injector

Century Dictionary and Cyclopedia

1. n. One who or that which injects; specifically, an apparatus for forcing water into a steam-boiler. It was first reduced to practical form by Giffard, hence often called Giffard's injector. It is essentially a jet-pump, in which a jet of steam is continuously changed by rapid condensation to a water-jet, the molecules of which are obliquely directed toward the longitudinal axis of the jet by the conical nozle through which the steam issues. There results from this a jet of water very much smaller than the steam-jet from which it is condensed, but retaining the same velocity. The entire energy of the jet is thus applied to a much smaller area than the cross-section of the steam-jet, this area being inversely as the density of the water is to that of the steam before condensation. Thus, a considerable part of the pressure upon the area of the steam-jet being concentrated upon a much smaller area by the conversion of the energy in the water-jet into work, the latter is competent to force other water into the boiler. The essential parts of the Giffard injector are shown in the diagram, in which a is the steam-pipe with conical nozle c, b the water-supply pipe, d d a combining-tube, e a water-tube leading to the interior of the boiler, and f an overflow for water and steam. A check-valve prevents back-flow. Adjustability of the steam-nozle and various modifications which increase efficiency and render the injector more convenient in use have been added by other inventors. In operation steam flows through the pipe a, and, driving the air out of d, produces a partial vacuum in b. Water rising through b to fill the partial vacuum surrounds the steam nozle and steam-jet, sudden condensation follows, and the energy of the water-jet so produced drives it and the water which has entered d past the central opening in d d and past the check-valve into the tube e, and thence into the boiler. The proportion of water to steam requires careful adjustment. In the Sellers injector the combining-tube is self-acting, and regulates the supply of water to the pressure of the steam. In other injectors a separate lever must be moved to adjust the apparatus to the pressure, to prevent waste of steam or water. In the diagram the excess of either water or steam escapes between the opposed nozles at feminine Injectors are also used to obtain a vacuum in continuous railroad-brakes, but in this instance the apparatus seems to be more properly an ejector. See ejector.

Wiktionary

1. n. Any of various devices that are used to inject something

GNU Webster's 1913

1. n. One who, or that which, injects.
2. n. (Mach.) A contrivance for forcing feed water into a steam boiler by the direct action of the steam upon the water. The water is driven into the boiler by the impulse of a jet of the steam which becomes condensed as soon as it strikes the stream of cold water it impels; -- also called Giffard's injector, from the inventor.

WordNet 3.0

1. n. a contrivance for injecting (e.g., water into the boiler of a steam engine or particles into an accelerator etc.)