Cleanroom Sampling Pump Layout for Atmospheric-Pressure Gas Analysis
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Solution Overview
Problem
The challenge in measuring airborne molecular contamination in clean rooms is the vacuum formation in long sampling lines, which affects the accuracy of gas analyzers, particularly those operating at atmospheric pressure, and the high cost and time required for conditioning due to increased line diameter and length.
Innovation Solution
A measuring station with a sampling pump configured to discharge gas flow at atmospheric pressure, combined with fluoropolymer materials and a buffer volume to stabilize the gas flow, allowing multiple gas analyzers to operate effectively without pressure variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the diameter of sampling lines is increased to limit vacuum, then gas flow conductance is improved, but the internal surface area for adsorption increases causing gas release and measurement interference
Solution Approach 1:
The patent applies different material properties to different parts of the sampling system. The sampling lines are made of fluoropolymer with smooth internal surfaces to minimize adsorption, while the sampling pump is designed with specific material composition and surface treatment to ensure low adsorption characteristics. This localized optimization of material quality resolves the contradiction between conductance and adsorption.
2Adaptability or versatility
If the length of sampling lines is increased to cover more test zones, then measurement coverage is improved, but vacuum effect increases and conditioning time increases
Solution Approach 1:
The patent changes the material parameters of the sampling lines by using fluoropolymer with specific surface properties. This material modification reduces adsorption characteristics, which in turn reduces the conditioning time required before measurements can be taken. This allows long sampling lines to be used without proportionally increasing conditioning time.
3Adaptability or versatility
If the number of gas analyzers is increased to measure more gas chemistries, then measurement capability is improved, but system complexity and cost increase
Solution Approach 1:
The sampling pump is designed with universal applicability to serve multiple gas analyzers with different gas chemistry requirements. The pump's design allows it to handle various gas types and flow rates, enabling a single pump system to support multiple analyzers without requiring separate dedicated pumps for each gas chemistry measurement.
4Measurement precision
If sampling lines are made of high purity fluoropolymer to reduce adsorption, then gas measurement accuracy is improved, but manufacturing cost increases
Solution Approach 1:
The patent applies fluoropolymer material specifically to the internal surfaces that contact gases, rather than requiring the entire sampling system to be made of expensive materials. This localized application of high-purity fluoropolymer to critical areas maintains measurement accuracy while reducing overall manufacturing cost.
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
Ensures accurate and efficient measurement of molecular contamination across multiple zones in clean rooms by maintaining atmospheric pressure at the gas analyzer inlets, reducing conditioning time, and minimizing cost through optimized pump and line design.
Implementation Method 1
The sampling pump is configured to draw the gas flow from the at least one sampling line, and to discharge the gas flow at atmospheric pressure +/−50 hPa
Implementation Method 2
at least one buffer volume arranged downstream of the sampling pump and upstream of the at least one gas analyzer, in the flow direction of the gas flow to be pumped
Implementation Method 3
These sampling lines may subsequently release some of the gaseous species conveyed, which may complicate interpretation of the measurement results. In order to limit this, it is preferable to use a material of very high purity with a very smooth internal surface finish to make the sampling lines
Data Source
AI summary
A measuring station for measuring airborne molecular contamination includes at least one gas analyzer and at least one sampling line fluidically connected to an inlet of the gas analyzer. The station includes at least one sampling pump arranged upstream of the gas analyzer in the flow direction of a gas flow to be pumped, and the sampling pump has a suction side fluidically connected to the at least one sampling line and a discharge side fluidically connected to the inlet of the gas analyzer. The sampling pump is able to draw a gas flow from the sampling line, and to discharge the gas flow at atmospheric pressure +/−50 hPa, preferably +/−30 hPa.