7.2.2  Foam or film methods

 

The principle of this method (Fig 4.30) relies on the development of a vacuum in a leaking tube. If the tube is then sealed at each end, the vacuum draws in a foam blanket or a film of polythene or paper, and thus identifies the location of the leak.

Tube leak detection by foam/film method

Generally two operators, each with a foam generator, are required. Pin-hole leaks with a leakage rate of 400 ml/h can be located, and 5000 tubes/hour can be tested.

The success of this method relies on being able to establish a vacuum of 330 mbar.

 

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