EPA mandates for emissions control in concrete and concrete products plants often require the installation of sophisticated dust-collection and air-filtration systems. Serious problems can arise when moisture is present in the compressed air used to clean the filter bags. A compressed air drying system can help ensure optimal performance. There are three basic dryer designs: single tower (deliquescent), regenerative (twin tower), and refrigerated. Single tower dryers require no electrical power for operation, have a very low pressure drop, and low capital and operating costs. These dryers use adsorbent, consumable desiccants as the drying medium. The desiccants must be replenished occasionally, but do not have to be removed or changed. Regenerative dryers can supply the lowest possible dew point and driest compressed air. Their twin towers use an adsorbent desiccant that attracts moisture to its surface. The towers alternately perform the drying function--one recharges while the other dries the air. The refrigerated dryer uses a refrigeration process to condense moisture from the air. Refrigerated dryers are designed for relatively clean indoor operations and require electricity to operate. keywords [aircompressor, compressed air dryers, production equipment]