Regular condition monitoring of cylinder drain oil (CDO) with on-board testing equipment is an excellent method to promptly and directly assess the health and condition of cylinder components (pistons, piston rings and cylinder liners) of two-stroke marine diesel engines. For the evaluation of the CDO conditionand optimization of the engine lubrication, Cylinder Drain Oil (CDO) analysis also called Scrape Down Analysis (SDA) is usually performed along with the measurement of the remaining base number (BN) and routine engine inspections.

The CDO analysis means closely monitoring of total iron content as per recommendations and practices of leading engine manufacturers. The total iron concentration provides an indication of excessive wear and tear of the components surrounding the engine combustion chamber. The total iron is the combination of two different wear types of engine cylinders:

1. abrasive iron wear caused by mechanical friction between piston ring package and cylinder liner → ferromagnetic iron particles;
2. corrosive iron wear or so-called “cold corrosion” (acid corrosion due to chemical reaction from combustion residues and sulphur present in the fuel oil) → non-magnetic iron salts.

As the surfaces of cylinder components can be subjected to different wear mechanisms simultaneously, only the measurement of total iron content, i.e., combination of corrosive and abrasive wear, can provide accurate and reliable results for the assessment of cylinder lubrication condition.
The test device TOTAL IRON CHECK is designed to conduct regular digital CDO analysis based on the chemical determination of the total iron content (corroded and/or abrasive type) in order to identify any occurring changes in the engine wear directly on board. Thereby, early identification of unusual measurement values (e.g., gradual, but constant increase of total iron concentration as well as high amounts detected) can provide early warning signs to the engine operator as an effective tool of preventive maintenancepractice.

The TOTAL IRON CHECK with its two-chamber measuring system enables testing of two CDO samples simultaneously. The glass vials with special reaction liquid are pre-heated in the chambers A and/or B of the test device. Then the CDO sample/ samples is/are added to start automatic measurement of the total iron content.

Test Device “TOTAL IRON CHECK” with Two Chambers for Testing Multiple Cylinder Units

The TOTAL IRON CHECK detects and measures all iron particles present in the CDO sample irrespective of their size, including also the large ones. The degree of total iron concentration that can be measured with the TOTAL IRON CHECK can be ranging up to 1100 mg/kg (ppm). The measured values will be automatically saved on the internal memory chip.
The degree of the measured total iron content can also be visually observed after the test. If any iron is contained in the CDO sample, the chemical reaction between the special reaction liquid and the iron will result in a blue color change of the liquid. The intensity of the blue color may vary from light to dark blue and directly depends on actual total iron concentration in the CDO sample.

Examples of Different Total Iron Concentration Measured in cylinder drain oil (CDO) Samples

The enhanced, redesigned version of the test device TOTAL IRON CHECK includes several updated features:

1. Upgraded navigation menu with the possibility to create individual named data slots for up to 20 different cylinders units
2. Large memory capacity: storage of 400 measured values with date and time stamps
3. USB to serial connection for transfer of test results into a terminal program and further into Excel or similar software

Test Device “TOTAL IRON CHECK” with USB Cable