Method for leakage control and localization of leakages in the internal faces of heat exchangers

1. A method for leakage control of the internal faces that separate a primary side and a secondary side of a plate heat exchanger, wherein the primary side contains a product and the secondary side contains a heat exchanging fluid maintained at a differential pressure with respect to the product disposed in the primary side during normal operation of the heat exchanger, the method comprising the steps of:

supplying a colorant-containing liquid to one of either the primary side or the secondary side of the heat exchanger,

supplying a clear liquid to the other one of the primary side or the secondary side,

maintaining a differential pressure between the primary side and secondary side that corresponds to the differential pressures prevailing during normal operation of the heat exchanger,

recycling the clear liquid, and

determining whether leakages in the plate heat exchanger are present by detecting the presence of the colorant in the clear liquid that has been recycled.

2. A method according to claim 1 wherein the viscosity of the colorant-containing liquid corresponds to the viscosity of a given liquid that passes through the corresponding side of the plate heat exchanger in actual operation.

3. A method according to claim 1 wherein the colorant is a fluorescent substance.

4. A method according to claim 1 wherein the detection of the colorant is effected by use of UV-light.

5. A method according to claim 1 wherein the colorant is a salt of fluoresceine.

6. A method as in claim 5 wherein the salt of fluoresceine is a sodium salt uranine.