Single Plunger Pump Gradient Liquid Feed Device Pulsation Control
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Solution Overview
Problem
Current linear gradient liquid feed devices for HPLC face challenges in achieving high responsiveness and low pulsation at low flow rates, leading to increased costs and device size, with existing high-pressure systems being impractical due to pulsation issues and the need for multiple plunger pumps.
Innovation Solution
A small-size, low-cost linear high-pressure gradient liquid feed device using single plunger pumps with variable stroke and discharge time settings, combined with a pulse damper to absorb pulsation, and a switching valve for efficient liquid handling, allowing for flexible flow rate control and reduced pulsation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single plunger pump is used to reduce device size and cost, then device complexity and cost are reduced, but pulsation increases and gradient responsiveness deteriorates
Solution Approach 1:
A pulse damper is introduced as an intermediary component between the single plunger pump and the mixing chamber to absorb pulsation. The pulse damper includes a damping element that reduces pressure fluctuations, thereby maintaining gradient responsiveness while allowing the use of a simpler single plunger pump configuration
Solution Approach 2:
The system dynamically adjusts the stroke volume and operating parameters of the single plunger pump to optimize performance at different flow rates. By varying the stroke volume and maintaining appropriate pump speed, the system achieves acceptable gradient responsiveness across a range of operating conditions
2Reliability
If multiple plunger pumps are used to reduce pulsation and improve gradient responsiveness, then gradient responsiveness improves, but device size and cost increase
Solution Approach 1:
Multiple carrier liquid supply functions are merged into a single plunger pump system. The single plunger pump alternately draws and discharges different carrier liquids from separate reservoirs, combining multiple functions into one pump unit while using a pulse damper to manage the inherent pulsation
Solution Approach 2:
The pulse damper serves as a mediator that decouples the pulsation-generating pump mechanism from the mixing and delivery system, allowing a single plunger pump to perform work that would traditionally require multiple pumps
3Speed
If pump speed is reduced to achieve low flow rates, then flow rate decreases, but gradient responsiveness deteriorates due to increased pulsation
Solution Approach 1:
The pulse damper is positioned in the flow path to absorb pulsation at low flow rates, enabling the system to maintain gradient responsiveness even when operating at reduced speeds where pulsation effects are most pronounced
Solution Approach 2:
The system changes operating parameters including stroke volume and pump cycle timing to optimize performance at low flow rates. By adjusting these parameters in conjunction with the pulse damper, the system maintains acceptable gradient responsiveness across the full range of operating speeds
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 solution enables high accuracy and speed in HPLC analysis while minimizing device size and cost, by improving gradient responsiveness and reducing pulsation, especially at low flow rates, through the use of single plunger pumps and a pulse damper.
Implementation Method 1
a pulse damper which is in communication with the mixer and configured to absorb pulsation that may occur during liquid feeding
Implementation Method 2
a single plunger pump that is capable of drawing and discharging a carrier liquid
Data Source
Figure 1
AI summary
A gradient liquid feed device allows reduction in size of a high performance liquid chromatography type sample analyzer. The gradient liquid feed device includes a plurality of carrier liquid reservoir tanks (51,52) configured to store carrier liquids of mutually different compositions, a plurality of single plunger pumps (1,2) capable of drawing and discharging the carrier liquid from the plurality of carrier liquid reservoir tanks, a mixer (3) configured to mix the carrier liquids discharged from the plurality of liquid feed pumps and feed the mixed carrier liquid, and a pulse damper (4) in communication with the mixer and configured to absorb pulsation that may occur during liquid feeding. The single plunger pumps (1,2) have a function for variably setting a length of stroke for drawing and discharging the carrier liquid and a function for variably setting a ratio between the carrier liquid drawing time and the carrier liquid discharge time.