Document g3BOKYGgae8qvEpDea9gGN09

American Society of Heating and Ventilating Engineers Guide, 1925-26 EXAMPLE IN THE USE OF THE CHART Determine the percentage of perfection of ventilation, in a room where the following conditions are observed. The' room to be occupied by persons normally clothed and doing light work. Dry Bulb Temperature..........................................:._..74 deg. Wet Bulb Temperature.............................................. 62 deg. Air Velocity................................................................. 50 ft. per min. Dust Count by Hill Counter..................................... 10,000 particles per cu. ft. Bacteria colonies developed in a 2 min. plate......... 10 Odors...................................... _....................................Faint CO, analysis inside Station No. 1............................. 6 parts in 10,000 CO, analysis inside Station No. 2................. ........... 6.3 parts in 10,000 CO,- analysis inside Station No. 3............................ 5.5 parts in 10,000 CO, analysis inside Station No. 4............................ 5.0 parts in 10,000 CO, analysis outside......... ......... .4.0 parts in 10,000 Other objectionable substances................................. None The effective temperature for the observed wet and dry bulb tempera ture and air motion is determined from the Table 96 to 102 in Chapter XVI. From Table 97 (See Chapter XVI) for 50 ft. per min. air velocity the intersection of the line for 74 deg. dry bulb and the column for 62 deg. wet bulb gives 65.3 deg. as the E. T. of the condition. For 100 per Cent perfection 62.5 deg. E. T. is required for persons doing light work whereas the existing condition is 65.3 deg. E. T. or 2.8 deg', too high, which gives according to the chart, 91.6 per cent perfection and 8.4 per cent penalization for this factor and a penalization of 7.6 per cent for imperfect ventilation. This is indicated in the chart, Fig. 71. 10,000 dust particles per cu. ft. of air gives according to the chart 96 per cent perfection and 4 per cent penalization for this factor and 1 per cent penalization for imperfect ventilation. 10 bacterial colonies on a 2 min. plate gives 98 pier cent perfection for this factor and a penalization of 1 per cent for imperfect ventilation. A faint odor or 90 per cent free from odors calls for a 10 per cent penalization for this factor and 1.5 pier cent penalization for imperfection, of ventilation. The average carbon dioxide content of the 4 samples taken in the room is 5.7 or 1.7 parts more than the outside sample, which, according to the chart, is 99.5 pier cent perfect for this factor and calls for 0.4 per cent penalization for imperfection of ventilation. There are no other injurious substances indicated hence no penalization is given for such factors. The variations of the carbon dioxide content of the four stations from their average are as follows:-- Station No. 1:_............................. ............... 6.3--5.7 -- 0.6parts per 10,000 " 2.................................................6.0-5.7 = 0.3 " " 10,000 " " 3--............................................. 5.7-5.6 = 0.1 " 10,000 " " 4...... :............. ...........................5.7-5.0 = 0.7 " 10,000 4[1.7 The average variation is....................... ..................... 0.42, and the - per centage of variation is X 100 -- 7.4 per cent. Therefore the percentage 5.7 distribution is 100 -- 7.4 = 92.6, and the percentage penalization for imperfect ventilation is 2.2. 204 American Society of Heating and Ventilating Engineers Guide, 1925-26 Fig. 73. Taking an Air Sample The percentage of perfection for each factor is indicated in the chart, Fig..71 and are summed up in Table 92. The sum of all the penalizations for imperfection in ventilation is 13.7 and the percentage of perfection of ventilation is 100 minus 13.7 or 86.3 which is shown in the last column of the chart. 205