Hazardous area classification
Hazardous area classification
(OP)
We have a number of storage vessels that are used for various solvents contained in a bund of approx 4" depth. All electrical items located in the bund are EEx rated for a zone 2 area. My question is whether the zoned area should continue beyond the confines of the bund and if so how to I establish how far both vetically and horizontally?





RE: Hazardous area classification
There are tables and graphs that enable estimating the concentrations of the vapour at a vertical and horizontal distance to verify whether these are lower than the LFL or the TLV of the particular solvent, using dispersion coefficients such as those given by the Pasquill-Gifford model.
I can recommend one book that has worked out examples: Chemical Process Safety: Fundamentals and Applications by Crowl and Louvar (Prentice Hall).