CHAPTER 22 SEAL TECHNOLOGY Bruce M. Steinetz NASA Lewis Research Center Cleveland, Ohio INTRODUCTION STATICSEALS Gaskets O-Rings Packings and Braided Rope Seals 629 629 629 634 637 DYNAMICSEALS Initial Seal Selection Mechanical Face Seals Emission Concerns Noncontacting Seals for High-Speed/Aerospace Applications Labyrinth Seals Honeycomb Seals Brush Seals 638 638 642 644 646 650 653 654 INTRODUCTION Seals are required to fulfill critical needs in meeting the ever-increasing system-performance requirements of modern machinery. Approaching a seal design, one has a wide range of available seal choices. This chapter aids the practicing engineer in making an initial seal selection. | CHAPTER 22 SEAL TECHNOLOGY Bruce M. Steinetz NASA Lewis Research Center Cleveland Ohio INTRODUCTION 629 DYNAMIC SEALS 638 638 Initial Seal Selection STATIC SEALS 629 Mechanical Face Seals 642 Gaskets 629 Emission Concerns 644 O-Rings 634 Noncontacting Seals for Packings and Braided High-Speed 1 Aerospace Rope Seals 637 Applications 646 Labyrinth Seals 650 Honeycomb Seals 653 Brush Seals 654 INTRODUCTION Seals are required to fulfill critical needs in meeting the ever-increasing system-performance requirements of modem machinery. Approaching a seal design one has a wide range of available seal choices. This chapter aids the practicing engineer in making an initial seal selection and provides current reference material to aid in the final design and application. This chapter provides design insight and application for both static and dynamic seals. Static seals reviewed include gaskets O-rings and selected packings. Dynamic seals reviewed include mechanical face labyrinth honeycomb and brush seals. For each of these seals typical configurations materials and applications are covered. Where applicable seal flow models are presented. STATIC SEALS Gaskets Gaskets are used to effect a seal between two mating surfaces subjected to differential pressures. Gasket types and materials are limited only by one s imagination. Table lists some common gasket materials and Table lists common elastomer properties. The following gasket characteristics are considered important for good sealing Selecting the gasket material that has the best balance of the following properties will result in the best practical gasket design. Chemical compatibility Heat resistance Compressibility Microconformability asperity sealing Recovery Creep relaxation Erosion resistance Compressive strength crush resistance Tensile strength blowout resistance Shear strength flange .
