Generally, Leak Detectors are tuned to detect helium.   Helium is a clean, mobile and inert gas that can be detected in very small quantities if it escapes from a pressurised chamber, or inversely if a pin-point spray of helium finds its way into a vacuum chamber through a leaking joint.   A Leak Detector is the simplest form of mass spectrometer, set to measure mass 4 (helium) only, and is packaged in a rugged format for the most demanding, routine operations.

Applications are numerous extending from the automotive industry to space research.