FARM WATER SUPPLY AND SEWAGE DISPOSAL 351 



321. Water Air-Pressure System. This system, shown 

 in Fig. 342, is usually called the hydro-pneumatic system. 

 In it the water is stored in an air-tight steel tank and is forced 

 thru the pipes to the fixtures by air pressure. As the water is 

 used, the pressure is gradually reduced. In some systems of 

 this type there is both a water and an air pump. The most 

 common type is equipped with only a water pump with air in- 

 take. To operate the system, the tank is filled with air, the 

 water is pumped in, and the air pressure increases as the vol- 

 ume of the air decreases. Only about two-thirds to three- 

 fourths of the volume of the tank is effective for water stor- 

 age. This is one of the principal objections to this system, 

 because to avoid pumping so often, an extremely large tank 

 must be provided if the water requirements are very large. 

 However, with electric power available, an automatic con- 

 trol can be provided and a smaller tank be used. Complete 

 equipment for a system of this kind includes an air-tight 

 tank, a force pump, pressure gauges, and other fittings, and 

 plumbing fixtures. 



322. Hydraulic Ram. Where there is a large quantity 

 of water with sufficient fall, a hydraulic ram is the cheapest 

 means of providing water pressure in the home. The first 

 cost is small, there is practically no upkeep, and it will run 

 continuously without any attention. Under ordinary condi- 

 tions, a ram will elevate about one-seventh of the water that 

 flows to it thru the drive pipe. A rule that can be used to de- 

 termine the approximate amount of water that will be deliv- 

 ered with a certain flow is: Multiply the number of gallons 

 of flow per minute by the number of feet of vertical fall be- 

 tween the source of water and the ram. Divide this by the 



