|MadSci Network: Chemistry|
The answer to your first question is yes, there are different grades of kerosene. They are not based on heat output, though, but on sulfur content.
Kerosene is not a specific chemical compound, it is a petroleum fraction. When petroleum is refined to produce fuels and lubricants, it is separated by boiling. The fraction of the oil which boils at relatively low temperatures is used to make gasoline. A fraction which boils at higher temperatures is used to produce diesel fuel. Kerosene is made from a fraction which boils at intermediate temperatures. The properties of kerosene are defined in a document from the American Society for Testing and Materials called ASTM Standard D-3699. (I would provide a link to this document, but it must be purchased from ASTM. You might find it in a university engineering library.) According to the National Kerosene Heater Association, the boiling range of commercial kerosene is 340 to 572 degrees Fahrenheit, and must have a flash point of 100.4 degrees Fahrenheit or higher. (The flash point is the temperature above which the fluid in question can be ignited.)
So here's the answer to your question. According to the Exxon USA Lubricants Encyclopedia, there are two grades of kerosene: 1-K and 2-K. The former grade is low-sulfur kerosene, with a maximum sulfur content of 0.04 percent by weight, and the latter can contain up to 0.30 percent sulfur. The sulfur content is important because the sulfur in the fuel forms some pretty nasty pollutants when the fuel is burned. Keeping the sulfur content as low as it is in 1-K kerosene allows the fuel to be burned without a flue to remove the exhaust products from the room (such as in a kerosene space heater). 2-K kerosene must be burned only in appliances with a flue.
Other than sulfur content, the two grades of kerosene have identical properties.
I hope this answers your question.
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