A. The action of the injector is due first to the difference between
"kinetic" or moving energy and "static" or standing energy; second, to
the fact that steam at a pressure travels at a very high velocity and
when placed in contact with a stream of water it is condensed into
water, and at the same time it imparts enough velocity to the water to
give it sufficient momentum to overcome a pressure even greater than the
original pressure of the steam. By imparting this velocity to the water
it gives it sufficient energy to throw open the check valves and enter
the boiler against high pressure.
50. Q. What is the difference between a lifting and a non-lifting
injector?
A. A lifting injector will create sufficient vacuum to raise the water
from the level of the tank. The steam tubes in a non-lifting injector
are different and it will not raise the water, but merely force it into
the boiler. A non-lifting injector must be placed below the level of the
water in the tank so the water will flow to it by gravity.
51. Q. Will an injector work with a leak between the injector and tank?
Why? Will it prime?
A. A lifting injector will not work if the leak is bad. It will not
prime because the air admitted through the leak destroys the vacuum
necessary to raise the water to the injector level. A non-lifting
injector will work, as the water will escape from the pipe instead of
air being drawn into it as with the lifting injector.
52. Q. If it primes well, but breaks when the steam is turned on wide,
where would you look for the trouble?
A. Insufficient water supply due to tank valve partly closed, strainer
stopped up or tank hose kinked, injector tubes out of line, limed up, or
delivery tube cut, or wet steam from the throttle.
53. Q. If it would not prime, where would you expect to find the
trouble?
A. Insufficient water supply, priming valve out of order, or with the
lifting injector the trouble might be caused by a leak between the
injector and tank.
54. Q. Will an injector prime if the boiler check leaks badly or if it
is stuck up? If the injector throttle leaks badly?
A. No.
55. Q. If steam or water shows at the overflow pipe when the injector is
not working, how can you tell whether it comes from the boiler check or
the injector throttle?
A. Close the main steam valve at the boiler, that will stop the leak if
it comes from the injector throttle.
56. Q. Will an injector prime if primer valve leaks? Will that prevent
its working?
A. It will prime, but not as readily as with priming valve in good
condition. This will not prevent its working, but it may waste some
water from the overflow.
57. Q. Will an injector work if air cannot get into the tank as fast as
the water is taken out?
A. No.
58. Q. If you had to take down a tank hose, how would you stop the water
from flowing out of the tank that has the syphon connections instead of
the old-style tank valves?
A. Open the pet cock at the top of the syphon before taking the hose
down.
59. Q. Is any more water used when the engine foams than when the water
is solid?
A. Yes, very much more.
60. Q. How would you prevent injector feed pipes or tank hose from
freezing in winter when not in use?
A. The steam valve should be slightly open to permit a slight
circulation of steam through the feed and branch pipes. The heater cock
should be closed and the drip cock under the boiler check or on the
branch pipe should be opened to insure a circulation of steam through
the branch pipe.
61. Q. How would you prevent the overflow pipe from freezing with a
lifting injector?
A. The overflow valve should be opened just enough to permit a little
steam to escape through the overflow pipe to prevent it from freezing.