Experimental evaluation of the performance of gas-phase air filters using a dynamic closed-loop test system

Volatile organic compounds (VOCs) are major gas-phase indoor air pollutants, and filtration is one of the promising methods to control indoor VOC concentration levels. An adsorption technique is commonly used for filtration of VOCs using adsorbents such as activated carbon. Unlike a particlefilter system, the applications of gas-filter systems have not been widely studied, and standards for the evaluation of gasfilter systems do not exist. As groundwork for standards development, this study proposes an experimental method that can evaluate the performance of gas filters in removing VOCs. Four different fibrous, activated carbon filters were tested using a
dynamic closed-loop test system with toluene as a representative VOC. Since in the proposed test system the level of VOCs in the supply air to the filter will increase as filter efficiency declines, the proposed test system is more similar to real-life filter applications than dynamic open-loop tests, where the load is always constant. The effects of injection rates, flow rates (or residence time), and the number of filter layers (or thickness) on the filter performances were investigated.