708 



HYDEAULICS AND ITS APPLICATIONS 



ART. 191. THE HUMPHREY GAS PUMP. 



In the Humphrey pump the expansive force following the ignition of 

 an explosive mixture of gas and air is directly utilised to pump water. 

 In its simplest form the pump consists of a combustion chamber C 

 (Fig. 342), fitted with valves A and E for the admission of gas and air 

 and for the exhaustion of the waste products of combustion. A continua- 

 tion of the combustion chamber forms a suction chamber W with its 

 suction valves V and the delivery main D, which discharges into the 

 elevated tank E T. The action of the pump is as follows : A compressed 

 charge of gas and air in C is ignited by an electric spark and expands, 



FIG. 342. Humphrey Gas Pump. 



driving forwards the column of water in the delivery pipe. Expansion 

 proceeds until the pressure falls to or below atmospheric, when the suction 

 valves V and the exhaust valve E open. In virtue of its momentum the 

 delivery column maintains its motion for some appreciable time, during 

 which water is drawn through the suction valves, part of this joining in 

 the motion .of the column and part entering the combustion chamber. 

 After a short time the momentum is destroyed and the column, acted] 

 upon by the pressure due to the delivery head, begins to return, closing 

 the suction valves and forcing the waste products out through the valve E. 

 This action is continued until the water level rises to that of this valve 

 which is closed by the impact, and the remaining products are compressed 

 into the space F. This compression continues until the column is broughi 

 to rest, when a second outward motion of the column ensues and th( 



