U.S. Navy Ship Salvage Manual Volume 6 - Oil Spill Response

S0300-A6-MAN-060cially in choppy water, because the suction hose does not always remain in oil, but primary oilwaterseparation can take place in the tank, with water drained from the bottom of the tank periodically.Table 5-2. Sorbent Performance.SorbentMaximum Oil Absorbing CapacityHigh Viscosity Oil(3,000 cSt at 25°C)Low Viscosity Oil(5 cSt at 25°C)Buoyancy AfterProlonged Contact withOil on WaterInorganic:Vermiculite 4 3 SinksVolcanic Ash 20 6 FloatsGlass Wool 4 3 FloatsSynthetic:Polyurethane Foam 70 60 FloatsUrea Formaldehyde Foam 60 50 FloatsPolyethylene Fiber 35 30 FloatsPolypropylene Fiber 20 7 FloatsPolystyrene Powder 20 20 FloatsNatural:Corn Cob 6 5 SinksPeanut Husks 5 2 SinksRedwood Fiber 12 6 SinksWheat Straw 6 2 SinksPeat Moss 4 7 SinksWood Cellulose Fiber 18 10 SinksSpecialized inlet heads are required for thin oil layers. These devices can recover oil in water asshallow as three inches or from the bottom of storage tanks. They operate on the fixed-weir principleand have quick connection points for standard 3- and 5-inch vacuum hoses.5-2.5.2 Nets. Nets can be used to collect nearly solid emulsions, tar balls and oil-soaked debris orsorbents. Seine-like nets are towed by two vessels or set across currents. Trawl-like nets can betowed by a single vessel. Fine-mesh fishing nets can be used, but purpose-built oil collection netsare available. Nets are well suited for containing loose particulate or matted sorbent such as straw,cotton, peat, vermiculite or synthetics. The oil is absorbed while the water passes through the nets.Some materials lose their buoyancy after soaking in oil and must be removed from the nets withoutdelay. Because water can pass through nets, current drag is lower than booms and they can bemoored across currents that might carry booms away. If current or towing speed is too great, however,oil and collected sorbents may be forced through the net.5-12