The Interaction of Sulfuric Acid Vapors and Zinc Surfaces

The corrosion of surfaces inadvertently exposed to the vapors of sulfuric acid due to the presence of lead acid batteries is of concern when banks of batteries and electronic equipment are collocated. It is also of concern when an aqueous solution of H2SO ~ is used in a static system to control the relative humidity. We exposed zinc coupons to various concentra-tions of vapors from both of the above sources at various concentrations. Surface concentrations of elements were evalu-ated by Auger electron spectroscopy and argon ion sputter depth profiling before, during, and after exposure. Significant sulfur deposition and corrosion only occurs in sealed volumes. This is in agreement with calculations that indicate very small amounts of fresh air flow are sufficient to dilute the battery acid vapors to well below the background level. This work shows that collocation of lead acid batteries and electronic equipment produces no degradation u der the normal condi-tions used in the test. The telephone system in North America operates on 48 V dc converted from the commercial c power grid. Backup battery systems provide power for the telephone network in the event of commercial power failure. Placing the local telephone switching system and battery system side by sid