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Maritime Case Study

Optimizing Filtration on Tug Boats


Doedijns, a Dutch producer of hydraulic power units




Company Profile

Doedijns is the international recognised system integrator that designs, manufactures, assembles and distributes engineered, cost effective and tailor made solutions to its global clients in a wide variety of industries, such as the oil & gas, mining, mobile equipment, offshore, renewable energy or heavy industry.


Products Used
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Hydraulic deck equipment such as towing / anchor winches and deck cranes are powered by a hydraulic system. The system reliability of this system is directly linked to the condition and cleanliness of the oil. Over time, the oil within the hydraulic system will become contaminated due to the extreme environment, heavy workloads and continuous use. The buildup of these contaminants will start to wear out the components, reducing the lifespan and creating possible unplanned maintenance and downtime.

Doedijns, a Dutch producer of hydraulic power units (HPU), is a preferred supplier for a big tug boat manufacturer. Together with RMF Systems they started a project with the goal to improve oil cleanliness by changing the filtration set-up. Cleanliness goal was set to ≤ ISO 19/17/14. In order to achieve this goal, efficient filtration was necessary.


Current set-up return filter & drain filter Improved set-up return filter & by-pass filter
  • 10 micron glass fiber elements in both filters
  • 10 micron glass fiber element in return filter
  • Depth filtration installed in bypass

Filtration of the drain flow needs to be monitored thoroughly. Increased drain pressure is not desirable as this can harm the pump.

Both filters are equipped with 10 micron filters. Smaller particles in the oil are therefore not filtered efficiently. These particles do need to be taken into consideration as they will affect the oil lifetime and the wear of components (LCC).

Drain flow remains unfiltered ensuring zero pressure drop. The added RMF Bypass Unit (BPU) focuses on the smaller particles (<10 micron).

The filter material is also capable of absorbing water, preventing chemical deterioration of the oil and the formation of rust.

System Specifications

Oil Type: Mobil DTE 10 EXCEL 46
Oil Volume: 700 liter