Evaluation of NBC Canisters against Phosgene-a Chemical Warfare Agent

摘要

Indigenously developed and bulk produced NBC canisters from eight different sources containing carbon (100 g) carbon impregnated with Cu (Ⅱ), Cr (Ⅵ), Ag (Ⅰ), NaOH, and pyridine were evaluated for their protective potential against phosgene (COCl_2), a highly toxic chemical warfare agent. Protection time (COCl_2 breakthrough time) was found to be 84 min for canisters of six different sources at 4.0 mg/l COCl_2 concentration and 30 l/min airflow under wet conditions of 30 ± 1℃ and 50 per cent RH. Protection time, however, varied from 63 min to 116 min for the canisters of other two sources under the similar conditions. Phosgene breakthrough time was also studied under dry conditions of 30℃ and 0.2 per cent RH (dry air was used from air cylinder) and found to be 37 min at 4.0 mg/l COCl_2 concentration and 30 l/min airflow. Effect of COCl_2 concentration on breakthrough time indicated that the canisters made by six out of eight manufacturers were similar, while canisters from other two sources had slight variations in carbon compactness, which was exemplified by the phosgene breakthrough behaviour. The study indicated that phosgene breakthrough time not only depends upon chemical degradation but is also influenced by carbon compactness. The results were supported by the CCl_4 breakthrough times of the canisters.