Document jBk8g35qoQ99OeJXNo8jyJx7O

HEATiNC VENTILATrNC AIR CONDITIONING GUIDE 1944 Table 1. Rates of Flow Through Branch Pipes Woodworking Machines Pipe Diameter, In. 3 4 5 6 7 8 Air Volume, Cfm 200 350 550 800 1100 1400 Table 2. Branch Pipe Size for Woodworking Machine Hoods Type of Machine Self feed table saw Other single saws Saws with Dado Head Band saws : Disc sanders Triple drum sanders Size, In. Min. Max.. No. OF. Branches 2 Minimum Diameter, In. Bottom Branch 5 Top Branch 4 Others 18 ' 1 18 1 4 5. 15 '2 . 2 4 4' 2 32 5 4 3 62 5 5 18 18 . 28 26 32 32 38 38 '. 48 1 .1 2 2 3 4; 5 4 5 .`5 4 44 4 30 1 7 30 36 1 8 36 42 1 9 42 48 1 10 Single drum sanders: (area in sq in.) 350 700 1400 Horizontal belt sanders - 9 Vertical belt sanders Jointers 6 , '9 '8 Single planers Tenoner 20 26 350 . 700 1400 2800 1 9 .2 14 2 61 r9 1 14 1 .8 20. 1 1 20 1 26 1 36 1 2 4a 5 6 7 54 6 4. 4 5 6 4 5 5 6 7 55 aNot over 10 in. diameter. 720 CHAPTER 40. INDUSTRIAL EXHAUST SYSTEMS Table 3. Rates of Flow Through Branch Pipes Grinding and Buffing Wheels Pipe Diameter, In. 3 4 5 6 7 Air Volume, Cfm 225 400 600 900 1200 rates of flow through each hood which have been found by experience to provide adequate control. For woodworking systems the rates of .flow given in Table 1, calculated on the basis of a branch velocity of 4000 fpm, are adequate for control. Using these air flow rates, Table 2 gives the size of pipe connections to be used with the more common wood working machines. Properly designed grinding and buffing wheel hoods have been found to be adequately controlled when the rates of air flow given in Table 3, calculated on the basis of a branch, velocity of 4500 fpm, are used. Table 4 gives the minimum branch pipe sizes to be used on the more common sizes of grinding and buffing wheels. In some states grinding, polishing and buffing wheels are subject to regulation by codes. (See Standards Chapter 48.) The static suction requirements, which range from to 5 in. water displacement in a U-tube, must be followed in such states although in several instances they may appear to be excessive. Frequently, in these operations, a large part of the wheel must be exposed and the dust-laden air within the hood is thrown outward by the centrifugal action of the wheel, thus counter acting useful inward draft. This tendency may be diminished by locating the connecting duct so as to create an air flow of not less than 200 fpm past the lower edge of the wheel. Controlling Air Velocities Exact determinations of hood control velocities are not available, but it is safe to assume that for most dusty operations they should not be less Table 4. Branch Pipe Sizes for Grinding and Buffing Hoods Type of Wheel Wheel Size Diameter, In. Min. Mix. Grinding Disc Grinding 9 18 24 30 20 Buffing, Polishing and Scratch brushing ____________ t____________ 8 16 24 9 18 24 30 36 20 30 8 16 24 30 721 Maximum Width In. i 3 4 5 6 .... 2 3 4 6 Area Sq In. 30 175 300 500 700 300 50 150 300 600 Branch Pipe Minimum Diameter, In. 3 4 5 6 7 4 5 3% 4 5 .6 f 1 i