THE AIR LIFT PUMP 705 



A very extensive series of experiments carried out by the Westinghouse 

 Air Brake Company in a 6-inch well, 174 feet deep, at Wilderning, Pa., 

 lead to the following general conclusions : 



(1) The rate of delivery of water, and the air consumption per gallon, 

 with fixed size of discharge pipe, are practically constant for all lifts, 

 provided the ratio of lift to submergence is maintained constant. 



(2) With a discharge pipe of given diameter, the delivery decreases 

 and the air consumption per gallon increases as the ratio of lift to 

 submergence increases. 



(3) With a fixed ratio of lift to submergence, the air consumption per 

 gallon decreases as the size of discharge pipe increases. 



(4) The least air pressure that will give continuous flow is the proper 

 pressure to use, A slightly lower pressure gives intermittent delivery 

 and the amount delivered is much decreased, though the air consumption 

 per gallon is slightly lower than with continuous flow. With pressure 

 higher than just enough to give continuous flow, the delivery is increased 

 somewhat, but the air consumption per gallon delivered is increased in 

 greater ratio; and with further increase in air pressure a point of 

 maximum delivery is reached, beyond which the delivery is decreased in 

 amount. The sound of the discharge is a reliable guide to proper 

 regulation of the air supply. 



(5) It appears from (2) that by increasing the submergence, i.e. 

 locating the foot piece deeper down in the water, for a given lift, the air 

 consumption is progressively reduced. But as the required air pressure 

 is increased with the greater depth, a cubic foot of air represents greater 

 power. A curve representing the variation of horse-power required per 

 gallon of water delivered, with depth varying, shows that the power first 

 decreases with increasing depth, then reaches a minimum and thence 

 increases. The ratio of lift to submergence at this minimum point may 

 be called the " economical ratio." 



(6) For a given size of discharge pipe the economic ratio decreases as 

 the lift increases ; i.e., the submergence should be increased in greater 

 ratio than the lift. For a given lift, the economical ratio increases 

 (submergence decreases) as the size of discharge pipe increases. 



(7) A tail piece, or projection of the discharge pipe below the air inlet, 

 is essential in starting, as it tends to prevent the air from backing down 

 into the well and rising in the casing outside the discharge pipe. 



(8) Anything in the shape of a jet or pipe introduced into the discharge 

 pipe to serve as air inlet has no value, and is, in fact, detrimental by 

 forming an obstacle to the free passage of water. 



H.A. z z 



