The Industrial Atmosphere Test for Contacts and Connectors: Some Design Parameters

Abstract

The work described deals with the parameters involved when generating a simulated industrial atmosphere containing 25 ppm of sulphur dioxide and 3,000 ppm of carbon dioxide, at 75% relative humidity and 25°C, rather than with the effect of this atmosphere on electrical characteristics of materials’ surfaces. A critical discussion is presented of the techniques for atmosphere generation proposed in BS 2011: Part 2Kb: 1970 and it is shown why those techniques can produce the specified atmosphere only when the ambient conditions are within a limited range. Modification to the generation techniques are described to indicate how the test conditions can be more closely controlled. Particular emphasis is placed on the control of humidity and the contributions to humidity of different gases and gas/air flow rates. Factors which affect the sulphur dioxide content and its analytical control are also mentioned. The results obtained in a commercial apparatus when operated over the 20-day test period are described. Finally, after some discussion of the test and its relation to other accelerated corrosion tests, recommendations are made for improvement of the BS specification.