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Boiler glossary H |
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| HANDHOLE -- An access opening in a
pressure part that permits inspection or tube rolling. HARD WATER-- Water which contains calcium or magnesium in an amount which require an excessive amount of soap to form a lather. HARDNESS -- A measure of the amount of calcium and magnesium salts in water. Usually expressed as grains per gallon or ppm as CaCO3 or °dH. HARTFORD LOOP -- A boiler piping configuration which eliminates unsafe lowering of boiler water level due to back up of boiler water into the return line. HEADER -- A small sidewall drum into which tubes are rolled. Used as distribution or collecting box for the steam generating tubes. HEAT CAPACITY -- The amount of heat necessary to raise the temperature of a given mass one degree. Heat capacity may be calculated by multiplying the mass by the specific heat. HEATING SURFACE -- Those surfaces which are exposed to products of combustion on one side and water on the other. This surface is measured on the side receiving the heat. HEAT SINK -- Anything that absorbs heat. It is usually part of the environment, such as the air, a river, or a lake. HEEL -- The ship tilt to one side. HFO -- Heavy Fuel Oil. The heaviest commercial fuel that can be extracted from crude oil. HOTWELL -- A tank for the condensate returns and from which the feed water pump takes its suction. The makeup water often goes into this tank. HUNTING -- An undesirable oscillation of appreciable magnitude, prolonged after external stimuli disappear. Hunting is evidence of operation at or near the stability limit. HVAC -- Heating, Ventilation and Air Conditioning HYDROKINETER -- A device formerly used in fire tube boilers to improve the water circulation during firing up. A jet stream from a steam nozzle near the boiler's bottom forces the colder water at the bottom to move towards the water surface. HYDRONIC HEATING -- A system that heats a space using hot water which may be circulated through a convection or fan coil system or through a radiant baseboard or floor system. HYDROSTATIC TEST -- A strength and tightness test of a closed pressure vessel by water pressure. |
© 2007 Lars Josefsson Boilers