Environmental testing for electric and electronic products - Part 2: Tests methods - Test Z/AM: Combined cold/low air pressure tests
1 Introduction
1.1 General
This part of GB/T 2423 deals with combined cold (with gradual change or sudden change of temperature) and low air pressure tests for both heat-dissipating and non-heat-dissipating specimens, see 8.2.2 and 8.2.8.
The object of the test is to determine the ability of components or equipment or other articles to be stored and used under a simultaneous combination of low temperature and low air pressure.
This combined test should normally be used only if the effects of combined environments will not be revealed by subjecting the specimen to single environments. The procedures given in this part are limited to the case of specimens which achieve temperature stability during the test procedure.
In the case of testing heat-dissipating specimens, this procedure applies only to the testing of one specimen at a time.
1.2 Low air pressure
The test procedure applies to air pressure down to 1kPa. At air pressures below or equal to 1kPa, it is unnecessary to consider the contents of the test procedure.
The relationship among altitude, pressure and temperature has not been indicated in this part. Such data should be obtained from special standards.
1.3 Temperature
1.3.1 The guidance given in GB/T 2423.1, Tests A, for the application of tests for non-heat-dissipating specimens versus tests for heat-dissipating specimens shall apply.
Note: Non-heat-dissipating specimens are defined as in GB/T 2421. The measurement of hottest spot temperature must not be made at low pressure.
1.3.2 Heat-dissipating specimens shall preferably be tested without forced air circulation in the chamber as for GB/T 2423.1, Tests A.
1.4 Normative references
The following normative documents contain provisions which, through reference in this part of GB/T 2423, constitute provisions of this part. For dated references, subsequent amendments to (excluding correction to), or revisions of, any of these publications do not apply. However, parties to agreements based on this part are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. For undated references, the latest edition of the normative document applies.
GB/T 2421.1 Environmental testing for electric and electronic products - Part 1: General and guidance (GB/T 2421.1-2008, IEC 60068-1:1988, IDT)
GB/T 2423.1 Environmental testing for electric and electronic products - Part 2: Test methods - Tests A: Cold (GB/T 2423.1-2001, IEC 60068-2-1:2007, IDT)
GB/T 2423.21 Environmental testing for electric and electronic products - Part 2: Test methods - Test M: Low air pressure (GB/T 2423.21-2008, IEC 60068-2-13:2005, IDT)
GB/T 2423.22 Environmental testing for electric and electronic products - Part 2: Test methods - Test N: Change of temperature (GB/T 2423.22-2002, IEC 60068-2-14:1984, IDT)
GB/T 2424.1 Environmental testing for electric and electronic products - Guidance for high temperature and low temperature tests (GB/T 2424.1-2005, IEC 60068-3-1:1974, IDT)
GB/T 2424.15 Basic environmental testing procedures for electric and electronic products - Guide for combined temperature/low air pressure tests (GB/T 2424.15-2008, IEC 60068-3-2:1976, IDT)
2 Object
To provide a standard test procedure to determine the suitability of components, equipments or other articles for use and/or storage under a combination of low temperature and low air pressure.
3 General description
This test is a combination of GB/T 2423.1, Tests Ab or Ad, and GB/T 2423.21, Test M.
Foreword II
1 Introduction
1.1 General
1.2 Low air pressure
1.3 Temperature
1.4 Normative references
2 Object
3 General description
4 Description of test apparatus
4.1 Test chamber
4.2 Mounting
5 Severities
5.1 General
5.2 Preferred combinations of temperature, air pressure and duration
6 Preconditioning
7 Initial measurements
8 Conditioning
8.1 General
8.2 Procedure for heat-dissipating specimen without artificial cooling of the specimen and for non-heat-dissipating specimen
8.3 Precautions when testing specimens with artificial cooling
9 Intermediate measurements
10 Recovery
11 Final measurements
12 Information to be given in the relevant specification
Annex NA (Informative) Components of the standard GB/T
