Design: The plate pack comprises of a number of heat exchanger plates, according to the heat transfer surface required Gaskets on the plates ensure that the flow channels are securely sealed from each other The gaskets also determine the direction of flow within the exchanger The frame enclosing the plate packs is held together with lightening bolts Connections for incoming and outgoing media are usually in the fixed frame plate of the heat exchanger In the case of multi-pass flow, connections have to be in the fixed frame and the pressure plates Operation: Adjacent plates form flow channels carrying alternately hot and clod media throughout the plate pack Normally, single-pass heat exchangers are used, permitting 100% counterflow of both products All port connections are located in the fixed frame plate providing a low-maintenance installation In cases of low temperature differences, or where these differences are to be fully utilizes, multi-pass Plate Heat Exchanger become more economical Provided the number of passes is the same for both media nearly 100% counterflow will be achieved