OPERATOR, UNIT, AND DIRECT SUPPORT MAINTENANCE
AIR COMPRESSOR FOR
INLAND AND COASTAL LARGE TUG (LT)
Compressors cooled by atmospheric air circulated around the
cylinders or casings.
Capacity of a compressor is the full rated volume of flow of gas
compressed and delivered at conditions of total temperature,
total pressure, and composition prevailing at the compressor
inlet. It sometimes means actual flow rate, rather than rated
volume of flow.
A valve that permits flow in one direction only. The compressor's
check valve allows airflow into the receivers.
Displacement of a compressor is the piston volume swept out
per unit time; it is usually expressed in cubic feet per minute.
Heat exchangers for removing the heat of compression be-
tween stages of a compressor. They usually condense and
remove a considerable amount of moisture as well.
Net volume actually displaced by the compressor piston at rated
machine speed, generally expressed in cubic feet per minute.
For multistage compressors, the piston displacement of the
first stage only is commonly stated as that of the entire ma-
The absolute total pressure of the discharge flange of a com-
Tanks used for the storage of air discharged from compres-
sors. They serve also to damp discharge line pulsations.
Machines in which the compression element is a piston having
a reciprocating motion in a cylinder.
A grooved wheel or pulley over which a drive belt runs.
Steps in the compression of a gas. In the case of reciprocating
compressors each stage usually requires a separate cylinder,
and in dynamic compressors, each requires a separate rotor
disc; in either case, the gas is passed through the stages in
Two Stage Compressor
Machines in which air or gas is compressed from initial pres-
sure to an intermediate pressure in one or more cylinders or
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