Document B5d2dy540wV5aop0eXDmka8MX

16 Am. Soc. of Heat.-Vent. Engineers Guide. 1922 tions .for different ranges of pressure may be obtained. The latter will be found more convenient and accurate for general field" use as they are so constructed that they may be mounted on a tripod or on any vertical or horizontal support. Having mounted the pitot tube and manometers as indicated in Fig. 3, it is usually the practice to connect them by means of rubber tubing, special care being taken to have air-tight connections. This can be tested by blowing into the tube and then closing the openings in the tube with the fingers and observing any drop in the manometer. If a noticeable drop occurs, it indicates loose connections.. When a static pressure above atmospheric exists in the duct, the manometers and pitot tube should be connected as shown in diagram for blowing tests. The upper manometer which is connected both to the dynamic and static tubes will record the difference or velocity pressure, while the lower manometer which is connected only to the dynamic tube, will record the dynamic pressure. Both of these readings will be positive. The static pressure can be obtained by subtracting the velocity pressure from the dynamic pressure. In making a test where the static pressure within the duct is below that of the atmosphere, connect apparatus as shown for exhausting test in Fig. 3. The upper manometer will record the velocity pressure which will be positive, while the lower manometer will record static pressure which will be negative. As stated in the above report, for accuracy the velocity corresponding to each reading should be calculated separately and then the velocities should be averaged. However, for field work, if the readings are taken at the positions shown in the centers of the rings or circles of equal area, there will be no appreciable error if the readings are averaged and the velocity computed on the mean. Corrections must be made for the specific gravity of the gasoline and the inclination of the manometer. Example--In a blowing test conducted as here outlined, using a manometer in clined 1 to 10 for the velocity reading, and using colored gasoline with a specific gravity of 0.74, a reading of one inch was observed. The air was practically dry at 120 deg. fahr., barometer at 30 in. The equivalent inches of water will be 1x1/10x0.74 or 0.074 inches of water. The weight of the air will be 0.0028862 x 30 W- :1 + 0.0021758x120" = 0.0687 0.074 then v = 1096.S 0.0687 1140 ft. per minute. Am. Soc. of Heat.-Vent. Engineers Guide, 1922 17 REPORT OF COMMITTEE ON STANDARD METHOD OF MEASURING THE VELOCITY OF AIR THROUGH WARM AIR REGISTERS WHEN THE ANEMOMETER IS USED (Transactions of the A. S. H. V. E., Vol. XIX, p. 203) The report in full is as follows: 1. The opening shall be divided into equal rectangular areas, no side of which shall be over 10 inches long, excepting where this would require more than ten readings, in which case the opening shall be divided into twelve equal areas. 2. Readings are to be taken in every case at the center of every area. 3. Readings are to be of one-half minute duration, the anemometer being held at the register base or in the plane of the opening. 4. Where the diffusers are used, the total area is to be computed on the basis of the periphery of the diffuser. 5. The average of the readings is to be considered as the average velocity at the opening. Where negative velocities are found, they are to be deducted in arriving at the average velocity. 6. In computing volume, the net area of opening is to be taken, the volume to be considered as the product of the average velocity and the net area of the opening. 7. If the anemometer is held two inches from the register face, no deduction shall be made for the area occupied by the register mesh. REPORT OF COMMITTEE ON TESTS ON TEMPERATURE CODE FOR TESTING HEATING SYSTEMS (Transactions of A. S. H. V. E., Vol. XVI, p. 44.) In this report, the Committee on Tests presented the following table, worked out from a formula incorporated in the 1903 report of the Committee on Standards. The table is for use only in case of direct radiation, steam or hot water, and should show the relative capacity of the radiation, although not necessarily showing the capacity of the boiler. ' Table 2. Indoor and Outdoor Temperatures Showing Equivalent Heating Capacity to 70 Deg. Inside and 0 Deg. Outside Outside Temperatures 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 Temp, of Radiator, deg. fahr. 160 71.1 72.2 73.4 74.5 75.6 76.7 77.9 79. 80.1 . 81.2 82.3 83.5 84.6 85.7 86.9 88. 170 180 190 200 210 Room Temperatures Deg. Fahr. 71.2 71.2 71.2 71.3 71.3 72.3 ' 72.4 72.5 72.6 72.7 73.5 73.7 73.8 73.9 74.7 74.7 74.9 75. 75 2 75.3 75.9 76.1 76.3 76.5 76.7 77. 77.3 77.6 77.8 78. 78.2 78.5 78.8 79.1 79.3 79.4 79.7 80.2 80.4 80.7 80.5 81. 81.3 81.7 82.- 81.7 82.2 82.6 83. 83.3 83. 83.4 83.9 84.3 84.7 84.1 84.6 85.1 85.6 86. 85.3 85.9 86.4 86.9 87.3 86.5 87.1 87.7 88.2 88.6 87.6 88.3 89. 89.5 90. 88.8 89.5 90.2 90.8 91.4 90. 90.8 91.5 92.1 92.6 92. 92.8 93.4 94. 94. 94.7 95.4 96. 96.6 98. 220 71.3 72.7 74.1 75.5 76.8 782 79.5 80.9 82.3 83.6 85. 86.4 87.7 89.1 90.4 91.8 93.2 94.5 95.9 97.2 98.6 100. 230 240 71.4 72.8 74.2 75.6 77. 78.3 79.7 81.1 82.5 83.9 85.3 86.7 88.1 89.5 90.9 92.2 93.6 95. 96.4 97.8 99.2 100.6 102. .... 71.4 72.8 74.2 75.7 . 77.1 78.5 79.9 81.3 82.7 84.1 85.5 87. 88.4 89.8 91.2 92.6 94. 95.4 96.9 98.3 99.9 101.2 102.6 104.