After the product has been dried, it is necessary to reduce its temperature. It is quite common to select a dryer/cooler combination to perform that task. In that design, the lower conveyors of multiple pass dryers extend beyond the dryer into a separate zone where ambient air is pulled through the product to reduce its temperature. Therefore, a typical two-stage dryer/cooler requires 15 minutes retention time for drying, 7 minutes cooling time, or a total of 22 minutes.