Hydrogen Leak Detection with Palladium MOS Sensor
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Solution Overview
Problem
Existing leak detection methods using helium as a tracer gas are costly and require high-powered vacuum systems, making them impractical for detecting large leaks, while methods using hydrogen are less sensitive and require complex setups.
Innovation Solution
A leak detection device utilizing a hydrogen sensor with a MOS type transistor, diode, and palladium catalyst, connected to a low-pressure enclosure with a multi-way valve and electronic control module, allowing for controlled pressure and gas admission, enabling sensitive detection of large leaks at low pressure without the need for expensive pumping units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If helium is used as tracer gas with mass spectrometer, then sensitivity is improved, but cost and device complexity increase
Solution Approach 1:
The patent replaces expensive helium gas with cheaper hydrogen gas as the tracer substance. While hydrogen has shorter lifetime in the vacuum environment, this substitution significantly reduces material costs while maintaining adequate detection capability for large leaks
Solution Approach 2:
The patent replaces the complex mass spectrometer system with a simpler hydrogen sensor based on palladium catalyst and MOS transistor. This substitution eliminates the need for complex vacuum pumping systems and mass spectrometry instrumentation, reducing both device complexity and cost
2Measurement precision
If helium method is used, then sensitivity is improved, but pumping unit size and cost increase
Solution Approach 1:
The patent changes the operating pressure parameter from high vacuum (required for helium mass spectrometry) to low vacuum (suitable for hydrogen detection). This parameter change allows the use of smaller, less expensive vacuum pumps while maintaining detection sensitivity for large leaks
3Ease of manufacture
If hydrogen is used as tracer gas, then cost is reduced, but sensitivity decreases
Solution Approach 1:
The patent applies local quality enhancement by using palladium catalyst specifically on the sensor surface to improve hydrogen detection capability. This localized catalytic enhancement compensates for the lower sensitivity of hydrogen compared to helium, enabling cost-effective detection
4Weight of stationary object
If vacuum pressure is reduced, then pumping unit size is reduced, but detection capability may be affected
Solution Approach 1:
The patent introduces palladium catalyst as an intermediary substance that enhances hydrogen detection at low vacuum pressures. The catalyst facilitates hydrogen molecule dissociation and sensor response, maintaining detection capability despite the reduced vacuum pressure
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
The device achieves high sensitivity for leak rates up to 10^-6 Pa.m3/s, is lightweight, inexpensive, and easily transportable, with a long-lasting hydrogen sensor that can be easily integrated into existing equipment, suitable for various industrial applications.
Implementation Method 1
a MOS type transistor whose gate is covered with a palladium catalyst
Implementation Method 2
a pumping means connected to the low pressure enclosure
Implementation Method 3
a pressure gauge configured to measure the pressure in a vacuum line formed by the low-pressure enclosure connected to the pumping means
Data Source
AI summary
The leak detection device, using hydrogen as a tracer gas, is intended to be connected to an object to be tested. The leak detection device comprises a hydrogen sensor placed in a low-pressure chamber containing a diode, a resistor, and a MOS transistor whose gate is coated with a palladium catalyst; a pumping means connected to the low-pressure chamber; a pressure gauge configured to measure the pressure in a vacuum line formed by the low-pressure chamber connected to the pumping means; and a multi-way valve comprising a first port allowing the admission of the gas stream containing the tracer gas into the vacuum line and a second port allowing the admission of neutral gas.The leak detection device may also include a particle filter, an electronic control module to operate the device, a mathematical model to calculate the leak rate, and a voltage balancing circuit for the sensor resistance. This process stabilizes the vacuum line pressure to prevent fluctuations in hydrogen measurements.