INJECTOR (from Lat. injicere, to throw in). An instrument for forcing water a in Which a jet III steam mingles with and forces a continuous jet of water into the same holler against its own pre-sure. There are numerous forms of injectors, the chief differences between which in the relative proportion- of the parts and in the means employed fur changing these proportions, either automatically or other wise. so as to adapt the instrument to the varia tion of steam or water supply. The accompanying diagram indicates the interior arrangement of the simplest form of injector. Steam from the boiler 'Kissing through the pipe a enters the re ceiving tube b. where it is joined by the water which enters the pipe c. The water condenses the steam in the combining tube d, and a water-jet is formed which miters the delivery tube e and thence past. the check valve j into the boiler below the waterline. The operation of
the injector is difficult to explain in popular terms. Briefly stated, however, steam escaping from under pressure has a much higher velocity than water would have under the same pressure and condition. The escaping steam from the receiving tube unites with the feed water in the combining tube, and gives to this water a velocity greater than it would have if escaping directly from the water-spa•e in the boiler. The injector was invented by Henri Jacques Glean!. a French mathemalkian and engineer, and is the most popular boiler-feeder now in use: practically every loeomotive engine boiler is fed by injectors. The history of the development of the injector, the principles of its action and descriptions of representative forms. are given in Kneass, Prac tice and Theory of the Injector (New York, MS).