Leak Testing via Carrier Gas Compression
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing leak testing methods face a trade-off between system sensitivity and response time, as increasing test gas suction capacity reduces signal response time but also decreases test gas pressure and sensitivity.
Innovation Solution
The method involves using a test gas gun to generate a test gas atmosphere externally around the test specimen without a test chamber, with one end connected to a carrier gas source and the other to a compressor pump, allowing the test gas sensor to be placed within a multi-stage pump arrangement to measure the high partial pressure of the compressed gas mixture, thereby achieving high sensitivity and fast response time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the test gas suction capacity is increased to reduce signal response time, then the response time is improved, but the test gas pressure decreases and system sensitivity is reduced
Solution Approach 1:
A carrier gas (nitrogen) is introduced as an intermediary substance to transport the test gas (helium) from the test specimen through the vacuum system to the sensor. The carrier gas creates a gas mixture that maintains sufficient test gas partial pressure for sensitive detection while enabling faster evacuation and reduced response time. The mass spectrometer detects helium in this nitrogen-helium mixture at a pressure of 10^-3 to 10^-6 mbar.
Solution Approach 2:
The system changes the pressure parameter from atmospheric pressure to vacuum conditions (10^-3 to 10^-6 mbar), which fundamentally alters the gas dynamics. Under vacuum conditions, the mean free path of gas molecules increases, allowing faster evacuation and reduced response time while maintaining detection sensitivity through the carrier gas mechanism. The compression ratio of the vacuum system is optimized to balance response time and sensitivity.
2Reliability
If a test chamber is used to contain the test specimen, then the test gas atmosphere can be maintained, but the system complexity and measurement time increase
Solution Approach 1:
The invention extracts the test specimen from the traditional enclosed test chamber and places it directly in the vacuum environment. The test specimen is mounted on a holder that allows direct exposure to the vacuum and introduction of test gas without requiring a separate atmospheric containment chamber. This eliminates the need for complex chamber sealing and pressure equalization mechanisms.
Solution Approach 2:
The system is segmented into distinct functional zones: the vacuum chamber for the test specimen, the carrier gas introduction point, and the mass spectrometer detection zone. This segmentation allows the test gas atmosphere to be maintained locally around the specimen while enabling direct vacuum connection and fast evacuation, reducing overall system complexity and measurement time.
3Measurement precision
If high test gas pressure is maintained to improve detection sensitivity, then the sensitivity is improved, but the response time increases due to slower evacuation
Solution Approach 1:
The system employs periodic or pulsed introduction of carrier gas during the measurement process. Carrier gas is introduced in controlled amounts to maintain sufficient test gas partial pressure for sensitive detection, then evacuated to reduce total pressure and enable fast response. This periodic cycling optimizes the balance between sensitivity and response time.
Solution Approach 2:
The system dynamically adjusts the carrier gas flow rate and vacuum pumping speed during measurement. The compression ratio of the vacuum system is optimized to maintain high test gas partial pressure when detection is performed, while enabling rapid pressure reduction when response time is critical. The mass spectrometer operates at variable pressure conditions (10^-3 to 10^-6 mbar) to optimize both sensitivity and response time.
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 approach enables high system sensitivity and fast response time by maintaining high test gas partial pressure, allowing for improved detection limits and reduced measurement times while minimizing carrier gas usage.
Implementation Method 1
the test gas sensor to be placed within a multi-stage pump arrangement so as to measure the high partial pressure of the compressed gas mixture
Implementation Method 2
a test gas sensor is connected to the outlet of the pump so as to determine the test gas partial pressure in the compressed gas mixture
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A test specimen (13) filled with test gas is placed in an evacuable test chamber (10). A carrier gas is introduced into the test chamber (10), creating a gas mixture of carrier gas and test gas. This gas mixture is drawn from the test chamber (10) by a compressor pump (15). A test gas sensor (17) is connected to the outlet of the compressor pump (15). The test gas is contained in the compressed gas mixture at a partial pressure increased by the compression ratio. This increases the sensitivity of the test gas detection and/or reduces the time constant of the measurement.