Science of Silence
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Oily Bilges

The International Maritime Organisation is progressively tightening legislation about spilling oil at sea. Currently, the limit is 15 milligrams per litre– roughly half a drop of diesel in a litre of water.

Pilot cutters, Yachts, Fishing Boats, Superyachts, Patrol Craft, Canal Boats, Lifeboats, Powerboats, and Ferries. All risk polluting their surroundings when they pump out their bilges. Bilge water invariably contains fuel oil, lubricating oil and grease which cannot be separated and is dumped into the seas and rivers of the world. Legislation to prevent this operates in most parts of the world, and is being progressively tightened. The allowable limits for oil in water discharge, currently 15 milligrams per litre, are set by The International Convention for the Prevention of Pollution from Ships (MARPOL ), under the secretariat of The International Maritime Organisation, a United Nations agency.

Wavestream ends this - Over the past years a new filtration system, based on XOil bonding technology, has been developed for the oil and shipping industries. XOil is a filter material which bonds with oil. It is processed into sheet form and converted into simple filter cartridges which fit easily and neatly into the pipework from bilge pumps. So effective is XOil that each filter cartridge will adsorb 3 times its own weight of oil. So efficient is XOil that even the smallest system will handle 40 litres per minute. So welcome is the technology that the entire BT Global Challenge fleet adopted it. So important is the development that Lloyds Register has given Type Approval to the basic product. More recently Wavestream has gained specific acceptance for use in boats CE marked in accordance with the Recreational Craft Directive.

XOil filter technology

Oily water is pumped down outside the XOil filter cartridge and the oil is bonded within the filter media. The water travelling up through the centre of the filter, and out of the boat, is almost entirely free from oil. Really oily bilge water, around 250 milligrams per litre, is generally reduced to below 12 milligrams per litre. Normal bilge water will be reduced to below 5 milligrams per litre. Serious oil spillages should be dealt with using absorbent pads prior to pumping through the filter. Filter cartridge replacement is explained in the usage instructions. A privately owned and well maintained boat should not need to replace the filter cartridge more than once a year.

One drop of diesel in half a litre of water equates to roughly 40 milligrams per litre. This is well over the legal limit set by MARPOL.

Pump Size

The filter sits between the electric bilge pump and the outlet. Pump size is important, and we’ll check this when you order. You’ll need a pump with a 4m head of water.

Big Spills

Wavestream will deal with diesel and lube oil in bilge water, but not the reverse! If you actually spill oil in the bilge, clean it up and wash the bilge with detergent – don’t try and pump it out through the filter.

Watermaker Protection

The Wavestream filter is ideal for water-maker protection, preventing oils causing fatal damage to delicate reverse osmosis membranes.

To view the Wavestream product range, then please click here.

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