Validation tests of hydraulic control oil filter

 Approval to test the final HCO filter design comes after successful concept testing on the crude oil tanker Stena Suède.
The HCO filter is a high-performance solution for the new generation of two-stroke engines in which traditional camshafts have been replaced by hydraulic control systems, says Alfa Laval, a developer of heat transfer, separation and fluid handling technologies. The hydraulic control system core components are dedicated valves fed with oil from the main system flow, which must be very finely filtered with minimal pressure drop, the company notes. Due to the sensitivity of the large centrifugal main pumps used to move the oil, additional pressure drop across the HCO filter would ultimately risk engine damage.
According to Alfa Laval, its HCO filter easily achieves this balance of fine filtration and excellent flow passage.
“Between its high performance and its compact nature, the Alfa Laval HCO filter will remove much of the cost and installation complexity associated with hydraulic control system protection,” commented Herve Gourdon, business manager for filters at Alfa Laval.
Extensive filter area is critical for filtration at 6μm, the very fine grade required for hydraulic control oil. Using new Alfa Laval Atrium technology, the company says, the Alfa Lava HCO filter provides a "tremendous" increase in filtering surface – with virtually no impact on pressure drop. This is possible through the special patented shape of the Atrium filter elements, as well as their smaller and highly optimised flow distribution system.
“With Alfa Laval Atrium technology, the Alfa Laval HCO filter reliably achieves the 6μm filtering needed to protect hydraulic control valves,” Gourdon said. “Yet the flow and pressure through the filter remain practically unaffected, which ensures a safe margin for the engine.”
A further advantage of the ample flow through the Alfa Laval HCO filter, according to the company, is the ability to backflush continuously. Unlike sequential backflushing, continuous backflushing prevents even temporary accumulation of pollutants. This, too, ensures there is no increase in pressure drop.
Because the backflushing is treated in a diversion chamber in the filter, it also contributes to a compact and easily installed solution, Alfa Laval says. No additional tank or separator is required, nor is any air or electrical connection needed, since backflushing is driven by the hydraulic motor.
The final design of the Alfa Laval HCO filter will be evaluated in three installations, each to be put through 3,000 hours of testing. This follows 14,000 hours of concept testing aboard the tanker Stena Suède, whose chief engineer, Paul Ash, remarked: “The filter is basically maintenance-free, the backflush cleaning works well and the operating pressure is steady.”