Latching Tool for Groundwater Sampling Seal Integrity
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Solution Overview
Problem
Conventional screen point groundwater sampling systems face issues with leakage and contamination from static water within the probe rod string, which can mix with the collected groundwater sample.
Innovation Solution
A latching tool is introduced that secures a mechanical pump or sample tubing to the drive head, creating a sealed barrier between the groundwater and static water, allowing for isolation and preventing contamination, and can be easily removed by applying sufficient force to shear a frangible structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional screen point sampling system is used, then groundwater can be collected, but static water within the probe rod string can leak and contaminate the sample
Solution Approach 1:
The system divides the fluid pathway into separate sealed zones using isolation structures (seals and barriers) positioned at the drive head and pump interface. This segmentation prevents mixing between groundwater being sampled and static water in the rod string, ensuring sample purity while allowing continuous operation.
Solution Approach 2:
Seal structures and barrier elements are introduced as intermediary components between the groundwater source and the rod string interior. These intermediaries create water-tight boundaries that block contamination pathways while allowing the sampling function to proceed uninterrupted.
2Reliability
If a latching tool is inserted to create a sealed barrier, then contamination is prevented, but the device complexity increases
Solution Approach 1:
The latching mechanism and sealing function are merged into a single integrated tool assembly. The latching tool combines mechanical engagement features with seal elements, allowing both functions to be performed by one component rather than requiring separate devices, thus limiting the increase in overall system complexity.
Solution Approach 2:
The latching tool is designed to perform multiple functions: mechanical latching to secure the pump, creating water-tight seals to prevent contamination, and providing structural support. This multi-functionality reduces the need for additional specialized components.
3Reliability
If the latching tool is securely engaged to maintain the seal, then sample isolation is maintained, but the tool cannot be removed without applying sufficient force
Solution Approach 1:
The latching mechanism transitions from a static locked position during sampling to a dynamic release state when sufficient force is applied. The frangible structure is designed to remain intact under normal sampling conditions but can be broken or deformed when a specific release force is applied, enabling tool removal while maintaining seal integrity during operation.
Solution Approach 2:
The mechanical properties of the frangible structure are designed to change under different force conditions. During normal operation, the structure maintains high strength to preserve the seal. When sufficient release force is applied, the structure undergoes a parameter change (fracture or deformation) that allows the tool to be removed while preserving the seal's functionality.
Data Source
AI summary
A screen point groundwater sampling system includes a drive head positioned between the upper end of a cylindrical housing and a lower end of a probe rod. A latching tool is provided to secure a mechanical pump to the drive head upon insertion of the latching tool into the inner bore of the drive head. The latching tool creates a water-tight seal between the drive head and the inlet of the mechanical pump to prevent contamination of the groundwater sample from water leaking into the probe rod string above the drive head. A frangible structure on the latching tool allows the mechanical pump to be removed from the drive head upon applying sufficient vertical force in an upward direction to shear the frangible structure. The latching tool can also be used to attach a sample tubing to the drive head for use with a pump located at the ground surface.