Gas Inlet System with Switchable Flow Restrictions
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Solution Overview
Problem
Current gas inlet systems for analytical apparatus, such as mass spectrometers, require multiple mass flow controllers for different collision gases, leading to high costs and slow gas switching due to large dead volumes in mass flow controllers.
Innovation Solution
A gas inlet system with a single gas flow controller and switchable flow restrictions allows for rapid gas switching by using a bypass gas line to adjust pressure and flow rates, minimizing the need for multiple controllers and reducing switching time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple mass flow controllers are used to control different collision gases, then gas flow control precision is improved, but device cost and system complexity increase
Solution Approach 1:
The system divides gas flow control into two independent parts: (1) a single mass flow controller that controls total gas flow to the collision cell, and (2) electronic control valves on each gas inlet line that control the distribution of gas among different collision gas lines. This segmentation allows one mass flow controller to effectively manage multiple gases without requiring separate controllers for each gas type.
Solution Approach 2:
The single mass flow controller serves multiple functions by controlling the total flow of different collision gases (helium, hydrogen, nitrogen) to the collision cell. The electronic valves enable this universal controller to selectively direct different gases through different inlet lines, making one device perform the work of multiple specialized controllers.
2Device complexity
If a single mass flow controller is used for different collision gases, then device cost is reduced, but gas switching time increases due to large dead volume
Solution Approach 1:
The system pre-configures separate inlet lines for different collision gases, each equipped with electronic control valves. When gas switching is required, the electronic valves can immediately redirect flow without requiring the mass flow controller to physically flush its internal dead volume. The electronic valves act in advance to prepare the gas path, enabling rapid gas type changes.
Solution Approach 2:
The system extracts the gas switching function from the mass flow controller and places it in electronic control valves positioned at the inlet lines. This separation removes the switching operation from the component with large dead volume (the mass flow controller) and places it in components (electronic valves) that can switch rapidly without significant dead volume constraints.
3Reliability
If multiple mass flow controllers are used for each collision gas, then gas switching reliability is improved, but system cost increases significantly
Solution Approach 1:
The system incorporates pressure sensors in the collision cell that provide feedback on the actual gas pressure and flow conditions. This feedback allows the control system to monitor and adjust the electronic valve positions and mass flow controller settings to maintain reliable gas delivery, compensating for the reduced number of controllers. The feedback mechanism ensures that gas switching and flow control remain reliable even with fewer controllers.
4Speed
If rapid gas switching is achieved using a bypass gas line, then gas switching speed is improved, but gas flow control complexity increases
Solution Approach 1:
The gas inlet system is segmented into a main flow path through the mass flow controller and a bypass path with electronic valves. This segmentation allows the bypass line to handle rapid gas type switching independently, while the main path maintains stable flow control. The parallel structure enables speed improvement without compromising flow control stability.
Data Source
AI summary
The present invention relates to a gas inlet system for an analytical apparatus. The gas inlet system comprises switchable flow restrictions for regulating gas flow rate. The invention also provides a system for calibrating gas flow rate in gas inlet systems, the system comprising a calibration line that comprises a gas flow meter, and that is arranged downstream of gas flow controllers in the gas inlet system. Methods of adjusting gas flow rates and methods of calibrating gas flow rates are also provided.