698 



HYDRAULICS AND ITS APPLICATIONS 



ART. 188. THE INJECTOR HYDRANT. 



Since the chief loss of energy in the ordinary jet pump is due to shock 

 at the collision of the two jets, it would appear that the total loss might be 

 diminished by diminishing the velocity of the high pressure, or increasing 

 that of the low pressure jet in stages, instead of at a single impact. 



This method has been applied with success by Mr. Greathead in the 



(High 



\Pr-essure 



{Supply 



FIG. 339. Injector Hydrant, 



construction of his injector hydrant (Fig. 339), which is adapted for fire 

 extinguishing purposes where a continuous supply of high pressure water 

 is available, as is the case near the pipe line from an hydraulic power 

 station. By itself, the water in the power main is of insufficient volume to 

 have any appreciable effect on a fire, but when used with an injector hydrant 

 in connection with a low pressure main the advantages of the system are 

 very great. As exemplifying the effect of a small jet of high pressure 

 water in increasing the height of the main jet, it is stated that while an 

 ordinary IJ-inch hydrant supplied from a main at 40 Ibs. pressure will 



