A. Running the compressor too fast; working against high pressure; air
piston packing rings leaking; air cylinder worn; air passages or
discharge pipe partially stopped up; air valves leaking; air valves
stuck shut; or lack of lubrication.
171. Q. How should the air end of the compressor be oiled, and what
grade of oil used?
[Illustration: Fig. 20. High Pressureiston Moving Upward. Low
Pressure Piston at Rest.]
A. Oil should be used sparingly in the low pressure cylinder, but more
is required in the high pressure cylinder, owing to higher temperature.
A good quality of valve oil should be used.
172. Q. How is the steam end of the compressor affected by the use of
too much oil?
A. This may cause the compressor to short stroke, and where the piston
type of valve is used, may cause the compressor to stop.