8-20 Change A
U.S. Navy Diving ManualVolume 2
Seals close clearances
Protects against corrosion
Transfers heat away from heat-producing surfaces
Transfers minute particles generated from normal system wear to the oil sump
or oil filter if so equipped
Lubricant Specifications. Unfortunately, the lubricant vaporizes into the air
supply and, if not condensed or filtered out, will reach the diver. Lubricants used
in air diving compressors must conform to military specifications MIL-L-17331
(2190 TEP) for normal operations, or MIL-H-17672 (2135 TH) for cold weather
operations. Where the compressor manufacturer specifically recommends using a
synthetic base oil, the recommended oil may be used in lieu of MIL-L-17331 or
Maintaining an Oil-Lubricated Compressor. Using an oil-lubricated compressor
for diving is contingent upon proper maintenance to limit the amount of oil intro-
duced into the divers air (see Topside Tech Notes, March 1997). When using any
lubricated compressor for diving, the air must be checked for oil contamination.
Diving operations shall be aborted at the first indication that oil is in the air being
delivered to the diver. An immediate air analysis must be conducted to determine
whether the amount of oil present exceeds the maximum permissible level in
accordance with table Table 4-1.
It should be noted that air in the higher stages of a compressor has a greater
amount of lubricant injected into it than in the lower stages. It is recommended
that the compressor selected for a diving operation provide as close to the required
pressure for that operation as possible. A system that provides excessive pressure
contributes to the buildup of lubricant in the air supply.
Intercoolers. Intercoolers are heat exchangers that are placed between the stages
of a compressor to control the air temperature. Water, flowing through the heat
exchanger counter to the air flow, serves both to remove heat from the air and to
cool the cylinder walls. Intercoolers are frequently air cooled. During the cooling
process, water vapor is condensed out of the air into condensate collectors. The
condensate must be drained periodically during operation of the compressor,
either manually or automatically.
Filters. As the air is discharged from the compressor, it passes through a moisture
separator and an approved filter to remove lubricant, aerosols, and particulate
contamination before it enters the system. Approved filters are listed in the
NAVSEA/00C ANU list.
Pressure Regulators. A back-pressure regulator will be installed downstream of
the compressor discharge. A compressor only compresses air to meet the supply
pressure demand. If no demand exists, air is simply pumped through the
compressor at atmospheric pressure. Systems within the compressor, such as the