Feasibility of the Total Hydrocarbon Analyzer for Evaluating the Life of Charcoal Beds.

In closed environmental systems such as nuclear submarines, personnel are exposed to hydrocarbon and other organic contaminants in the atmosphere. These contaminants are removed in part by the use of adsorbent charcoal beds in the ventilating system. A technique has been developed to assess the performance of these beds and to predict when replacement is required. A series of test tube-size charcoal beds were preloaded with varying amounts of n-decane and then challenged with n-hexane in air. The NRL-developed Total Hydrocarbon Analyzer was used to analyze both the influent and the effluent air streams. The effluent n-hexane concentration was a sensitive indicator of the degree of depletion of adsorptive capacity of the charcoal, even for a bed with substantial bypass leakage. The ratio of effluent to influent concentration constitutes a performance ratio for the bed. Periodic monitoring of this ratio and its trends is proposed as a means of assessing useful bed life. Author