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Leak Detection

Last updated: December 18, 2019

What Does Leak Detection Mean?

Leak detection is a method in which the existence of a leak within a system is determined. The techniques are utilized across a wide range of systems where a container must seal in some material. The variety of detection methods can be classified as internal or external, depending on where the leak detection system (LDC) is located.

Leaks are often the final effect of corrosion, where the deterioration of a metal container breaks down to the point that the contained material escapes. Because leak detection may reveal corrosion, it provides an alternative method for corrosion testing when other methods fail.


Corrosionpedia Explains Leak Detection

The mechanism of leak detection depends on the leak detection system (LDS) used. Common methods include:

  • Gas sniffing or chemical detection methods
  • Pressure methods
  • Acoustic methods

Many leak detection methods involve the detection of a molecule, such as helium, hydrogen, Freon, radioisotopes or dyes. In these methods, the molecule is added to the system and detected externally with a detection method suitable for the type of molecule. When using gases, the technique is called gas sniffing. Helium leak detectors are effective and popular due to their small size and the chemical inertness of helium gas. Helium leak detectors work by using mass spectrometry.

Pressure is a physical property of sealed systems that is useful for detecting leaks. A pressure drop in a system or a pressure increase in a vacuum chamber indicates a leak has formed. Overpressurization can make a leak more noticeable. In systems with a slight overpressure, coating the outside surface with soapy water helps to detect a leak because bubbles form at the leakage site.

Another method detects leaks by using acoustic vibrational waves that propagate from the site of a high pressure gas or fluid leak. This type of detection is made possible with ultrasonic microphones.

Every LDS has its own sensitivity level. When comparing different methods for an application, one must consider the sensitivity, the cost, and the compatibility of the method with the system at hand. Specific methods include:

  • Helium leak detection
  • Halogen leak detection
  • Dye penetration
  • Radioisotope detection
  • Bubble testing
  • Pressure monitoring
  • Flow monitoring
  • Thermal conductivity
  • Ultrasonic leak testing
  • Spark testing
  • Biological leak detection

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