Alfa Laval’s Moatti 290 filter for hydraulic control oil (HCO) has been approved by MAN Diesel & Turbo for use on its modern two-stroke engines.
The decision follows validation tests aboard three Stena Bulk IMOIIMAX vessels.
The Alfa Laval Moatti 290 filter is designed for the new generation of MAN Diesel &Turbo two-stroke engines, in which hydraulic control systems have replaced traditional camshafts.
The valves of these systems are actuated by a small flow of lube oil, which must be very finely filtered without creating additional pressure drop, the company said. The new filter achieves this using Alfa Laval Atrium technology, which is designed to provide a tremendous increase in filtering surface within a compact space.
Alfa Laval began discussing the filter with MAN Diesel & Turbo in 2008, when the engine manufacturer started its transition from camshafts to hydraulic control systems. The fine HCO filtration required by the engine design demanded an entirely new filter technology, the company said. Alfa Laval’s prototype HCO filter, presented in 2014, spent over 24 000 hours in concept testing aboard the Suezmax crude oil tanker Stena Suède.
The Alfa Laval Moatti 290 filter is built to the most recent MAN Diesel & Turbo recommendations, which require both an automatic filter and a redundant filter with high enough efficiency to retain particles of 6 µm and below. These are incorporated into the same frame, with a specially designed changeover valve to prevent any leakage during maintenance.
The redundant filter, which is manually cleanable, can be used not only during maintenance, but also for initial oil cleaning or when new oil is added into the system. It is not used, however, to clean the small flow of oil that provides continuous backflushing. Instead, this flow is cleaned in a diversion chamber before it is returned to the sump.
The continuous backflushing of the Alfa Laval Moatti 290 filter is driven by the pressure of the oil itself, the company said. This means no electricity or air supply is needed, which is one of several ways the filter simplifies installation. Because backflushing is performed in the automatic filter stage, with a cleanable surface-filter cartridge used to provide redundancy, reliance on disposable filters is eliminated.