Fuel Injector


Components
  1. Hexagon Nut
  2. Washer
  3. Setting Screw
  4. Press Piece
  5. Pressure Spring
  6. Spring Cup
  7. Supporting or Injector Body
  8. Seal Ring
  9. Nozzle Needle
  10. Dowel Pin
  11. Nozzle Body or Injector Nozzle
  12. Nozzle Tensioning Nut
Problems

    MAN B&W fuel injector
  • Fuel spraying at different pressure then fixed one- After combustion carbon deposits forms around the injector nozzle tip and sometime injector nozzle orifice blocked and need pressure more than the actual pressure(for MAN B&W 9L 58/64 engine 310+/-10 bar).Sometimes setting screw get loosen after a long operation and fuel inject at a pressure lower than actual pressure.
  • Fuel injection pattern changed - Due to carbon deposits forms around the tip of the fuel injector some nozzle orifice get closed or stucked and fuel spraying pattern changed(for MAN B&W 9L 58/64 engine injector nozzle have 18 pores of 0.82mm and 0.85mm diameter).
  • Droplet forms at the tip of injector nozzle- Due to varying pressure and nozzle needle problems droplet forms at the tip of the injector nozzle,combustion take place at the tip and carbon deposit forms.
  • 'O' ring damage- If proper nozzle cooling system is not provided,then heat generated due to friction damage the 'O' ring and nozzle cooling water leakage take place. Also low quality 'O' rings damage with in very short life cycle.
  • Internal crack in injector body- Sometimes internal crack take place due to varying thermal stress in the injector body and cause fuel leakage.
Maintenance Work
Before disassembling wash injector in fuel oil(generally diesel) and remove all carbon deposits.
  • Check the 'O' rings, if damaged changed the rings.
  • With the help of vice unscrew the nozzle tensioning nut.
  • Loosen Hexagonal nut and turn off the setting screw.
  • Disassembled all the parts and clean them in fuel oil.
  • With suitable cleaning wire clean the nozzle orifice.
  • If lapping is necessary at the surfaces of nozzle body and supporting body remove the dowel pins and with the help of proper abrasive paste finish the lapping operation.
  • If nozzle needle sticked in the nozzle,with the help of fuel oil free it by lapping.
  • During pressure test if cracked body found,replace it with a new one.

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