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Boiler glossary N |
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| NAPHTA -- An oil distillate. Naphta is an
intermediate product between gasoline and kerosene. It is known as a light
product because of the low molecular weight of the hydrocarbons making it
up. NAPHTHA -- A generic term applied to a petroleum fraction with an approximate boiling range between 50°C and 205°C. NATURAL CIRCULATION -- The circulation of water in a boiler caused by differences in density. NATURAL DRAUGHT -- The draught or airflow through a furnace induced by a funnel and dependent on the height and the temperature difference between the ascending gases and the atmosphere. NITROGEN DIOXIDE -- NO2 This compound of nitrogen and oxygen is formed by the oxidation of nitric oxide (NO) that is produced by the combustion of solid fuels. Below 17°C the formula is N2O4 and the molecule is colorless. Decomposed by water, forming a mixture of nitric and nitrous acids. NORMALIZING -- A heat treatment applied to steel. Involves heating above the critical range, followed by cooling in air. Is performed to refine the crystal structure and eliminate internal stress. NORMALLY CLOSED CONTROL VALVE -- A control valve that closes when the diaphragm pressure is reduced to atmospheric. NORMALLY OPEN CONTROL VALVE -- A control valve that opens when the diaphragm pressure is reduced to atmospheric. NOx -- Abbreviation for all of the family of oxides of nitrogen. NOZZLE -- A short flanged or welded neck connection on a drum or shell for the outlet or inlet of fluids; also an orifice for spraying a liquid like fuel oil. NPSH -- Net Positive Suction Head is the liquid pressure that exists at the suction end of a pump. If the NPSH is insufficient, the pump can cavitate. |
© 2007 Lars Josefsson Boilers