Gas Safety Shutoff Using Dual Absolute Pressure Sensing
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Solution Overview
Problem
Conventional gas safety devices with differential pressure measurement type pressure sensors require a through-hole in the flow path, which can lead to gas leakage due to deformation or failure at high temperatures, and are costly to improve for heat resistance.
Innovation Solution
The use of two absolute pressure sensors, one inside and one outside the flow path, to measure absolute pressures and determine gas supply pressure fluctuations, eliminating the need for a through-hole and allowing for a simpler, cheaper design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a differential pressure measurement type pressure sensor is used to measure gas pressure, then gas supply pressure can be measured, but a through-hole must be provided in the flow path which can lead to gas leakage when temperature becomes extremely high
Solution Approach 1:
The pressure measurement function is segmented into two separate absolute pressure sensors: one sensor (first absolute pressure sensor) measures gas pressure inside the flow path, and another sensor (second absolute pressure sensor) measures atmospheric pressure outside the flow path. The differential pressure is calculated by subtracting the atmospheric pressure from the gas pressure. This segmentation eliminates the need for a through-hole in the flow path, preventing gas leakage while maintaining measurement capability.
2Reliability
If heat resistance of the pressure sensor is improved to prevent gas leakage at high temperatures, then reliability improves, but the cost becomes very expensive
Solution Approach 1:
The measurement system is segmented into two standard absolute pressure sensors placed in different locations (inside and outside the flow path), replacing the need for a single high-temperature resistant differential pressure sensor. This allows the use of conventional, cost-effective sensor technology while maintaining system reliability.
Solution Approach 2:
The atmospheric pressure sensor acts as an intermediary reference that allows the gas pressure sensor to operate without direct exposure to high-temperature gas flow. By measuring atmospheric pressure separately and calculating the differential, the system achieves accurate pressure measurement without requiring expensive heat-resistant materials.
3Ease of operation
If a through-hole is provided in the flow path for pressure sensor injection, then pressure measurement is enabled, but gas can leak through the through-hole during fire or high-temperature events
Solution Approach 1:
The pressure measurement function is divided between two sensors located in different environments. The first absolute pressure sensor is positioned inside the flow path to measure gas pressure, while the second absolute pressure sensor is positioned outside the flow path to measure atmospheric pressure. This segmentation eliminates the need for a through-hole in the flow path, thereby preventing gas leakage during fire or high-temperature events while maintaining pressure measurement capability.
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
Prevents gas ejection during high-temperature events, reduces costs by eliminating the need for a through-hole and expensive heat-resistant components, and enhances reliability by minimizing electrical noise interference.
Implementation Method 1
a first absolute pressure sensor disposed inside the flow path to measure an absolute pressure of the gas
Implementation Method 2
a second absolute pressure sensor disposed outside the flow path to measure an absolute pressure of atmospheric pressure
Implementation Method 3
a gas pressure determination unit that measures a change in gas supply pressure from the absolute pressure of the gas and the absolute pressure of the atmospheric pressure measured by the first absolute pressure sensor and the second absolute pressure sensor, respectively
Implementation Method 4
a flow rate measurement unit for measuring a flow rate of the gas flowing through the flow path
Data Source
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AI summary
Provided is a gas safety device including: flow path (1) for flowing gas; flow rate measurement unit (15) for measuring a flow rate of the gas flowing through flow path (1); absolute pressure sensor (5) disposed inside flow path (1) to measure an absolute pressure of the gas; absolute pressure sensor (7) disposed outside flow path (1) to measure an absolute pressure of atmospheric pressure; and gas pressure determination unit (8) that measures a change in gas supply pressure from the absolute pressure of the gas and the absolute pressure of the atmospheric pressure measured by absolute pressure sensor (5) and absolute pressure sensor (7), respectively. The gas safety device further includes shutoff valve (2) that shuts off flow path (1), and control circuit (9) that controls flow rate measurement unit (15) and that causes shutoff valve (2) to shut off flow path (1) when determining abnormality from the flow rate of the gas measured by flow rate measurement unit (15) or the change in gas supply pressure measured by gas pressure determination unit 8.