Detonator Thermal Insulation for Premature Activation Prevention
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Solution Overview
Problem
Flying plate detonators are unsafe due to the risk of premature activation from exposure to high temperatures, such as in a fire, where the first pyrotechnic composition can react and cause unintended propulsion and detonation of the secondary explosive.
Innovation Solution
The detonator incorporates thermal insulation means, such as a ceramic, plastic, or composite envelope surrounding the squib stage to delay temperature rise, ensuring the squib stage remains protected until the secondary explosive has detonated, using materials with low thermal conductivity (less than 0.24 W·m−1·K−1) and a minimum thickness of 0.5 mm to achieve a 30-second time offset before internal temperature reaches critical levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the squib stage is made sensitive to optical or electrical initiation, then the detonator can be reliably activated, but the squib stage becomes vulnerable to premature reaction from heat exposure
Solution Approach 1:
A thermal insulation layer is introduced as an intermediary between the external environment and the squib stage. This insulation layer acts as a mediator that blocks thermal energy from reaching the pyrotechnic composition, allowing the squib stage to remain insensitive to thermal effects while maintaining its optical/electrical sensitivity for reliable initiation.
Solution Approach 2:
The thermal insulation properties of the squib stage are modified by adding materials with low thermal conductivity. This changes the thermal parameter of the system, creating a time delay between external heat exposure and internal temperature rise, thereby preventing premature reaction while preserving initiation reliability.
2Object-affected harmful factors
If thermal insulation means are added to protect the squib stage, then thermal sensitivity is reduced, but the device complexity increases
Solution Approach 1:
A thin thermal insulation layer is applied as a flexible coating or shell around the squib stage. This thin film approach provides effective thermal protection without adding significant structural complexity or bulk to the detonator design.
Solution Approach 2:
The thermal insulation layer is constructed from composite materials that combine thermal insulation properties with mechanical compatibility. These composite materials provide effective thermal protection while maintaining device simplicity and avoiding complex structural additions.
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
This solution significantly reduces the risk of premature detonation by maintaining the squib stage's stability during temperature increases, ensuring the secondary explosive decomposes before the primary pyrotechnic composition reacts, thereby enhancing safety and preventing unintended triggering.
Implementation Method 1
thermal insulation means surrounding the squib stage for delaying the temperature rise thereof
Implementation Method 2
materials with low thermal conductivity (less than 0.24 W·m−1·K−1)
Data Source
AI summary
A detonator includes a flying plate propelled by a squib stage including at least one first pyrotechnic composition and/or one first explosive, the plate being propelled onto a relay stage including at least one secondary explosive, wherein the detonator is provided with thermal insulation surrounding the squib stage for delaying the temperature rise thereof.