Document 44n0ZLg405eOO0de0Vy4NGp2x

American Society of Heating and Ventilating Engineers Guide, 1936 the logarithmic scale at the left, read a number which, divided by 10, will give the answer. Example 15. Weight per Cubic Foot of Dry Air and Relative. Density: From the point where, for example, the 70 F vertical dry-bulb line intersects curve E, pass to right side and read 0.075 lb; if cubic feet per pound are desired, divide 1 by this amount. The relative density is read immediately to the right as 1.00. Example 16. Weight per Cubic Foot of Saturated Air and Relative Density: From the point where, for example, the 70 F vertical line intersects the curve D, pass to the right and read weight per cubic foot as 0.07316 with a relative density of 0.9755 for saturated air at 70 F. Example 17. Weight per Cubic Foot and Relative Density of Partially Saturated Air: Air at 50 F and a wet-bulb temperature of 46 F is to be heated to 130 F. . The wet- and dry-bulb lines intersect at a dew-point temperature of 42 F. Pass to the left where this dew-point line intersects the saturation line and then pass in a vertical direction to where the 42 F dry-bulb line intersects with curve D. Then pass directly to the right and read the weight per cubic foot of saturated air at 42 F as 0.07844 and the relative density as 1.046. The absolute temperature at 42 F is 502, and at 130 F is 590. Therefore, g5g0g2 = 0.851. The weight of 1 cu ft of air at 50 F dry-bulb and 46 F wet-bulb when heated to 130 F is 0.07844 X 0.851 = 0.06675, and the relative density is 1.046 X 0.851 = 0.89. PROPERTIES OF STEAM Steam is water vapor which exists in the vaporous condition because sufficient heat has been added to the water to supply the latent heat of evaporation and change the liquid into vapor. This change in state takes place at a definite and constant temperature which is determined solely by the pressure of the steam. The volume of a pound of steam is the specific volume which decreases as the pressure increases. The reciprocal of this, or the weight of steam per cubic foot, is the density. (See Table 6.) Steam which is.in.contact with the water from.which it-was.generated is known as saturated steam. If it contains no actual water in the form of mist or priming, it is called dry saturated steam. If this be heated and the pressure maintained the same as when it was vaporized, its temperature will increase and it will become superheated, that is, its temperature will be higher than that of saturated steam at the same pressure. PROPERTIES OF WATER Composition of Water. Water is a chemical compound (H20) formed by the union of two volumes of hydrogen and one volume of oxygen, or two parts by weight of hydrogen and 16 parts by weight of oxygen. Density of Water. Water has its greatest density at 39.2 F, and it expands when heated or cooled from this temperature. At 62 F a U. S. gallon of 231 cu in. of water weighs approximately lb, and a cubic foot of water is equal to 7.48 gal. The specific volume of water depends on the temperature and it is always the reciprocal of its density. (See Table 7.) Water Pressures. Pressures are often stated in feet or inches of water column. At 62 F, with ft equal to the head in feet, the pressure of a ' column of water is 62.383ft lb per square foot, or 0.433ft lb per square inch. A column of water 2.309 ft (27.71 in.) high exerts a pressure of one pound, per square inch at 62 F. Boiling Point of Water. The boiling point of water varies with the pressure; it is lower at higher altitudes. A change in pressure will always 26 Chapter 1--Fundamentals of Heating and Air Conditioning Table 6. Properties of Saturated Steam: Pressure Table1 Ab*. !*. Tmp. Lb./Sq. In- D*f. P. Pt V4" Hg 58.S3 70.44 1 Hg 79.06 lW'Bjt 91.75 %"Be 101.17 108.73 115.08 Specific Volume Sat. Sat. Liquid Eup. Vapor VI Vfg V, 001603 12S6.9 1256.9 0.01605 856.5 856.5 0.01607 652.7 652.7 0.01610 4454 4454 0.01613 339.S 339.S 0.01616 2754 2754 0.01618 2314 2314 1.0 101.76 3.0 126.10 3.0 141.49 4.0 152.99 6.0 16245 6.0 170.07 7.0 176.85 8.0 18247 9.0 188.28 10.0 11.0 12.0 13.0 14.0 14.696 19341 197.75 201.96 205.88 209.56 212.00 0.01614 0.01623 0.01630 0.01636 3334 173.94 11844 90.72 333.9 173.96 11846 90.74 0.01641 0.01645 0.01649 0.01652 0.01*656 73.59 62.03 53.68 4748 42.42 73.61 62.05 53.70 4749 42.44 0.01658 0.01661 0.01664 0.01666 0.01669 0.01670 38.44 35.15 32.40 30.06 28.05 2640 38.45 35.17 32.42 30.08 28.06 26.82 16.0 18.0 20.0 22.0 24.0 26.0 28.0 30.0 32.0 34.0 86.0 38.0 21642 222.40 227.96 233.07 23742 24245 246.41 2S044 254.05 257.58 260.94 264.16 0.01673 0.01678 0.01682 041685 0.01689 0.01692 0.01695 0.01698 0.01701 0.01704 0.01707 0.01710 24.75 22.16 20.078 18463 16.924 15.701 14.647 24.76 22.18 20.095 18480 16.941 15.718 14464 13.728 12.923 12409 11.570 10.998 13.745 12.940 12426 11.587 11.015 40.0 42.0 44.0 46.0 48.0 267.24 270.21 273.06 275.81 278.45 0.01712 0.0171S 0.01717 0.01719 0.01722 x10.480 10 10 9.582 9.189 8,829 ::10.497 10.027 9499 9407 8446 60.0 62.0 64.0 66.0 68.0 281.01 283.49 285.90 288.23 29030 0.01724 0.01726 0.01728 0.01730 0.01732 8.496 8.189 7.902 7.636 7388 8.514 8.206 7.919 7.6S3 7.405 60.0 62.0 64.0 66.0 68.0 292.71 294.85 296.94 298.98 300.98 0.01735 0.01737 0.01739 0.01741 0.01743 7.155 6.937 6.732 6.539 63S7 7.172 6.955 6.749 6456 6475 70.0' 72.0 74.0 76.0 78.0 302.92 304.82 306.68 30830 310.28 0.01744 0.01746 0.01748' 0.01750 0.01752 6.186 6.024 5X70 5.723 5384 6403 6.041 5487 5.741 5.602 80.0 82.0 84.0 86.0 88.0 312.03 0.01754 313.74 0.01756 31S.42 0.01757 317.06 0.01759 318.68 0.01761 5.4S2 S325 5304 5X89 4X79 5470 5443 5422 5.107 4.997 90.0 92.0 94.0~ 96.0 9S.0 320127 321.83 . 323.37 . 324. 32637 0X1763 0.01764 0.01766 0.01768 0X1769 4X74 4.773 4.676 4.584 4.494 4492 4.791 4.694 4.602 4412 Total Heat Sat. Sat. Liquid Erap. Vapor hf hff hg 2648- 10584 108S.7 38.47 1052.5 1091.0 47.06 59.72 69.10 7643 82.96 1047.8 10404 1035.7 1031.5 1027.9 1094.9 1100.6 11044 1108.1 11104 Entropy Sat. Sat. Aba. Prat*. Liquid Evap. Vapor Lb./Sq. In* Sf 04533 0.0754 0.0914 0.1147 0.1316 0.1450 0.1561 Sfc 2.0422 1.9856 1.9451 14877 14468 1.8148 1.7885 8c 2.0955 2.0609 2.0365 2.0024 1.9784 1.9598 1.9446 P "Bg .."Be Be 1*6" Hg 2" Hg V4"Hg 3"Bg 69.69 10354 93.97 1021.6 10943 1012.7 12043 1005.9 1105.0 1115.6 1122.0 1126.8 130.10 137.92 144.71 150.75 156.19 1000.4 995.8 991.7 988.1 9844 1130.6 1133.7 1136.4 1138.9 114L0 161.13 165.68 169.91 17345 177.55 180.00 9814 979.1 976.5 974.1 9714 9702 1143.0 11444 1146.4 1147.9 11494 1150.2 0.1326 0.1750 0.2009 0.2198 1.8442 1.9769 1.7442 1.9192 1.6847 14856 1.6420 14618 1.0 2.0 3.0. 4.0 02348 02473 02580 0.2674 0.2758 1.6088 1.5814 1.SS82 14379 1.5200 14435 14287 14162 14053 1.7958 6.0 6.0 7.0 8.0 9.0 02834 02903 02968 03027 03082 03119 1.5040 1.4894 1.4760 1.4636 1.4521 1.4446 1.7874 1.7797 1.7727 1.7663 1.7604 1.7564 10.0 11.0 18.0 18.0 14.0 14.696 18445 190.48 196.09 20145 206.05 21044 214.75 967.4 963.5 959.9 956.6 953.4 950.4 947.7 1151.8 1154.0 1156.0 11574 11S9.S 1161.0 1162.4 03184 03274 03356 03431 03500 03564 03624 1.4312 1.7496 1.4127 1.7402 13960 1.7317 13809 1.7240 13670 1.7170 13542 1.7106 13422 . 1.7046 16.0 18.0 20.0 22.0 24.0 26.0 28.0 218.73 22240 226.09 22941 232.79 945.0 942.5 940.0 937.7 935.5 1163.7 1165.0 1166.1 11672 V63J 03680 03732 03783 03830 0J876 13310 13206 13107 13014 1.2925 1.6990 1.6938 1.6890 1.6844 1.6800 30.0 32.0 34.0 36.0 38.0 235.93 238.95 *241.86 244.67 24747 9334 931.2 929.2 9272 925.4 1169.2 11702 1171.1 1171.9 1172.7 03919 03961 0.4000 0.4039 0.4076 12840 12759 12682 12608 12537 1.6759 1.6720 1.6683 1.6647 1.6613 40.0 42.0 44.0 46.0 48.0 249.98 25242 254.99 25748 259.71 923.5 921.7 920.0 9184 926.6 .11733 11743 1175.0 1175.7 1176.4 0.4111 0.414S 0.4178 0.4210 0.4241 12469 1.2404 12340 12279 12220 1.6580' 1.6549 1.65181.6489 1.6461 60.0 62.0 54.0 66.0 68.0 261.98 26448 26643 26843 270.49 915.0 913.4 922.9 910.4 908.9 1177.0 1177.6 11782 1178.8 1179.4 0.4271 12162 0.4300 12107 0.4329 12053 0.4356 .12001 0.4384 1.1950 1.6434 1.6407 1.6382 1.6357 1.6333 60.0 62.0 64.0 66.0 68.0 .272.49 274.45 27647 27845 280.09 907.4 1179.9 906.0 1180.5 904.6 1181.0 9032 -1181.5 901.9 1182.0 0.4410 0.4435 0.4460 0.4485 0.4S09 1.1900 1.1852 1.1805 1.17S9 1.1714 1.6310 1.6287 1.6265 1.6244 1.6223 70.0 72.0 74.0 76.0 78.0 281.90 . 283.67 28S.42 287.13 28840 900.5 8992 897.9 896.7 895.4 1182.4 1182.9 1183.4 11832 11842 0.4532 0.4555 0.4578 0.4599 0.4621 1.1670 1.1627 1.1586 1.1545 1.1505 1.6202 1.6182 1.6163 1.6144 1.6126 80.0 82.0 84.0 86.0 88.0 290.45 292.07 29347 29525 "29640 8942 1184;6 893.0 .1185.0 891.8 1X85*4 490.6 1185.8 869.4 11862 0.4642 0.4663 0.4683 0.4703 0.4723 1.1465 1.1427 1.1389 1.1352 1.1316 1.6107 1.6090 1.6072 1.6055 1.6033 90.0 92.0 94.0 90.0 88.0 .Abstracted from Sfeom Tables and 27