Helium Leak Detection: Essential Applications Across Aerospace, Power & Electronics Industries

Helium: The Superior Gas for Safe and Sensitive Leak Detection

Due to its inert chemical properties, lighter-than-air nature, and characteristics as a colorless, odorless, non-toxic, non-flammable gas with a boiling point of -268.9°C, helium offers significantly higher operational safety compared to hydrogen. The application of helium leak detection has expanded from research institutions to industrial enterprises and even individual businesses, demonstrating its vast and growing utility.

I. Aerospace & High-Tech Industry

1. Rocket Engines & Motors: Helium mass spectrometers are employed using a combined method of positive pressure sniffer probes and helium hood testing. This significantly enhances leak detection sensitivity, ensuring engine quality. Rocket body leak checks integrate sniffer probes, helium hoods, accumulation methods, and other techniques. This advanced methodology boosts sensitivity, overcoming the limitations of basic sniffer methods.

2. KM6 Space Environment Simulator: This massive facility features a main vacuum chamber (12m diameter, 22m height), auxiliary chambers, and crew modules, totaling 3500m³. Its complex structure involves thousands of meters of welded joints. Negative pressure helium mass spectrometer leak testing is used. Each weld is sealed within a test box connected to a dedicated pumping system to achieve low vacuum. Introducing helium into the box creates a higher concentration and pressure relative to the spectrometer, effectively increasing detection sensitivity.

3. Spacecraft, Satellites, Valves, Electronics & Sensors: Helium mass spectrometers and associated leak testing techniques are extensively utilized for components in spacecraft, satellites, various valves, electronic components, and sensors.

II. Power Industry

SF6 high-voltage circuit breakers and zinc oxide (ZnO) arresters are critical components in power plants and transmission systems. Leaks can cause widespread or localized power outages, disrupting industrial production and daily life, leading to substantial, often incalculable, economic losses.

1. Power Plants & Equipment: Helium mass spectrometers are the preferred choice for leak testing in power plants, specifically for high-voltage transformers, capacitors, circuit breaker tubes, and other critical components, employing various tailored methods.

2. Zinc Oxide (ZnO) Arresters: These are constructed by stacking ZnO discs (selected based on voltage rating, cross-section, thickness, and quantity) within a porcelain housing, which is then filled with nitrogen and sealed. Operation: During a lightning strike or overvoltage, the ZnO discs’ resistance drops sharply, shunting high current to ground and protecting the transmission line. If a leak causes the internal pressure to drop, external humid air can ingress. This moisture degrades the ZnO discs’ properties, potentially leading to thermal runaway and catastrophic failure (explosion).

3. High-Voltage Switchgear: Aluminum castings within enclosures often contain porosity (micro-shrinkage holes). These leak paths can be complex and difficult to detect. The common solution is the helium hood method: evacuate the test piece, surround it with helium gas, and measure the helium ingress rate after a set time. This method uses minimal helium while offering high detection sensitivity.

III. Electronics Industry

Helium leak detection is crucial for: Microwave tubes, vacuum tubes, transistors, integrated circuits (ICs), sealed relays, various sensors, and implantable medical devices like pacemakers.

IV. Vacuum Systems, Instruments, & Other Key Applications

• Components: Piping, fittings, valves, bellows.

• Equipment: Various vacuum pumps, exhaust manifolds, electron microscopes, mass spectrometers, electron beam/ion beam lithography systems, laser isotope separators, high-energy accelerators, medical accelerators, irradiation accelerators, coating machines, thin-film vacuum gauges.

• Consumer Goods: Stainless steel vacuum flasks, bottle caps, pot lids, lunch boxes.

• Refrigeration: Refrigerators, air conditioners, absorption chillers (LiBr), automotive AC systems, evaporators, condensers, compressors, cryogenic storage tanks.

• Nuclear Industry: Uranium enrichment equipment, storage vessels, nuclear power plant components.