the test chamber should continue to be main- tained at more than 95 %. Care should be taken that the condensed moisture on specimens other than heat-active components does not dv u
19、p during the subsequent intermediate test. This page intentionaiiy left blank -,-,- This page intentionally left blank -,-,- This page intentionally left blank -,-,- ISO 9022=5:1994(E) 0 ISO ICS 37.020.00 Descriptors: optics, Optical equipment, tests, environmental tests, low temperature tests, low pressure tests. Price based on 4 pages -,-,-