This manufacturer of shell-and-tube heat exchangers has developed a new safety heat exchanger for applications where the fluids cannot be mixed or contaminated. Compared with the single-wall tube bundle, this double-wall design is characterized by a construction with two tube sheets at each end of the bundle (diagram). Then, two tubes are fitted one inside the other, with leakage space between them designed in such a way as to guarantee the thermodynamic performance of the heat exchanger. Should the inner or outer tube leak, the process fluid enters the leakage space and triggers an alarm. The units can be designed with a wide range of shell diameters and tube bundle lengths, and it is possible to select different materials for the inner and outer tubes. — Flovex S.p.A., Grezzago, Italy