Applications of Compressed air on Merchant Ships
Compressed air is used on merchant ships for a variety of applications some of which are being mentioned below:
•automation and control of main engines, auxiliary engines,etc.
•starting of the main engines, auxiliary engines, emergency generators, emergency fire pumps, etc.
•heaving the life boat up by the use of an air motor.
•pressurizing fresh and sanitary water used in accommodation.
•in the sewage plant for conducting aerobic sewage breakdowns.
•in fog horns and ships whistles.
•in pneumatic tools like pneumatic grinder, pneumatic chisels, pneumatic drills, pneumatic spanners, etc.
•in painting operations.
Applications of Compressed air onboard naval ships
Compressed air is used for various applications on modern surface warships.
Low pressure air up to 10 bar is used for control air and general service, as well as for wave-guide.
Medium pressure up to 40 bar is used for diesel engine starting both for main engine or propulsion diesel and/or auxiliary diesel engine starting. High pressure air up to 350 bar is used for breathing air, weapon or aviation-air supply and for gas-turbine starting.
Pneumatic gas-turbine starting has the advantage of far fewer system requirements compared to hydraulic starting or starting by an auxiliary power unit (APU), as in most cases a high-pressure air system has to be installed onboard for other applications. In addition, the pneumatic power can easily be stored in high-pressure bottles and is instantly available. If more than one gas turbine is installed, pneumatic starting allows bleed air from a gas turbine already running to start another gas turbine. As a result of these advantages pneumatic starting remains the preferred starting method for today’s naval designs.
Compressed Air in Submarines
The importance of the air systems to a submarine cannot be overemphasized since virtually every operation in the diving and surfacing procedure is dependent upon air provided by one or more of the compressed air systems. Some of the more important operations depending on air pressure are the following:
Compressed air, is necessary in order to surface, submerge, attack, and cruise.
The main propulsion engines are started by air.
The main hydraulic system operates because of the air pressure maintained in the air-accumulator flask.
Torpedoes are discharged from the submarine by air.
Tanks are blown by air.
These functions, of course, are in addition to the use of compressed air and oxygen to revitalize the air in the ship after long periods of submergence.
Pressure in the boat, a test for tightness, utilizes air.
The compressed air systems represent, therefore, one of the most versatile of all systems aboard a submarine, in that they are capable of performing either as primary or secondary functions many of the operations performed in a submarine.
Therefore, high quality compressed air must be monitored continuesly to ensure a consistently accurate performance of vital applications such those mentioned above, as well as demand efficiency and reliability.