RUNNING WATER FOR FARM BUILDINGS 439 



Hoiv the ram operates. — The water flows down through the 

 supply pipe "G," passing into "B" and on through the outlet 

 in the impetus valve ^^F," until the constantly increasing pres- 

 sure lifts this valve and closes it. This stops the flow of water 

 in this direction, and the shock due to its sudden stoppage causes 

 it to force open the check valve "E,'^ which is the only other 

 outlet. AMien sufficient water passes through "E" into the air- 

 chamber *' A," to relieve the pressure due to the sudden stoppage 

 in *'B,'^ the check valve ''E" closes, the impetus valve "F" 

 opens again and the same operations are repeated. The air in 

 the chamber ''A," acts as a cushion, absorbing the shock and 

 maintaining a steady, even flow of water through the delivery 

 jDipe ''H." As shown by this description of the ram's action, a 

 portion of the water is wasted to operate the ram, but the power 

 which operates it is obtained at no cost, and no attention is 

 required. 



How to select a ram. — In order to determine the size, the ram 

 should be for any certain service, the following data and meas- 

 urements should be ascertained. The measurements referred to 

 are illustrated in Fig. 8. 



1. Quantity of water in gallons per minute available for 

 supply. 



2. Quantity of water in gallons required at discharge in 

 twenty-four hours. 



3. Vertical fall in feet, from supply to proposed location of 

 ram'^A." 



4. Distance from supply to ram "B." 



5. Vertical distance from ram to point of discharge ^'C." 



6. Required length of discharge pipe from ram ''D." 



For example, suppose we ^\^sh to force water to an elevation 

 of forty feet above the ram ; by referring to the table below, we 

 find that a No. 4 ram with a flow of seven gallons per minute 

 delivered to the ram, Avith a fall (A) of five feet, through forty 

 feet of drive pipe (B) will elevate about thirty-five gallons per 

 hour, or eight hundred and forty gallons in twenty-four hours 

 to a point forty feet above the ram. 



