=An Injector= is an automatic machine attached to a boiler, for
injecting or forcing water into it and at the same time heating the
water to a very high temperature, which saves fuel and prevents the
danger of sudden contraction of the plates and flues. It can be used
independently and is indispensable on a farm engine.
In piping an injector to boiler, use as short and as straight pipes as
possible and especially avoid short turns. Take steam directly from
boiler, and have a globe valve in steam pipe close to injector; have
the water suction or supply pipe independent of any other connection,
and it must be supplied with a globe valve close to injector. This
pipe and connections must be absolutely air tight; the slightest leak
will cause trouble. The discharge pipe to boiler must be supplied with
a tight and reliable check valve. If valve leaks, the injector will
become hot and cause no end of annoyance. It is a good plan to put a
stop valve between check and boiler in discharge pipe, so that check
valve maybe taken off and repaired, or a new one put on without loss
of time. A foot of straight pipe screwed into the overflow assists in
starting an injector, especially at low pressure.
[Illustration: American U. S. Injector.]
Q. How do you start an injector to work?
A. To start an injector, open the suction valve wide, then open steam
valve. If water appears at the overflow, close and open quickly the
suction valve, opening only about ¼ of a turn if at low steam pressure,
and one turn or more if at high steam pressure, regulating the water
supply according to steam pressure. The injector is controlled entirely
by the valve in suction pipe, or by the suction lever after the steam
is turned on.
Q. Will an injector work with hot supply water?
A. An injector will not work if the water that is delivered from the
tank is too hot to condense the steam.
Q. What are the principal causes of an injector not working accurately?
A. Leak in suction pipe, supply cut off by strainer being clogged,
loose lining inside the hose, leak in the stem of valve, too little
steam pressure to lift, dirt in the tubes, red lead blown or drawn
in through steam or supply pipe, bad check valve, not lift enough or
none at all, new boiler full of grease, wet steam, obstruction in the
connection to the boiler.
If injector fails, examine at all of these points before condemning.
The most common trouble is a leaky suction.
In describing the method of connection and operating an injector the
foregoing may have to be modified in some instances, as there are a
great many different kinds and styles of injectors which operate and
connect differently, but the above if followed carefully and with a
little discretion will be found useful.
Bear in mind, however, that the injector does not start to work to
boiler as soon as it gets the water. At first the water will run out
of the overflow. At this point you start the injector working to the
boiler by closing and opening the water valve as quickly as possible
_with a jerk, or as nearly with one motion as you can_.
Q. How do you find the maximum and minimum capacity of injectors?
A. Injectors are controlled entirely by the suction valve after steam
is turned on. To find the maximum capacity of an injector after
starting, gradually open the suction valve in supply pipe until steam
“breaks” and water comes out of the overflow, then start the injector
again and you will know about how far the suction valve can be opened
without causing the “break.”
To find the minimum capacity of the injector, manipulate the suction
valve in the same manner in exactly the opposite direction.