sprinkling systems, flushing systems, machinery-cooling water systems, washdown systems, andother systems as required. The fire-main systemis used primarily to supply the fireplug and thesprinkling system; the other uses of the system aresecondary.Naval ships have three basic types of fire-mainsystems: the single-main system, the horizontal-loop system, and the vertical-loop system. Thetype of fire-main system in any particular shipdepends upon the characteristics and functions ofthe ship. Small ships generally have straight-line,single-main systems. Large ships usually have oneof the loop systems or a composite system, whichis some combination or variation of the followingthree basic types:The single-main fire-main system consistsof one main that extends fore and aft. The mainis generally installed near the centerline ofthe ship, extending forward and aft as far asnecessary.The horizontal-loop fire-main system con-sists of two single fore-and-aft, cross-connectedmains. The two mains are installed in the samehorizontal plane but are separated athwartshipsas far as practical.The vertical-loop fire-main system consistsof two single fore-and-aft, cross-connected mains.The two mains are separated both horizontallyand vertically. As a rule, the lower main is locatedbelow the lowest complete watertight deck, andthe upper main is located below the highestcomplete watertight deck.A composite fire-main system consists oftwo mains installed on the damage control deckand separated athwartships. A bypass main isinstalled at the lower level near the centerline.Cross connections are installed alternately betweenone service main and the bypass main.Communications EquipmentDamage control communications are vital toa ship’s survival during emergency conditions. Ifadequate damage control (DC) communicationsare not maintained, the entire DC organizationcould break down rapidly and fail to perform itsprimary functions.The following communication methods areused for DC communications:Sound-powered battle telephone circuitsInterstation two-way intercomsShip’s service telephonesShip’s loud speaker or general announcingsystemVoice tubesMessengersDetailed information on each method can befound in Damage Controlman 3 & 2, NAVED-TRA 10572.Electrical SystemsDCPOs perform periodic maintenance (PM)on electrical systems within their division spaces.They must know the location of fuse boxes andcircuit breakers that control the circuits. Propertag out procedures are also required to preventharm to other crew members while the PM isperformed.You should be able to identify the followingelectrical systems in your areas:LightingLighting panelsElectrical power outletsMotors and fansCasualty power terminals and panelsBattle lanternsWatertight ClosuresThe watertight integrity of a naval ship isestablished when the ship is built. This originalwatertight integrity may be reduced or destroyedthrough enemy action, storm damage, collision,standing, or negligence. As a duty DCPO, youwill be responsible for ensuring the propermaterial condition is set. Later in this chapter wewill discuss in depth the material conditions andrequired reports.7-6
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