US Patent 7159449 Method of detecting leakage in a heat exchanger

A method is provided for detecting leakage in a heat exchanger by circulating a tracer under pressure from the first side of said heat exchanger to the second side and then from the second side to the first side subsequent to reversing the direction of the pressure. In order to prevent a false test result it has previously been necessary to make sure that all tracers, for example electrolytes, colorants, or fluorofors, were rinsed from the first side prior to circulating the tracers from the second side to the first side. This time consuming and at the same time unreliable rinsing process is avoided by the method of the present invention by adding a second tracer from the second side.