Polyamides are a subject of enduring interest because of their variety, their complex internal structures, their commercial importance and versatility, and their various chemistries of preparation and of long‐term use. The present review introduces these polymers and then discusses the first of the above aspects, namely the variety of the polyamides. Here, together, the full family is presented, classified conveniently according to the types and combinations of monomers from which they are constructed. magnified image

The continuous transport of a liquid requires a pump, and the continuous transport of a gas or vapor requires a fan, blower, or compressor. All of these devices are described by the general term fluid movers. Specialized fluid movers are required for the transport of liquid‐and‐gas mixtures and of slurries and suspensions of solids in liquid or gas. The vast majority are mechanically driven. A few eductors and ejectors use another fluid as the motive source This chapter is organized into two broad sections i.e.; on liquid transport and on gas transport, and within each section it describes the technology of both the dynamic and the positive‐displacement devices. In the case of gas compression, where pressure, volume, and temperature are all in flux, an outline of the relevant thermodynamics is provided. Dynamic devices include centrifugal, axial, mixed flow, and jet pumps.

Gas movers with low fractional rise of pressure are discussed. These devices are fans (subsuming the term blower) and are of two types, centrifugal and axial. For both types, the principles are presented including the derivation and application of the important rules of affinity. The relation is shown between vendor specification and fan performance. The variety of fan geometries is surveyed and the interaction is examined between a fan and other process components upstream and downstream. Also reviewed are essential auxiliaries, namely fan drives, flow conditioners, noise and vibration controls, and drive seals.

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