This standard specifies the characteristics of seven types of butyrometers used to determine the fat content of whole, partially skimmed and skimmed milk, using the Gerber method described in standard UNE 34-898. NOTE — The method that uses the butyrometer from 0 to 0.5%, using double amounts of milk and reagents than those normally used is not described in the current UNE 34-898 but will be included in it when it is revised. Recommended caps for butyrometers are described in Annex A and a recommended method for determining errors in butyrometer scales is described in Annex B. These annexes are not part of this standard.