Document Rjrzw6DEvd5g7v0NOQ8kGE9Lk

1939Heating Ventilating Air Conditioning Guide Velocity (continued) through heating units, 610 measurement of, 827 through openings, 714 through towers,. 632 sound effect of, 697 meter, 829 steam, through an orifice, 823 in underground pipes, 781 water, in pipes, 342, 344, 346 wind, choosing, 124 measurement of, 694 on natural draft equipment, 533 in natural ventilation, 687 Vent, vents, on traps, 303 in unit ventilators, 443 . Ventilation, 49, 687, 845, (see also Air Dis tribution) of barns, 695 in drying, 679 of garages, 696 in hospitals, 616, 620 mechanical, 75 with roof ventilators, 689 natural, 75 air changes per .hour, 125 -- control of, 691 general rules for, 693 heat to be removed by, 692 openings location of, 691 skylights, 689 types of, 689 windows, 689 for public buildings, 68 quantity of air necessary for, 68 railway air conditioning, 627 by registers, 691 for schools, 69 by stacks, 688, 691 symbols, 851 Ventilator, ventilators, - roof. 689. 843 unit, 241, (see also Unit Ventilators) Venturi chimney, 186 Vibration of..machine.mountings, 605 . Vitiation of air, 49 Volume, of air and saturated vapor, 12 conversion equations, 848 furnace, 839 specific; 3 of saturated steam, 28 of water, 27 W-Z Wall, walls, absorption of heat, 153 air leakage through, 120 of chimneys, 201 condensation on, .139 fire, 658 heat transmission coefficients for, 87, 88, 95, 102, 104, 106 radiators, output, 270 solar radiation on, 150, 151 time lag through, 153 Warm air heating systems, 845. gas-fired furnaces for, 226 gravity, 383 mechanical, 399 Washers, air. 409, 517, 642, 835 Water, boiling point of, 27 from city mains, 476, 526 cooling, equipment, 625. quantity, 527 temperature, 624, 526 Water (continued) hot, domestic supply, 799, 813 boilers. 815 demand for, 819 electric heating of, 763 pipe sizes for, 814 storage of, 814, 818 heating systems, 337, (see also Hot Water Heating Systems) inches of, 841 line, in boilers, 264, 265, 281 in water supply systems, 806 make-up, 534 meters, disc, 805 pans; for humidification, 409 pipe, 803 press' ires, 27 probable usage, 801, 820 properties of, 27 as a refrigerant, 39, 41 replacement of, 634 supply piping, 799 down-feed systems, 802 mains, 806 up-feed systems, 804 temperature, maximum-main, 526 from wells, 524 thermal properties of, 27 vapor, 5, 10, 12 given off in combustion of gas, 181 heat content, 12, 23 mean specific heat-of, 3 weight of saturated, 12 Weatherstripping, 124 Weight, of air, 6 conversion equations, 848 of steam, 28 of vapor, 12 of water, 27 Welding, 361, 372 neck flanges, 377, 878 Well water refrigeration control of,<;718 Well water temperature, 524 Wet-bulb temperature, (see Temperature, Wet- bulb) Wet return, 846 Wind, in cities, 186, 146 effect on heating requirements, 185 forces in natural ventilation, 119, 687 prevailing, direction-of,. 125, 146 records of velocity and direction, 136, 148 velocity on natural draft equipment, 533 - average, 125, 135, 146, 687 equivalent, in tall buildings, 126 used in calculations, 125 . , Window, windows,' air leakage through, 122, 124 clearance of sash,. 123 coefficients of transmission of, 115 comparison of various shades for, -154 crack. 122 measurement of, 122 solar radiation through, 153 storm sash, 123 Winter, comfort zone, 61, 62 conditioning, apparatus for, 399, 415 cooling in, 145 humidification in, 61, 66, 409 inside temperature, 132 relative humidity in, 66 " temperatures, 136 wind velocities and directions, 136 Zero, absolute, 835 Zone, zoning, for air conditioning systems, 416 automatic control, 704 comfort, 61, 62, 64, 837 control of steam heating systems, 298 water supply systems, 799 XXIV Chapter 1 AIR, WATER AND STEAM Dalton's Law, Temperatures, Air Properties, Humidity, Rela tive Humidity, Specific Humidity, Relation of Dew Point to Relative Humidity, Adiabatic Saturation of Air, Total Heat and Enthalpy, Psychrometric Chart, Properties of Water, Properties of Steam AIR conditioning has for its objective the supplying and maintaining, in a room or other enclosure, of an atmosphere having a composition, temperature, humidity, and motion which will produce desired effects upon the occupants of the room or upon materials stored or handled in it. Dry air is a mechanical mixture of gases composed, in percentage of volume, as follows1: nitrogen 78.03, oxygen 20.99, argon 0.94, carbon dioxide 0.03, and small amounts of hydrogen and other gases. Atmospheric air at sea level is given in percentage by volume as: N, 77.08, O2 20.75, water vapor 1.2, A 0.93, CO2 0.03 and H2 0.01. The amount of water vapor varies greatly under different conditions and is frequently one of the most important constituents since it affects bodily comfort and greatly affects all kinds of hygroscopic materials. DALTON'S LAW A mixture of dry gases and water vapor, such as atmospheric air, obeys Dalton's Law of Partial Pressures; each gas or vapor in a mixture, at a given temperature, contributes to the observed pressure the same amount that it would have exerted by itself at the same temperature had no other gas or vapor been present. If p = the observed pressure of the mixture and pu pit ps, etc. = the pressure of the gases or vapors corresponding to the observed temperature, then P = /> + pt + Pi, etc. (1) TEMPERATURES Air is said to be saturated at a given temperature when the water vapor mixed with the air is in the dry saturated condition or, what is the equiva lent, when the space occupied by the mixture holds the maximum pos sible weight of water vapor at that temperature. If the water vapor 1International Critical Tables.