Medium-pressure systems provide compressed air within the range of 151 to 1,000 psig pressure. These systems are not extensive and are generally provided with individual compressors located near the loads. Medium-pressure systems are mainly used for the starting of diesel engines, soot blowing of boilers and high-temperature water (HTW) generators, and hydraulic lifts.

Some Navy vessels do not have a separate air compressor to supply a direct medium-air pressure.

Instead, compressed air from HP air systems is stored in the users air flasks (banks) at high pressure. Then when needed, the air is routed through a pressure-reducing

Figure 6-4.A maintenance Index page for low-pressure air compressor systems (page 3 of 3).

manifold. In this case, medium-air pressure maintenance requirements are coupled with the HP air systems PMS. Troubles and repairs to medium-pressure systems are the same as the LP and HP air systems. Those medium-pressure air systems equipped with air compressors should have a separate preventive maintenance schedule.