First Edition, April 2013 - This guideline covers the hygienic aspects of disc stack centrifuges used to separate fractions of liquid food products or to remove dense solid matter from products. The hygienic operation of a disc stack centrifuge, which is a complex machine with the purpose of collecting non-milk-solids (NMS) or other solid matter from liquid products, relies on proper cleaning by CIP/COP. Therefore, this guideline deals with cleaning as well as design. The guideline does not cover cyclonic types of separators, decanters, basket centrifuges or other types of devices.