Helium Leak Detection Through Mass Spectrometer

What is a Helium Mass Spectrometer?

Helium Mass Spectrometer leak detection is a widely used industrial technique for pinpointing leaks. This method dates back to World War II, where it was first applied to detect leaks in uranium enrichment plants. Today, with enhancements, this technique remains one of the most accurate methods for leak detection. Typically, the system or container to be tested is filled with helium and placed in a vacuum chamber, where the mass spectrometer and residual gas analyzer identify any leaks and their rate.

Why is Helium Suitable for Leak Detection?

Helium is an ideal tracer gas for leak detection due to its small atomic size, allowing it to pass even through the tiniest leaks. It is non-toxic, non-flammable, chemically inert, and found in the atmosphere at low levels (5 ppm). This makes it perfect for detecting micro-leaks at standard temperature and pressure, with sensitivity levels ranging from 10⁻⁵ to 10⁻¹² Pa·m³·s⁻¹. Despite these benefits, helium is cost-effective and readily available.

Key Properties of Helium for Leak Detection

● Non-toxic and non-flammable: Safe for various industrial environments.

● Chemically inert: Does not react with other materials, reducing contamination risks.

● Small atomic size: Allows for detection of minute leaks.

● Low atmospheric presence: Minimal interference from environmental helium.

Types of Leaks

In general, leaks can be categorized into two main types:

1. Residual Leaks

Residual leaks occur due to manufacturing defects or product damage. They often result from faulty seals, creating actual pathways for leakage.

2. Virtual Leaks

Virtual leaks are not true leaks but occur due to gases trapped, absorbed, or frozen during manufacturing, which later escape (outgassing). These leaks appear as defects, resulting in false positives during leak detection. While no vacuum system is flawless, it’s possible to control leak rates to maintain the necessary vacuum levels.

Helium Mass Spectrometer Leak Detection Methods

Before beginning, the system’s pressure-handling ability should be confirmed to avoid any damage. Systems are tested for leaks using two main methods:

1. Vacuum Test (Outside-In Method)

In this method, the detector is placed inside the system, which is then vacuumed. Helium is sprayed externally onto potential leakage points. If helium penetrates, the detector confirms a leak. This is also known as the spray probe method.

2. Pressure Test (Inside-Out Method)

Here, the system is placed in a vacuum chamber, which is then filled with helium. Leakage points are identified using a sniffer probe, and the leak rate is determined. It’s important to stabilize the detector beforehand and ensure the atmospheric helium concentration is below 5.2 ppm to avoid interference.

Important Considerations for Leak Testing

● System Pressurization: Confirm the system can handle pressure without large leaks.

● Pre-Test Preparation: Ensure air is removed to prevent helium dilution.

● Detector Stabilization: Run the detector for one hour before testing.

● Environmental Preparation: Wait another hour post-test to reset helium levels.

How Helium Leakage is Detected

When helium particles exit a leak, they are ionized by an electron beam and accelerated by high voltage. A magnetic field separates these ions by their mass-to-charge ratio, and the ionized helium particles generate an electric signal. Signal strength indicates the helium concentration, with minor leaks registering at around 10-15 amps. This process requires low pressure, maintained by vacuum pumps, for optimal detector performance.

Industrial Applications of Helium Mass Spectrometer Leak Detection

This technique is widely used across industries, particularly in systems requiring vacuum environments and in manufacturing lines producing refrigerators, air conditioners, food packaging, bottled drinks, oil tanks, valves, and fire extinguishers.

What Xiamen Taixing Mechanical and Electrical Co., Ltd. (TX®) Offers

Xiamen Taixing Mechanical and Electrical Co., Ltd. (TX®) leverages years of experience to provide customized, secure leak detection services and products for various industrial needs. We offer automated setups, a wide range of calibration accessories, and comprehensive training to make leak detection efficient and reliable for your business. Our additional industrial services are also available to enhance your operations.

FAQs

Q1: Why is helium preferred over other gases for leak detection?
A1: Helium is non-toxic, non-flammable, chemically inert, and has a small atomic size, making it ideal for detecting even the smallest leaks. It is also rare in the atmosphere, allowing for highly sensitive detection without interference.

Q2: What is the difference between residual and virtual leaks?
A2: A residual leak is an actual physical defect like a damaged seal, while a virtual leak is not a true leak. Virtual leaks occur when trapped gases are released, giving a false positive result, also known as outgassing.

Q3: How accurate is the helium mass spectrometry method for leak detection?
A3: Helium mass spectrometry is highly accurate, capable of detecting leaks as small as 10⁻¹² Pa·m³·s⁻¹. It remains one of the most precise leak detection methods available for industrial applications.

Q4: How long does a typical helium leak detection test take?
A4: The test usually takes a few minutes, but warm-up time for the detector and post-test vacuuming of helium add roughly two hours in total.

Q5: What types of products can benefit from helium leak detection?
A5: Helium leak detection is essential for products requiring airtight seals, such as refrigerators, air conditioners, food packaging, valves, and various types of vacuum systems.