Search Results

A wide variety of fibers have been evaluated as possible replacements for asbestos in gasket compositions. The studies to date indicate that no single material can be considered as a completely satisfactory alternative. However, compositions with blends of fibers and fillers have been made that will meet the general processing and performance criteria of conventional asbestos-rubber materials.

The room temperature and elevated temperature (300°F) compression behavior for a select series of fibrous/elastomeric composites has been studied at stress levels up to 200,000 psi. Fiber reinforcement consisted of both asbestos and non-asbestos. It was found that the strain at room temperature could be largely explained in terms of the composite's pore volume fraction and that material failure was not observed in the materials formulated for this study. At elevated temperature, the binder volume fraction for these materials can be used to predict the material response. Test methods and data analyses are discussed.

An expert system has been designed to help transfer gasket engineering expertise from a Research and Development environment to the gasket specifying business. This paper will describe the complex requirements of today's gasket applications, how material properties and gasket engineering are used to make a material recommendation, and how an expert system has been utilized to bring this expertise to the gasket specifiers.

The subject of fluid permeation through porous media has been invoked as a basis for the study of gas and liquid leakage through fibrous gasket materials. The study has encompassed a variety of annular specimen sizes, specimen porosities and structures, fluid viscosities, and fluid pressure. To provide some control of material properties, the ASTM F37 Method B test method was modified to incorporate shims in the fixture. This modification prevents material creep during the test and provides a known porosity for each leakage measurement. The resulting data is highly reproducible and can be related to the intrinsic pore structure of the tested material. The technique can be utilized as a means to study the pore structure for purposes of optimizing gasket formulations; conversely, from a knowledge of the structure the leakage rate can be predicted as a function of sample geometry, state of compression, fluid viscosity, and fluid pressure.