Dual Thermal Actuator Gas Valve for Fire-Safe Shutoff
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Solution Overview
Problem
Existing electrically controllable gas valves, such as those using shape memory alloys, risk unintentional opening during external heating events like fires, leading to potential gas explosions, as they fail to securely close in such scenarios.
Innovation Solution
Incorporating a second temperature path converter that activates above a higher overtemperature threshold to ensure the gas valve closes, potentially using shape memory alloys or expansion fluids, and arranging these converters in series or parallel with a spring mechanism to coordinate movements, ensuring priority and irreversible closure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a single temperature path converter is used to open the valve at a certain temperature, then the valve can be controlled to open under normal operating conditions, but the valve will unintentionally open during external heating events such as fires
Solution Approach 1:
The temperature response function is segmented into multiple distinct thresholds by using separate temperature path converters. The first converter responds to normal operating temperatures to open the valve, while the second converter responds only to fire-level temperatures to close the valve. This segmentation allows the system to differentiate between normal and emergency conditions, resolving the contradiction between automatic operation and fire safety.
Solution Approach 2:
The second temperature path converter acts as an intermediary safety mechanism that overrides the first converter's opening action when fire conditions are detected. This intermediary component mediates between the normal operation signal and the emergency shutdown requirement, ensuring that fire conditions always result in valve closure regardless of the first converter's state.
2Extent of automation
If the valve is designed to open with heating, then the valve can be automatically controlled, but the valve opens unintentionally during external heating such as fire
Solution Approach 1:
The second temperature path converter is pre-configured to trigger a counteracting action (valve closure) when fire-level temperatures are detected. This preliminary anti-action is built into the system design, so that when external heating reaches fire levels, the automatic response is immediately to close the valve, preventing the harmful effect of gas explosion even though the first converter may have opened the valve for normal operation.
3Reliability
If a second temperature path converter is added to close the valve at higher temperatures, then the valve can be secured closed during fire, but the device complexity increases
Solution Approach 1:
Both temperature path converters are merged into a single actuator assembly that controls the same valve mechanism. The converters work together within one integrated structure, sharing common components such as the piston and valve stem. This merging approach achieves the reliability benefit of fire-safe closure while minimizing the increase in overall device complexity by consolidating the dual temperature response functions into a unified actuator design.
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 gas valve securely closes during fires, preventing gas explosions and allowing for safe operation by prioritizing the second temperature path converter's function to ensure the gas supply is shut off, even in the presence of external heat sources like extinguishing water.
Implementation Method 1
a first temperature path converter (9) which is heated by means of an electric heater (10), so that the actuator (8) comprises a second temperature path converter (11)
Implementation Method 2
the second temperature path converter (11) which, when a second overpart temperature which is above a second overtemperature higher than the first overtemperature is exceeded, acts on the closure part (1) in a second direction in which the gas passage (2, 3) is closed
Implementation Method 3
a spring is provided between at least one of the temperature-path converters and the closure member and / or between the two temperature-path transformers
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The valve has a driver (8) comprising a temperature path converter (9). The temperature path converter is provided in excess temperature higher than ambient temperature. The driver comprises another temperature path converter (11).