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Engineering Dictionary _

Engineering Dictionary

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1. ABDC: Abbreviation for after bottom dead center.

2. ABMA - American Boiler Manufacturers Association.

3. ABRASION - The wearing away of a surface by rubbing, as with sandpaper on wood.

4. ABRASION RESISTANCE - The ability of a material to resist surface wear.

5. ABRASIVE EROSION - Erosive wear caused by the relative motion of solid particles which are entrained in a fluid, moving nearly parallel to a solid surface.

6. ABSOLUTE HUMIDITY - Amount of moisture in the air, indicated in kg/kg of dry air.

7. ABSOLUTE PRESSURE - Total pressure measured from an absolute vacuum. It equals the sum of the gauge pressure and the atmospheric pressure corresponding to the barometer.

8. ABSOLUTE PRESSURE - Air at standard conditions (70F air at sea level with a barometric pressure of 29.92 in Hg) exerts a pressure of 14.696 psi. This is the pressure in a system when the pressure gauge reads zero. So the absolute pressure of a system is the gauge pressure in pounds per square inch added to the atmospheric pressure of 14.696 psi (use 14.7 psi in environmental system work) and the symbol is "psia".

9. ABSOLUTE TEMPERATURE SCALE - A scale of temperature measurement in which zero degrees is absolute zero.

10. ABSOLUTE TEMPERATURE: The temperature measured when absolute zero is used as a reference. Absolute zero is -273.16C or 469.69F, and is the lowest measured temperature known.

11. ABSOLUTE VELOCITY -

12. ABSOLUTE ZERO - A hypothetical temperature at which there is total absence of heat. Since heat is a result of energy caused by molecular motion, there is no motion of molecules with respect to each other at absolute zero. It is theoretically the coldest possible temperature.

13. ABSOLUTE ZERO TEMPERATURE - Temperature measured from absolute zero (-459.67F, or -273.16C).

14. ABSORBENT - A material which, due to an affinity for certain substances, extracts one or more such substances from a liquid or gaseous medium with which it contacts and which changes physically or chemically, or both, during the process. Calcium chloride is an example of a solid absorbent, while solutions of lithium chloride, lithium bromide, and ethylene glycols are liquid absorbents.

15. ABSORBER - That part of the low side of an absorption system, used for absorbing vapor refrigerant.

16. ABSORPTION - A process whereby a material extracts one or more substances present in an atmosphere or mixture of gases or liquids accompanied by the material's physical and/or chemical changes.

17. ABSORPTION REFRIGERATION SYSTEM - One in which the refrigerant, as it is absorbed in another liquid, maintains the pressure difference needed for successful operation of the system.

18. ABSORPTION REFRIGERATOR - Refrigerator that creates low temperatures by using the cooling effect formed when a refrigerant is absorbed by chemical substance.

19. ABSORPTION SYSTEM - A refrigeration system in which the refrigerant gas evolved in the evaporator is taken up in an absorber and released in a generator upon the application of heat.

20. ABSORPTION TOWER - A tower or column, which effects contact between a rising gas and a falling liquid, so that part of the gas may be taken up by the liquid.

21. ABT: Abbreviation for automatic bus transfer; an automatic electric device that supplies power to vital equipment. This device will shift from the normal power supply to an alternate power supply any time the normal supply is interrupted.

22. ACCELERATION - The rate of change of velocity, as a function of time. Expressed in m/s.

23. ACCELERATION DUE TO GRAVITY - The rate of increase in velocity of a body falling freely in a vacuum. Its value varies with latitude and elevation. The International Standard is 32.174 ft. per second per second.

24. ACCELERATION PERIOD - In cavitation and liquid impingement erosion, the stage following the incubation period, during which the erosion rate increases from near zero to a maximum value.

25. ACCELRATION - The time rate of change of velocity; i.e., the derivative of velocity; with respect to time.

26. ACCEPTABLE WELD - A weld that meets all of the requirements and the acceptance criteria prescribed by the welding specifications.

27. ACCESSIBLE HERMETIC - An assembly of motor and compressor, inside a single bolted housing unit.

28. ACCUMULATOR - Storage tank which receives liquid refrigerant from evaporator and prevents it from flowing into suction line before vaporizing.

29. ACETONE - A filler added to acetylene cylinders, capable of absorbing 25 times its own volume of acetylene.

30. ACID - Literally hitter, but chemically the state of a water solution containing a high concentration of hydrogen ions.

31. ACID ATTACK - Caused by an incomplete flushing after an acid cleaning process of boilers or similar equipment.

32. 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 by subsequently draining, washing, and neutralizing the acid by a further wash of alkaline water.

33. ACID CONDITION IN SYSTEM - Condition in which refrigerant or oil in a system, is mixed with vapor and fluids that are acidic in nature.

34. ACID EMBRITTLEMENT - A form of hydrogen embrittlement that may be induced in some metals by an acid.

35. ACID GAS - A gas that that forms an acid when mixed with water. In petroleum processing, the most common acid gases are hydrogen sulfide and carbon dioxide.

36. ACID RAIN - Atmospheric precipitation with an pH below 5.6 to 5.7.

37. ACID SOAK - A method of acid cleaning, in which the acid is pumped into the boiler and rests there for a period of time.

38. ACIDIC - The reaction of a substance with water resulting in an increase in concentration of hydrogen ions in solution (see acid).

39. ACIDIFIED - The addition of an acid (usually nitric or sulfuric) to a sample to lower the pH below 2.0. The purpose of the acidification is to "fix" a sample so it will not change until it is analyzed.

40. ACIDITY - Represents the amount of free carbon dioxide, mineral acids, and salts (especially sulfates of iron and aluminum) which hydrolyze to give hydrogen ions in the water. The acidity is reported as millie equivalents per liter of acid, or ppm acidity as calcium carbonate, or pH, the measure of hydrogen ion concentration.

41. ACOUSTIC - A term pertaining to sound, or the science of sound.

42. ACROSS THE LINE - A method of motor starting, which connects the motor directly to the supply line on starting or running.

43. ACTION - Refers to the action of a controller. It defines what is done to regulate the final control element to effect control.

44. ACTIVATED ALUMINA - Chemical which is a form of aluminum oxide. It is used as a drier or desiccant.

45. ACTIVATED CARBON - Is a specially processed carbon, used as a filter drier. Commonly used to clean air.

46. ACTIVATED SLUDGE - An aerobic biological process for conversion of soluble organic matter to solid biomass, removable by gravity or filtration.

47. ACTIVE STORAGE PILE - A method of stockpiling coal, sometimes called live storage. The pile is located outside the plant but adjacent to it, and usually contains four or five days of operating supply. The pile is not compacted, as it is not stored long enough to be exposed to the hazard of spontaneous combustion.

48. ACTUATOR - The portion of a regulating valve, which converts mechanical, fluid, thermal, or electrical energy; into mechanical motion to open or close the valve seats or other such devices.

49. ADDITIVE: A material that is added to improve fuel or oil.

50. ADIABATIC - Occurring with no addition or loss of heat from the system under consideration.

51. ADIABATIC CHANGE - A change in the volume, pressure, or temperature of a gas, occurring without a gain of heat or loss of heat.

52. ADIABATIC COMPRESSION - Compressing a gas without removing or adding heat.

53. ADIABATIC COOLING - A method in which paramagnetic salts are pre-cooled, and then demagnetized, thereby producing further cooling.

54. ADIABATIC EFFICIENCY -The ratio of actual work output of a heat engine to the ideal output.

55. ADIABATIC EXPANSION - The expansion of a gas, vapor, or liquid stream from a higher pressure to a lower pressure, with no change in enthalpy.

56. 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.

57. ADIABATIC PROCESS - A thermo-dynamic process in which no heat is extracted from or added to the system of the process.

58. ADIABATIC SATURATION PROCESS - A process to determine absolute or relative humidity.

59. ADJUSTABLE DIFFERENTIAL - A means of changing the difference between the control cut-in and cutout points.

60. ADJUSTABLE RESISTOR - A resistor whose value can be mechanically changed, usually by the use of a sliding contact.

61. ADSORBENT - A material which has the ability to cause molecules of gases, liquids or solids to adhere to its internal surfaces without changing the adsorbent physically or chemically. In water treatment, a synthetic resin possessing the ability to attract and to hold charged particles.

62. ADSORPTION - The adhesion of the molecules of gases, dissolved substances, or liquids in more or less concentrated form, to the surface of solids or liquids with which they are in contact. Commercial adsorbent materials have enormous internal surfaces.

63. ADSORPTION INHIBITORS - They are materials which caused them to be adsorbed on to the metal surface due to their polar properties.

64. ADVECTION - The transfer of heat by horizontal movement of air.

65. AERATION - Exposing to the action of air, like blowing air through water before discharging to a river.

66. AERATION CELL - (see oxygen cell)

67. AEROBIC - A condition in which "free" or dissolved oxygen is present in water.

68. AERODYNAMIC NOISE - Also called generated noise, self-generated noise; is noise of aerodynamic origin in a moving fluid arising from flow instabilities. In duct systems, aerodynamic noise is caused by airflow through elbows, dampers, branch wyes, pressure reduction devices, silencers and other duct components.

69. AFTERCOOLER: A device used on turbo-charged engines to cool air that has undergone compression.

70. AGGLOMERATE - The clustering together of a few or many particles into a larger solid mass.

71. AGITATOR - A device used to cause motion in confined fluids.

72. AIR - A substance containing by volume approximately 78 - 79% nitrogen; 20.95% oxygen, .94% argon, traces of carbon dioxide, helium, etc.

73. 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.

74. AIR BIND: The presence of air in a pump or pipes, which prevents the delivery of liquid.

75. AIR BLAST TRANSFORMER - A transformer cooled by forcing a circulation of air around its windings.

76. AIR BLANKETING - An accumulation of air in a heat exchanger or other vessel which impedes heat transfer.

77. AIR BLEEDER: A device that removes air from a hydraulic system. Types include a needle valve, capillary tubing to the reservoir, and a bleed plug

78. AIR CAPACITOR - Is a capacitor, which uses air as the dielectric between the plates.

79. AIR CHANGES - A method of expressing the amount of air leakage into or out of a building or room in terms of the number of building volumes or room volumes exchanged.

80. AIR CLEANER - A devise used to remove air borne impurities [A device (filter) for removing unwanted solid impurities from the air before the air enters the intake manifold]

81. AIR COIL - Coil on some types of heat pumps used either as an evaporator or a condenser.

82. AIR COMPRESSOR: A device used to increase air pressure.

83. AIR CONDITIONER - They are basically refrigeration devices cooling air and rooms rather then food compartments.

84. AIR CONDITIONER, UNITARY - An evaporator, compressor, and condenser combination; designed in one or more assemblies, the separate parts designed to be assembled together.

85. AIR CONDITIONING -The process of treating air to simultaneously control its temperature, humidity, cleanliness, and distribution to meet the requirements of the conditioned space.

86. AIR CONDITIONING UNIT - An assembly of equipment for the treatment of air so as to control, simultaneously, its temperature, humidity, cleanliness and distribution to meet the requirements of a conditioned space.

87. AIR CONDITIONING, COMFORT - The process of treating air so as to control simultaneously its temperature, humidity, cleanliness and distribution to meet the comfort requirements of the occupants of the conditioned space.

88. AIR COOLER - A factory-encased assembly of elements whereby the temperature of air passing through the device is reduced.

89. AIR DEFICIENCY - Insufficient air, in an air-fuel mixture, to supply the oxygen required for complete oxidation of the fuel.

90. AIR DIFFUSER - A circular, square, or rectangular air distribution outlet, generally located in the ceiling and comprised of deflecting members discharging supply air in various directions and planes, and arranged to promote mixing of primary air with secondary room air.

91. AIR DIFFUSION AERATORS - They are aerators into which air is pumped into the water through perforated pipes, plates, or any other method.

92. AIR DUCT - A tube or conduit for conveying air from one place to another.

93. AIR EJECTOR: A jet pump that removes air and non-condensable gases.

94. AIR FLOTATION - A process of accelerating sedimentation, by introducing air into the water, this lowers the density of the water, and increases the differences in the densities of the water and the suspended particles. (DAF), Dissolved Air Flotation.

95. AIR-FUEL RATIO: The ratio (by weight or by volume) between air and fuel.

96. AIR GAP -The space between magnetic poles, or between the rotating and stationary assemblies in a motor or generator.

97. AIR HANDLER - The fan blower, heat transfer coil, filter, and housing parts, of a system.

98. AIR HEATER / PREHEATER - The air-heater is in the path of the boiler gases after the economiser, so that the air for combustion absorbs heat from the gases before they enter the stack.

99. AIR HEATER ELEMENT - When applied to Rotary airheaters, the plate bundles forming the heat exchange surfaces.

100. AIR INFILTRATION The leakage of air into a room through cracks in doors, windows, and other openings.

101. AIR PURGE - The removal of undesired matter by replacement with air.

102. AIR SATURATED - Moist air in which the partial pressure of the water vapor is equal to the vapor pressure of water at the existing temperature. This occurs when dry air and saturated water vapor coexist at the same dry-bulb temperature.

103. AIR SENSING THERMOSTAT - A thermostat unit, in which the sensing element is located in the refrigerated space.

104. AIR STANDARD - Air having a temperature of (20C), a relative humidity of 36 percent, and under a pressure of 14.70 PSIA. The gas industry usually considers (16C) as the temperature of standard air.

105. AIR-STARTING VALVE: A valve that admits compressed air to the air starter for starting purposes.

106. AIR VENT - Valve, either manual or automatic, to remove air from the highest point of a coil or piping assembly.

107. AIR WASHER - A water spray system or device for cleaning, humidifying, or dehumidifying the air.

108. AIR, AMBIENT - Generally the air surrounding the object.

109. AIR, DRY - Air without contained water vapor.

110. AIR, OUTDOOR - Air taken from outdoors and, therefore, not previously circulated through the system.

111. AIR, RECIRCULATED - Return air passed through the conditioner before being again supplied to the conditioned space.

112. AIR, REHEATING - In an air conditioning system, the final step in treatment, in the event the temperature is too low.

113. AIR, RETURN - Air returned from conditioned or refrigerated space.

114. AIRBORNE SOUND - Sound which reaches the point of interest by radiation through the air.

115. AIR-COOLED CONDENSER - Heat of compression is transferred from condensing coils to surrounding air. This may be done either by convection or by a fan or blower.

116. AIR INFILTRATION - The leakage of air into a setting or duct.

117. AIR-SENSING THERMOSTAT A thermostat unit, in which the sensing element is located in the refrigerated space.

118. ALCOHOL BRINE - A water and alcohol solution, which remains as a liquid below 0C.

119. ALGAE - A minute fresh water plant growth which forms a scum on the surfaces of recirculated water apparatus, interfering with fluid flow and heat transfer. Lower form of plant life, usually green and blue green algae appear in cooling water systems. They are responsible for copious amounts of stringy green slime masses.

120. ALIGN: To bring two or more components of a unit into the correct positions with respect to one another.

121. ALIVE - A term referring to a circuit in which a current is flowing. Also referred to as live.

122. ALKALI - A substance having marked basic properties. Applying to hydroxides of potassium, sodium, lithium, and ammonium. They turn red litmus to blue. Includes hydroxides of the alkaline earth metals of barium, strontium, and calcium.

123. ALKALINE - Having a pH greater than 7.

124. ALKALINE BOIL-OUT - Employed to remove oil and grease deposits from heating surfaces.

125. ALKALINITY - An expression of the total basic anions (hydroxyl groups) present in a solution. It also represents, particularly in water analysis, the bi-carbonate, carbonate, and occasionally, the borate, silicate, and phosphate salts which will react with water to produce the hydroxyl groups.

126. ALLEN TYPE SCREW - A screw with a recessed hex shaped head.

127. ALLOWANCE: The difference between the minimum and the maximum dimensions of proper functioning.

128. ALLOY - A substance having metal properties and being composed of two or more chemical elements of which at least one is a metal (A mixture of two or more different metals, usually to produce improved characteristics)

129. ALLOY STEEL - Steel containing specific quantities of alloying elements (other than carbon)and commonly accepted amounts of manganese, copper, silicon, sulfur, and phosphorus).

130. ALTERNATING CURRENT (AC) - Electric current in which the direction of the current alternates or reverses. In a 60 Hertz (cycle) current, the direction of current flow reverses in 1/120th of a second; most commonly used current.

131. ALTERNATOR - A device which converts mechanical energy, into alternating current.

132. ALTIMETER - An instrument used to measure the height above a reference point, such as ground or sea level.

133. ALUM - Is an aluminum sulfate or filter alum. Acts in the range of 5.0 to 8.0 pH.

134. ALUMINA - Aluminum oxide occasionally found as an impurity in water in very small amounts.

135. AMBIENT AIR TEMPERATURE - Temperature of fluid (usually air) which surrounds object on all sides.

136. AMBIENT CONDITIONS - The conditions of temperature, pressure, and humidity, existing around an instrument.

137. AMBIENT TEMPERATURE - The temperature of the air surrounding the equipment.

138. AMBIENT NOISE -The normal sound in a room or other location.

139. AMERICAN STANDARD PIPE THREAD - A type of screw or thread, commonly used on pipe fittings to assure a tight seal.

140. AMERICAN WIRE GAUGE (AWG) - A system used in the United States for measuring the size of solid wires.

141. AMINE - A chemical use in water treatment as a filming or neutralizing agent to protect the metal parts.

142. AMMETER - An instrument for measuring the magnitude of electric current flow.

143. AMMETER SHUNT - A low-resistance conductor, placed in parallel (shunt) with an ammeter movement, so that most of the current flows through the shunt, and only a small portion flows through the ammeter. This extends the useful range of the meter.

144. AMMONIA - Chemical combination of nitrogen and hydrogen (NH3). Ammonia is a very efficient refrigerant and identified as R-117.

145. AMORPHOUS - A solid not having a repetitive three-dimensional pattern of atoms.

146. AMPACITY - A wire's ability to carry current safely, without undue heating. The term formerly used to describe this characteristic was current capacity of the wire.

147. AMPERAGE - An electron or current flow of one coulomb per second, past a given point in a circuit.

148. AMPERE - The unit used for measuring the quantity of an electrical current flow. One ampere represent a flow of one coulomb per second.

149. AMPERE HOUR - A term used for rating battery capacity. As stated, an ampere for an hour; ex: 5 amperes for 20 hours = 100 amp hour on a 20 hr rating.

150. AMPERE TURNS - A term used to measure magnetic force. It represents the product of amperes, times the number of turns of the coil, in an electromagnet.

151. AMPLIFICATION - The process of obtaining an output signal greater than the input signal, through auxiliary power controlled by the input signal. The process of increasing the strength, current, power, or voltage, of the signal.

152. AMPLITUDE - The maximum instantaneous value of alternating current or voltage. It can be in either a positive or negative direction. The greatest distance through which an oscillating body moves from the mid point.

153. ANAEROBIC - A condition in which "free" or dissolved oxygen is not present in the water.

154. ANALYSIS - Quantitative determination of the constituent parts (The process of determining the composition of a substance, by chemical or physical methods).

155. ANALYSIS, ULTIMATE - Chemical analysis of solid, liquid or gaseous fuels. In the case of coal or coke, determination of carbon, hydrogen, sulfur, nitrogen, oxygen, and ash.

156. ANEMOMETER - An instrument for measuring the velocity of a fluid.

157. ANGLE OF LAG OR LEAD - The phase angle difference, between two sinusoidal wave forms having the same frequency.

158. ANGLE VALVE - A type of globe valve design, having pipe openings at right angles to each other. Usually one opening on the horizontal plane and one on the vertical plane.

159. ANGSTROM UNITS - A unit of wave length, equal in length to one ten billionth.

160. ANHYDROUS CALCIUM SULFATE - A dry chemical, made of calcium, sulfur, and oxygen.

161. ANION - A negatively charged ion such as the chloride ion, Cl-.

162. ANION INTERCHANGE - The displacement of one negatively charged particle by another on an anion-exchange material. This principle is used with water treatment.

163. ANNEAL - To soften by heating and allowing to cool slowly (To heat a metal and to cool it in such a manner as to toughen and soften it. Brass or copper is annealed by heating it to a cherry red color and dipping it suddenly into water while hot. Iron or steel is slowly cooled from the heated condition to anneal).

164. ANNEALING - A process of heat treating metal, to get the desired properties of softness and ductility, (easy to form).

165. ANNUNCIATOR: A device, usually electro-mechanical, used to indicate or transmit information. See ENGINE ORDER TELEGRAPH.

166. ANODE - In electrolysis or electrochemical corrosion, a site where metal goes into solution as a cation leaving behind an equivalent of electrons to be transferred to the opposite electron, called the cathode.

167. ANODIZING - The treatment of a metal surface whereby the metal is made anodic.

168. ANSI - American National Standard Institute, which is an organization defining standards for computer language.

169. ANSI-B.31.1 - Power Piping.

170. ANSI-B.31.5 - Refrigeration Piping.

171. ANTHRACITES - Coals containing 90 per cent or more carbon and 10 percent or less volatile matter. They light up less readily but burn with an intense heat, without smoke and with little flame.

172. ANTI KNOCK VALUE - A premature explosive combustion, as the detonation of the fuel air mixture in an internal combustion engine, produces a characteristic knock. The Anti Knock Value is the measure of its resistance to the condition which tends to produce this knock.

173. ANTICIPATING CONTROL - One which, by artificial means, is activated sooner than it would be without such means, to produce a smaller differential of the controlled property. Heat and cool anticipators are commonly used in thermostats.

174. ANTICIPATORS - A small heater element in two-position temperature controllers which deliberately cause false indications of temperature in the controller in an at tempt to minimize the override of the differential and smooth out the temperature variation in the controlled space.

175. ANTI-CORROSIVE ADDITIVE - A lubricant additive to reduce corrosion.

176. ANTI-FOAM ADDITIVE (FOAM INHIBITOR) An additive used to reduce or prevent foaming.

177. ANTIFOAM AGENTS - The reduction of carry over by the addition of polymerized esters, alcohols, and amides. The antifoam agent is absorbed on the steam generating surface resulting in a hydrophobic condition, causing fewer but larger steam bubbles, which readily coalesce. These agents also weaken the wall of the bubble formed, causing them to quickly burst on the water surface.

178. ANTIFOULANTS - Are materials which prevent fouling from depositing on heat transfer equipment. Materials that prevent deposits forming; include anti- oxidants, metal coordinators, and corrosion inhibitors. Compounds that prevent deposition are surfactants. They act as detergents or dispersants.

179. ANTIFREEZE - Compounds of glycols or alcohols, that lower the freezing point of cooling water systems.

180. ANTIFRICTION BEARING: A bearing containing rollers or balls plus an inner and outer race. The bearing is designed to roll, thus minimizing friction.

181. ANTIOXIDANT - A substance which when added in small amounts to petroleum products, will delay or inhibit undesirable changes; such as the formation of gum, sludge, and acidity, which are brought about by oxidation.

182. ANTI-OXIDANT - An additive for the purpose of reducing the rate of oxidation and subsequent deterioration of the material.

183. ANTI-SCUFFING LUBRICANT - A lubricant that is formulated to avoid scuffing.

184. ANTI-SEIZURE PROPERTY - The ability of the bearing material to resist seizure during momentary lubrication failure.

185. ANTI-WEAR ADDITIVE - A lubricant additive to reduce wear.

186. API - American Petroleum Institute.

187. API GRAVITY (API DEGREE) - A measure of density used in the US petroleum industry.

188. APPARENT (EMF) - The apparent voltage, as measured by the drop in pressure due to a current flowing through a resistance.

189. APPARENT WATTS - The product of volts times amperes, in an alternating current circuit.

190. APPROCH TEMPERATURE - The difference in the temperature of the boiler feedwater leaving the economizer section compared to the water in the steam drum, typically it is in between 1040 OF (Calculating the "actual" approach temperature, and comparing it to the "as-designed" approach temperature is an effective tool in assessing performance in the "back end" of the HRSG, and indicates how well the economizer is operating).

191. AQUEOUS - Watery. A substance containing water.

192. AQUIFER - A porous, subsurface geological structure carrying or holding water.

193. ARC - A flash, caused by an electric current ionizing a gas or vapor.

194. ARC BRAZING - A brazing process in which the heat required is obtained from an electric arc.

195. ARC FURNACE - An electric furnace, in which heat is produced by an arc between two electrodes.

196. ARCING: Electrons leaping the gap between the negative and the positive poles

197. ARC WELDING - A group of welding processes which produce coalescence of metals by heating them with an arc, with or without the application of pressure, and with or without the use of a filler metal.

198. ARC WELDING - A process where coalescence is obtained by heating with an electric arc.

199. ARCHIMIDES PRINCIPAL - States that an upward force acting on a body wholly or partly submerged in a fluid, is equal to the weight of the fluid displaced, and acts through the center of gravity of the fluid displaced, or the center of buoyancy.

200. ARGON ARC PROCESS -

201. ARMATURE - the rotating part of an electric motor or generator. The moving part of a relay or vibrator.

202. ARMATURE AIR GAP - The air space between the stationary and rotating parts of a motor or generator, through which magnetic lines of force pass.

203. ARMATURE BACK AMPERE TURNS - The magnetic field produced by current flowing in the armature winding, that opposes and reduces the number of magnetic lines of force, produced by the field magnets of a motor or generator.

204. ARMATURE BAR - Copper bars used in place of wire windings, in large armatures, generators, or motors.

205. ARMATURE CIRCUIT - The path that the current takes, in flowing through the windings from one brush to another.

206. ARMATURE COIL - The loop or coil of copper wire, placed on the armature core, and forming part of the winding.

207. ARMATURE CORE -The laminated iron part of the armature, formed from thin sheets or disks of steel, on which the windings are placed.

208. ARMATURE CURRENT - The current flowing from the armature of a generator, to the armature of a motor. Not including the current taken by the shunt field.

209. ARMATURE DEMAGNETIZATION - The reduction in the effective magnetic lines of force, produced by the armature current.

210. ARMATURE REACTION - The magnetic effect of current flowing in the armature windings (The effect, that the magnetic field produced by the current flowing in the armature, has on the magnetic field produced by the field coils).

211. ARMATURE REGULATING RESISTORS - Are resistors, designed to regulate the speed or torque of a loaded motor, by placing a resistance in the armature or power circuit.

212. ARMATURE RESISTANCE - The resistance of the wire used in the windings of the armature, measured between the rings or brushes, or from positive to negative terminals.

213. ARMATURE SLOT -The groove or slot in the armature core, into which the coils or windings are placed.

214. ARMATURE TESTER - Any device used for locating faults or defects in the armature winding.

215. ARMATURE VARNISH - Is a liquid put on the field and armature windings, to improve the insulation of the cotton covering on the wires.

216. ARMATURE WINDING - All of the copper wire placed on the armature, and through which the current flows.

217. AROMATICS - A group of hydrocarbons of which benzene is the parent. They are called "aromatics" because many of their derivatives have sweet or aromatic odorous.

218. ARTIFICIAL MAGNET - Is a manufactured magnet, which is distinguished from a natural occurring magnet.

219. ASHRAE - The American Society of Heating, Refrigeration, and Air Conditioning Engineers.

220. ASME - American Society of Mechanical Engineers.

221. ASME APPENDIX SECTION I - Explains matter which is mandatory, unless specifically referred to in the rules of the code, including formulas.

222. ASME BOILER CODE - The boiler code listing standards, specified by the American Society of Mechanical Engineers, for the construction of boilers.

223. ASME PART PEB SECTION I - Requirements for electric boilers.

224. ASME PART PFH SECTION I - Requirements for feedwater heaters.

225. ASME PART PFT SECTION I - Requirements for firetube boilers.

226. ASME PART PG SECTION I - General requirements for all methods of construction.

227. ASME PART PMB SECTION I - Requirements for miniature boilers.

228. ASME PART PVG SECTION I - Requirements for organic fluid vaporizer generators.

229. ASME PART PW SECTION I - Requirements for boilers fabricated by welding.

230. ASME PART PWT SECTION I - Requirements for watertube boilers.

231. ASME SECTION I - Power Boilers.

232. ASME SECTION II - Material specifications.

233. ASME SECTION III - Nuclear Power Plant Components.

234. ASME SECTION IV - Heating boilers.

235. ASME SECTION IX ASME SECTION V - Nondestructive examination.

236. ASME SECTION VI - Recommended rules for the care and operation of heating boilers.

237. ASME SECTION VII - Recommended rules for the care and operation of power boilers.

238. ASME SECTION VII APPENDIX - Consists of conversion factors for converting Imperial units to SI Units.

239. ASME SECTION VII SUBSECTION C1 - Rules for routine operation of power boilers.

240. ASME SECTION VII SUBSECTION C2 - Operating and maintaining boiler appliances.

241. ASME SECTION VII SUBSECTION C3 - Rules for inspection.

242. ASME SECTION VII SUBSECTION C4 - Prevention of direct causes of boiler failure.

243. ASME SECTION VII SUBSECTION C5 - Is partial rules for the design of installations.

244. ASME SECTION VII SUBSECTION C6 - Operation of boiler auxiliaries.

245. ASME SECTION VII SUBSECTION C7 - Control of internal chemical conditions.

246. ASME SECTION VIII - Pressure vessels.

247. ASME SECTION X - Fiberglass reinforced plastic pressure vessels.

248. ASME SECTION XI - Rules for inservice inspection of Nuclear Power Plant components.

249. ASPECT RATIO - The ratio of the length to the width, of a rectangular air grille or duct.

250. ASPIRATING PSYCHROMETER - A device which draws sample of air through it to measure humidity.

251. ASPIRATION - Production of movement in a fluid by suction created by fluid velocity.

252. ASTM - American Society for Testing and Materials.

253. ASYNCHRONOUS - Not having the same frequency. Out of step, or phase.

254. ASYNCHRONOUS GENERATOR - An induction generator.

255. ASYNCHRONOUS MOTOR - An induction motor, whose speed is not synchronous with the frequency of the supply line.

256. ATDC: Abbreviation for after top dead center

257. ATMOSPHERE - Is the mixture of gases and water vapor surrounding the earth.

258. ATMOSPHERIC ELECTRICITY - Is static electricity, produced between cloud fronts in the atmosphere.

259. ATMOSPHERIC PRESSURE (BAROMETRIC PRESSURE) - Pressure exerted by the weight of the atmosphere; standard atmospheric pressure is 101.325 kPa or 1.01325 bars or 14.696 psia or 29.921 inches of mercury at sea level.

260. ATMOSPHERIC RELIEF VALVE - Automatic valve for relieving pressure in a condenser should it rise slightly above atmospheric.

261. ATOM - The smallest complete particle of an element, which can be obtained, yet which retains all physical and chemical properties of the element.

262. ATOMIC NUMBER - The number of protons found in the nucleus of an atom, of an element.

263. ATOMIC WEIGHT - The weight of an elementary atom, in relation to the weight of an atom of hydrogen. A hydrogen atom being taken as 1.00g.

264. ATOMIZE - Process of changing a liquid to minute particles or a fine spray.

265. ATTEMPERATING WATER IMPURITY - Refers to turbine deposits caused by impurities in the water used for attemperators. (Chemicals used with attemperating water should be of the volatile type).

266. ATTEMPERATOR - An apparatus for reducing and controlling the temperature of a superheater vapor or a fluid.

267. ATTENUATION - The sound reduction process in which sound energy is absorbed or diminished in intensity as the result of energy conversion from sound to motion or heat.

268. ATTRITION - The rubbing of one particle against another in a resin bed; frictional wear that will affect the site of resin particles.

269. AUTOMATIC - Self-acting. Operating by its own mechanism, when activated by some triggering signal.

270. AUTOMATIC CONTROL - The process of using the differences, between the actual value, and desired value, of any variable, to take corrective action, without human intervention.

271. AUTOMATIC CONTROLLER - A device that measures the value of a measured variable, and operates to correct or limit the deviation from a selected reference. Both measuring and control applications.

272. AUTOMATIC DEFROST - System of removing ice and frost from evaporators automatically.

273. AUTOMATIC EXPANSION VALVE (AEV) - A type of metering device that senses low-side pressure and modulates in order to maintain low-side pressure constant.

274. AUTOMATIC EXTRACTION UNIT TURBINE - Bleeds off part of the main steam flow at one, two, or three points. Valved partitions between selected stages control the extracted steam pressure at the desired level. When extracted steam flowing through the unit does not produce enough shaft power to meet the demand, more steam flows through the turbine to exhaust. Located between steam supply and process steam headers.

275. AUTOMATIC FROST CONTROL - Control which automatically cycles refrigerating system to remove frost formation on evaporator.

276. AUTOMATIC GOVERNING SYSTEM - A system which correlates steam flow, pressure, shaft speed, and shaft output, for any one turbine unit.

277. AUTOMATIC ICE CUBE MAKER - Refrigerating mechanism designed to automatically produce ice cubes in quantity.

278. AUTOMATIC RESET (INTEGRATION) - Is a type of control, in which the controller output, changes at a rate proportional to the deviation or error. The output will continue to change as long as any deviation or error exists.

279. AUTOMATION - The employment of devices, which automatically control one or more functions.

280. AUTOTRANSFORMER - A transformer in which both primary and secondary coils, have turns in common. The step up or step down of voltage, is accomplished by taps in common windings.

281. AUXILIARY CONTACTS - A set of contacts that perform a secondary function, usually in relation to the operation of a set of primary contacts.

282. AUXILIARY MACHINERY: Any system or unit of machinery that supports the main propulsion units or helps support the ship and the crew. Examples of auxiliary machinery are pumps, evaporators, steering engines, air-conditioning and refrigeration equipment, laundry and galley equipment, deck winches, and so forth.

283. AVAGADRO'S HYPOTHESIS - States that equal volumes of different gases, at the same temperature and pressure, will contain equal numbers of molecules.

284. AVAGADRO'S NUMBER (N) - The number of elementary units such as atoms, formula units, molecules, or ions, that constitute one mole of the said particle.

285. AVERAGING ELEMENT - A thermostat sensing element which will respond to the average duct temperature.

286. AXIAL: In a direction parallel to the axis. Axial movement is movement parallel to the axis.

287. AXIAL EXPANSION Expansion parallel to the line of the rotor.

288. AXIAL FLOW COMPRESSOR - Uses rotor blades shaped like airfoils, to bite into the air, speed it up, and push it into the subsequent stationary blade passages. These passages are shaped to form diffusers, that slow up the incoming air, and make it pressurize itself by catching up with the air ahead of it.

289. AXIAL THRUST The tendency for a turbine shaft to move axially in line with the bearings as a result of the force produced by the steam flow.

290. AXIS: The centerline running lengthwise.

291. AZEOTROPE - Having constant maximum and minimum boiling points.

292. AZEOTROPIC MIXTURE - Example of azeotropic mixture - refrigerant R-502 is mixture consisting of 48.8 percent refrigerant R-22 and 51.2% R-115. The refrigerants do not combine chemically, yet azeotropic mixture provides refrigerant characteristics desired.

293. ABBIT METAL : (see bearing, babbit).

B

294. BABBIT: An antifriction metal lining for bearings that reduces the friction between moving components.

295. BACKLASH: The distance (play) between two movable components.

296. BACK PRESSURE A pressure exerted contrary to the pressure producing the main flow (Pressure in low side of refrigerating system; also called suction pressure or low-side pressure).

297. BACK PRESSURE TURBINE A turbine from which all the steam is exhausted at some pressure above atmospheric for use in afactory process or for central heating (The Exhaust of the turbine is used for another process instead of condrnsing the same in a condenser).

298. BACK SEATING - Fluid opening/closing such as a gauge opening or to seal the joint where the valve stem goes through the valve body.

299. BACK WORK RATIO - Is the fraction of the gas turbine work used to drive the compressor.

300. BACKGROUND NOISE - Sound other than the wanted signal. In room acoustics, the irreducible noise level measured in the absence of any building occupants.

301. BACKING RING - Backing in a form of a ring, generally used in welding of piping.

302. BACKWASH - The counter-current flow of water through a resin bed (that is, in at the bottom of the exchange unit, out at the top) to clean and regenerate the bed after exhaustion (water treatment). Also, the process whereby a filtering mechanism is cleaned by reversing the flow through the filter.

303. BACKWARD-CURVED FAN BLADING - Backward-curved fan blading has the most suitable characteristics for boiler forced-d raught fans and is widely used for this purpose.

304. BACTERIA - Microscopic unicellular living organisms.

305. BAFFLE - Plate or vane used to direct or control movement of fluid or air within confined area.

306. BAGHOUSE - A chamber containing bags for filtering solids out of gases.

307. BALANCED DRAUGHT - The use of a forced-d raught fan to force combustion air into the furnace either through the fuel bed or through the burner, coupled with the use of an induced-draught fan to draw the gases through the boiler. Thus a state of balance is maintained in the combustion chamber.

308. BALANCED VALVE: A valve in which the fluid pressure is equal on both sides (the opening and closing directions).

309. BALL BEARING: A bearing that uses steel balls as its rolling element between the inner and outer ring (race).

310. BALL CHECK VALVE: A valve consisting of a ball held against a ground seat by a spring. It serves to check the flow or to limit the pressure of a liquid or substance.

311. BALLAST GAS - Are the nonflammable portion of the gas, such as carbon dioxide.

312. BAROMETER - Instrument for measuring atmospheric pressure. It may be calibrated in pounds per square inch, in inches of mercury in a column in millimeters or kPa.

313. BARRING GEAR Equipment for slowly rotating the turbine shaft when it is off load. Sometimes called 'turning or 'trolling gear.

314. BASE - An alkaline substance.

315. BASE LOAD - Base load is the term applied to that portion of a station or boiler load that is practically constant for long periods.

316. BASE METAL - The metal present in the largest proportion in an alloy. (Copper is the base metal in brass)

317. BASE METAL - The substrate metal that is coated or protected by a surface coating.

318. BASICITY - The ability of a substance to boost the pH after neutralizing all the acid species.

319. BATCH OPERATION - The utilization of ion-exchange resins to treat a solution in a container wherein the removal of ions is accomplished by agitation of the solution and subsequent decanting of the treated liquid.

320. BAUDELOT COOLER - Heat exchanger in which water flows by gravity over the outside of the tubes or plates.

321. BAUMANN EXHAUST - A special design of the exhaust end of a turbine to give extra effective area for the exhaust steam to pass to the condenser.

322. BBDC: Abbreviation for before bottom dead center.

323. BDC: Abbreviation for bottom dead center. The position of a reciprocating piston at its lowest point of travel.

324. BEARING: A mechanical component, which supports and guides the location of another rotating or sliding member.

325. BEARING, AIR - A bearing using air as a lubricant.

326. BEARING, ALIGNING - A bearing with an external spherical seat surface that provides a compensation for shaft or housing deflection or misalignment.

327. BEARING, ANNULAR - Usually a rolling bearing of short cylindrical form supporting a shaft carrying a radial load.

328. BEARING, ANTI-FRICTION - A bearing containing a solid lubricant.

329. BEARING, AXIAL LOAD : (see bearing, thrust)

330. BEARING, BABBIT - A bearing metal of non-ferrous material, containing several tin-based alloys, mainly copper, antimony, tin and lead.

331. BEARING, BALL - A rolling element bearing in which the rolling elements are spherical.

332. BEARING, BIG END - A bearing at the larger (crankshaft) end of a connecting rod in an engine.

333. BEARING, BIMETAL - A bearing consisting of two layers.

334. BEARING, BOTTOM END - (see bearing, big end)

335. BEARING, BUSH - A plain bearing in which the lining is closely fitted into the housing in the form of a bush, usually surfaced with a bearing alloy.

336. BEARING, CHATTER - Vibration of a shaft journal because of excessive clearance at the bearing surfaces.

337. BEARING, CIRCULAR STEP - A flat circular hydrostatic bearing with a central circular recess.

338. BEARING, CLEARANCE: The distance between the shaft and the bearing surface.

339. BEARING, FIXED PAD - An axial or radial load bearing equipped with fixed pads, the surface of which a are contoured to promote hydrodynamic lubrication.

340. BEARING, FLOATING - A bearing designed or mounted to permit axial displacement between shaft and housing.

341. BEARING, FLOATING RING - A type of journal bearing that includes a thin ring between the journal and the bearing. The ring floats and rotates at a fraction of the journal rotational speed.

342. BEARING, FLUID - (see hydrostatic bearing)

343. BEARING, FULL JOURNAL - A journal bearing that surrounds the journal by a full 360.

344. BEARING, GAS - A journal or thrust bearing lubricated with gas.

345. BEARING, HALF JOURNAL - A bearing extending 180 around a journal.

346. BEARING, JOURNAL - A machine part in which a rotating shaft revolves or slides.

347. BEARING, KINGSBURRY TRUST

348. BEARING, MAGNETIC - A type of bearing in which the force that separates the relatively moving surfaces is produced be a magnetic field.

349. BEARING, MAIN - A bearing supporting the main power-transmitting shaft.

350. BEARING, MITCHELL -(see tilting pad bearing).

351. BEARING, NEEDLE - A bearing in which the relatively moving parts are separated by long thin rollers that have a length-to-diameter ratio exceeding 5.0.

352. BEARING, NONCONTACT - A bearing in which no solid contact occurs between relatively moving surfaces.

353. BEARING, PEDESTAL - A bearing that is supported on a column or pedestal rather than on the main body of the machine.

354. BEARING, PIVOT - An axial load bearing, radial-load-type bearing which supports the end of a shaft or pivot.

355. BEARING, POROUS - Made from porous material, such as compressed metal powders, the pores acting either as reservoirs for holding or passages for supplied lubricant.

356. BEARING, ROLLER - A bearing in which the relatively moving parts are separated by rollers.

357. BEARING, RUBBING - A bearing in which the relatively moving parts slide without deliberate lubrication.

358. BEARING, SELF-ALIGNING - A roller-element bearing with one spherical raceway that automatically provides compensation for shaft or housing deflection or misalignment.

359. BEARING, SELF-LUBRICATING - A bearing independent of external lubrication. These bearings may be sealed for life after packing with grease or may contain self-lubricating material.

360. BEARING, SLEEVE - A cylindrical plain bearing used to provide radial location for a shat, which moves axially. Sleeve bearings consist of one or more layers of bearing alloys, bonded to a steel backing.

361. BEARING, SLIDE - A bearing used or positioning a slide or for axial alignment of a long rotating shaft.

362. BEARING, STEP - A plane surface bearing that supports the lower end of a vertical shaft.

363. BEARING, THRUST - A bearing in which the load acts in the direction of the axis of rotation.

364. BEARING, TILTING PAD - A pad bearing in which the pads are free to take up a position at an angle to the opposing surface according to the hydrodynamic pressure distribution over its surface.

365. BEARING, TRUNNION - A bearing used as a pivot to swivel or turn an assembly.

366. BED - A mass of ion-exchange resin particles contained in a column.

367. BED DEPTH - The height of the resinous material in the column after the ion exchanger has been properly conditioned for effective operation.

368. BED EXPANSION - The effect produced during backwashing when the resin particles become separated and rise in the column. The expansion of the bed due to the increase in the space between resin particles may be controlled by regulating backwash flow (typical with water treatment).

369. BEDPLATE

370. BELLOWS - Corrugated cylindrical container which moves as pressures change, or provides a seal during movement of parts.

371. BELLOWS SEAL - A type of mechanical seal that utilizes a bellows for providing secondary sealing.

372. BENDING MOMENT - The algebraic sum of the couples or the moments of the external forces, or both, to the left or right of any section on a member subjected to bending by couples or transverse forces, or both.

373. BERNOULLI'S THEOREM - In stream of liquid, the sum of elevation head, pressure head and velocity remains constant along any line of flow provided no work is done by or upon liquid in course of its flow, and decreases in proportion to energy lost in flow.

374. BICACARBONATE ALKALINITY - The presence in a solution of hydroxyl (OH-) ions resulting from the hydrolysis of carbonates or bicarbonates. When these salts react with water, a strong base and a weak acid are produced, and the solution is alkaline.

375. BICARBONATE - An ion or salt of carbonic acid, containing hydrogen, carbon, and oxygen (HC03), such as sodium bicarbonate, NaHC03.

376. BIMETAL STRIP - Temperature regulating or indicating device which works on principle that two dissimilar metals with unequal expansion rates, welded together, will bend as temperatures change.

377. BIMETALLIC COUPLE - A joint or union of two dissimilar metals.

378. BIMETALLIC ELEMENT -

379. BIOCIDE - A chemical used to control the population of troublesome microbes.

380. BLACK LIQUOR - The liquid material remaining from pulpwood cooking in the soda or sulfate papermaking process.

381. BLADE CLEARANCE (STEAM TURBINE)

382. BLADE DEPOSITES - Impurities carried over in the Steam and deposited on the turbine blades as afine coating.

383. BALDE FOULING - The accumulation on turbine blades of impurities carried over from the boiler with the steam.

384. BLADE LOSS - Loss caused by the inefficiency of blading.

385. BLADE SEALS

386. BLADE VELOCITY

387. BLAST FREEZER - Low-temperature evaporator which uses a fan to force air rapidly over the evaporator surface.

388. BLAST FURNACE GAS - Is the waste product from furnaces used to smelt iron ores.

389. BLEEDER (BLEEDER VALVE) - A valve designed to slowly relief a liquid or gas form system.

390. BLEEDING - Slowly reducing the pressure of liquid or gas from a system or cylinder by slightly opening a valve.

391. BLEEDOFF - The continuous removal of water from a re-circulating water system.

392. BLEEDOFF RATE - The rate at which water is continuously removed from a system.

393. BLOCK DIAGRAM: A diagram in which the major components of a piece of equipment or a system are represented by squares, rectangles, or other geometric figures, and the normal order of progression of a signal or current flow is represented by lines.

394. BLOWBY: Exhaust gases that escape past the piston rings.

395. BLOWDOWN - In connection with boilers or cooling towers, the process of discharging a significant portion of the aqueous solution in order to remove accumulated salts, deposits and other impurities.

396. BLOWDOWN-SAFETY VALVE - The difference between the pressure at which a safety valve opens and at which it closes.

397. BLOW-OFF VALVE - A specially designed, manually operated, valve that connects to the boiler for the purpose of reducing the concentration of solids in the boiler or for draining purposes. (Often called bottom blowdown.)

398. BLOWER: A low-pressure air pump, usually a rotary or centrifugal type of pump, that supplies air above atmospheric pressure to the combustion chambers of an internal-combustion engine.

399. BLUEPRINTS: Copies of mechanical or other types of technical drawings.

400. BOILER - Closed container in which a liquid may be heated and vaporized.

401. BOILER BLOW PIPING: Piping from the individual boiler blow valves to the overboard connection at the skin of the ship.

402. BOILER DESIGN PRESSURE: Pressure specified by the manufacturer, usually about 103% of normal steam drum operating pressure.

403. BOILER EFFICIENCY - The term Boiler efficiency" is often substituted for combustion or thermal efficiency. True boiler efficiency is the measure of fuel-to-steam efficiency.

404. BOILER FEED WATER - Deaerated water in the piping system between the deaerating feed tank and the boiler (The total water fed to a boiler producing steam. This water is the mixture of return steam condensate and makeup water).

405. BOILER HORSEPOWER - The work required to evaporate 34.5 lb of water per hour into steam from and at 100C.

406. BOILER LOAD: The steam output demanded from a boiler, generally expressed in pounds per hour (lb/hr).

407. BOILER LOAD FACTOR - The ratio of the actual output of a boiler to the possible maximum output for the same number of steaming hours.

408. BOILER LAY-UP - Storing and protecting the boiler when not in use.

409. BOILER REFRACTORIES: Materials used in the boiler furnace to protect the boiler from the heat of combustion.

410. BOILING - (See vaporization)

411. BOILING OUT - The boiling of high alkaline water in boiler pressure parts for the removal of oil, greases, prior to normal operation or after major repairs.

412. BOILING POINT - The temperature at which the vapor pressure of a liquid equals the absolute external pressure at the liquid-vapor interface.

413. BOILING TEMPERATURE - Temperature at which a fluid changes from a liquid to a gas.

414. BONNET: A cover used to guide and enclose the tail end of a valve spindle.

415. BORE - Inside diameter of a cylinder.

416. BOSCH METERING SYSTEM: A metering system with a helical groove in the plunger, which covers or uncovers ports in the pump barrel.

417. BOTTOM BLOW: A procedure that removes suspended solids and sludge from a boiler.

418. BOTTOM DEAD CENTER: See BDC.

419. BOUNDARY LUBRICATION - Lubrication between bearing surfaces where the lubricant layer is of variable thickness because of the impossibility of obtaining perfectly smooth bearing surfaces.

420. BOURDON TUBE - Thin-walled tube of elastic metal flattened and bent into circular shape, which tends to straighten as pressure inside is increased. Used in pressure gauges.

421. BOYLES' LAW - If the temperature on a gas is constant, the volume is inversely proportional to the pressure. By formula - VP = V1P1

422. BRAKE HORSEPOWER (bhp): The usable power delivered by an engine.

423. BRAKE MEAN EFFECTIVE PRESSURE (bmep): Mean effective pressure acting on the piston, which would result in a given brake horsepower output if there were no losses from friction, cooling, or exhaust. Bmep is equal to mean indicated pressure times mechanical efficiency.

424. BRAKE THERMAL EFFICIENCY: Ratio of power output (in the form of brake horsepower) to equivalent power input (in the form of heat from fuel.

425. BRANCH CIRCUIT - Wiring between the last overcurrent device and the branch circuit outlets.

426. BRASS - A copper-zinc alloy containing up to 40% zinc and some smaller amounts of other metals.

427. BRAYTON CYCLE (also referred to as the Joule Cycle) - A rotating machine in which compression and expansion take place. Gas turbine are such an example.

428. BRAZE - A weld produced by heating an assembly to suitable temperatures and by using a filler metal having a liquidus above 450C. The filler metal is distributed between the closely fitted facing surface of the joint by capillary action.

429. BRAZING, BLOCK - A brazing process in which the heat required is obtained from heated blocks applied to the parts to be joined.

430. BREAKER POINTS: Metal contacts that open and close a circuit at timed intervals.

431. BREAKTHROUGH - The first appearance in the solution flowing from an ion-exchange unit of unabsorbed ions similar to those which are depleting the activity of the resin bed. Breakthrough is an indication that regeneration of the resin is necessary.

432. BRINE - Water saturated with a chemical such as salt.[ (1) A highly concentrated solution of salt in water, normally associated with the over-board discharge of distilling plants. (2) Any water in which the concentration of chemical salts is higher than seawater].

433. BRITISH THERMAL UNIT, (BTU) - The Btu is defined as the heat required to raise the temperature of a pound of water thru 1F.

434. BRITTLENESS - The tendency of a material to fracture without first undergoing significant plastic deformation.

435. BRONZE - A copper-rich copper tin alloy with or without small proportions of other elements.

436. BRUSH: The conducting material, usually a block of carbon, bearing against the commutator or slip rings through which the current flows in or out.

437. BTDC: Abbreviation for before top dead center.

438. BTU - British Thermal Unit.

439. BUFFER - A substance used in solution, which accepts hydrogen ions or hydroxyl ions, added to the solution as acids or alkalis, minimizing a change in pH.

440. BULB - The name given to the temperature-sensing device located in the fluid for which control or indication is provided. The bulb may be liquid-filled, gas filled, or gas-and-liquid filled. Changes in temperature produce pressure changes within the bulb which are transmitted to the controller.

441. BULGE - A local distortion or swelling outward caused by internal pressure on a tube wall or boiler shell due to overheating.

442. BULL GEAR: The largest gear in a reduction gear train-the main gear, as in a geared turbine drive.

443. BURNER - A device for the introduction of fuel and air into a furnace at the desired velocities, turbulence and concentration.

444. BURNER WINDBOX - A plenum chamber around a burner that maintains an air pressure sufficient for proper distribution and discharge of secondary air.

445. BURNER WINDBOX PRESSURE - The air pressure maintained in the windbox or plenum chamber measured above atmospheric pressure.

446. BUS BAR - A heavy, rigid metallic conductor which carries a large current and makes a common connection between several circuits. Bus bars are usually uninsulated and located where the electrical service enters a building; that is, in the main distribution cabinet.

447. BUSHING: A renewable lining for a hole in which a shaft, rod, or similar part moves.

448. BUS TRANSFER: A device for selecting either of two available sources of electrical power. It may be accomplished either manually or automatically.

449. BUTTERFLY VALVE: A lightweight, relatively quick acting, positive shutoff valve.

450. BYPASS - A pipe or duct, usually controlled by valve or damper, for conveying a fluid around an element of a system.

451. BYPASS - Passage at one side of, or around, a regular passage.

452. BYPASS FEEDER - A closed tank that is installed in a system in "bypass," that is, in a side stream taken off the system and leading back to the system rather than directly in-line.

C

453. CAKING - Coals may be broadly classed as non-caking, slightly-caking, medium-caking and strong-caking. On a furnace grate, caking coals soften and become plastic within a certain temperature range; fluid material exudes on to the surface of the coal particles; and gas pressure in the caking mass causes the fluid material to cover the surface of the pieces of coal and to act as a cement.454. CALCAREOUS COATING OR DEPOSIT - A layer consisting of a mixture of calcium carbonate and magnesium hydroxide deposited on surfaces being cathodically protected against corrosion, because of increased pH adjustment to the protected surface.

455. CALCIUM - A scale forming element found in boiler feedwater.

456. CALCIUM CHLORIDE - A substance used to obtain calcium chloride brine.

457. CALCIUM SULFATE - Chemical compound (CaSO4) which is used at a drying agent or desiccant in liquid line dryers.

458. CALIBRATION - A process of dividing and numbering the scale of an instrument; also of correcting or determining the error of an existing scale, or of evaluating one quantity in terms of readings of another.

459. CALORIE - It is equal to the amount of heat required to raise the temperature of one gram of water one degree Celsius.

460. CALORIMETER - Device used to measure quantities of heat or determine specific heats.

461. CALORIFIC VALUE - The heat-producing value of a substance. A measure of the total heating-power of a fuel, for example coal or oil. Usually expressed as the number of kilo Jouless evolved when one kilogramme of the fuel is completely burned.

462. CAM: A rotating component of irregular shape. It is used to change direction of the motion of another part moving against it. (For example, rotary motion is changed into reciprocating or variable motion.)

463. CAM FOLLOWER (VALVE LIFTER): A part that is held in contact with the cam and to which the cam motion is imparted and transmitted to the push rod.

464. CAM NOSE: That portion of the cam that holds the valve wide open. It is the high point of the cam.

465. CAMSHAFT: A shaft with cam lobes.

466. CAMSHAFT GEAR: The gear that is fastened to the camshaft.

467. CANGE OF STATE - Change from one phase, such as solid, liquid or gas, to another.

468. CAPACITANCE - The property of an electric current that permits the storage of electrical energy in an electrostatic field and the release of that energy at a later time.

469. CAPACITOR, (CONDENSER) - A device that can store an electric charge when voltage is applied.

470. CAPACITY - The adsorption activity possessed in varying degrees by ion-exchange materials. This quality may be expressed as kilograins per cubic foot, gram-milliequivalents per gram, pound-equivalents per pound, gram-milliequivalents per milliliter, and so on, where the numerators of these ratios represent the weight of the ions adsorbed and the denominators represent the weight or volume of the adsorbent.

471. CAPILLARY - The name given to the thin tube attached to the bulb which transmits the bulb pressure changes to the controller or indicator. The cross sectional area of the capillary is extremely small compared to the cross section of the bulb so that the capillary, which is usually outside of the controlled fluid, will introduce the smallest possible error in the signal being transmitted from the bulb.

472. CAPILLARY TUBE - The capillary tube is a metering device made from a thin tube approximately 0.5 to 6 metre long and from 0.025 to 0.090 inches in diameter which feeds liquid directly to the evaporator. Usually limited to systems of 1 ton or less, it performs all of the functions of the thermal expansion valve when properly sized.

473. CARBON DIOXIDE - Compound of carbon and oxygen (CO2) which is sometimes used as a refrigerant. Refrigerant number is R-744.

474. CARBON FILTER - Air filter using activated carbon as air cleansing agent.

475. CARBON RINGS

476. CARBON TETRACHLORIDE - Colorless nonflammable and very toxic liquid used as a solvent. It should never be allowed to touch skin and fumes must not be inhaled.

477. CARBONACEOUS EXCHANGER - Ion-exchange materials of limited capacity prepared by the sulfonation of coal, lignite, peat, and so on.

478. CARBONATE - An ion or salt of carbonic acid, containing carbon and oxygen such as calcium carbonate. (CaC03)

479. CARBONATE HARDNESS - That hardness caused in water by bicarbonates and carbonates of calcium, and magnesium.

480. CARBONATE-POLYMER TREATMENT - A treatment method using synthetic polymers, generally used with high hardness (60-70) ppm and high alkalinity.

481. CARBOXYLIC - A term describing a specific acidic group (COOH) that contributes cation-exchange ability to some resins.

482. CARBURETOR: An apparatus for supplying atomized and vaporized fuel mixed with air to an internal-combustion engine.

483. CARRYOVER - (1) Boiler water entrained with the steam (by foaming or priming). (2) Particles of seawater trapped in vapor in a distilling plant and carried into the condensate. (The moisture and entrained solids forming the film of steam bubbles, as a result of foaming in a boiler. This condition is caused by a faulty boiler water condition. See also foaming).

484. CASCADE - A series of stages in which the output of one stage is the input of the next stage.

485. CASCADE SYSTEMS - Arrangement in which two or more refrigerating systems are used in series; uses evaporator of one machine to cool condenser of other machine. Produces ultra-low temperatures.

486. CASING: A housing that encloses the rotating element (rotor) of a pump or turbine.

487. CASING THROAT: An opening in a turbine or pump casing through which the shaft protrudes.

488. CASUALTY: An event or series of events in progress during which equipment damage and/or personnel injury has already occurred. The nature and speed of these events are such that proper and correct procedural steps are taken to limit damage and/or personnel injury only.

489. CASUALTY POWER SYSTEM: Portable cables that are rigged to transmit power to vital equipment in an emergency.

490. CATALYST: A substance used to speed up or slow down a chemical reaction, but is itself unchanged at the end of the reaction.

491. CATALYTIC ACTION - The action whereby certain substances promote or assist a chemical change without themselves being permanently changed.

492. CATHODE - In electrolysis or electrochemical corrosion, a site on a surface where actions in solution are neutralized by electrons to become elements that either plate out on the surface or react with water to produce a secondary reaction.

493. CATHODIC PROTECTION - A method of preventing corrosion by making the metal a cathode in a conducting medium by means of a direct electrical current that is galvanic.

494. CATHODIC PROTECTION - Reduction of corrosion rate by shifting the corrosion potential of the electrode towards less oxidizing potential by applying an external electromotive force.

495. CATION - A positively charged ion that migrates through the electrolyte toward the cathode under the influence of a potential gradient.

496. CATION-EXCHANGE SOFTENERS - 497. CATIONIC - The condition of a polymer, colloid, or large particle having exchangeable anions on its surface and an opposite, positive charge on the substrata.

498. CAUSTIC CRACKING - A form of stress-corrosion cracking most frequently encountered in carbon steels or iron-chromium-nickel alloys that are exposed to concentrated hydroxide solutions at temperature of 200 to 250C.

499. CAUSTIC EMBRITTLEMENT - An obsolete term replaced by caustic cracking.

500. CAUSTIC SODA - A common water treatment chemical, sodium hydroxide.

501. CAVITATION - The formation and collapse, within a liquid, of cavities or bubbles that contain vapor or gas or both. In general, cavitation originates from decreases in static pressure in the liquid. In order to erode a solid surface by cavitation, it is necessary for the cavitation bubbles to collapse on or close to that surface.

502. CAVITATION EROSION - Progressive loss of original material from a solid surface due to continuing exposure to cavitation.

503. CELSIUS TEMPERATURE SCALE - A thermometric scale in which the freezing point of water is called 0C and its boiling point 100C at normal atmospheric pressure.

504. CENTANE NUMBER - A measure of ignition quality of a fuel or petroleum with reference to normal centane high-ignition quality fuel with an arbitrary number of 100.

505. CENTRIFUGAL COMPRESSOR - Pump which compresses gaseous fluids by centrifugal force.

506. CENTRIFUGAL FORCE - A force exerted on a rotating object in a direction outward from the center of rotation.

507. CENTRIFUGAL FORCE -On a centrifugal pump, it is that force which throws water from a spinning impeller.

508. CENTRIFUGAL PUMP - A pump consisting of an impeller fixed on a rotating shaft and enclosed in a casing, having an inlet and a discharge connection. The rotating impeller creates pressure in the liquid by the velocity derived from centrifugal force.

509. CENTRIFUGAL PUMP - Pump which produces fluid velocity and converts it to pressure head.

510. CETANE VALUE: A measure of the ease with which diesel fuel will ignite.

511. CHAIN GRATER STROKER - A grate formed by a moving continuous chain of cast-iron links, built in various widths to suit the boiler.

512. CHANGE OF STATE - Condition in which a substance changes from a solid to a liquid or a liquid to a gas caused by the addition of heat. Or the reverse, in which a substance changes from a gas to a liquid, or a liquid to a solid, caused by the removal of heat.

513. CHANNELING - Cleavage and furrowing of the bed due to faulty operational procedure, in which the solution being treated follows the path of least resistance, runs through these furrows, and fails to contact active groups in other parts of the bed, (water treatment).

514. CHARGE - Amount of refrigerant placed in a refrigerating unit.

515. CHARGING BOARD - Specially designed panel or cabinet fitted with gauges, valves and refrigerant cylinders used for charging refrigerant and oil into refrigerating mechanisms.

516. CHARLS LAW - Gas volume is directly proportional to absolute temperature.

517. CHECK VALVE - Device which permits fluid flow in one direction.

518. CHELATE - Is a molecule, similar to an ion exchanger, capable to withdraw ions from their water solutions into soluble complexes.

519. CHEMICAL CLEANING - Using a solvent solution to remove mill scale and corrosion products.

520. CHEMICAL ENERGY: Energy stored in chemicals (fuel) and released during combustion of the chemicals.

521. CHEMICAL FEEDLINE - The line which feeds the boiler treatment chemicals into the boiler.

522. CHEMICAL PRECIPITATION - When the chemicals react with the dissolved minerals in the water to produce a relative insoluble reaction product. A typical example of this takes place with the lime-soda softening process.

523. CHEMICAL REFRIGERATION - System of cooling using a disposable refrigerant. Also called an expendable refrigerant system.

524. CHEMICAL STABILITY - Resistance to chemical change which ion-exchange resins must possess despite contact with aggressive solutions.

525. CHILL FACTOR - Calculated number based on temperature and wind velocity.

526. CHILLED-WATER SYSTEM - A re-circulating water system using water chilled in a refrigeration machine as a source for cooling.

527. CHILLER/HEATERS - A unit that supplies either chilled water for cooling or hot water for heating, (HVAC).

528. CHLORIDE - An ion, compound, or salt of chlorine, such as sodium chloride (NaCl) or calcium chloride (CaCl2).

529. CHLORINATION - A process in which chlorine gas or other chlorine compounds are added to the water for the purpose of disinfecting.

530. CHOKE TUBE - Throttling device used to maintain correct pressure difference between high-side and low-side in refrigerating mechanism. Capillary tubes are sometimes called choke tubes.

531. CHORDAL THERMOCOUPLE - A thermocouple installed in furnace tubes, designed to measure the effectiveness of water treatment within the boiler.

532. CIRCUIT - An electrical arrangement requiring a source of voltage, a closed loop of wiring, an electric load and some means for opening and closing it.

533. CIRCUIT BREAKER An electromagnetic or thermal device that opens a circuit when the current in the circuit exceeds a predetermined amount. Circuit breakers can be reset [A switch-type mechanism that opens automatically when it senses an overload (excess current)]

534. CIRCULATING WATER: Water circulating through a heat exchanger (condenser or cooler) to transfer heat away from an operating component.

535. CIRCULATION RATIO - The ratio of water entering a circuit to the steam generated by that passes that circuit in a unit of time.

536. CLARIFIER: A water tank containing baffles that slow the rate of water flow sufficiently to allow heavy particles to settle to the bottom and light particles to rise to the surface. This separation permits easy removal, thus leaving the clarified water. The clarifier is sometimes referred to as a settling tank or sedimentation basin.

537. CLAY - Finely suspended earth mineral sometimes found as an impurity in water.

538. CLEARANCE SPACE - Space between top of piston and the valve plate.

539. CLEARANCE VAPOR - The vapor remaining in the clearance space at the end of each discharge stroke.

540. CLOSED COOLING SYSTEM: Consisting of two entirely separate circuits-a freshwater circuit and a seawater circuit.

541. CLOSED CYCLE - is the gas turbine arrangement, in which the exhaust is directed back again to compressor without coming in contact with the atmospheric air.

542. CLOSED FEEDWATER HEATER - An indirect-contact feedwater heater. Steam and water are separated by tubes.

543. CLOSED FEED VALVE - A valve for automatically controlling the condensate level in a condenser when feed-water is introduced directly into the condenser.

544. CLOSED RE-CIRCULATING WATER SYSTEM - A system using as a heat-transfer medium water that continuously circulates through closed piping and heat exchanger without evaporation.

545. CLUTCH: A form of coupling that connects or disconnects a driving or driven member.

546. COCOAGULANT - A substance that promotes the clumping of particulate matter in water, forming a larger mass and thus promoting settling of particulates and clarification of the water.

547. COAGULATION - Is the process whereby finely divided particles of turbidity and color, capable of remaining in suspension indefinitely, are combined by chemical means into masses sufficiently large to effect rapid settling.

548. COALESCENCE - The gathering together of coagulated colloidal liquids into a single continuous phase.

549. COAL EQUIVALENT OF A FUEL - The amount of coal which would have to be burned to supply an amount of electricity equal to that supplied by the other fuel being compared, for example oil.

550. COAL SEGREGATION - The tendency for the small lumps of coal to separate out from the fine coal between the bunkers and the stoker hoppers.

551. COALING RATE - The amount of electricity which can be generated from one tonne of coal used. This figure is useful as a check on unit efficiency, but can also be misleading when coal quality varies.

552. COCK: A valve that is opened or closed by a quarter turn of a disk or a tapered plug. When a plug is used, it is slotted to correspond with the ports in the valve.

553. CODE INSTALLATION - Refrigeration or air conditioning installation which conforms to the local code and/or the national code for safe and efficient installations.

554. CO-EFFICIENT OF CONDUCTIVITY - Measure of the relative rate at which different materials conduct heat. Copper is a good conductor of heat and, therefore, has a high coefficient of conductivity.

555. COEFFICIENT OF EXPANSION - A measure of the change in length or volume of an oject, specifically, a change measured by the increase in length or volume of an object per unit length or volume.

556. COEFFICIENT OF FRICTION - The dimensionless ratio of the friction force (F) between two bodies to the normal force (N) pressing these bodies together - m (f) = (F/N)

557. COEFFICIENT OF PERFORMANCE (COP) - Ratio of work performed or accomplished as compared to the energy used under designated operating conditions.

558. COEFFICIENT OF THERMAL EXPANSION

559. COGENERATION - A term used to describe the combination of different thermodynamic cycles for the purpose of increasing all-over cycle efficiency.

560. CO-GENERATION GENERATION - a term applied to identify the generation of people interested in co-generation.

561. COLD - The absence of heat; a temperature considerably below normal.

562. COLD DECK -The cooling section of a mixed air zoning system.

563. COLD IRON CONDITION: An idle plant, when all services are received from an external source such as shore or tender.

564. COLD JUNCTION - That part of a thermoelectric system which absorbs heat as the system operates.

565. COLD PROCESS - A water treatment process carried out at room temperature.

566. COLD START - The starting up of a turbine when cold. Such starts require a carefully worked out programme if damage is to be avoided.

567. COLD WALL - Refrigerator construction which has the inner lining of refrigerator serving as the cooling surface.

568. COLLOIDAL - A state of suspension in a liquid medium in which extremely small particles are suspended and dispersed but not dissolved.

569. COLLOIDS - Organic matter of very fine particle size, usually in the range of 10-5 to 10-7 cm in diameter. It tends to inhibit the formation of dense scale and results in the deposition of sludge, or causes it to remain in suspension, so that it may be blown from the boiler.

570. COLUMN OPERATION - Conventional utilization of ion-exchange resins in columns through which pass, either upflow or downflow, the solution to be treated.

571. COMBINED FEEDER CUTOFF - A device that regulates makeup water to a boiler in combination with a low-water fuel cutoff.

572. COMBINED STEAM-GAS PLANT - where a gas turbine is combined with steam plant in order to utilize the waste heat.

573. COMBINED TREATMENT - A method of physical treatment , followed by the addition of chemicals to remove oxygen.

574. COMBUSTIBLE LOSS - The loss representing the unliberated thermal energy occasioned by failure to oxidize completely some of the combustible matter in the fuel.

575. COMBUSTION The burning of fuel in a chemical process accompanied by the evolution of light and heat (The act or process of burning).

576. COMBUSTION AIR: The air delivered to a boiler furnace, engine, or gas turbine combustor to support burning of atomized fuel.

577. COMBUSTION CHAMBER: The chamber in which combustion mainly occurs.

578. COMBUSTION-CHAMBER VOLUME: The volume of the combustion chamber (when the piston is at TDC) measured in cubic centimeters.

579. COMBUSTION CYCLE: A series of thermo-dynamic processes through which the working gas passes to produce one power stroke. The full cycle is-intake, compression, power, and exhaust.

580. COMBUSTION EFFICIENCY - The effectiveness of the burner to completely burn the fuel. A well designed burner will operate with as little as 10 to 20% excess air, while converting all combustibles in the fuel to useful energy.

581. COMFORT CHART - A chart showing effective temperatures with dry-bulb temperatures and humidities (and sometimes air motion) by which the effects of various air conditions on human comfort may be compared.

582. COMFORT COOLER - System used to reduce the temperature in the living space in homes. These systems are not complete air conditioners as they do not provide complete control of heating, humidifying, dehumidification, and air circulation.

583. COMFORT COOLING - Refrigeration for comfort as opposed to refrigeration for storage or manufacture.

584. COMFORT ZONE - (Average) the range of effective temperatures over which the majority (50 percent or more) of adults feels comfortable; (extreme) the range of effective temperatures over which one or more adults feel comfortable. An area on the psychrometric chart which shows conditions of temperature, humidity and sometimes air movement in which most people are comfortable.

585. COMMON NEUTRAL - A neutral conductor that is common to, or serves, more than one circuit.

586. COMMUTATOR: The copper segments on the armature of a motor or generator. It is cylindrical in shape and is used to pass power into or from the brushes.

587. COMPENSATING DEVICE: Mechanical or hydraulic action which prevents over correction of change.

588. COMPONENT: Individual unit, or part, of a system; also, the major units which, when suitably connected, comprise a system.

589. COMPOSITION - The elements or chemical components that make up a material and their relative proportions.

590. COMPOUND - They are chemically combined elements with definite proportions of the component elements.

591. COMPOUNDING - The use of many rows of blades in separate cylinders in a turbine, to absorb more efficiently the kinetic energy of the steam.

592. COMPOUND GAUGE - Instrument for measuring pressures both above and below atmospheric pressure.

593. COMPOUND REFRIGERATING SYSTEMS - System which has several compressors or compressor cylinders in series. The system is used to pump low pressure vapors to condensing pressures.

594. COMPOUND TURBINE - One in which the steam is expanded in a number of separate cylinders. In a tandem compound turbine they are In line and the rotors are coupled. In a cross-compound turbine the cylinders are in two lines driving two generators.

595. COMPRESSION - Term used to denote increase of pressure on a fluid by using mechanical energy.

596. COMPRESSION RING: The piston rings used to reduce combustion leakage to a minimum.

597. COMPRESSION RATIO - Ratio of the volume of the clearance space to the total volume of the cylinder. In refrigeration it is also used as the ratio of the absolute low-side pressure to the absolute high-side pressure.

598. COMPRESSION, ADIABATIC - Is compressing a gas without removing or adding heat.

599. COMPRESSION STROKE: That stroke of the operating cycle during which air is compressed into a smaller space creating heat by molecular action.

600. COMPRESSOR - Pump of a refrigerating mechanism which draws a low pressure on cooling side of refrigerant cycle and squeezes or compresses the gas into the high-pressure or condensing side of the cycle.

601. COMPRESSOR - The pump which provides the pressure differential to cause fluid to flow and in the pumping process increases pressure of the refrigerant to the high side condition. The compressor is the separation between low side and high side.

602. COMPRESSOR DISPLACEMENT - Volume, in cubic inches, represented by the area of the compressor piston head or heads multiplied by the length of the stroke.

603. COMPRESSOR SEAL - Leak proof seal between crankshaft and compressor body in open type compressors.

604. COMPRESSOR SURGING - An instability of air flow with axial compressor on the first stages of these compressors. Air flow might even be reversed that point.

605. COMPRESSOR TURBINE - in terms of a gas turbine arrangement, it is the turbine which drives the compressor only.

606. COMPRESSOR, CLEARANCE POCKET - Small space in a cylinder from which compressed gas is not completely expelled. This space is called the compressor clearance space or pocket. For effective operation, compressors are designed to have as small a clearance space as possible.

607. COMPRESSOR, ROTARY BLADE - Mechanism for pumping fluid by revolving blades inside cylindrical housing.

608. COMPRESSOR, SINGLE-STAGE - Compressor having only one compressive step between low-side pressure and high-side pressure.

609. COMRESSIBILITY - The ease which a fluid may be reduced in volume by the application of pressure, depends upon the state of the fluid as well as the type of fluid itself.

610. CONCENTRATION - (1) The weight of solids contained in a unit weight of boiler or feed water. (2) The number of times that the dissolved solids have increased from the original amount in the feedwater to that in the boiler water due to evaporation in generating steam.

611. CONDENSATE - The liquid formed by condensation of a vapor. In steam heating, water condensed from steam; in air conditioning, water extracted from air, as by condensation on the cooling coil of a refrigeration machine.

612. CONDENSATE DEPRESSION: The difference between the temperature of condensate in the condenser hotwell and the saturation temperature corresponding to the vacuum maintained in the condenser.

613. CONDENSATE POLISHER - A device used to clean the returning condensate to the boiler feedwater system.

614. CONDENSATE PUMP - Device to remove water condensate that collects beneath an evaporator.

615. CONDENSATION - Process of changing a vapor into liquid by extracting heat. Condensation of steam or water vapor is effected in either steam condensers or dehumidifying coils, and the resulting water is called condensate.

616. CONDENSE - Action of changing a gas or vapor to a liquid.

617. CONDENSER - An apparatus used to transfer heat from a hot gas, simultaneously reducing that gas to a liquid.

618. CONDENSER CLINING - The removal of deposits on the circulating-water side of condenser tubes, to restore efficient heat-transfer.

619. CONDENSER BACK PRESSURE - The absolute pressure at the top of a condenser, usually expressed in inches of mercury.

620. CONDENSER LEAKAGE - Leakage within the condenser, whereby condensate becomes contaminated by impurities contained in the circulating water.

621. CONDENSER PRESSURE DROP - The difference in pressure between the exhaust-steam inlet at the top of the condenser and the condensate take-off at the bottom.

622. CONDENSER SHELL - The outer casing and supporting structure of the condenser.

623. CONDENSER TUBE - The heat transfer surface in a condenser.

624. CONDENSER TUBE FOULING - The formation of foreign matter on the circulating-water side of the condenser-tube surface.

625. CONDENSER-WATER SYSTEM - A re-circulating cooling water used as a heat transfer fluid for the condensation of a gas.

626. CONDENSING BLEEDER TURBINE

627. CONDENSING TEMPERATURE - The temperature at which the condensing gas is returned to a liquid at the same pressure.

628. CONDENSING TURBINE The exhau