Plate heat exchanger with leakage detector

Plate heat exchanger for exchanging of heat from one fluid to another, comprising

• a stack of double-wall elements (9-12, 23-26), which between themselves form flow passages (13-15, 32-34) for the two fluids, and each one of which comprises two thin heat exchange plates (1-8), each having a central heat exchange portion (18) and a sealing portion surrounding the heat exchange portion and said portions abutting directly against corresponding portions of another heat exchange plate,
• a sealing member (28-31), which sealingly abuts against adjacent double-wall elements (9-12, 23-26) along the sealing portions of their respective heat exchange plates and delimits a flow passage (13-15, 32-34) between the double-wall elements, and
• joining means arranged to press the double-wall elements (9-12, 23-26) directly against each other in areas of the heat exchange portions of the respective plates, and indirectly against each other via the sealing members (28-31) in areas of the sealing portions of the heat exchange plates,
• characterized by at least one channel (40-42) in each double-wall element (9-12, 23-26) between the two heat exchange plates (1-8) thereof, which channel (40-42) is formed between limited parts of the sealing portions of the heat exchange plates, said parts being located just opposite each other, and which extends across the sealing portions connecting an area inside the sealing portions to the surrounding of the plate heat exchanger (35), remaining parts of the sealing portions abutting directly against each other.