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194  Deck machinery and  hull equipment

                  and  communications. The  diesel  engine  has  its  own  supply  system,
                  usually of light diesel  oil for  easy starting.  Batteries,  compressed  air  or
                  an  hydraulic accumulator may be used  for  starting the  machine.  Small
                  machines  may be  air  cooled  but  larger  units  are  arranged  usually  for
                  water  cooling  with  an  air  cooled  radiator  as  heat  exchanger  in  the
                  system.  A  small  switchboard  is  located  in  the  same  compartment  to
                  connect the  supply to the  various emergency services  (see Chapter  14).
                    Modern  systems are  arranged  to  start  up  the  emergency  generator
                  automatically when the  main power supply fails. The  system should  be
                  checked regularly and operated to ensure its availability if required. Fuel
                  tanks should be kept full, ample cooling water should be in the radiator
                  cooling  system,  and  the  starting  equipment  should  be  functional.
                  Batteries of course,  should be  fully  charged  or  air  receivers  full.
                    The  emergency fire pump is arranged  to supply the  ship's fire main
                  when  the  machinery  space  pump  is  not  available.  One  possible
                  arrangement,  as  used  on  large  tankers,  is  shown  diagrammatically  in
                  Figure  10.11.  A diesel engine with  its own  fuel  supply system, starting

                                       Diesel  Engine



                    Discharge  to  Fire  Main      Hyd  Oil  Pump






















                 Discharge  to
                 Main  Fire
                 Pump  Suction
                                        Submersible
                                        Hyd  Oil
                               Booster  Motor  Driven  Hyd  Oil Supply
                   Sea  Suction  Pump   Pump        and  Return
                 Figure  10.11 Emergency fire pump
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