The oil used to lubricate the cylinders of large 2-stroke marine diesel engines has to contend with high temperatures and acidic products formed during the combustion of sulphur-rich bunker oils.
Cylinder oil is used on a continuous loss basis. In recent times ship operators have taken to running engines at reduced speeds (so-called slow steaming) as a means of improving fuel consumption.
Unfortunately, slow steaming is accompanied by a drop in engine temperature which allows acid to build up on the cylinder liners thereby promoting their “cold corrosion”. The iron compounds formed by this process are then flushed from the engine by the cylinder oil. This leads to excessive liner wear, requiring expensive replacement. The iron found in used cylinder oil samples typically exists in various forms, each one having its own particular properties. For example, metallic iron particles worn off the cylinder liner by cat fines exhibit strong ferromagnetism and may be detected. There are cold corrosion test kits to aid in this condition monitoring process.
Performing cold corrosion test
To perform a Parker Kittiwake cold corrosion test you will require the following:
- The sample of your cylinder scraped down oil.
- One millilitre syringe.
- Comparator and color wheel.
- Two cuvettes
- Reagents One, Two and Three
- Pouring lid for each reagent bottle
First, fill both sample vials to the five-millilitre graduation line with Reagent One.
Prepare your cylinder scrape down oil sample with some gentle agitation for approximately 30 seconds. Using the syringe, add 0.2-millilitres of the sample to each of the cuvettes.
Fill, one of your cuvettes to the 10-millilitre graduation line with Reagent Two and the other with Reagent Three. Be sure both cuvettes are capped, secured and shake vigorously for approximately 30 seconds.
Leave for four and a half minutes for the layers to settle out.
Insert the color wheel into the comparator.
Place the cuvette containing Reagent Two into the centermost slot and the cuvette with Reagent Three into the anterior-most slot.
Rotate the color wheel clockwise until the color of the anterior-most window matches that of the inner.
Read the concentration figure in PPM directly from the wheel.
Watch the video to follow along with the steps:
Please visit parker.com/kittiwake for more information.