Activatedhyphen;break arc durations have been measured for various organic compounds and contact metals. These durations were determined as a function of exposure (partial pressure of organic contaminant times the contact open time) for each metal and organic compound. The metals studied were palladium, gold, silver, rhenium, 60 Pdhyphen;40 Ag, and 73 Pdhyphen;27 Ni (wtpercnt;). Organics used were diethylphthalate, isopropyl alcohol, trichlorotrifluoroethane (Freon 113), benzene,nhyphen;hexane, cyclohexane, and phenol. The experimental results show three separate regimes with respect to exposure and agree well with the previous models of contact activation which have been generalized to include constant arc durations at short exposures. The steadyhyphen;state average arc duration, which is proportional to contact erosion, was found to be a function of both the contact material and exposure for a particular organic material. The data has been statistically analyzed and the results indicate that in the adsorptionhyphen;sitehyphen;limited regime (high exposure) the metals can be divided into groups according to their activation susceptibility, while the organic materials all belong to a single group. In the diffusionhyphen;limited regime (intermediate exposure) ranking was observed for both the metals and organics, with larger differences noted for the organics. Finally in the initial activation region (low exposure) the individual differences between the organic or metal effects cannot be distinguished to 95percnt; confidence. However, the degree of activation of a specific metalhyphen;activant pair can be quite different than that expected from the average behavior of the metal over all activants, and the average behavior of the activant over all metals. Thus the metalhyphen;activant pair is critically important in establishing the degree of activation.
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