When a piece of food contact equipment is in constant use it should be cleaned and sanitized every?

Food-service equipment should be carefully cleaned and sanitized, in order to prevent foodborne illnesses. Cleaning is the process of removing traces of food from surfaces while sanitizing is the process of removing microorganisms from surfaces. In general, food-contact equipment should be cleaned and sanitized after each use of the equipment. However, when the food-contact equipment is in constant use, it should be cleaned and sanitized every four hours.

This movement is also referred to as  glacial plucking