Modeling gas collection systems for corrosion testing

Abstract

The fire community has become increasingly concerned by potential damage due to corrosion by combustion products from a fire. Since evidence of corrosion may be found days after the actual fire and in areas remotely connected to the fire scene, this type of damage has been described as ‘non-thermal fire damage’. A number of factors influencing corrosion have been identified. These include (i) concentration of corrosive gases; (ii) exposure time; and (iii) environmental conditions. There are a number of tests under development to determine the corrosive effect of combustion products on metals. These tests typically consist of combustion cell, an exposure chamber and corrosion monitoring targets. In this paper, some of the methods under consideration for combusting and collecting the combustion products from material test samples are analyzed and modeled. These systems are described as closed combustion cell-closed exposure chamber, open combustion cell-flow through exposure chamber, and open combustion cell-piston-cylinder exposure chamber. The analyses of the three systems reveal the design and operating parameters of the three systems. The influence of the design and operating parameters on the concentration of a corrosive species are obtained for two types of yield profiles. The important findings of the analyses are (i) there is an upper limit on the system parameter γ ∗ c based upon the availability of oxygen; (ii) there is an upper limit on the parameter γ ∗ c based upon the need to retain the combustion products for corrosion reactions to proceed.