Document MojXrBEQEKZ45QBkv4O0m2qYa

American Society of Heating and Ventilating Engineers Guide, 1934 - Vacuum Heating System: A two-pipe steam Keating system equip ped with the necessary accessory apparatus which will permit operating 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. 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 Head or Pressure:: The head or pressure required to create the velocity of flow, that is, the head or pressure required to accelerate the mass from a state of rest to the velocity at the point measured. Ventilation: The process of supplying or removing air by natural,or mechanical means, to or from any space. Such air may or may riot 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 the1 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 for fan circulation, it is termed a fan furnace system or a centralfanfurnace system. A fan furnace system may include air washers, and filters. Wet-Bulb Temperature: The lowest temperature w;hich a water wetted body will attain when exposed to an air current. (This .is the temperature of adiabatic saturation). 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). ABBREVIATIONS2 Absolute............................. :......... :..... ........ -............................................ ......... ...... .............:.abs Acceleration, due to gravity......................................................... .....................,..... .....................,.g Acceleration, linear.............--.......---..... 1................--........ ............................................... ....... ... ..a Air horsepower...........'...............................-.............-........ ....... . .......... :..... - ^'r hp Alternating-current (as adjective)................................................................................................ -a-c Ampere............ ........ ..................................... --................... ......................................... --................ .amp Ampere-hour...;!-:........:......................... --........................ .............. --.............. ....... :........ amp-hr II,'roni compilations of abbreviations approved by the Americdn-Standards Association...... 5% Chapter 42--Heating and Ventilating Standard Terms Area.............................................................. ................. --................................... ..........................A Atmosphere-..... ........................................................................................................ ...--;............. atm Average............................................................... ..................................... :............................................avg Avoirdupois...:..... ..............................;..... :______ ___;..... ;....... :....... ....... ........................... .-........avdp Barometer......................................................... ................................................................................... bar. Boiler pressure..--,...... ...........,.................. ,................. ....... ........................................ ......................bp Boiling point...__,.......................................,.............................. .. .. . ...................._,......................bp Brake horsepower....... ,.......,.............. ,....................... .............. ........ ......... ......... ................. .........bhp Brake horsepower-hour........._............. .................... ................................................................ bhp-hr British thermal unit..................... ,............,____ ......................... ,........ .......................,............. Btu Calorie,--,----.--............................................................ ,......................... ........................ ,..... cal Centigram..................,,.......................... ......... .......... .......................................:.............. ;...........eg Centimeter , ......... .............. ,, --...,........................ .................................................cm Centimeter-gram-second (system)...,...,....... ....... ........... ............................................................ cgs Change in specific volume during vaporization............................. ............... ............................,v{g Cubic.,............... ................ ....................,.............................. ............,...........................,....,,................. :cu Cubic foot............... ,...... ..................................................... ............,......... .................._......... ........ cu ft Cubic feet per minute--..................,...... ..................................................,................ ,............._.....cfm Cubic feet per second,...----.,.............................. .................. ,......... ................................ .............. cfs Decibel................. ................. ,........ ,....... ,................ ................. .................................. ........................db Degree3..:--...................................................................... deg or Degree centigrade---------.................... .......................... :;... ;................ ................ ...................... C Degree. Fahrenheit--........ ............................ ,...... ............................................ .............................. F Degree Kelvin...:....................... ....... ,..... ..................... ....................................................................... .K Degree Reaumur...____--....... ..... ;...... ............... ;.................................................................................R Density, Weight per unit volume, Specific weight--.............................................. d or p (rho) 1 Diameter..................................................................................... .........................................:...D or diam Direct-current (as adjective)................................................................................ .;........................d-c Distance, linear................. ........................................................ ................................................... ............s Dry saturated vapor, Dry saturated gas at saturation pressure and temperature, Vapor in contact with liquid......:........................................... ...... ......................... Subscript g Entropy (The capital should be used for any weight, and the small letter for unit weight) ...-..........: : .............. :...................... ....- C...................................-- ................5 OT S Feet per minute....................... .................. ...................................... ............. ..................................fpm Feet per seconds .:.........--.......... .. . . ........ --....................................... ,................................ ...fps Foot............ :........----........................... ;............................... :........... ................................. ;.............--ft Foot-pound........................................................................ ..............;....... .......................................ft-lb Foot-pound-second (system).................................. .................................... .......................... ;.........fps Force, total load......................:........................... ........... .............................. ......................................F Freezing point...................................... ,...................................................................................... ,........fp Gallon...................................................... gal Gallons per minute................................................ .......................,........................................... ,...... gpm Gallons per second.............................................................................:................. ...................gps Gram___ ;............. ^................... ................................................ ............. ::______ ___ -...... .....................g Gram-calorie:.......... ...g-cal Head................................................................................. :................................................................H or h Heat content, Total heat, Enthalpy. (The capital should be used for any weight and the small letter for unit weight).......................... ............................................... ...II or h Heat content of saturated liquid, Total heat of saturated liquid, Enthalpy of saturated liquid, sometimes called heat of the liquid.!....................................... :..........hi Heat content of dry saturated vapor, Total heat of dry saturated vapor, Enthalpy of dry saturated vapor.............................. hg Heat of vaporization at constant pressure........... ......... ................ ...............................L or Afg Horsepower........................................................................ .:................... ......................... ...........'hp Horsepower-hour..._......................................................................................... ................. ,............hp-hr Inch...........................................................:..................................................................................... .'...`...in. i *It is recommended that the'abbreviation for the temperature scale,. F, C, K, etc., be included in express sions for numerical temperatures but, wherever feasible, the abbreviation for degree be omittedas .68 F;; 597,