Document zzgoQdXrXp6d72B4rL5X0N767

794 Chapter 47 1945 Guide Velocity: The time rate of motion of a body in a fixed direction. In the fps system ' it is expressed in units of one foot per second. V = --. Velocity Pressure: The difference due to velocity between total pressure and static pressure. It is supposed to equal the kinetic energy per unit volume of the fluid at the point of measurement. Ventilation: The process of supplying or removing air by natural or mechanical means,' to or from any space. Such air may or may not have been conditioned. (See Air Conditioning.) . Warm Air Heating System: A warm air heating plant consists of a heating unit (fuel-burning furnace) enclosed in a casing, from which the heated air is distributed to the various rooms of the building through ducts. If the motive head producing flow depends on the difference in weight between the heated air leaving the casing and the cooler air entering the bottom of the casing, it is termed a gravity system. A booster - fan may, however, be used in conjunction with a gravity-designed system. If a fan is used to produce circulation and the system is designed especially fdr fan circulation, it is . termed a fan furnace system or a central fan furnace system. A fan furnace system may include air washers and filters. Wet-Bulb Temperature: Thermodynamic wet-bulb temperature is the temperature at which liquid or solid water, by evaporating into air, can bring the air to saturation adiabatically at the same temperature. Wet-bulb temperature (without qualification) is the temperature indicated by a wet-bulb psychrometer constructed and used according to.. specifications. (A.S.M.E. Power Test Codes, Series.1932, Instruments and Apparatus,. Part 18.) Wet Return: That part of a return main of a steam heating system which is filled with water of condensation. The wet return usually is below the level of the water line in the boiler, although not necessarily so. (See Dry Return.) CHAPTER 48 -^Iblreuiationi, Sijmlois, Standards Standard Abbreviations; Standard Symbols; Conversion Equations; Graphical Symbols for Piping, Ductwork, Heating and Ventilating, Refrigerating; Specific Heat Table; State Codes or Standards THIS chapter contains information regarding abbreviations, symbols, conversion equations, and State codes, which are of particularinterest to the engineer engaged in heating, ventilating, and air conditioning. ABBREVIATIONS Abbreviations are shortened forms of names and expressions employed in texts and tabulations and should not generally be used as symbols in equations. Most of the following abbreviations have been compiled from a list of approved, standards1. In general the period has been omitted in all abbreviations except where the omission results in the formation of an English word. Absolute---............................ ................ Air horsepower............................... ;_... Alternating-current (as adjective)... Ampere....... ....................................... Ampere-hour....................................... Atmosphere........................................ Average................................................ Avoirdupois.......... ............................ u Barometer........................................... Boiling point........................................ Brake horsepower..--................. Brake horsepower-hour................ ,;... British thermal unit........................... British thermal units per hour........ Calorie........ ............................. .......... Centigram.................. ;................. ....... Centimeter........................................_.. Centimeter-gram-second (system)... Cubic.................................................... Cubic foot............................. '............. Cubic feet per minute....................... : Cubic feet per second.................:...... Decibel...... ............ ............................ . Degree5........... ,.................... ................ Degree Centigrade_____ '........ ......... Degree Fahrenheit____ :___________ Degree Kelvin.................................... Degree Reaumur.....................-- Diameter........................................... .. Direct-current (as adjective)--....... Feet per minute--............................... Feet per second.............. Foot--.................. .................. Foot-pound................................ Foot-pound-second (system)............ Freezing point.................................... --.........~abs -- ...... air.hp ---------- a-c _______ amp __ :_amp-hr ------------ atm -------- ---avg _______ avdp ------------ bar. -------------- bp .....-------- bhp _____ bhp-hr..... ,____ Btu ---------- Btuh --------------cal --........eg .......... cm -------- cgs --------- cu ____cu ft _____cfm _____ cfs _____ db .:_.d_eg_o..r.c ____ F ______ K ______ R ___ diam ------- .d-c ____ fpm -------- fps. _______ft ____ ft-lb -r-fPS----------fp Abbreviations for Scientific and Engineering Terms, Z10.1-194I (American Standards Association). d?IO,nl,nen*le<1.11131 abbreviation for the temperature scale. F. C. X. be included in expressions lor numerical temperatures but, wherever feasible, the abbreviations for degree be omitted; as 68 F.