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NORA Oilheat Technicians Manual

Chapter 2—Heating Oil and Its Properties 2-7 the truck, and to use diverters on the “blow or whistle pipes” (underground fill pipes) when filling underground tanks. Major factors in fuel degradation 1. Chemistry of the fuel • Heat causes the oxidation of organics • The presence of sulfur and nitrogen hasten degradation • Corrosion creates iron oxides (rust) • Presence of Gels caused by mercaptan sulfur • Incompatible fuels 2. Microbiological effects 3. The tank and its environment— moisture, fuel circulation due to temperature differences 4. Lack of tank maintenance and poor design and installation that prevent adequate tank inspection, withdrawal of water and sediment, improper or no filtration, and lack of corrosion protection. Fuel stability Fuels degrade over time. If the fuels are contaminated, they will degrade even more quickly. The stability of heating oil depends a great deal on the crude oil sources from which it was made, the severity of the refinery process, the use of additives and any additional refinery treatment. Fuels that are stored for long periods of time and subjected to temperature extremes may form excessive amounts of sediments and gums that can plug filters, strainers, and nozzles. Detecting “out of spec” oil Occasionally, a bad batch of oil will be delivered. When that happens, there will be many service calls. If there is a spike in calls and they appear to be fuel related, you should alert your service manager. A fuel sample might show that the fuel can be fixed with additives, or the fuel may need to be replaced. Water problems The worst fuel problem is water in the oil tank. Water enters the tank in the following ways: 1. Condensation 2. Broken tank gauge (outside tank) 3. Loose fill or vent fittings and missing caps 4. Directly from delivery trucks 5. Leaking vent, fill pipes, or tank 6. Pumping old oil into a new tank Sludge Sludge is a combination of water, colonies of bacteria, degraded fuel, and other contaminates like sand, grit and rust. The ability of bacteria to grow almost anywhere and reproduce amazingly fast makes it an all too common problem. The bacteria live in the water and eat the fuel. They break the fuel down into hydrogen, CO2, and carbon rich residue. The bacteria also create sticky slime or gum to protect themselves. Scientists call this slime “biofilm.” This deterioration of fuel is a natural occurrence that will appear in all tanks unless proper maintenance is performed. The sludge grows at the oil-water line and when stirred up can to lead serious and recurring service problems—most notably plugged fuel lines, filters, strainers, and nozzles. Sludge is acidic and may eventually destroy the tank from the inside. Chapter 2 Heating Oil


NORA Oilheat Technicians Manual
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