476 



WATER SUPPLY AND SEWAGE DISPOSAL 



O 



PUMP, 

 HEAD, 



558. The Suction-pump. Water for household and farm 

 use is usually lifted out of moderately deep wells by SUCTION- 

 PUMPS. A common suction-pump consists of two parts, the 

 PUMP-HEAD, and the PUMP-RUN. When made of wood, the 

 head is usually from 6 to 8 in. square and about 7 or 8 ft. in 



length. This head is hollow, that is, a hole 

 3 or 4 in. in diameter is bored throughout 

 its length (Fig. 290). Into the lower end 

 of the head a metal tube, the CYLINDER, is 

 fitted. The cylinder is made smooth and 

 true on its inner surface; when of iron it 

 is often lined with enamel. Fitting closely 

 into this cylinder is the PLUNGER or 

 BUCKET. This plunger, or bucket, carries 

 the PLUNGER-VALVE which opens easily 

 upward but which prevents any water 

 above it from passing downward. The 

 plunger is raised and lowered by means of 

 the PLUNGER-ROD, attached to the PUMP- 

 HANDLE. 



Fitting closely into the lower end of the 

 HEAD is the PUMP-RUN, or the SUCTION-PIPE. 

 In the common wooden pump this run is 

 about 4 in. square and has a hole about 1J^ 

 or 2 in. in diameter bored throughout its 

 length. At the lower end of the cylinder, 

 below the plunger, is a second valve, the INLET-VALVE. This 

 valve also permits the water to pass upward but prevents a 

 downward flow. 



559. How the Suction-pump Works. The way in which the 

 suction-pump works is made clearer by studying the sketches 

 of the common iron cistern pump (Fig. 291). As the handle is 

 forced downward, the plunger rod and plunger are raised. 

 The water which is already above the plunger, or bucket, is 

 lifted till it stands higher than the spout, out of which it runs. 

 But what raises or lifts the water in the run and cylinder below 



VENT- 



PUMP 

 RUN 



PLUNGER 



-ROD 



ASCENDING 



PLVNCE.R 

 .VA.LVE 

 CLOSED 



-CYLINDER 



INLET 



VALVE: OPEN. 



FIG. 290. The suc- 

 tion pump. 



