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WATER-PRESSUIiE REGULATOR.

valent to the pressure that is desired in the chamber E.Another pipe puts this press in communication with the maininlet pipe, and it is also connected with a waste-pipe. Thepress and the various pipes are connected, so that as long asthe pressure in C does not exceed that desired in E, the ramremains stationary at its lowest point; but when this pressureis exceeded, the ram rises, thereby opening a communicationhetween the pipe D and the waste-pipe, which immediatelyrelieves the pressure in C, whereupon the valve A falls. Thisprocess is repeated as often as the pressure in C (and conse-quently in E) rises above that to which the hydraulic ram isset. Any rise in the outlet pressure, due to lessened con-sumption, will of itself close the valve A.

A modification of this valve is to make the piston B ofsmaller diameter than the valve, and to leave the chamber Copen to the atmosphere. The separate regulating apparatuscan then be dispensed with. In this case the inlet pressureon the valve is not completely balanced; but, acting on thegreater area of the valve, tends to lift it, and will do so untilthe total outlet pressure on the top of the valve is equal to thetotal unbalanced inlet pressure.