A report presents an analysis of stresses and deflections in resistance temperature detectors (RTDs) of various model numbers with standard sizes and shapes. The RTDs are assumed to be installed in pipes that contain flows of oxygen and hydrogen in a test facility at Stennis Space Center. The analysis, performed in a spreadsheet format, involves calculation of maximum stresses and deflections for each RTD under specific fluid conditions. The drag force is entered as a circular reference in the spreadsheet and must be calculated iteratively. The equation for drag force is used to calculate the allowable fluid density for a given velocity. The deflection of the RTD at the inner pipe wall is also compared with the

maximum allowable deflection at that point. The output of the analysis is a curve, for each RTD model and size, of fluid density versus flow speed. On the basis of allowable stress and deflection, it is deemed to be safe to operate an RTD at any point below its curve. Thus, the collection of curves serves as a guide for preliminary selection of RTDs for the facility.

This work was done by Michael Jee of Lockheed Martin for Stennis Space Center. SSC-00064


NASA Tech Briefs Magazine

This article first appeared in the June, 1998 issue of NASA Tech Briefs Magazine.

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