74 



SMALL WATER SUPPLIES. 



Delivery 



^Snifter 

 Valve 



spring, which is fitted to the injection pipe and con- 

 nected to the water 

 chamber. When the 

 water closes the waste 

 valve by its momen- 

 tum, it forces up the 

 piston at the same 

 time as it opens the 

 delivery valve. This 

 will assist in the re- 

 coil of the water. 

 When purchasing a 

 ram it is important 

 to specify that all 

 valves arid moving 

 parts should be of 

 best gun-metal, and 

 when fixing, all pipes 

 should be at least 3 ft. 

 below ground to pro- 

 tect them from frost. Suitable means must always 

 be provided for conveying away the waste water as 

 rapidly as possible. At the same time, the efficient 

 working of a hydraulic ram remains unimpaired even 

 if it is flooded. Rams will not usually work well 

 when the delivery head is more than twenty-five 

 times the working head, friction in the delivery pipe 

 (as found by methods shown in the previous chapter) 

 being taken into due consideration. 

 A ram may fail or lose efficiency by 



(a) Friction in the drive pipe. 



(b) Waste valve too heavily loaded, 

 (r) Check valve too heavily loaded, 



FIG. 56. 



