Uses of Compressed air onboard ships For automation and control of main and auxiliary machinery and equipment. For starting of Main engines, auxiliary engines, emergency generator engine etc., For pressurizing the hydrophores for domestic fresh water and sanitary water used in accommodation. For use in sewage plant for conducting aerobic sewage breakdowns. For soot blowing of the boilers. For use in fog horns and ships whistles. For heaving the life boat up by the use of an air motor. Used in pneumatic pumps for oil transfer and pneumatically driven hand tools such as grinder/ chisels/ drills/ spanners/ jacks/ etc., For use as general service air for use in general cleaning & painting operations. Generally two pressures of air are used: High pressure air - 30 bar (Used for starting the main/auxiliary engines) Low pressure air - 7 bar (Used for control and service air)