Document n915gzvqL62ZEY16GoLzBK6z

American Society of Heating and Ventilating Engineers Guide, 1937 ` 0 Chapter 44--Terminology and floor when supported from below. Other descriptive words include free delivery when the unit is not intended to be attached to ducts or similar resistance-producing devices, and pressure when for use with such ducts. Complete description requires the use of several of these qualifyjne words or phrases. See Chapter 13. 8 ABBREVIATIONS2 'r Absolute.----- -- ;tv Arceleration, aue to gravity....................... .................... % Acceleration, linear.-- ............................................. ............................................... g .............................................. a .....................................air hp Up-Feed System {steam): A steam heating system in which the supply mains are below the level of the heating units which they serve Vacuum- Heating System: A two-pipe steam heating system equip, ped with the necessary accessory apparatus which will permit operating Alternating-current (as adjective).--............. -....................................... ........................................ amp Ampere-----;--........................... Ampere-hour..........................................-............................- amp-hr ...... A Area---,-.......................... Atmosphere- -........................................ .......... :.......................................... .. ....................._..................atm the system below atmospheric pressure when desired. Vapor: Any substance in the gaseous state. Vapor Heating System: A steam heating system which operates under pressures at or near atmospheric and which returns the condensa tion to the boiler or receiver by gravity. Vapor systems have thermo static traps or other means of resistance on the return ends of the heating units for preventing steam from entering the return mains; they also have a pressure-equalizing and air-eliminating device at the end of the dry return. Direct Vent Vapor System: A vapor heating system with air valves which do not permit re-entry of air. Average.--;........... -...................................................................... f Avoirdupois--.......................................-......................................... Barometer.--......................................................... Boiler pressure....................................-................................ \ Boiling point.-----............................................ Brake horsepower.......................................................... > Brake horsepower uuui.......................... --.....-----................... ~ British thermal unit............................. .......--......................... *.......... H .................................... avdp ............................................bp ............................................bp ................bhp ................................... bhp-hr ..........................................Btu ......................................... cal 1 i Centimeter.........................-- -...... .---:................................... ............................................cm X Change in specific volume during vaporization............ ....... .............. ............................................. cu Vapor Pressure: The equilibrium pressure exerted by a vapor in contact with its liquid. Velocity: The time rate of motion of a body in a fixed direction. In . t 31 . c.u ft ........................................ efra .............................. .cfs ............ .......db the fps system it is expressed in units of one foot per second. V = ~. Velocity Pressure: The pressure corresponding to the velocity of Dcgi cc *" ** 4 j 1 S' ...... C ........... ........................F ............... ............. K R flow. It is a measure of the kinetic energy of the fluid. Density, Weight per unit volume, Specific weight-......................... .........................-d or p (rho) 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 1 d = -- been conditioned. (See Air Conditioning.) Warm Air Heating System: A warm air heating plant consists of a Diameter.................... ............. . Direct-current (as adjective) _D or diam ................ d-c 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 Distance, linear-----Dry saturated vapor, Dry saturated gas at saturation pressure and temperature, Vapor in contact with liquid___________________________ ___ 1----------------- Subscript g Entropy (The capital should be used for any weight, and the small letter for unit weight between the heated air leaving the casing and the cooler air weight.).............................................................. ............ ........................... -..................... or s 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 Feet per minute.............................................. fpm Feet per second..................................................................................................................-.........fps Foot........................... :......................... 1...................................................................................... .....ft Foot-pound:................................................................................... ft-lb especially for fan circulation, it is termed a fan furnace system or a centralfanfurnace system. A fan furnace system may include air washers and filters. Foot-pound-second (system)............... .;........................................................................... fps Force, total load........................................................ ............... --~.................................................F Freezing point........................................ fp Gallon..................................... ............................................................. :......................................... gal Wet-Bulb Temperature: The lowest temperature which a water wetted body will attain when exposed to an air current. This is the temperature of adiabatic saturation. Gallons per minute............................... ..............................................................:..................... gpm Gallons per second................................................................................ :..................................... gps Gram.................................................... ........................................................ .............. ................. Gram-calorie............................................... ................................. ................. ..........................g-cal 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. 798 *From compilations of abbreviations approved by.the American Standards Association, Z, 10 a, c, f. and i. As a general rule the period is omitted in all abbreviations except where the omission results in the formation of an English word. *It is recommended that the abbreviation for the temperature scale, F, C, K, be included in expressions for numerical temperatures but, wherever feasible, the" abbreviation for degree be omitted; as 68 F. 799 ;i i: :f I' J