Sampling Pump Closed-Loop Control for Variable Restriction
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Solution Overview
Problem
Conventional sampling pumps often fail or provide inaccurate flow measurements when drawing air samples through needle traps due to high variable restrictions, leading to premature failure and inconsistent flow rates.
Innovation Solution
A sampling pump system equipped with a mass flow sensor and controller that uses closed-loop control to manage air flow independently of variable restrictions, ensuring accurate measurement and loading of analytes onto traps by adjusting pumping rates based on atmospheric pressure and temperature corrections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional pumps are used to draw air through needle traps, then the system is simple and cost-effective, but the pump fails prematurely and provides inaccurate flow measurements due to high variable restrictions
Solution Approach 1:
The patent implements a closed-loop control system where a mass flow sensor continuously measures the actual flow rate through the needle trap and feeds this information back to the controller. The controller adjusts the pump operation in real-time based on this feedback, ensuring accurate flow control despite high variable restrictions. This feedback mechanism resolves the contradiction by maintaining pump reliability through adaptive control while accepting the necessary system complexity.
Solution Approach 2:
The patent replaces traditional mechanical flow control methods with electronic control based on mass flow sensor measurements. Instead of relying on fixed mechanical restrictions or manual adjustments, the system uses electronic signals to control the pump motor speed and flow rate dynamically. This substitution resolves the contradiction by improving reliability through precise electronic control while managing the added complexity through integrated electronics.
2Measurement precision
If pumps operate with high variable restrictions from needle traps, then the system can handle trap loading, but the pump experiences premature failure and inaccurate flow measurements
Solution Approach 1:
The mass flow sensor provides continuous feedback on actual flow conditions, allowing the controller to detect and compensate for deviations from the target flow rate. This feedback loop ensures measurement precision by comparing actual measurements against expected values and adjusting pump operation accordingly, while also protecting pump durability by preventing operation under excessive restriction conditions.
Solution Approach 2:
The patent implements dynamic flow control where the pump operating parameters are continuously adjusted based on real-time mass flow measurements. Rather than operating at fixed speeds, the pump dynamically adapts its flow rate to match the requirements of the needle trap loading process. This dynamic operation resolves the contradiction by maintaining measurement precision through adaptive control while extending pump durability by avoiding sustained operation under harmful high-restriction conditions.
3Quantity of substance
If fixed flow rates are used for sampling, then the pumping process is simple to control, but the volume of air sample drawn is inaccurate when restrictions vary
Solution Approach 1:
The controller integrates mass flow sensor measurements over time to calculate the actual volume of air sample drawn through the trap. This feedback mechanism allows the system to compensate for variations in flow rate caused by changing restrictions, ensuring accurate quantification of the air sample volume despite the added control system complexity.
Solution Approach 2:
The patent replaces simple time-based or fixed-flow control with electronic integration of mass flow measurements. The controller uses electronic integration to calculate the cumulative volume of air sampled, substituting mechanical flow control with electronic measurement and calculation. This substitution resolves the contradiction by providing accurate air sample volume measurement while managing the complexity through integrated electronic control and calculation capabilities.
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 system effectively prevents pump failure and ensures consistent, accurate air sample loading onto traps, maintaining flow accuracy even with varying restrictions, thereby improving the reliability and precision of sampling processes.
Implementation Method 1
a mass flow sensor fluidically coupled to the fluid flow line and configured to measure mass flow in the air sample drawn through the trap
Implementation Method 2
a pump configured to fluidically couple to the trap through a fluid flow line and configured to draw the air sample through the trap
Implementation Method 3
the controller configured to correct for atmospheric pressure and temperature during operation of the pump
Data Source
AI summary
Certain configurations of devices and systems which are configured to draw a selected volume of an air sample into a trap are described. In some examples, the devices and systems comprise a pump and a mass flow sensor to draw a selected volume of the air sample through a trap even where variable restriction occurs.