Leak Detection Using Oxygen Concentration Measurement
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Solution Overview
Problem
Existing leak detection methods face challenges with high costs and instability of helium as a test gas, and oxygen's suitability is limited due to its prevalence in the atmosphere, leading to measurement difficulties under vacuum conditions.
Innovation Solution
Filling the test specimen with oxygen-free gases like nitrogen or argon and measuring oxygen concentration changes in an air-filled test chamber, using a lambda probe to detect leaks without the need for vacuum conditions, allowing for stable and cost-effective leak detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If helium is used as test gas, then leak detection accuracy is improved, but cost increases and availability becomes unstable
Solution Approach 1:
The patent replaces expensive helium with inexpensive, readily available air as the test gas medium. Air contains approximately 21% oxygen, which serves as the detectable marker gas. This substitution dramatically reduces test gas costs and eliminates supply instability while maintaining leak detection capability through oxygen concentration measurement.
Solution Approach 2:
The patent changes the detection parameter from measuring helium concentration directly to measuring oxygen concentration changes. By monitoring the oxygen content in the carrier gas before and after passing over the test object, the system detects leaks without requiring expensive helium. This parameter transformation enables use of common air instead of specialized test gases.
2Quantity of substance
If oxygen is used as test gas, then cost is reduced and availability is improved, but measurement precision deteriorates due to atmospheric oxygen presence
Solution Approach 1:
The patent extracts and isolates the oxygen measurement function from the complex vacuum environment. By using a lambda probe that specifically measures oxygen concentration in the carrier gas flow, the system separates the detection function from the test chamber vacuum conditions. This allows oxygen to be used as an effective marker gas despite its presence in atmospheric air.
Solution Approach 2:
The patent introduces carrier gas as an intermediary medium. The carrier gas transports oxygen from the test object environment to the lambda probe sensor. This intermediary enables indirect measurement of oxygen concentration changes caused by leaks, overcoming the challenge of measuring oxygen directly in the presence of atmospheric background oxygen.
3Difficulty of detecting and measuring
If vacuum conditions are used for oxygen measurement, then oxygen detection is enabled, but signal stability deteriorates due to significant signal drift
Solution Approach 1:
The patent creates equipotential conditions for the lambda probe by maintaining atmospheric pressure (approximately 1 bar) in the measurement environment. The probe operates in the carrier gas flow at ambient pressure, eliminating the vacuum conditions that cause signal drift. This pressure equalization stabilizes the measurement signal while preserving oxygen detection capability.
Solution Approach 2:
The patent replaces the vacuum-based measurement system with a pressure-based carrier gas flow system. Instead of measuring oxygen in vacuum conditions, the system uses pressurized carrier gas to transport oxygen to the sensor at atmospheric pressure. This mechanical substitution eliminates vacuum-related signal instability while maintaining detection functionality.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method enables accurate leak detection using readily available and inexpensive gases, improving measurement accuracy over traditional methods while reducing vacuum technology requirements and avoiding the need for expensive helium.
Implementation Method 1
The oxygen concentration is measured using an oxygen sensor, for example in the form of a lambda probe
Data Source
Figure 1~2
AI summary
The invention relates to a method for detecting a leak in a test object (12), said method comprising the following steps: the test object (12) is inserted into a test chamber (14); the test object (12) is filled with a test gas; and the pressure in the test chamber (14) and the pressure in the test object (12) are adjusted such that the test chamber pressure is lower than the test object pressure. The method is characterised in that the test chamber (14) contains air and the test object (12) is filled exclusively with an oxygen-free gas; in order to detect a leak in the test object (12), the oxygen content of the air in the test chamber (14) is measured with an oxygen sensor .