Depending upon type, some plates employ diagonal flow while others are designed for vertical flow . Plates are pressed in thicknesses between 0.5 to 0.9 mm and the degree of mechanical loading is important. The most severe case occurs when one process liquid is operating at the highest working pressure, and the other is at zero pressure. 

PLATE ARRANGEMENT

Comparison of plate heat exchanger plate arrangement to the tube and shell side arrangement in a shell and tube exchanger is charted , the number of passes on the tube side of a tubular unit can be compared with the number of passes on a plate heat exchanger.