A concentrator is a capture device that removes VOCs and HAPs from the exhaust air stream. A complete concentrator system requires some sort of destruction or recovery device. Concentration of the VOCs is accomplished through a continuous adsorption and desorption process. Adsorption is the process by which the VOC molecules present in the process exhaust air stream are collected and retained on the surface of the adsorbent media. This surface reaction takes place as the total volume of process exhaust is directed through the media, leaving the air environmentally acceptable for discharge into the atmosphere.

In the desorption phase, a separate, smaller air stream is directed through an isolated zone of adsorbent media in the opposite direction of the adsorption airflow. The desorption air stream is typically 5% to 10% of the adsorption volume, depending on solvent type and concentration, and is at a much higher temperature. The heat releases the previously collected molecules into the isolated desorption air stream. This air, with its increased VOC concentration, is then routed to the final destruction or recovery device.