Archive for August, 2009
Many edible vegetable and animal oils, and also fats, are used for various in cooking and food preparation. In particular, many foods are fried in oil much hotter than boiling water. Oils are also used for flavoring and for modifying the texture of foods e.g. Stir Fry.
Health advantages are claimed for a number of specific oils such as omega 3 oils (fish oil, flaxseed oil, etc), evening primrose oil and olive oil. Trans fats, often produced by hydrogenating vegetable oils, are known to be harmful to health.
Almost all oils burn in air generating heat, which can be used directly, or converted into other forms of fuels by various means. For example, heating water into steam which is funneled into a turbine which turns a generator, which then produces electricity. Oils are used as fuels for heating, lighting (e.g. kerosene lamp), powering combustion engines, and other purposes. Oils used for this purpose nowadays are usually derived from petroleum, (fuel oil, diesel oil, gasoline (petrol), etc), though biological oils such as biodiesel are gaining market share.
Many oils have higher boiling points than water and are electrical insulators, making them useful for liquid cooling systems, especially where electricity is used.
Due to their non-polarity, oils do not easily adhere to other substances. This makes oils useful as lubricants for various engineering purposes. Mineral oils are more suitable than biological oils, which degrade rapidly in most environmental conditions.
Color pigments can be easily suspended in oil, making it suitable as supporting medium for paints. The slow drying process and miscibility of oil facilitates a realistic style. This method has been used since the 15th century.
Crude oil can be processed into petroleum, plastics, and other substances.
An oil is a substance that is in a viscous liquid state (“oily”) at ambient temperatures or slightly warmer, and is both hydrophobic (immiscible with water) and lipophilic (miscible with other oils, literally). This general definition includes compound classes with otherwise unrelated chemical structures, properties, and uses, including vegetable oils, petrochemical oils, and volatile essential oils. Oil is a nonpolar substance.
The term oil is often used colloquially to refer to petroleum.
Types of oils
All oils, with their high carbon and hydrogen content, can be traced back to organic sources. Mineral oils, found in porous rocksunderground, are no exception, as they were originally the organic material, such as dead plankton, accumulated on the seafloor in geologically ancient times. Through various geochemical processes this material was converted to mineral oil, or petroleum, and its components, such as kerosene, paraffin waxes, gasoline, diesel and such. These are classified as mineral oils as they do not have an organic origin on human timescales, and are instead
derived from underground geologic locations, ranging from rocks, to underground traps, to sands.
Other oily substances can also be found in the environment, the most well-known being asphalt, occurring naturally underground or, where there are leaks, in tar pits.
Petroleum and other mineral oils, (specifically labelled as petrochemicals), have become such a crucial resource to human civilization in modern times they are often referred to by the ubiquitous term of “oil” itself.
Oils are also produced by plants, animals and other organisms through organic processes, and these oils are remarkable in their diversity.
Oil is a somewhat vague term to use chemically, and the scientific term for oils, fats, waxes, cholesterol and other oily substances found in living things and their secretions, is lipids. Lipids, ranging from waxes to steroids, are somewhat hard to characterize, and are united in a group almost solely based on the fact that they all repel, or refuse to dissolve,
in water, and are however comfortably miscible in other liquid lipids. They also have a high carbon and hydrogen content, and are considerably lacking in oxygen compared to other organic compounds and minerals.
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The sidewall provides the lateral stability for the tire. The thicker the sidewall, the more stability the tire will posses. The sidewall also helps to protect the body piles
Cap piles are only added on high speed tires. These are extra layers of polyester fabric which helps to keep everything in place.
Layers added to the tire for durability and stability. The more layers, or plies, the more durable the tire. Typical car tires have two plies while a jet airliner tire may have as many as 30 plies.
The inner liner serves as the main surface responsible for containing the air.
Present in steel-belted radials. Located under the tread. Help to provide strength and puncture resistance to the tire. Also helps keep the tire flat for better contact patch.
Added pieces of material that serve to shield the inner liner. These covers help prevent buckling.
Consists of a loop of steel wire that is wound around the base of the tire and covered with rubber. This piece holds the tire in the rim and prevents it from pulling away. Special precaution is taken to ensure the correct size of the bead and lip of the rim.