^[1]In the Thirteenth Edition, the material on prime movers was prepared by Donald H.Hall and Lawrence R.Mizin.

6.1.1 Steam Engines and Steam Turbines

Steam prime movers are either reciprocating engines or turbines, the former being the older, dominant type until 1900. Reciprocating engines offer low speed (100 to 400 r/min) high efficiency in small sizes (less than 500 hp), and high starting torque, and are almost foolproof. In the Industrial Revolution they powered mills and steam locomotives. Steam turbines are a product of the twentieth century and have established a wide usefulness as prime movers. They completely dominate the field of power generation and are a major prime mover for variable-speed applications in ship propulsion (through gears), centrifugal pumps, compressors, and blowers. Single steam turbines can be built in greater capacities (over 1,000,000 kW) than any other prime mover. Turbines offer high speeds (1800 to 25,000 r/min) and high efficiencies (over 85% in larger units); require minimum floor space with relatively low weight; need no internal lubrication; and operate at high steam pressures [5000 lb/in ² (gage)], high steam temperatures (1050 F), and low vacuums [0.5 inHg (abs)]. Steam turbines have no reciprocating mass (with resulting vibrations) nor parts subject to friction wear (except bearings) and consequently provide very high reliability at low maintenance costs.

6.1.2 Steam-Engine Types and Application

The former great...