The distinction between what is and is not a product contact zone is not always easy to make, especially in open systems where the product is exposed to the processing environment and not the product is exposed to the processing continuously protected by enclosure in a pipeline or vessel. Direct product contact surfaces include pipeline interiors, convey- ors, product storage vessels, fillers, utensils, work tables, mixers grinders, and so forth. Nonproduct contact sites include structural components of machinery; the exterior of equipment, pipelines and vessels; walls; motors; bearings; floors and floor drains of buildings; heating, ventilation, and air-conditioning cquipment forklifts; workers' garments and footwear; mechanics' tools; and cleaning tools