STP646

    Investigation of Atmospheric Exposure Factors that Determine Time-of-Wetness of Outdoor Structures

    Published: Jan 1978


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    Abstract

    Wetness of outdoor structures is caused partly by condensation of water from the atmosphere, which we recognize as dew. Rain is the source of part of the wetness. The condensation process means that heat must be removed from air at the surface where condensation occurs. This heat exchange process by radiation from the exposed surface to the cold sky is examined in detail. Temperature differences between an insulated black surface, facing skyward, and ambient air conditions were observed to be as high as 8°C (15° F). Effects of wind velocity, orientation, and surface characteristics are given. Time-of-wetness measurements for test panels exposed at Miami, Florida are reported, including the “black box” exposure method used for coated panels. Comparisons of time-of-wetness investigations reported by Guttman and Sereda are given.

    Keywords:

    atmospheric corrosion, environments, test panels, corrosion rates, panel radiation, sky radiation


    Author Information:

    Grossman, PR
    Vice president, Q-Panel Co., Cleveland, Ohio


    Paper ID: STP27311S

    Committee/Subcommittee: G01.04

    DOI: 10.1520/STP27311S


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