Document qMX2oanE18LNyrK9byGyB5Zk

Safety Engineering Tables 1596 TABLE 47-H A GUIDE TO VENTILATION RATES FOR TYPICAL INDUSTRIAL EQUIPMENT (Concluded) State or Local Regulations Should Be Consulted and Followed Where Higher Ventilation Rates Are Specified Operation Pharmaceuticals Blenders Coating pans Centnfuges Hammer mills Oscillators Shakers Mixers Process kettles and tanks Pouring hoods Foundry Rock drilling Dry dnllmg (rock). Rubber calender rolls Quartz fusing Screens Vibrating Fiat deck Type oj Hood Fully enclosed Hood Enclosure Local hood Hood Enclosure Ventilation Av Flow Usual Transport Velocity (fpm) 100 to 200 fpm through opening 120 cfm exh 24-in diam pan 60 cfm supply direct to pan Dif ferential 60 cfm 250-300 fpm through opening 200 fpm but not less than 50 cfm 2,500-3.500 3.000 1.500-2.000 Not less than 75 cfm per sq ft of plan area 100-250 fpm through opening or manhole 2,500-3,500 1,500-2,000 Side hood 200 to 300 cfm per linear ft of hood with slot velocities of 1500 fpm Exhaust take-off every 6 to 10 ft Special trap (see references) Canopy-side panels Booth on bench Enclosure 60 cfm-vertical (downward) work 200 cfm-horizontal work 75-100 fpm indraft 150-200 fpm at face 150-200 fpm indraft through hood openings but not less than 25-50 cfm per sq ft of screen area 3,500 3,500 3,500 3,500 Remarks and References Exhaust required only when filling or emptying Flexible exhaust hood connec tion extended into pans Feed opening covered to greatest possible extent Centrifuge to be provided with cover for 50-75 per cent of opening Hood with slot at each end of mixer Ref 33 Use higher ventilation rate when contents are being heated Ref 20 Ref 26, 27 May vary with size and speed of drill Wet dnlling offers alternate control Ref 24.31 Ref 34, 35 Ref 15,19