7.2.1  Fluorescein method


The steam side of the condenser is flooded to above the tubenest with a 10 mg/kg solution of the sodium salt of fluorescein. A search is carried out in the waterbox using ultra-violet light to detect traces of fluorescein. The tube which is leaking is therefore identified.

There are, however, disadvantages of this method:

  • It is restricted to underslung condensers off-load.
  • The reverse action of water pressure on the tubes compared with normal operation is known to close up the leak in some cases.
  • The water pressure is low at the top of the condenser and small leaks may escape detection.
  • Residual fluorescein can affect feedwater and boiler water analysis, and impair judgement as to whether repair of the leak was successful.
  • This method requires an operator to carry it out.


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