Fluid Hammer Case Study

Overview

Fluid hammer, also referred to as water hammer, is a common problem in fluid flow systems with sudden shifts in flow direction. Resulting shock waves produce pressures of extreme intensity that can destroy many components of the fluid systems (including pipes) and appropriate dampers are often needed. Where possible, components are made more robust to withstand overpressure.

Problem & Solution

A client was interested in improving the materials and design used to manufacture a pressure sensor used in a medical application where an overpressure of about 20X full-scale operating range was needed. Field failures were experienced when a fluid-filled package with sensor was dropped or when an on/off stop valve was switched. The problems seemed sporadic. Investigations into shipment lots led to certain lots being problem prone. A more detailed analysis of these lots in combination with failure analysis, inspections under a scanning electron microscope (SEM), and finite-element analysis (FEA) showed problems that were the result of subtle geometric variations of the sensor. Improvements were implemented to develop a more consistent manufacturing process that stabilized variations, with a further analysis report provided to show how design and material improvements could be made to improve overall robustness.

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