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www.sea-technology.com October 2014 / st 55 cant savings. For example, the guide feed rate for Wärtsilä RTA and RT- fex engines equipped with the Pulse Lubrication Sys- tem as original equipment is 0.7 to 0.8 grams per kilowatt-hour of cylinder lubricating oil, when pre- viously the average would have been 1 to 1.2 grams per kilowatt-hour. Electronic lubrication systems can reduce cyl- inder oil consumption, but these are open loop systems that do not provide feedback on the impact of such reduction, and, sensibly, a safety buffer is often applied. Without a reli- able feedback system to accurately monitor the effect on the engine, changing feed rates based solely on the OEM's recommendations could increase associ- ated wear caused by underlubrication and seriously harm the engine. To penetrate the lubrication safety buffer, safely achieve the true optimum feed rate and realize maximum savings, offine or online tools are available to closely moni- tor lubrication conditions. Laboratory Analysis Laboratory testing to monitor scrape-down oils is a pri- mary method used to inform adjustment of lubrication lev- els. Each of the oil majors provides a drain oil analysis pro- gram. For example, Exxon Mobil's (Irving, Texas) Signum Oil Analysis and Shell's (Hague, Netherlands) Rapid Lubricants Analysis heighten savings by monitoring the engine to deter- mine its sensitivity to particular parameters, optimize lube oil feed rate, and improve maintenance management and extension of overhaul periods. Flame Marine (Ulverston, England) is perhaps the best- known independent provider of detailed diagnostics. The company estimates that overlubrication of cylinder lubricat- ing oil in slow-speed, two-stroke marine diesel engines can C old corrosion is an unintend- ed consequence of progress. Longer piston strokes in new- generation, fuel-effcient marine engines bring a change in oper- ating conditions within the cylin- der liner to a cooler temperature that is below the dew point, along with higher pressure. Previously, sulfur in the engine was in gas form as sulfur oxide (SOx). Now, it combines with the condensation to form liquid sul- furic acid, resulting in corrosion on the liner surface. The result- ing iron compounds formed are fushed into the cylinder oil, lead- ing to excessive wear of the cylin- der liner. Over-Lubricating to Tackle Cold Corrosion Increasing the feed rate of an alkaline lubricant is one obvious solution to counteract increased acidity within the cylinder liner—and a short-term one when operating costs climb as lubricant oil is over-applied. With often four times the normal level of required lubricant being used, this amounts to a substantial cost. Minimizing both fuel and lube oil consumption is high on the agenda in this effciency-conscious era. Even a 0.1 gram per kilowatt-hour reduction in cylinder oil dosage rep- resents a signifcant yearly saving for the vessel owner. Suc- cessful feed rate optimization relies upon identifying exactly how much cylinder lube oil injection can be acceptably re- duced to achieve the optimum operating conditions. Electronically Controlled Lubricating Systems The MAN (Munich, Germany) Alpha Lubricator, Wärt- silä's (Helsinki, Finland) Pulse Lubricating System (PLS) and Hans Jensen (Hadsund, Denmark) SIP system all aim to in- ject cylinder oil into the cylinder at the exact position and time for optimal effect. These systems have achieved signif- Optimizing Feed Rate in the Fight Against Cold Corrosion Constant Real-Time Monitoring to Prevent Engine Cylinder Liner Damage By Dr. Steve Dye Parker Kittiwake's Cold Corrosion Test Kit.