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722 CHAPTER 52 1960 Guide Table 3 .... A Guide to Ventilation Rates for Typical Industrial Equipment Stef* or Local Regulations Should be Consulted and followed Where Higher Yeatdaftoa Mo* ore SpecrSed OperaSon Type of Hood Ventilation Air Bow 'Jsual Transport Velocity Fpa Jtanarfci and Reference! Abrasive blast rooms Tight enclosure with air 60-100 fpm downdraft (long (sand, grit, or shot) inlets (usually in rooms of tunnel proportions roof) 100 fpm crossdraft) 3500 Ref. 8. Many codes specify minimum downdraft of 80 fpm Abrasive blast cabinets Tight enclosure with 20 air changes per minute but access openings not less than 500 fpm through all openings 3500 Ref. 14 Asbestos: Carding Spool winding Enclosure Local Hoods 800 cfm per machine 50 cfm per spool 3000 3000 Ref. 2, 16; 17. See references for details and other opera tions Bagging: Open Bag Top Booth or enclosure (pro vide spillage hopper) Paper bags--100 cfm per sq ft open area Cloth bags--200 cfm per sq ft open area 3500 3500 Ref. 18 Barrels--Dnims (filling Local Hood or removing material by scoop) Booth 100 cfm sq ft of container crosssection 3500 100 fpm at face 3500 Ref. 15, 19. Hood with 1-in. slot extending 120 to 180 deg container. Does not confine spillage. Confine spillage--also recom mended for container up setting Belt conveyors Hood at transfer point Belt speeds less than 200 fpm-350 cfm per foot of belt width, but not less than 150 fpm through open area. Beit speeds over 200 fpm--500 cfm per foot ol belt width but not less than 200 fpm through open area 3500 Ref. 18, 20 Bins (closed top) Connect to bin top away 150-200 fpm through open area from feed point at feed points 3500 Ref. 19, 20 Bucket elevators light casing required 10 cfm per sq ft of elevator cas ing cross-section 3500 Ref. 19 Brick cutting and sising Local Hood 500 cfm (abrasive cut-off Booth with saw at face 150 fpm at face wheel used dry) of booth 3500 3500 Ref. 7,19. For portable opera tions. Control not as effec tive as booth Ceramics Dry pan Dry press Aerographing Fettling, brushing, sag ger filling, and unload Enclosure Local at die Local at die At supply bin Booth Downdraft or side hood 200 fpm through all openings 500 cfm 500 cfm 500 cfm 100 fpm (f&ee) 100-150 cfm per sq ft of plan area of dust producing operation 3500 3500 3500 3500 3500 Ref. 19,21, 22 Automatic feed Manual feed Manual feed Cooling Tunnels (foundry Enclosure molds) Crushers and grinders Enclosure 75-100 cfm per running foot ol enclosure 200 fpm through openings 3500 Ref. 20 Ref. 18, 23 Furnaces Stationary melting pots for oooferrous Tilting or rocking melting for non-ferrous Electric Arc for Steel Enclosure Canopy 100-200 fpm at hood opening 3000-6000 cfm Hood attached to rool 2500 cfm per ton charged ring 1500-2000 1500-2000 2500-3500 Ref. 11, 15, 22, 24, 25 Use higher ventilation rate for toxic fumes Ventilation rate can be ma terially reduced with more complete enclosures General ventilation of melting room may be substituted but* involves greatly in creased ventilation rate Industrial Exhaust Systems 723 Table 3 . .. A Guide to Ventilation Rates for Typical Industrial Equipment (Continued) State or Local Regulations Should bo Consulted and Followed Where Higher Ventilation Redo* are Specified Operation Type of Hood Vonfflation Air Bow Usual Tiansper Velocity Fpm Remarks and References Furnaces Forge (hand) Canopy 200 fpm at face 1500 Ref. 24 Garage (tail pipe at serv icing location) Local hood slipped over 100 cfm thru 3-in. flexible duct tail pipe for autos up to 200 hp 200 cfm thru 4-in. flexible duct for trucks and autos above 200 hp 400 cfm thru 4^-in. flexible duct for Diesel engines 2000 Ref. 15 Granite cutting and fin ishing ' Pneumatic hand tools Local hood Surfacing machine Local hood Ref. 28, 27 500 cfm 5500-6000 500 cfm for tools up to 2%-in. diameter 1000 cfm for 2>g- to 2%-in. di ameter 5500-6000 Typical hood 3 x 8 in. opening with 3-in. flange Hood surrounds tool Grinders Polishers, buffers, etc. Portable Standard wheel hood Downdraft bench Swing frame Kitchen range Booth Booth Canopy See Table 5 Bench type, 2-400 cfm per sq ft of exhaust grille but not less than 150 cfm per sq ft of plan working area. 100 fpm at face 100-200 fpm indraft through opening in booth face 3500 3500 3000 Ref. 22, 28 Ref. 15, 19, 22, 29 Recommended for larger parts (Usual cfm per grinder 2000- 4000) 100 fpm at hood face 1500-1800 Provide drip gutter on all in terior vertical walls to catch condensed grease. Ref. 30 Laboratory hood (pro Booth type vide with door) 50-100 fpm Ref. 24, 31. Air supply loca tion very critical Metaiizing Local hood Booth 200 fpm at hood face 125-200 fpm at booth face 3500 3000 Ref. 15. Not recommended for toxic materials Use higher ventilation rates for toxic materials Mixers Enclosure 100-200 fpm through feed and 3000-3500 Ref. 19, 22 inspection openings Motion picture projector Enclosure (carbon arc) 12-100 efzn (for fume and gas re moval) directly exhausted from projector housing Ref. 31. 1000-1500 cfm or 20-30 air changes per hour for heat removal Pharmaceuticals Blenders Coating pans Fully enclosed Hood Centrifuges Enclosure Hammer mills Oscillators Shakers Mixers Local hood Hood Process kettles and Enclosure tanks 100 to 200 fpm through opening 2500-3500 120 cfm exh 24-in. dia pan 60 cfm supply direct to pan Differential 60 cfm 3000 250-300 fpm through opening 1500-2000 200 fmp but not less than 50 cfm 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 percent of opening Not less than 75 cfm per sq ft of plan area 100-250 fpm through opening or manhole 2500-3500 1500-2000 Hood with slot at each end of mixer Ref. 33. Use higher ventilation rate when contents are being heated