Document 85991p05YRrBR8aLybX2q6JLd

American Society of Heating and Ventilating Engineers Guide, 1932 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. The relation between pressure and specific volume for dry saturated steam is given by the experimental equation (Goodenough) as: where = 484.2 (1) p -- the pressure in pounds per square inch. v -- the specific volume. The total heat of a dry saturated vapor for any pressure and temperature is the sum of the heat required to raise the temperature of one pound of the liquid from the freezing point to the given temperature and cor responding pressure plus the heat required entirely to vaporize it at this pressure. Steam which is in contact with the water from which it was generated is called wet saturated steam if it contains more or less actual water in the form of mist or priming. The percentage of dry steam in a mixture of steam and water is known as the quality (x) of the steam. The total heat of wet vapor at any pressure and temperature is the sum of the heat required to raise the temperature of one pound of the liquid from the Table 5. Velocities of Dry Air in Feet per Minute (At Various Temperatures) Corresponding to Various Velocity Pressures in Ounces per Square Inch1 Barometric Pressure 29.921 In. PresBURE Ounces Inches 50 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 . 1-3 1.5 1.6 1.8 2.0 2.2 2.4 2.8 3.0 0.1734 0.3468 0.5202 0.6936 0.8670 1.0400 1.2140 1.3870 1.5605 1.7340 1.9073 2.0808 2.2540 2.4275 2.6010 2.7742 3.1210 3.4680 3.8145 4.1615 4.5080 4.8550 5.2020 1635 2313 2833 3272 3658 4007 4329 4626 4907 5172 5426 5664 5896 6120 6335 6543 6942 7315 7672 8012 8338 8654 8960 From Fan Engineering. 60 1653 2338 2864 3307 3698 4051 4375 4677 4960 5229 5485 5725 5960 6186 6404 6614 7017 7395 7755 8099 8429 8748 9057 70 1667 2358 2888 3335 3729 4085 4412 4716 5002 5273 5531 5774 .6011 6238 6457 6670 7076 7457 7820 8168 8500 8822 9134 Temperature, Deo. Fahr. 80" 1683 2380 2915 3367 3765 4124 4454 4761 5050 5323 5584 5828 6068 6297 6520 6734 7143 7528 7894 8245 8581 8906 9220 100 1714 2424 2969 3428 3833 4199 4535 4848 5142 5420 5685 5935 6179 6412 6638 6856 7274 7665 8038 8396 8737 9068 9388 150* 200 300 500" 550 1788 2530 3098 3578 4000 4382 4733 5059 5366 5656 5933 6194 6448 6692 6928 7155 7591 8000 8462 8762 9118 9464 9798 1860 2632 3223 3722 4162 4559 4924 5263 5582 5884 6172 6443 6708 6962 7207 7444 7897 8322 8727 9115 9486 9845 10193 1996 2824 3458 3994 4466 4892 5283 5647 5990 6314 6623 6914 7198 7470 7733 7987 8473 8930 9364 9781 10179 10564 10938 2244 3174 3887 49 5019 5498 5938 6347 6733 7098 7444 7772 8090 8396 8692 8977 9524 10037 10525 10995 11440 11873 12293 2410 3405 4175 4850 5395 5900 6380 6820 7250 7625 8000 8350 8700 9020 934S 9650 10220 10780 11300 11800 12280 12750 13200 540 Chapter 39--Physical Data freezing point to the given temperature and corresponding pressure plus the heat required to vaporize the part * at this pressure. AIR Composition. Air is a mechanical mixture made up, by volume, of 20.91 per cent of oxygen and 79.09 per cent of nitrogen, or by weight, of 23.15 per cent of oxygen and 76.85 per cent of nitrogen. Air as found in nature always contains other constituents in varying amounts, such as carbon dioxide, ozone, water vapor, dust, bacteria,, etc. The specific density or weight per cubic foot of dry air decreases with an increase in temperature; and the specific volume, or volume per pound, increases with such increase. The specific heat of air at constant pressure, or the Btu required to raise the temperature of one pound one degree Fahrenheit, varies from 0.2375 to 0.2430 as determined by various in vestigators. The value 0.24 is recommended for engineering calculations. It has been found that a given volume of air expands when heated under constant pressure, and again that if the temperature of a given volume of air be kept constant and the pressure increased, contraction takes place. These changes follow definite laws, which apply to other gases as well as air, known as the laws of perfect gases.. These laws do not generally apply to steam, since it is not a perfect gas, but superheated steam at high temperatures follows the laws approximately. (See Tables 5, 6, 7 and 8). Boyle's Law refers to the relation between the pressure and volume of a Table 6. Velocities of Dry Air in Feet per Minute (At Various Temperatures) Corresponding to Various Velocity Pressures in Inches of Water1 Barometric Pressure 29.921 In.. Pressure Inches Ounces 50" 0.25 0.5 0.75 1.0 1.75 2.50 4.00 6.00 0.0577 0.1154 0.1443 0.1730 0.2308 0.2884 0.3460 0.4037 0.4326 0.4614 0.5190 0.5?68 0.7209 0.8650 1.0092 1.1535 1.2975 1.4418 1.5860 1.7300 2.3070 2.8840 3.4600 1242 1757 ; 1965 2151 2485 2778 3043 3287 3402 3524 3728 3929 4393 4812 5197 5556 5892 6211 6514 6807 7857 8772 9623 60" 1255 1776 1986 2175 2512 2808 3076 3323 3439 3552 3768 3971 4440 4864 5254 5616 5956 6278 6585 6879 7942 8867 9728 Temperature, Deo. Fahr. ' 70" 80" 100" 150" 200" 1266 1791 2003 2193 2533 2832 3102 3351 3468 3582 3800 4005 4478. 4905 5298 5664 6007 6332i 6641 6937 8010 8943 9810 1278 1808 2022 2214 2557 2859 3131 3383 3501 3616 3836 4043 4520 49S2 5348 5718 6064 6392 6704 7003 8086 9027 9903. 1300 1841 2059 2254 2603 2911 3188 3445 3565 3682 3906 4117 4602 5042 5446 5822 6174 6508 6827 7130 8233 9192 10083 1358 1921 2149 1413 2000 2235 2352 2717 3038 2447 2827 3160 3327 3595 3720 3462 3740 3870 3843 3997 4076 4241 4296 - 4470 4804 5262 5683 4997 5474 5912 6076 6443 6792 6320 6704 7066 7124 7440 8592 7412 7742 8940 9593 9980 10523 10950 300" 1516 2145 2399 2626 3033 3391 3715 4013 4153 4290 4550 4796 5362 5874 6344 6783 7193 7582 7952 8307 9581 10710 11750 500 550" 1704 2411 2696 1830 2895 2952 3409 3812 3175 3660 4175 4510 4668 4490 5020 4821 5114 5390 5185 33UU 5795 6027 6602 7131 6470 7633 ' 7624 8085 8523 8195 9150 8938. ,, 9600 9336 10780 11580 12037 12900 13203 14180 From Fan Engineering. 541