That the condensation of the steam is necessary to complete the process will be evident, for if the steam were not condensed in the combining chamber, it would remain a light elastic body and, though moving at high speed, would have a low degree of energy.
Some injectors are given special names by their makers, such as ejectors and inspirators, but the term injectors is the general name covering the principle upon which all these devices act. The exhaust steam injector is a type different from any of the above-named, in that it uses the exhaust steam from a non-condensing engine. Exhaust steam represents fourteen and seven-tenths (14.7) pounds of work, and when the steam entering the injector is condensed the water is forced into the boiler upon the same general principle as in all injectors.
The injector can be, and frequently is, used as a pump to raise water from one level to another. It has been used as an air compressor, exhauster and also for receiving the exhaust from a steam engine, taking the place, in that case of both condenser and air pump.
The injector is not an economical device, but it is simple and convenient; it occupies a very small space, is not expensive and entirely free from severe strains on its durability; moreover, where a number of boilers are used in one establishment, it is very convenient to have the feeding arrangements separate, so that each boiler may be a complete generating system in itself and independent of its neighbors.
_The following text_ is intended to describe the instruments illustrated on pages 244, 246, 248 and 250.
_The “Manhattan” automatic injector_ is shown in perspective and outline upon page 244. This instrument is made by Messrs. Schaeffer & Budenberg of New York City.
This injector is designed for portable and semi-portable engines and boilers, and is also adapted for stationary boilers _requiring no high lift_. Its main features are simplicity and positive automatic action. It works under pressures ranging from 30 to 150 lbs., either lifting or non-lifting.
The letters in the outline cut refer to the parts:
_a._ Steam Nozzle. _b._ Combining Nozzle with Flap. _c._ Delivery Tube. _d._ Screw Cap. _e._ Cap Screw for Overflow. _f._ Overflow Valve. _g._ Tail Pipe. _h._ Tail Pipe Nut.