The modified Wheeler equation was applied in three different approaches to study the effects of dry airflow rate and charcoal bed weight on organic vapor respirator cartridge breakthrough curves. The three approaches included variation of sorbent bed weight, variation of penetration fraction, and variation of bed residence time. Challenge concentrations of acetone (67641) in dried air ranged from 1010 to 1100 parts per million. The experimental data were used to plot the 1 percent acetone breakthrough time versus total cartridge bed weight at airflow rates ranging from 32 to 95 liters per minute (l/min) and versus bed residence time for airflow rates ranging from 32 to 115l/min. The rate coefficient was found to increase with increasing airflow rate, whereas adsorption capacity was essentially constant. Semilog plots of acetone breakthrough curves for one cartridge at four airflow rates showed some curvature. The overall average adsorption capacity values were time, and breakthrough fraction variation methods, respectively. Values of the rate coefficient, however, differed with the various methods and were influenced by airflow rate and the selected penetration fraction. Guidelines for use of the modified Wheeler equation were given. The authors conclude that the equation does not characterize the system completely and has limitations.