determined from the capacities given in the price lists which sized
injector must be selected.

An injector must always be selected having a maximum capacity in excess
of the water consumed. If the exact amount of water consumed per hour
is not known, and cannot be easily determined, the proper size can be
approximately determined from the nominal H. P. of the boiler. The
usual custom has been to allow 7 I/2 gallons of water per hour, which is
a safe rule for the ordinary type of boiler.

WHAT A GOOD INJECTOR OUGHT TO DO.

With cold feed water, a good injector with a two foot lift ought to
start with 25 pounds pressure and work up to I50 pounds. With 8 foot
lift, ought to start at 30 pounds and work up to I30. With feed water
heated to I00 degrees Fahrenheit it should start with the same lift,
that is, will say 2 foot, at 26 and work Up to I20, and at 8, from 33 up
to I00. You will see by this that conditions, consisting of variation of
temperature in the feed water and different lifts, change the efficiency
of your injector very materially, and the water can soon get beyond the
ability of your injector to work at all. The above refers more
particularly to the single tube injector. The double tube injector
under the same conditions as above should work from I4 pounds to 250,
and from I5 to 2I0, but as this injector is not generally used on farm
engines you will most likely not meet with it very often.

The injector should not be placed too near the boiler, as the heat from
it will make it difficult to start the injector each time after it has
been standing idle.