Results with boiling of water, sugar juice, milk, wort and salt solutions in a pilot plant plate evaporator (heat transfer area 0.4 m(2) plate width 0.2 m, plate height 1.0 m) are described. Specified criteria relations are used for evaluation of data from the pilot plant and industrial plate evaporators for water, milk, juices and stillage concentration. For the liquids specified above fouling factors were determined. (C) 2003 Elsevier Ltd. All rights reserved.