Tracer-gas leak testing
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A tracer-gas leak testing method is a nondestructive testing method that detects gas leaks. A variety of methods with different sensitivities exist. Tracer-gas leak testing is used in the petrochemical industry, the automotive industry, the construction industry[1] and in the manufacture of semiconductors, among other uses.
Types
[edit]Several tracer-gas leak testing methods exist, including:
- Detection of leaks using helium mass spectrometer, which provides high sensitivity
- Hydrogen leak testing, which provides the best mobility
- Refrigerant gas leak detection, for refrigeration applications
Method selection
[edit]Typical leakage rates
[edit]The nature of the product or the process and the process gases will set the leak rate requirement:
| System | Allowed leak rate (mbar L/s) |
|---|---|
| Chemical process equipment | 10−1–1 |
| Beverage can | 10−5 –10−6 |
| Vacuum pumped system | 10−5–10−7 |
| IC-package | 10−7–10−8 |
| Airbag cartridge | 10−8 |
| Pacemaker | 10−9 |
| Closed vacuum system | 10−9 |
Sensitivity of methods
[edit]Based on the target leak rate, the table below will help to choose the most suitable method.[2]
| Method | Sensitivity (leak rate in mbar l/s) |
|---|---|
| Ultrasonics | 10−1 |
| Bubble test in water | 10−2 |
| Pressure decay | 10−2 |
| Vacuum decay | 10−2 |
| Acoustic emission detectors | 10−3 |
| Bubble test in soapy water | 10−4 |
| Gas-specific thermal conductivity detector | 10−5 |
| Halogen detector | 10−5 |
| Photoacoustic spectroscopy | 10−6 |
| Hydrogen sniffer | 10−6 |
| Residual gas analyser | 10−7 |
| Dye penetrant | 10−8 |
| Radioactive tracer | 10−10 |
| Helium mass spectrometry vacuum testing | 10−11 |
Applications
[edit]Typical applications of tracer-gas leak testing include:
- In petrochemical plants, hydrocracking, vapocracking, catalytic reforming, and steam reforming are all hydrogen-based processes, in which were hydrogen leak testing is required.
- When manufacturing semiconductors, all processes taking place in a process chamber at atmospheric pressure or under vacuum – diffusion, oxidation, LPCVD, PECVD, PVD and ion implantation – require helium or hydrogen leak testing.
- In vehicles, airbags have to be tested for leaks so they remain functional for a long time. As well as airbags, the air conditioning system, fuel system, and exhaust system require testing for leaks.
- Pacemakers and catheters have to be tested for efficacy and longevity.
- On planes, tracer-gas leak testing is used to quickly and safely locate fuel leaks,[3] as well as to check oxygen distribution devices and cabin pressurization systems.
- Refrigeration and air conditioning must have the lowest possible rate of loss of refrigerant gases (contributing to ozone depletion).
- Sewage and drinking water networks, to reduce loss of water and make sure drinking water is not contaminated by sewage.
Standards
[edit]Several standards apply to leak testing and more specifically to tracer-gas leak testing methods, for example:
- BS EN 1779:1999; leak tightness by indication or measurement of gas leakage,
- BS EN 13185:2001 Non-destructive testing. Leak testing. Tracer gas method,
- BS EN 13192:2002 Non-destructive testing. Leak testing. Calibration of reference leaks for gases.
References
[edit]- ^ Batajtis, Damian. "Tracer Gas as a Method for Water Leak Detection" (PDF). Wizard Leak Detection. Archived (PDF) from the original on 12 November 2023. Retrieved 12 November 2023.
- ^ "Leak Detection Sensitivity Guide - VIC Leak Detection". VIC Leak Detection. Retrieved 2017-06-15.
- ^ Townsend, Mark; correspondent, defence (2007-11-11). "MoD accused over spy plane deaths". The Guardian. ISSN 0261-3077. Retrieved 2017-06-15.
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