Gas Chromatography Valve Duty Cycle Pressure Estimation

Solution Overview

Problem

Measuring the precise pressure of a pressurized gas source coupled with a gas chromatography (GC) system is costly and complex, and existing solutions often require additional hardware that increases system complexity.

Innovation Solution

A method for estimating gas supply pressure in a GC system by measuring the runtime valve duty cycle and using calibration data to estimate the supply pressure, without adding additional hardware to the GC system.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If additional pressure sensors are added to directly measure supply pressure, then measurement precision is improved, but device complexity and cost increase

Engineering Contradiction:

Improvesupply pressure measurementVSAvoidhardware complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent uses the valve duty cycle as an intermediary parameter to indirectly measure supply pressure. Instead of directly measuring pressure with sensors, the system measures the valve opening percentage required to maintain downstream pressure, which correlates to supply pressure. This intermediary measurement approach achieves accurate pressure monitoring without adding complex pressure sensing hardware.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces mechanical pressure sensors with an electronic control-based measurement system. By using the electronic pneumatic control module to measure valve duty cycle and calculate supply pressure from this data, the system substitutes direct mechanical pressure measurement with an electronic calculation approach, reducing hardware complexity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If additional pressure sensors are added to directly measure supply pressure, then measurement precision is improved, but cost increases

Engineering Contradiction:

Improvesupply pressure measurementVSAvoidsystem cost

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent uses the valve duty cycle as an intermediary parameter to indirectly measure supply pressure. Instead of directly measuring pressure with sensors, the system measures the valve opening percentage required to maintain downstream pressure, which correlates to supply pressure. This intermediary measurement approach achieves accurate pressure monitoring without adding complex pressure sensing hardware.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces mechanical pressure sensors with an electronic control-based measurement system. By using the electronic pneumatic control module to measure valve duty cycle and calculate supply pressure from this data, the system substitutes direct mechanical pressure measurement with an electronic calculation approach, reducing hardware complexity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Device complexity

If existing GC system components are used to estimate supply pressure, then device complexity is reduced, but measurement precision may be compromised

Engineering Contradiction:

Improvehardware simplicityVSAvoidsupply pressure estimation

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent implements a feedback mechanism where the system continuously monitors valve duty cycle and uses this information to estimate supply pressure. The calibration data stored in the controller allows the system to compare expected valve behavior with actual behavior, providing accurate supply pressure estimation through feedback from the existing control system components.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent performs preliminary calibration to establish the relationship between valve duty cycle and supply pressure before normal operation. By pre-storing calibration data that maps duty cycle values to supply pressure values, the system prepares the necessary reference information in advance, enabling accurate real-time estimation without adding measurement hardware.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS20250052731A1Methods and systems for estimating gas supply pressure

Publication Date: 2025.02.13 AGILENT TECHNOLOGIES INC

AI summary

Methods and systems for estimating gas supply pressure are described herein. The method can include measuring a runtime valve duty cycle for a valve of a gas chromatography system. The method can include estimating a runtime supply pressure from the runtime valve duty cycle and at least one of a runtime flow rate or downstream pressure based on one or more calibration valve duty cycles corresponding to one or more calibration supply pressures and one or more calibration flow rates. The method can include, responsive to determining the runtime supply pressure is greater than a threshold supply pressure value, generating a notification that the runtime supply pressure is greater than the threshold supply pressure value.