The precision of cylinder lubrication in large two-stroke diesel engines with crosshead bearing helps to increase the overall life of the engine. Thus, the Austrian manufacturer KRAL AG is offering its existing Volumeter series of flowmeters to precisely monitor the quantity of lubricating oil in the cylinders. Crosshead bearings are used in large engines where the use of simple connecting rods is impossible due to the transverse forces that would put intolerable wear on the piston and cylinder.
Usually crosshead bearings are used with high stroke/bore ratios (stroke about 300 cm, bore about 100 cm). According to the specifications indicated by the engine manufacturer, burning oil residue makes it necessary to utilize expensive lubricating oils for the cylinders, while the quantity of lubricant entering the cylinder is usually determined by injector geometry.
The experts at KRAL said that with some engines in operation there can be significant deviations to the values set by the manufacturer, which often result in excessive lubrication of the cylinder, causing damage to the cylinder and piston. KRAL calculated that excess lubrication in two-stroke large marine engines can cost up to US$277 000 per ship, annually. KRAL’s Volumeter Series offers a precise cise measurement of the quantity of lubricating oil in the cylinder, while its electronics determine and manage the best values, in order to stay as close as possible to the manufacturer’s indications.
KRAL Volumeters are compact positive-displacement meters and they work with virtually any liquid from low-viscosity liquids, like petrol, to high-viscosity liquids. Their measurement precision is accurate to ±0.1% of the flow rate. The liquid to be measured flows straight into the Volumeter and drives two spindles inside the measurement chamber. Poles on the wheel at the end of each spindle generate an impulse for a sensor, which transmits the signal to the KRAL electronic unit. The electronics use the spindles’ rotational speed, determined by the registered impulses, and the chamber volume to determine the liquid flow. By increasing the number of poles on the wheel, the resolution of the measurement is increased.
For those modern two-stroke engines that are already equipped with cylinder oil measurement systems, KRAL can offer an easy retrofit with its Volumeter. The company is available for a professional evaluation of the installation characteristics, as well as to perform the retrofit operation itself.