BOILERS AND GENERATION OF STEAM 317 



by the height in feet and divide by 33,000; the quotient will 

 be the H. P. required. The formula is: 



W XH 



H. P. = 



33,000 



EXAMPLE. Find the H. P. required to pump 4406.33 gal. of water 

 per hour to a height of 40 ft. above the source of supply. 



If a pump will raise 4406.33 gals, of water per hour, it will raise 

 4406.33 -h 60, or 73.438 gals, per minute; and as 1 gal. of water 

 weighs 8ji Ibs., 73,438 gals, weigh 73.438 X 8j/ or 611.983 Ibs. 

 This weight of water is to be raised 40 ft. high. Then by formula : 



W X H _ 611.983 X 40 _ 24,479.32 _ 

 33,000 33,000 33,000 



358. Injectors and Ejectors. The injector (Fig. 168) is 

 an apparatus for forcing water against pressure by the direct 

 action of steam on the water. It is universally used on loco- 

 motive and sometimes on stationary boilers. Steam is led 

 from the boiler through a pipe, which terminates in a nozzle 

 surrounded by a cone. This cone-shaped pipe is connected 

 with the water tank or well where the water is stored. When 

 steam is turned on, so as to pass into the injector, it rushes 

 from the nozzle and thereby creates a partial vacuum in the 

 cone. Since this pressure in the cone is now less than the 

 atmospheric pressure in the water well, the water is forced 

 up to the cone. As the steam meets this water it condenses, 

 but not before its force has imparted enough of its velocity 

 to the water to give the latter sufficient momentum to force 

 down the valve that prevents the steam and water of the 

 boiler from escaping. An injector does not work well if the 

 feed water is too hot, as in that case the steam does not con- 

 dense quickly. 



