Principles of naval engineering - Historic Naval Ships Association

1PRINCIPLES OF NAVAL ENGINEERINGat normal speeds. The motor-driven pumpserves as standby for the other two lube oilservice pumps.Figure 9-23 illustrates the lube oil supplyand lube oil drain piping of the service systemon the frigates DLG 14 and DLG 15.COMPRESSED AIR SYSTEMSCompletely independent compressed air systemswith individual compressors include thehigh pressure air system, the ship's serviceair system, the aircraft starting and coolingair system, the combustion control air system,the air deballasting system, and the oxygennitrogenproducer air system. For other services,air is taken from the high pressuresystem or from the ship's service air system,as required. Air is provided by high pressure,medium pressure, or low pressure air compressors,as appropriate.The high pressure air system is designedto provide air above 600 psi and up to 5000 psifor charging air banks and, at required pressures,for services such as missiles, dieselengine starting and control, torpedo charging,and torpedo workshops. When air is requiredfor these services at less than the system pressure,the outlet from the high pressure airsystem is equipped with a reducing valve.Air for diesel engine starting and controlis provided on some ships by a medium rangecompressure at a pressure of 600 psi or fromthe high pressure system, through appropriatereducing valves.The ship's service compressedair system isa low pressure system that is installed onpractically all surface ships. This system providescompressed air at the required pressurefor the operation of pneumatic tools, the operationof oil-burning forges and furnaces, thecharging of pump air chambers, the cleaningof equipment, and a variety of other uses. Theship's service air system is normally designedfor a working pressure of 100 psi; on shipssuch as tenders and repair ships, however,where there is a greater demand for air, thesystem is designed for a higher working pressure(usually about 125 psi). The ship's serviceair system is normally supplied from a lowpressure air compressor; on some ships, however,the system may be supplied from a higherpressure system, through reducing valves.An aircraft starting and cooling air systemis installed on aircraft carriers. This systemis designed to provide air at various temperatures(50° to 500° F) and pressures (48 psia to62 psia) by gas turbine. The system suppliescompressed air to meet the conditions of startingand cooling aircraft being served.Combustion control air systems (more properlycalled boiler control air systems) areinstalled on some ships to provide supply airfor the pneumatic units in automatic boilercontrol systems. A boiler control air systemusually consists of an air compressor, an airreceiver, and the piping required to supplyair to all units of the boiler control systemOn some older ships, compressed air for theoperation of the boiler controls is taken fromthe ship's service air system, through reducingvalves.An air deballasting system is provided onsome ships for deballasting by air. This systemis designed to provide large quantities of air(7500 cubic feet per minute) at low pressure(200 psi). All compressors discharge to a commonair loop distribution which feeds all ballasttanks.Oxygen-nitrogen producer air systems areinstalled on aircraft carriers and submarinetenders. The air is supplied by high pressureair compressors, via oil filters and moistureseparators, directly to the oxygen- nitrogenproducer.FIREMAIN SYSTEMSThe firemain system receives water pumpedfrom the sea and distributes it to fireplugs,sprinkling systems, flushing systems, auxiliarymachinery cooling water systems, washdownsystems, and other systems as required.There are three basic types of firemainsystems used on naval ships: the single mainsystem, the horizontal loop system, and thevertical loop system. The type of firemainsystem installed in any particular ship dependsupon the characteristics and functions of theship. Small ships generally have single mainfiremain systems; large ships usually haveone of the loop systems or a composite systemwhich is some combination or variation of thethree basic types.The single main firemain system consistsof one main which extends fore and aft. Themain is generally installed near the centerlineof the ship, extending as far forward and as faraft as necessary. The horizontal loop firemainsystem consists of two single fore-and-aft226