This section briefly describes the Boiler and various auxiliaries in the Boiler Room.
A boiler is an enclosed vessel that provides a means for combustion heat to be transferred to water until it becomes heated water or steam. The hot water or steam under pressure is then usable for transferring the heat to a process. Water is a useful and inexpensive medium for transferring heat to a process. When water at atmospheric pressure is boiled into steam its volume increases about 1,600 times, producing a force that is almost as explosive as gunpowder. This causes the boiler to be an equipment that must be treated with utmost care.
ABSOLUTE PRESSURE - Pressure above zero pressure; the sum of the gauge and atmospheric pressures.
ACCUMULATOR - (STEAM) A pressure vessel containing water and/or steam, which is used to store the heat of steam for use at a late period and at some lower pressure.
ACID CLEANING - The process of cleaning the interior surfaces of steam generating units by filling the unit with dilute acid accompanied by an inhibitor to prevent corrosion, and subsequently draining, washing and neutralizing the acid by a further wash of alkaline water.
ACIDITY - Represents the amount of free carbon dioxide, mineral acids and salts (especially sulphates of iron and aluminum) which hydrolyze to give hydrogen ions in water and is reported as milliequivalents per liter of acid, or ppm acidity as calcium carbonate, or pH the measure of hydrogen ions concentration.
ADIABATIC FLAME TEMPERATURE - The theoretical temperature that would be attained by the products of combustion provided the entire chemical energy of the fuel, the sensible heat content of the fuel and combustion above the datum temperature were transferred to the products of combustion. This assumes: No heat loss to surroundings and no dissociation.
AIR - The mixture of oxygen, nitrogen, and other gases, which with varying amounts of water vapor, forms the atmosphere of the earth.
AIR ATOMIZING OIL BURNER - A burner for firing oil in which the oil is atomized by compressed air, which is forced into and through one or more streams of oil which results in the breaking of the oil into a fine spray.
AIR DEFICIENCY - Insufficient air, in an air-fuel mixture, to supply the oxygen required for complete oxidation of the fuel.
AIR-FREE - The descriptive characteristic of a substance from which air has been removed.
AIR-FUEL RATIO - The ratio of the weight, or volume, of air to fuel.
AIR INFILTRATION - The leakage of air into a setting or duct.
AIR, SATURATED - Air which contains the maximum amount of water vapor that it can hold at its temperature and pressure.
AIR VENT - A valved opening in the top of the highest drum of a boiler or pressure vessel for venting air.
ALARM - A suitable horn, bell, light or other device which when operated will give notice of malfunction or off normal condition.
ALKALINITY - Represents the amount of carbonates, bicarbonates, hydroxides and silicates or phosphates in the water and is reported as grains per gallon, or ppm as calcium carbonate.
ALLOWABLE WORKING PRESSURE - See design pressure.
AMBIENT AIR - The air that surrounds the equipment. The standard ambient air for performance calculations is air at 80 °F, 60% relative humidity, and a barometric pressure of 29.921 in. Hg, giving a specific humidity of 0.013 lb of water vapor per lb of dry air.
Guidelines for drinking-water quality, third edition, incorporating first and second addenda
Volume 1 - Recommendations
The third edition of the Guidelines has been comprehensively updated to take account of developments in risk assessment and risk management since the second edition. It describes a“Framework for Drinking-water Safety”and discusses the roles and responsibilities of different stakeholders, including the complementary roles of national regulators, suppliers, communities and independent “surveillance” agencies.
The first and second addenda, which update the third edition, have been incorporated in this volume. The first addedum includes more guidance on management of emergencies and unforeseen events, additions concerning chlorination by-products and developing standards for volatile substances, and several new fact sheets for chemical substances. The second addendum includes more guidance on household water management, rainwater harvesting, vended water, temporary water supplies, and pesticides used for vector control in drinking water sources. It also includes a series of new microbial and chemical fact sheets. Moreover, “expanded” fact sheets are included for key chemical risks such as arsenic, fluoride and nitrate/nitrite.
N.B Text changes arising from revisions to the First and Second Addendum are marked by a thin and thick black line in the left margin respectively.
CHEMICAL COSTS OF WATER TREATMENT DUE TO DIMINISHED WATER QUALITY: A CASE STUDY IN TEXAS
The cost of municipal water treatment due to diminished water quality represents an important component of the societal costs of water pollution. Here, the chemical costs of municipal water treatment are expressed as a function of raw surface water quality. Data are used for a three year period for 12 water treatment plants in Texas. Results show that when regional raw water contamination is present, the chemical cost of water treatment is increased by $95 per million gallons from a base of $75. A one percent increase in turbidity is shown to increase chemical costs by one fourth of a percent.