Influence of physical/chemical characteristics of organic vapors and gas mixtures on their contact compatibility

The formation of carbon on the contact surfaces of commercial relays by thermal decomposition of organic vapors emanating from various organic materials may cause an undesirable increase of the contact resistance in the range of several Ohms. Previous investigations revealed that the contact compatibility of an organic vapor in combination with a certain contact material depends mainly on its chemical structure. There are additional correlations between the contact compatibility on the one hand and a few parameters of the vapors like volatility, the basic structure type of the molecule (e.g., aromatic or aliphatic, length of the carbon chain), certain active groups on the other hand. The contact compatibility values of a few mixtures of organic vapors investigated corresponded to those of their individual components. Humidity and oxygen concentration of the atmosphere influenced the phenomenon effectively