10. _To remove incrustations_ caused by water containing lime or other
impurities, place parts for a reasonable time in a bath of mineral oil
or diluted muriatic acid consisting of 4 parts of water to 1 part of
acid.
NOTE.—The lettered parts shown above apply to both the “Manhattan”
and the “Peerless” injectors. See page 252 for the names of the
parts corresponding with the letters.
_The exhaust steam injector_ utilizes the escaping vapor from the
engine cylinder, hence the saving in fuel and water is very marked
where certain conditions are favorable.
It condenses by means of the smallest possible quantity of cold water
the largest possible quantity of exhaust steam and _puts it into the
boiler without the aid of any other power than the exhaust steam
itself_. It can be attached to any class of non-condensing engine, and
its use increases the power both of the engine and boilers.
[Illustration: FIGS. 534 AND 535.]
It is worked by waste steam, just as ordinary injectors are worked by
live steam from the boiler.
The first cost and subsequent wear and tear of pumps are avoided. The
power required to work pumps, of whatever construction, is saved: the
exhaust injector doing the same work by the condensation of waste steam.
The waste steam, in passing through the injector, heats the feed-water
to a temperature of about 190° F. The condensation in the injector of
so large a quantity of waste steam reduces back pressure considerably,
and necessarily increases the power of the engine.
It is not uncommon for these injectors to form a vacuum of a half-inch
of mercury within the exhaust pipe, which of course helps the engine to
that extent.
[Illustration: FIG. 536.—See page 260.]
These injectors work with great success on stationary engines and
boilers, also on steamers, tugs, dredges, etc., as their operation
during the roughest weather is not affected by the motion of the
vessel.
_The high pressure_ exhaust steam injector is shown in Figs. 537 and
538—the last being an outline exhibiting the internal arrangement of
the instrument: these injectors are made to work at all pressures up to
and not exceeding 150 lbs. to the square inch.
[Illustration: FIG. 537 AND 538.]
_The high pressure exhaust steam injector_ is worked _by waste steam
up to 75 lbs. pressure only_, and a little live steam is introduced at
the top of the injector to force water against pressures higher than 75
lbs. It will be noticed from sectional cut that _the live steam does
not come in contact with the water until after the exhaust steam has
been condensed and has done its work_. The _exhaust steam alone_ gives
an impetus to the water equal to 75 lbs.; it also _heats_ it up to
about 190° F. Its advantages are the same as those of the plain exhaust
injector, the heat of the small jet of live steam which is used to
overcome the excessive pressure being brought back into the boiler.
It raises the temperature of feed-water up to 90° Fahr. if working
against a pressure of 105 lbs., and up to 86° Fahr. against 120 lbs.
boiler pressure. It is regulated in the same manner as the plain
exhaust steam injector.
It is not necessary _to use live steam while working against any
pressure below 75 lbs., when exhaust steam alone will suffice_.
Fig. 539 represents the piping of the high pressure exhaust steam
injector, the operation of which is described in the following
paragraphs:
_This injector can be worked under various conditions._
1. If boiler pressure does not exceed 75 lbs. per square inch, exhaust
steam only is required. In this case steam is admitted by valve A.
[Illustration: FIG. 539.]
2. For pressures exceeding 75 lbs. exhaust steam is admitted as before,
also a little live steam, slowly, by valve C.
3. If engine is not running, live steam is gradually admitted by valve
B, so that it may expand in pipe F. In case of high boiler pressure
additional live steam is introduced by valve C.
_To start this injector._