Tham khảo tài liệu 'improving machinery reliability 3 episode 14', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Providing Safety and Reliability Through Modern Sealing Technology 559 being pushed toward a five-year goal in refineries and chemical plants in the United States and around the world. Increased emphasis on economics and energy conservation is forcing seal manufacturers and end users to select new seal designs that will run at higher temperatures pressures and speeds than ever before. In some of these instances the requirements are met by simple changes in materials but more frequently radical changes in design and fundamental modes of operation are required in order to achieve the performance advantages sought by the end user. Another factor adding to the changes in seal design and sealing systems is the basic understanding of seal technology. The basic way we do things has been changing. Fundamental modes of lubrication seal materials and analytical tools have advanced significantly greatly expanding the range of application and enhancing the performance of mechanical seals. A broad overview of fundamental seal technology will help end users understand how fundamental changes may result in more economical and reliable sealing solutions in the future. Seat Classification All sealing devices can be classified into two generic classifications static and dynamic Figure 13-35 . Static seals include such products as gaskets sealants and direct-contact sealing devices. Dynamic seals which will be the broader point of discussion in this segment are classified into two broad categories rotating seals and reciprocating seals. Our focus will primarily be on rotating sealing devices. Types of Seals Under the broad classification of axial end-face mechanical seals there are two types of seals pusher and non-pusher seals which can be found in four different arrangements single double tandem and staged. Pusher-type seals refer to axial end-face mechanical seals with a semi-dynamic secondary sealing device Figure 13-36 . The term semi-dynamic secondary sealing device is used to
