Bubble method: the "intuitive guard" in air tightness testing and analysis of industry standards

Bubble method: "Intuitive Guardian" in Air Tightness Testing and Analysis of Industry Standards

In the field of industrial manufacturing and product quality inspection, air tightness is one of the core indicators that determine product safety and reliability. The bubble method (immersion method/smearing method), as one of the oldest and most intuitive testing methods, is still widely used in electronics, automobiles, packaging and other industries. It is like a "silent guard" that protects the product's sealing line through visible bubbles. This article will deeply analyze the value and limitations of this classic method from the perspective of technical principles, international standards, actual cases and humanized applications.

1. The principle and operation of the bubble method: the scientific logic behind the simplicity

The core principle of the bubble method is to determine whether there is a leak by observing whether the product generates bubbles in the liquid.

The specific steps include:

Pretreatment: Clean and dry the surface of the object to be tested to ensure that there is no interference from impurities.

Inflation and pressurization: Fill the object to be tested with gas (such as air or nitrogen) to make its internal pressure slightly higher than the ambient pressure.

Immerse in water or apply detection liquid: Immerse the object completely in the sink, or apply soapy water or other detection liquid on the surface.

Observation and recording: If there is a leak, bubbles will be formed when the gas escapes, and the degree of leakage can be judged by the position and frequency of the bubbles.

Data support:

Sensitivity range: Usually it can detect defects with a leakage rate ≥1×10⁻³ mbar·L/s, which is suitable for preliminary screening of obvious leaks.

Test pressure: Common in low-pressure environments (such as 5-50 kPa), and it is adjusted according to product requirements.

2. International standards and industry specifications: "Compliance Guide" for the bubble method

Although the bubble method is simple, its application must strictly follow international and industry standards to ensure the authority of the test results.

Related international standards:

ISO 9972: In building air tightness testing, the bubble method is allowed to assist in locating leaks.

ASTM E779: In the US building energy efficiency standard, the bubble method can be used as a supplement to the pressure difference method.

Industry-specific standards:

Automotive manufacturing: SAE J2310 recommends the bubble method for preliminary sealing verification of parts such as doors and sunroofs.

Packaging containers: China's national standard GB/T 17344 clearly lists the bubble method as one of the testing methods for hazardous packaging containers.

Usually, when companies choose standards, they will combine the actual application scenarios of the products. For example, the waterproof test of electronic products (such as mobile phone rain test) often uses the immersion method, while automotive parts rely more on the smearing method to quickly locate leaks.

3. Advantages and Disadvantages Analysis: Why is it still the "first choice for initial screening"?

Advantages:

Intuitive and efficient: Operators do not need complex training and can quickly judge the results by naked eyes, which is suitable for rapid screening of production lines.

Low cost: Only basic equipment such as water tanks and air pumps are required, and small and medium-sized enterprises can also implement it easily.

Environmentally friendly: Use water or non-toxic test fluid to reduce the risk of chemical pollution.

Limitations:

Limited accuracy: It is difficult to detect tiny leaks (such as pores <0.1 mm), and further verification is required in combination with pressure drop method or helium detection method.

Subjective influence: The results rely on manual observation, and there may be a risk of misjudgment.

4. Practical application cases: "Cross-border protection" from mobile phones to aerospace

Consumer electronics: Before mass production, a certain brand of mobile phones simulates rainwater environment through a water immersion test box. If no bubbles appear within 10 minutes, it is considered waterproof.

Automobile manufacturing: A car company uses the smearing method to detect the sealing of headlights, locates the leakage point within 30 seconds, and improves efficiency by 40%.

Packaging industry: According to GB/T 17344, a dangerous goods container manufacturer uses the bubble method to sample batches of products, and the missed inspection rate is reduced to less than 0.5%.

"When our engineers see bubbles rising slowly in the sink, it is not only the exposure of a defect, but also the fulfillment of the user's safety commitment." - This sense of responsibility is the reason why the bubble method is still irreplaceable in the digital age.

5. Future Outlook: Dual Upgrades of Intelligence and Humanization

Although the bubble method has limitations, its combination with emerging technologies is opening up new possibilities:

Automation Improvement: For example, the patented equipment of Shenzhen Liwen Electromechanical automates the detection process through electric telescopic rods and intelligent clamping systems, reducing human dependence.

AI-assisted analysis: In the future, it may be possible to automatically capture bubble dynamics through image recognition technology to improve accuracy and objectivity.

Industry Call:

Enterprises need to find a balance between "efficiency" and "accuracy". For high-value products (such as aerospace parts), it is recommended to use the bubble method as the initial screening, and then combine it with precision methods such as helium detection to form a multi-level detection system.