Helium Leak Testing
As a professionally driven firm, we are affianced in offering Helium Leak Testing to our customers. This testing is provided by our deft technocrats who possess wide experience in their respective domain and well versed with all the latest technological advancements. This testing is used for detection of helium leak calibrations, and our experts quickly locate the smallest leaks in any vacuum system, pressure system, hermetic system, etc. Offered Helium Leak Testing is highly appreciated for hassle-free management, reliability, timely delivery and cost effectiveness.
Leak testing is employed to detect leaks and determine the rate at which a fluid i.e. a liquid or gas will penetrate from inside a tight component or assembly to the outside or vice versa as a result of pressure differential between the two regions or of permeation of somewhat extended barrier. It
has become conventional to use the term "leak" to refer to an actual discontinuity or passage through which a fluid flows or permeates. "Leakage" refers to the fluid that has flowed through a leak. "Leak rate" refers to the rate of fluid flow per unit of time under a given set of conditions, and is properly expressed in units of mass per unit of time. Standard leak rate refers to the rate of flow 0 atmospheric air under conditions in which inlet pressure is 0.1 Mpa 5%; outlet pressure is leass tha l Kpa; temperature is 298Ki5 and dew point is less than -298K.
The term "minimum detectable leak" refers to the smallest hole or discrete passage that can be detected and "minimum detectable leak rate" refers to the smallest detectable fluid flow rate. The amount of leakage required for a leak testing instrument to give a minimum detectable signal can be determined. This amount is generally used to denote the sensitivity of the instrument. Instrument sensitivity is independent of test conditions, but when an instrument is applied to a test, the sensitivity of the test depends on the existing conditions of pressure, temperature and fluid.
Mass Spectrometer based Helium Leak Detection
For very sensitive leak testing, Mass Spectrometer based Helium Leak Detector is used. The commercial helium leak detector can detect the presence of less than one part of helium in 10 million parts of air. The helium leak detector is portable mass spectrometer especially designed to be highly sensitive to helium gas. It is an instrument for separating and sorting of atoms of different mass. Gas molecules entering the mass spectrometer are bombarded by electron emitted from a heated filament. The ion beam produced by the electron bombardment is accelerated in the form of narrow beam by means of an electric field. The ions then pass between the poles: pieces of a permanent magnet. The magnetic field deflects the ions in circular path. The radius of curvature of the path depends upon the mass of the ion. Ions having equal mass will all emerge from the magnetic field at a certain position. The helium leak detector is adjusted so that only the helium ions are collected. The flow of helium ions to the collector induces a minute electrical current which can be detected, amplified and used to activate an electrical meter to control the pitch of an audio signal generator.
Helium is generally used for leak detection because it is an inert gas and does not react with other gases and materials in the system. Helium is not present in any significant quantity in atmosphere, thus causing little interference in sensitive leak detection work. Helium, having light mass, passes through small leaks more readily as compared to other heavier gases.
There are five different techniques in using helium leak detector. They are
- Probe Technique
- Envelope Vacuum Technique
- Sniffer Technique
- Envelope Pressure Technique
- Pressurization Technique
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