WARNING

Reciprocating air compressors used to produce breathable air used in diving operations use special lubricating oil. Failure to observe these specific precautions set by NAVSEA maintenance instructions could lead to fatal injury of the diver.

AIR COMPRESSOR TROUBLESHOOTING

Years of development have made the air compressor a rugged and dependable machine. However, as with any machine, problems do arise. As a CM-1, it is your job to troubleshoot the air compressor once it has malfunctioned.

Now, the large reciprocating type of air compressor (used for construction purposes) is rarely found in the NCF. For this reason, the following troubleshooting procedures detailed in this chapter are for the vane and screw types of air compressors.

CAUTION

For exact information on the equipment you are working on, go to the manufacturer's maintenance and repair manual.

There are several ways to troubleshoot equipment to eliminate possible problems. The best way is to first ask the operator the following questions: Did it start at all? How did it shut down? What noises did it make? Was there any smoke or unusual smell? Next, get the book and do some reading! DO NOT JUST GET IN THERE AND REPLACE A FEW PARTS. Sure, you may correct the problem, but this type of "repair" work wastes government money, and you did not do your job as a troubleshooter. After your short study period, check the machine and be sure it is safe to start. Look for obvious damage, open discharge lines, broken air or oil lines, oil leaks, and clogged air filters. Prestart check the unit. If you determine the unit is safe to start, do so, but watch the engine oil pressure, and if it does not come up immediately, the power source is the problem. Shut the unit down quickly and take it to the shop for a detailed inspection by the mechanics. If the oil pressure is correct, watch the air pressure buildup next. If the air pressure buildup does not come up, stop the unit because the vane and screw types of air compressors depend on air pressure for lubrication. If the air pressure comes up slowly or if the compressor fails to unload, finally stalling the unit, check for a sticking air intake control valve. If the compressor does start and there is no apparent problem, do not leave the scene right away. The problem could be that the unit has tripped to shutdown due to overheating oil. Let the unit thoroughly cool down. Then simulate the conditions by starting and working the unit. Watch the gauges to see how fast the oil temperature rises. From the book (You did read it didn't you?), you know the limits for oil temperature. Return the unit to the shop if you see these limits exceeded Finally, noise. If the unit starts and the noise level exceeds that of a normal running unit, return the unit to the shop for inspection and repair. DO NOT JEOPARDIZE THE HEALTH OF THE CESE FOR THE SAKE OF THE PROJECT. See table 8-1 for a more detailed listing of troubleshooting the vane and screw types of air compressors.

AIR COMPRESSOR OVERHAUL

Because of the durability of the vane and screw types of air compressors, major overhaul is seldom required. A properly maintained unit will perform reliably for 10,000 hours or more. When a major overhaul is required, the following preparations apply to air compressors as to other components discussed in this TRAMAN; have a clean work area; obtain all special tools; get the manufacturer's repair manual; preclean the unit. Once you have done this-think SAFETY, use a hoist for the heavier parts. You are now ready to start your overhaul.

The primary wear point on the rotary type of air compressor is the rotor vanes. For this reason, the unit has been designed to allow for simplified inspection of the vanes by the removal of the rear cover of the compressor (fig. 8-20).

ATTENTION

Before the rotor vanes can be the removed from most rotary compressors, rotor must be positioned correctly (fig. 8-21).

The rotor vanes should slide out easily offering little or no resistance. Rotor vanes that resist removal indicate problems. Once you remove the rotor vanes, shine a light inside the rotor compartment and slots. Inspect the condition of the rotor slots. The slots should be clean and have straight edges. A worn-rotor slot would most likely have a slight saw-toothed effect on the trailing edge - a condition that can cause rapid rotor vane wear. Next, inspect the inside of the rotor compartment for