Investigation of mechanical seals

Abstract

A general description of the mechanical seal problem is given with references to historical background. The design criteria, establishing the basic configuration, and the evolution of the final design of the experimental apparatus are presented in detail. The description of the supporting equipment and instrumentation is given; calibration curves are included in the appendix. The modifications and suggested improvements in the apparatus are discussed in detail. A complete set of manufacturing drawings for the apparatus that was built and used for the experimental work is on file in the Mechanical Engineering Department of California Institute of Technology; the drawings are not included in the thesis, but prints or microfilm copies are available. In the experimental work, the qualitative determination of the clearance geometry and the fluid film behavior in the clearance of an operating seal are described. Measured leakage rates and friction coefficients are presented in graphical form together with the pertinent operating variables. Photographs of typical interference fringe patterns and seal face failures at various stages are included. The sealing mechanism is established and discussed with references to the photographs and numerical data. The usefulness of the balance ratio of a mechanical seal as a basic parameter is established; the correlation of leakage rates and friction coefficient values with the balance ratio and other operating variables is discussed. The frictional heat rate per unit seal area is shown to be the important criterion for predicting seal failures under different operating conditions. An evaluation of experimental errors is included. In conclusion a program is proposed for continuation of the experimental work and salient points in the results are summarized.