Supercritical Fluid Chromatograph Pressure Valve Cavitation Erosion
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Solution Overview
Problem
Pressure control valves in supercritical fluid chromatographs face damage due to cavitation and erosion when operating at high pressures, leading to reduced durability and frequent replacements, even when using hard materials like SUS316L.
Innovation Solution
The pressure control valve features a pressure control surface coated with a diamond-like carbon (DLC) film or subjected to nitriding treatment, providing significantly higher hardness and resistance to cavitation, thereby reducing erosion and extending the lifespan of the pressure control block.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a hard material such as SUS316L is used as the pressure control block, then impact resistance and pressure resistance are improved, but cavitation-induced erosion still occurs leading to reduced durability
Solution Approach 1:
The patent applies a DLC coating specifically to the pressure control surface where cavitation occurs, rather than treating the entire block uniformly. This localized enhancement of hardness and erosion resistance at the critical surface resolves the contradiction by maintaining impact resistance of the base material while adding cavitation resistance where needed.
Solution Approach 2:
The patent creates a composite structure by combining the SUS316L base material with a DLC coating layer. The SUS316L provides impact and pressure resistance, while the DLC coating provides cavitation and erosion resistance, together achieving both strength and durability.
2Reliability
If the pressure control valve operates at high pressure of 10 MPa or more, then supercritical fluid chromatography function is maintained, but carbon dioxide vaporizes and generates dry ice damaging the pressure control surface
Solution Approach 1:
The patent acknowledges that cavitation and dry ice generation are inevitable at high pressure operation, but converts this harmful effect into a manageable issue by applying a DLC coating that resists erosion from these phenomena, allowing the system to operate at required high pressures without damage.
Solution Approach 2:
The patent changes the physical parameter of the pressure control surface by applying a DLC coating with significantly higher hardness and erosion resistance, enabling the surface to withstand the harsh high-pressure environment and cavitation effects that would otherwise cause damage.
3Measurement precision
If the gap between the valve body and block plane is reduced for high resolution pressure control, then pressure control precision is improved, but the valve body and block plane are more susceptible to damage from cavitation
Solution Approach 1:
The patent enhances only the pressure control surface with DLC coating, providing localized erosion resistance at the critical gap region where cavitation occurs, allowing reduced gap dimensions for high precision control without increased susceptibility to damage.
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 enhanced hardness of the pressure control surface significantly reduces cavitation-induced erosion, allowing for longer operation without replacement and lowering maintenance costs by maintaining precise pressure control in supercritical fluid chromatographs.
Implementation Method 1
a pressure control surface provided as a plane at a bottom portion of the opening portion... The pressure control surface is made of a material having higher hardness than a hard material having impact resistance and abrasion resistance
Implementation Method 2
a pressure control surface provided as a plane at a bottom portion of the opening portion... subjected to nitriding treatment
Implementation Method 3
a valve body driving portion provided on a side opposite to the pressure control surface with the valve body interposed therebetween that adjusts an amount of a gap between the valve body and the pressure control surface by pressing the valve body
Implementation Method 4
carbon dioxide may be vaporized due to a steep drop in the pressure of a mobile phase and is instantly cooled by the heat of vaporization, thereby generating dry ice
Implementation Method 5
carbon dioxide may be vaporized due to a steep drop in the pressure of a mobile phase and is instantly cooled by the heat of vaporization
Data Source
AI summary
A pressure control valve is provided with a pressure control block. The pressure control block has a pressure control block having an opening portion provided on one outer surface, a pressure control surface provided as a plane at a bottom portion of the opening portion, and two internal channels having openings at the respective end portions of the pressure control surface. A sheet-like valve body having elasticity and arranged so as to cover the pressure control surface is provided in the opening portion of the pressure control block. A valve body driving portion is provided on a side opposite to the pressure control surface with the valve body interposed therebetween that adjusts an amount of a gap between the valve body and the pressure control surface by pressing the valve body in a direction perpendicular to the pressure control surface. The pressure control surface has higher hardness than a hard material.