Manhole Cover Assembly with Pivotable Legs for Pressure Relief
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Solution Overview
Problem
Conventional manhole covers are prone to being displaced or becoming projectiles during explosions, causing structural damage and failing to relieve pressure effectively, due to their weight and design.
Innovation Solution
A manhole cover assembly with pivotable and slidable legs that can configure between a restraint mode and a removal mode, allowing limited vertical displacement to release pressure and prevent complete removal during explosive events, while enabling secure reseating and removal when necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the manhole cover is made heavy (e.g., cast iron with concrete infills), then it remains in place during normal traffic, but it becomes a projectile during explosions and causes structural damage
Solution Approach 1:
The manhole cover system transitions from a static fixed state to a dynamic controlled-release state during explosions. The cover is designed to pivot on hinge pins and is restrained by extendable latches that can engage or disengage based on pressure conditions, allowing the cover to dynamically respond to varying operational states rather than remaining permanently fixed
Solution Approach 2:
The explosion pressure that would normally cause harmful projectile motion is converted into a beneficial controlled venting mechanism. The extendable latch and pivot system allows the cover to rotate open during explosions, directing the harmful pressure in a controlled manner to vent safely rather than causing uncontrolled damage
2Stability of the object's composition
If the manhole cover is bolted or fastened to the frame, then it prevents displacement during explosions, but it fails to relieve pressure and may cause structural damage to underground area or surrounding surface structure
Solution Approach 1:
The restraint system transitions from a permanently fixed state to a dynamically controllable state. Extendable latches can engage to prevent displacement during normal operation, then automatically or manually disengage to allow controlled venting during pressure events, creating a dynamic system that adapts to different operational conditions rather than remaining statically fixed
Solution Approach 2:
The system converts the potentially harmful uncontrolled pressure buildup into a beneficial controlled venting mechanism. By allowing the cover to pivot and open in a controlled manner through the hinge and latch system, the dangerous pressure is directed in a manageable way to relieve stress on the underground infrastructure
3Reliability
If the manhole cover is designed to pivot and extend like Swiveloc, then it releases explosive pressure in a controlled fashion, but the extendable latch includes multiple interfitting components that add expense and may become susceptible to failure
Solution Approach 1:
The restraint system is divided into modular components: hinge pins that provide pivot points, extendable latches that provide restraint, and a heavy-duty cover. This segmentation allows each component to perform its specific function independently, simplifying the overall system while maintaining reliability through functional specialization rather than requiring all components to work together in complex interfitting arrangements
Data Source
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AI summary
A manhole cover assembly configured to behave as a relief valve in an explosion event, opening so that fluid, such as air or explosive gas, may vent from an underground area. The manhole cover assembly may include a manhole cover and a frame, and may be configured to limit movement of the manhole cover with respect to the frame in response to increased pressure on the manhole cover. In one embodiment, the manhole cover may include legs having angled surfaces adapted to substantially center or guide the manhole cover in the frame while the manhole cover displaces to release pressure. In another embodiment, one or more legs slidable within the manhole cover to enable configuring the manhole cover between a restraint mode and a removal mode.