FLOW DIAGRAM plate Heat Exchangers are used mainly for liquid to liquid heat exchange, but are also suitable for some liquid to gas and liquid to condensing vapor combination. Single-pass countercurrent flow A single-pass Plate Heat Exchanger, has the advantage that all the connections are located on the fixed framefacilitating a low maintenance costs.   Single-pass flow     Multi-pass countercurrent flow If there are only slight temperature differences between the fluids, a multi-pass installation is required, in this case, the connections are located on the fixed frame and the loosed frame.   Multi-pass flow     Use of an intermediate plate which allows several duties to be performed within the same frame.   Use of an intermediate plate