Curved Anti-Backflow Flap for Fire Hydrant Retrofit
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Solution Overview
Problem
Existing solutions for preventing backflow into fire hydrants are either not practical for retrofitting, restrict water outflow, or are ineffective in preventing contamination of municipal water supplies, as they are either positioned inside the hydrant tower or unduly restrict the flow of water.
Innovation Solution
A hollow cylindrical anti-backflow insert with a curved flap and inflow fin that can be easily retrofitted into the outflow nozzle of a fire hydrant, featuring a hinge mechanism, curved flap seal, and anti-tamper protrusions to prevent backflow without obstructing water outflow, and secure the insert in place.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a flat anti-backflow disc or flap is positioned at the base of the fire hydrant tower, then backflow prevention is achieved, but water outflow is unduly restricted
Solution Approach 1:
The patent applies curvature by using a dome-shaped anti-backflow insert instead of a flat disc or flap. The curved surface allows water to flow over the top of the dome during normal operation, maintaining unrestricted outflow, while the shape prevents backflow by directing incoming fluid along the curved surface without allowing it to penetrate into the hydrant system.
2Reliability
If existing backflow prevention devices are installed inside the fire hydrant tower, then backflow is prevented, but the devices are not practical for retrofitting fire hydrant outlets
Solution Approach 1:
The patent extracts the backflow prevention function from the internal hydrant tower structure and relocates it to an external outlet component. The dome-shaped insert is designed to be installed in the fire hydrant outlet itself, separating the backflow prevention mechanism from the tower interior and enabling retrofitting of existing outlets without modifying the hydrant tower structure.
Solution Approach 2:
Instead of placing the backflow prevention device inside the hydrant tower as in conventional designs, the patent inverts the approach by positioning the dome-shaped insert in the outlet. This reversal allows the device to function at the point where water exits the hydrant, providing backflow prevention at the critical interface while enabling easy retrofitting.
3Reliability
If existing backflow prevention systems are positioned inside the outlet of a fire hydrant, then backflow is prevented, but the devices unduly restrict water outflow and are not suitable for retrofitting
Solution Approach 1:
The dome-shaped curved surface allows water to flow smoothly over the top during normal operation, maintaining unrestricted outflow. The curved geometry creates a flow path that naturally directs water over the dome rather than blocking it, while simultaneously preventing backflow by directing incoming fluid along the curved surface.
Solution Approach 2:
The patent applies different functional qualities to different parts of the dome-shaped insert. The curved outer surface is designed to guide and direct fluid flow, while the interior surface provides a sealing interface. This differentiation of local qualities allows the single component to simultaneously maintain unrestricted outflow and prevent backflow penetration.
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 solution effectively prevents backflow into fire hydrants while maintaining unobstructed water outflow, providing a cost-effective and simple method to secure municipal water supplies from contamination by unauthorized access.
Implementation Method 1
The flap has a hinge to attach the flap rotatably within the insert to the interior surface and top portion of the insert, near the rear end of the insert, so that outflow of water from the fire hydrant will cause the flap to rotate towards the front end and top portion of the insert.
Implementation Method 2
When the curved flap seal reversibly engages the perimeter of the flap, the rear end of the insert is reversibly closed.
Implementation Method 3
When the flap is rotated upwards to the top portion of the insert the inflow fin protrudes into the interior of the insert sufficiently to catch an inflow stream of liquid so as to force the flap downward against the curved flap seal.
Implementation Method 4
The hinge may have a spring to bias the flap towards the curved flap seal.
Data Source
AI summary
An cylindrical hollow anti-backflow insert that can rapidly retrofit a fire hydrant to prevent a forced liquid inflow into the fire hydrant after simple insertion of the insert into the outflow nozzles of a fire hydrant. A curved anti-backflow flap having a hinge at one end and an inflow fin at an opposite end is positioned within the insert. Outflow of water from the fire hydrant will cause the flap to rotate upwards, at which point the inflow fin protrudes into the interior of the insert sufficiently to catch any forced liquid inflow stream which will force the flap downward towards a curved flap seal. The curved flap seal reversibly engages the perimeter of the flap, thereby reversibly closing the rear end of the insert and preventing the forced inflow of liquid into the fire hydrant.