Hydraulic oil cleaning system Europafilter (marketed by the UK’s Armada Marine Hydraulics) turned out winner of this year’s ‘Spirit of Innovation’ competition in the ‘Marine Equipment, Hydraulics and Materials’ category at Seaworks 2012.

The patented filter was the result of research embarked on in the early 1980’s by Norwegian innovator, Aegir Björnsson, who set the bar high indeed in a quest to invent a device that would make used oil as clean as or even cleaner than new oil. Evidently he succeeded as we shall see, but first how does it work?

Hydraulic Oil Impurity

Analysis of the content of impurities in hydraulic oil after running for some time in a system, usually reveals a large amount of particles smaller than 5 micron. More than 70% of these particles may be smaller than 1 micron; the reason being that such tiny particles pass through existing filters.

These particles, smaller than one micron, can be divided into two types: hard particles which cause wear in sliding surfaces or which may come from outside the system, and oxidation products coming from the hydraulic oil itself.

Unique Filter Element

Aegir Björnsson decided that the solution to this problem was to be found in the design of the filter unit, although other approaches had been taken, and in the mid-80’s he took out a patent on the special kind of filter element he had been working on.

In the prototype filter he wound a cellulose material around a cartridge with a special technique and then inserted it under pressure into an outer plastic patron, so that the fluid flowed axially in channels the same length as the unit. A deep filter was thus formed where the particles were successfully trapped along the direction of flow by capillary-type action.

The result, after further testing, was a filter element able to trap particles down to 0.1 micron with a very high capacity and which additionally removed water in all its forms.

Case Study

MF Hardingen: Photo credit Harald Sætre Wiki CCL

Norwegian coastal ferry operators Tide ASA, who operate a fleet of eighty ships, were getting reports of noisy operation, overheated, bow-door hydraulics on its Norwegian coastal RoRo ferry MF Hardingen.

High oil working temperatures were found to be the cause of a build-up of varnish deposits in the hydraulic system, creating valve manoeuvring problems and interfering with the hydrostatic balance of the oil system.

A Europafilter unit connected to the oil reservoir successfully cleaned the contaminated oil, varnish deposits were removed, and the operating temperature was found to have reduced from 70C to 45C six days after installation; six weeks later it was down to 40C and the NAS value was 3. Problems solved.