Document jygnVbbm80om1oq1xEv52Y222

686 CHAPTER 32 1953 Guide Air Duct Design 687 CU FT OF AIR PER MINUTE CU FT OF AIR PER MINUTE Fig. 1. Friction of Air in Straight Ducts For Volumes of 10 to S000 cfm (Based on Standard Air of 0.075 lb per cu ft density flowing through average, clean, round, galvanized metal ducts having approximately 40 joints per 100 ft.) No safety factor Included. Caution: Bo not extrapolate below chart. Fig. 2. Friction of Air in Straight Ducts For Volumes of 1000 to 100,000 cfm (Based on Standard Air of 0.075 lb per cu ft density flowing through average, clean, round, galvanized metal ducts having approximately 40 joints per 100 ft.) No safety factor included. Figs. 1 and 2, covering volume ranges of 10 to 2000 cfm, and 1000 to 100,000 cfm, respectively. These charts were developed by the A.S.H.V.E. Re search Laboratory.1 They do not include any safely factor. The charts, Figs. 1 and 2, were constructed from the basic flow equation for the pressure loss in circular ducts (see Chapter 4):