Permissible diffusion resistance of polymer coatings against water vapour and its diffusion effective film thickness

摘要

If coatings are used during rehabilitation measures on the shell of cooling towers, the allowed resistance against diffusion of water vapour on the outside has to be known to prevent damages by enhancement of water in the border zones of the shell. It is possible to plot the transport of heat and humidity in the shell of the cooling tower and thereby determine the limit for the resistance against diffusion for the outer coating. In addition to that we have to consider the effective film thickness for diffusion.