Nov-21
Page 12 of 132
59812-K001 Rev 10
1
1.1
INTRODUCTION
High temperatures, in excess of 200
o
C that occur on bearing surfaces under initial failure conditions, can
lead to a rapid generation of oil vapour When the hot vapour contacts the relatively cooler atmosphere
of the crankcase it condenses into a fine mist, with typical particle sizes of around 0.5 to 5 microns in
diameter. When the density of these particles reaches between 30 to 50 mg/l (Milligrams per litre),
depending upon the type of oil, an explosive condition exists.
Piston Rod Seal
Cross Head Slides
Cross Head Bearing
Top End Bearing
Bottom End Bearing
Main Bearing
Figure 1
Areas of Failure 2 Stroke Engine
Piston Seizure
Cam Shaft Bearings
Bottom End
Bearing
Top End Bearing
Piston Blow By
Main Bearing
Figure 2
Areas of Failure 4 Stroke Engine
A fire or explosion needs three constituents: fuel, oxygen and an ignition source. Remove one of these
and no explosion will occur. Similarly, within the crankcase, the three constituents which could cause
an explosion are air, oil mist
oil mist density can be measured at levels as low as 0.05 mg/l and give early warning of a rise in oil mist
density.
Oil Mist Detection (OMD) techniques have been used to monitor diesel engine crankcases for potential
explosive conditions and early detection of bearing failures. The systems available rely mainly on
analysing the optical density of oil mist samples drawn from the crankcase compartments, through pipes
to the detector. While these systems proved successful in the past, engine design has improved
Summary of Contents for Graviner Mk6
Page 16: ...Nov 21 Page 16 of 132 59812 K001 Rev 10 Height 309mm Width 559mm Depth 118 5mm Weight 8 7kg ...
Page 26: ...Nov 21 Page 26 of 132 59812 K001 Rev 10 Figure 9 Junction Box Installation ...
Page 29: ...Nov 21 Page 29 of 132 59812 K001 Rev 10 Figure 12 Detector Head Installation ...
Page 46: ...Nov 21 Page 46 of 132 59812 K001 Rev 10 Figure 36 System Drawing ...
Page 47: ...Nov 21 Page 47 of 132 59812 K001 Rev 10 Figure 37 Wiring Diagram ...
Page 112: ...Nov 21 Page 112 of 132 59812 K001 Rev 10 6 6 1 CONTROL PANEL Figure 158 Control Panel Door ...
Page 123: ...Nov 21 Page 123 of 132 59812 K001 Rev 10 ...
Page 126: ...Nov 21 Page 126 of 132 59812 K001 Rev 10 ...