AN ASSESSMENT OF THE EFFECTS OF CONCENTRATION FLUCTUATIONS ON THE PENETRATION OF TOXIC VAPORS THROUGH A CARBON BED

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Authors
  1. Yee, E.
Corporate Authors
Defence Research Establishment Suffield, Ralston ALTA (CAN)
Abstract
A simple mathematical model for the penetration of a vapor through an absorbent carbon bed has been used to investigate the effects of naturally induced concentration fluctuations on the breakthrough time and the degree of penetration through the bed. The model shows that the breakthrough profile through a carbon bed at time of t sub r depends on the instantaneous inlet concentration at the retarded time t sub r and on the dosage level to which the bed is exposed up to time t sub r. The retarted time t sub r is determined by the residence time of the air stream in the carbon bed. Computer simulations, using a steady and a time-varying (fluctuating) inlet concentration with the same dosage over a fixed exposure time, show that the time-varying exposure can result in a breakthrough time that is reduced by 50% and a breakthrough (exit) concentration that is increased by 25-fold compared with that from the steady exposure. In consequence, the effect of concentration flunctuations on vapor penetration through a carbon bed can be significant, and its neglect can lead to an underestimation of the penetration (at least for the simple local rate of removal mechanism assumed for the present model.
Keywords
Activated carbon filters;Breakthrough profile;Carbon bed;Charcoal;Gaseous adsorbates;Toxic vapours;CBW
Report Number
DRES-M-1457 — Memorandum
Date of publication
01 May 1995
Number of Pages
32
DSTKIM No
95-02653
CANDIS No
151935
Format(s):
Document Image stored on Optical Disk;Hardcopy

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