Hollow-Stem Hydrant Valve Cartridge for Freeze-Safe Sampling
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Solution Overview
Problem
Existing sampling stations and hydrants face challenges with freezing issues due to external water contamination and damage from evacuation pipes, and plug-and-seat valves are difficult to service, especially in hard-to-reach locations.
Innovation Solution
The operating stem of a hydrant is made hollow with an inlet at the lower end and an outlet at the upper end, which can be used as an evacuation tube, and includes a valve cartridge with a fixed and moveable portion connected by a threaded connector, allowing for easy removal and servicing of components, positioning them below the frost line to prevent freezing and reduce vibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an external evacuation pipe is used to prevent freezing, then the standpipe can be emptied, but the evacuation pipe is subject to damage and flash freezing
Solution Approach 1:
The evacuation function is nested within the operating stem itself. The hollow operating stem contains the evacuation passage internally, eliminating the need for a separate external evacuation pipe. This nested design protects the evacuation passage from external damage and prevents flash freezing by keeping the evacuation path within the insulated standpipe structure.
Solution Approach 2:
The evacuation function is merged with the operating stem structure. The operating stem serves dual purposes: actuating the valve and providing the evacuation pathway. This consolidation eliminates the separate evacuation pipe that was vulnerable to damage and freezing, as the stem is protected by the standpipe housing.
2Reliability
If a subterranean drain hole is used to prevent freezing, then the standpipe can be emptied, but ground water may contaminate the sampled water
Solution Approach 1:
The operating stem acts as an intermediary evacuation pathway that connects the bottom of the standpipe to the top without requiring contact with external ground water. By using the existing valve actuation stem as the evacuation route, the system achieves drainage functionality while maintaining water integrity and preventing contamination from external sources.
3Ease of operation
If the operating stem extends above ground for manual operation, then the valve can be operated easily, but the screw threads are subject to freezing
Solution Approach 1:
The operating stem is segmented into functional zones: the upper portion extends above ground for manual operation while the lower portion with threaded connections remains below the frost line. This segmentation allows the operational interface to be accessible while protecting the vulnerable threaded connections from freezing conditions.
4Reliability
If the valve assembly is positioned below the frost line to prevent freezing, then freezing is avoided, but servicing becomes difficult
Solution Approach 1:
The valve assembly is designed with dynamic accessibility. The entire valve cartridge can be removed from the standpipe and serviced above ground, transforming a static underground component into a dynamically serviceable unit. This allows the valve to remain positioned below the frost line for freezing protection while enabling easy removal and maintenance from above ground level.
Data Source
AI summary
A hydrant includes a standpipe, a discharge nozzle, and a subterranean valve operated by a valve stem. The operating stem is hollow and has an inlet at its lower end and a drain outlet at its upper end, thereby providing a path to flush the sampling station when the subterranean valve is shut and the discharge nozzle and drain outlet are open by applying a differential pressure. The subterranean valve includes a cartridge having a fixed portion and a moveable portion. The fixed portion is fixed to the end of the stem and turns with it but does not move axially. The moveable portion moves axially but does not rotate. The fixed and moveable portions are connected to each other by a threaded connector. The cartridge, including a valve plug, a valve seat, and a threaded operating mechanism can be removed simply by removing a top cap on the standpipe.