168. Q. If an intermediate discharge valve breaks or sticks open, what effect will it have on the compressor, and how may it be located?
A. If an intermediate discharge valve breaks or sticks open, no air will be compressed by that end of the compressor where is located the defective valve, as the air will simply flow back and forth from the high to the low pressure cylinders; no air will be taken in from the atmosphere through the strainer as the pistons move from the defective valve.
169. Q. If a final discharge valve breaks, what effect will it have on the compressor?
A. Main reservoir air will be free to return to the high pressure cylinder as the high pressure piston moves from the defective valve; therefore, no air will be taken in through the receiving valve of the high pressure air cylinder at the end where is located the defective valve. The low pressure piston will make a slow stroke toward the defective valve and a normal stroke from it; while the high pressure piston will make a slow stroke toward the defective valve and a quick stroke from it. Defective air valves may generally be located by noting the temperature of the valve chamber in which they are located.
170. Q. What will cause the compressor to run hot?
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?
Fig. 20: High Pressure Piston Moving Upward. Low Pressure Piston at Rest.