156 



WATER CONDUCTORS AND ACCESSORIES 



the Johnson valve or gate valve. In cases where leakage through 

 the valve can be carried off through an ample drain, the valve 

 can be used very satisfactorily. 



The Johnson Hydraulic Valve. This valve consists essen- 

 tially of a circular body forming an enlargement of the pipe line 



Open 



Closed 



FIG. 82. Johnson Hydraulic Valve. (Wellman-Seaver-Morgan Company.) 



or penstock, and having an internal cylindrical chamber contain- 

 ing a sliding plunger (Fig. 82). The closed end of the internal 

 chamber and the nose of the plunger are of conical form. They 

 are designed to guide the water smoothly as it enters and leaves 



