588 



HYDRAULICS AND ITS APPLICATIONS 



barrel and admits an equal volume (neglecting the volume of the plunger 

 rod if this is used) at the other end of each stroke. Fig. 275 shows a 

 direct steam-driven pump of this type having centre-packed plungers, 1 



FIG. 275. Central- Packed Double- Acting Plunger Pump. 



and designed for 80 strokes per minute, with 10-inch plunger ; 12-inch 

 stroke; 18-inch steam cylinder; 10-inch suction and 7-inch discharge pipes. 

 Fig. 276 shows an outside end-packed plunger pump of this type, 

 suitable for moderately high pressures, the two plungers carrying cross- 

 heads which are connected by side rods, while Fig. 277 shows a similar 



FlG. 276. Double-Acting Duplex Outside End-Packed Plunger Pump : 6-inch 

 plunger ; 12-inch steam cylinder ; 12-inch stroke ; 5-iuch suction ; 4-inch 

 delivery ; 80 strokes per minute ; up to 300 Ibs. per square inch. 



purnp as constructed for the highest pressures. This latter pump has a 

 separate valve box for each end of the cylinder, the construction of the 

 valves (which are 1 inch in diameter) and of the valve box, being 

 shown in Fig. 278. 2 



1 By courtesy of the Buffalo Steam Pump Company. 



2 Figs. 277 and 278 are inserted by courtesy of the makers Messrs. Henry Berry & Cc 

 Leeds. 



