Hydrant Operating Nut Locking Assembly Against Unauthorized Removal
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Solution Overview
Problem
Conventional hydrant operating nuts can be easily removed by unauthorized users with standard tools, posing a security risk in applications where tamper-resistance is desired.
Innovation Solution
The implementation of tamper-resistant operating nuts on hydrants, secured by snap rings, tightening nuts, dowel pins, or shear nuts, which require specialized tools for removal, ensuring the nuts remain securely in place.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional hex nut is used to hold the operating nut on the hydrant stem, then the operating nut can be easily installed and removed with standard tools, but this makes the hydrant vulnerable to unauthorized removal and tampering
Solution Approach 1:
The fastening system is divided into multiple independent components: the operating nut, the specialized securing nut with non-circular profile, and the corresponding non-circular threaded bore in the stem. This segmentation allows each component to perform its specific function - the operating nut for water control and the specialized nut for secure attachment that prevents unauthorized removal.
Solution Approach 2:
The patent employs asymmetric geometry by using a non-circular profile (such as square, rectangular, or other polygonal shapes) for both the securing nut and the threaded bore. This asymmetric design means that only a matching specialized tool with the corresponding non-circular profile can engage and remove the nut, effectively preventing removal with conventional circular wrenches and tools.
2Reliability
If a specialized non-circular nut is used to secure the operating nut, then unauthorized removal is prevented, but the device complexity increases due to specialized tools and components
Solution Approach 1:
The specialized non-circular nut serves multiple functions: it secures the operating nut to the stem, prevents unauthorized removal through its asymmetric profile, and provides a positive locking mechanism. This multi-functionality reduces the need for additional separate security devices, thereby limiting the increase in overall system complexity.
Solution Approach 2:
The securing nut with non-circular profile is nested within or adjacent to the operating nut assembly, with the non-circular threaded bore integrated into the stem structure. This nested arrangement allows the security feature to be incorporated within the existing hydrant structure rather than adding separate external components, thus minimizing the increase in device complexity.
Data Source
AI summary
A hydrant comprising: an operating stem comprising a threaded distal end extending from the hydrant; an operating nut comprising a first end facing the hydrant, an opposed second end, and a central bore defined in the operating nut and extending from the first end to the second end, the operating nut positioned on the operating stem such that a portion of the stem is positioned in the central bore and the threaded distal end of the stem extends beyond the second end of the operating nut; a snap ring positioned on the stem, the snap ring configured to prevent the operating nut from being removed from the operating stem without removing the snap ring; and a tightening nut rotatably secured to the stem, the tightening nut comprising internal threads configured to matingly engage the threaded distal end of the stem.