Document 159a7Bzjq1gzLyGDyXJOv2m6d

784 CHAPTER 31 1957 Guide Air Duct Design .02 .03 .04 .06 ,08 J,2 .3 ,4 .6 I2 785 3 4 6 8 10 CU FT OF AIR PER MINUTE CU F T OF AIR PER MINUTE Fig. 2. Friction of Air in Straight Ducts For Volumes of 10 to 2000 cfm (Based on Standard Air of 0.075 lb per cu ft density flowing through average, clean,round, galvanized taetd ducts having approximately 40 joints per 100 ft.) Caution: Do notextrapolate below chart. .03 04 06 08 J .2 .3 .4 .6 .8 I 2 34 FRICTION LOSS IN INCHES OF WATER PER 100 FT Fig. 3. Friction of Air in Straight Ducts For Volumes of 1000 to 100,000 cfm on Standard Air of 0.075 lb per cu ft density flowing through average, clean, round, galvanised etai duets having approximately 40 joints per 100 ft.) factors may be obtained from Fig. 4.' Most ductwork today is fabricated from galvanized iron or aluminum sheet metal, or flexible tubing. Fig. 5 presents in graphical form the recommended correction factors for alumi num ductwork.4 The correct friction loss for ducts other than sheet metal