Strictly saying, it is not possible to conduct comprehensive cylinder scrape down analysis on board because shore laboratory tests the various sample parameters and inclusion of wear elements. Regular ship doesn't have required equipment for this purpose.
Here is a list of parameters and additives normally tested by the laboratory:
K Viscosity at 40°C (cSt), K Viscosity at 100 °C (cSt), Flash Point (°C), Water (% vol), Soot (% wt), Base Number (mgKOH/g), Oxidation (abs/cm), Acid Number (mgKOH/g), Barium (Ba), Calcium (Ca), Magnesium (Mg), Phosphorus (P), Zinc (Zn), Sodium (Na), Silicon (Si), Sulphur (S), Lithium (Li), Aluminium (Al), Chromium (Cr), Copper (Cu), Iron (Fe), Lead (Pb), Tin (Sn), Molybdenum (Mo), Nickel (Ni), Titanium (Ti), Silver (Ag), Manganese (Mn), Vanadium (V).
However, highlighted tests from the above list could be done on board:
- Iron (Fe)
- Base Number (mgKOH/g)
- Water (% vol)
Lube Oil Base Number and Water content tests are parts of regular Lube Oil condition monitoring which all vessels must implement and normally conducted on a weekly basis using on board LO test kit. It is advisable to collect cylinder scrape down samples at least monthly and analyze them at least for presence of Water and residual Base Number.
Water in scrape down samples may tell about:
- cooling water leakage
- excessive moisture in scavenging air + faulty piston rings
- scavenging drain line steam blow leaking (if installed)
Residual Base Number
Should be in the range 20-35. BN lower that 20 indicates lack of cylinder oil and values above 35 most likely indicate excessive feed rate.
In order to measure Iron (Fe) content which represents wear rate of piston rings and liner (mostly liner) a special Fe Test Kit should be supplied on board.
The actual test procedure is simple.
1. Sampled oil must be filled in a special container.
2. Container sealed with a cap and inserted into the machine.
3. After a moment on the machine's screen appears "container out" animation and container must be removed from the slot. Than a sample Fe content in ppm displayed on the screen.
Please note, that shore laboratory equipment is more advanced and use a different technology. We recommend to prioritize shore lab results.
Keep track of cylinder scrape down analysis records to minimize the cylinder oil consumption and keep the engine operating in a safe (green) zone.
