Operating conditions for | Crossdraft, |_Įlectrostatic and | Negligible. TABLE G-10 - MINIMUM MAINTAINED VELOCITIES INTO SPRAY BOOTHS An adequate air replacement system is one which introduces replacement air upstream or above the object being sprayed and is so designed that the velocity of air in the booth cross section is not less than that specified in Table G-10 when measured upstream or above the object being sprayed. Minimum duct velocity = 4,500 ft/min branch, 3,500Įntry loss = 0.45 velocity pressure for tapered takeoff Ġ.65 velocity pressure for straight takeoff.Įxcept where a spray booth has an adequate air replacement system, the velocity of air into all openings of a spray booth shall be not less than that specified in Table G-10 for the operating conditions specified. | 25 | 1 | 6 | 880 | WhenįIGURE G-8 A TYPICAL HOOD FOR A BELT OPERATIONīelt width W. Hoods must conform to structural strength and materials asįIGURE G-7 HORIZONTAL DOUBLE-SPINDLE DISC GRINDER EXHAUST NOTE: If grinding wheels are used for disc grinding purposes, | 30 | 6 | 6 1/2 | 1,040Įntry loss = 0.15 velocity pressure for tapered takeoff 0.65įIGURE G-5 CRADLE POLISHING OR GRINDING ENCLOSUREĮntry loss = 0.45 velocity pressure for tapered takeoff.įIGURE G-6 HORIZONTAL SINGLE-SPINDLE DISC GRINDER EXHAUST Note: Baffle to reduce front opening as much as possible.įIGURE G-4 STANDARD BUFFING AND POLISHING HOOD _|_|_|_|_Įntry loss = 0.45 velocity pressure for tapered takeoff 0.65įIGURE G-3 A METHOD OF APPLYING AN EXHAUST ENCLOSURE Minimum slot velocity=2,000 ft/min - 1/2-inch (1.27 cm) slot width. | 30 | 2 | 5 1/2 | 1,480 |Įntry loss=1.0 slot velocity pressure + 0.5 branch velocity pressure. Figure G-8 shows a typical hood for a belt operation.įIGURE G-1 VERTICAL SPINDLE DISC GRINDER EXHAUST HOOD ANDįigure G-1 - Vertical Spindle Disc Grinder Exhaust Hoodĭia. The hood should extend almost to the belt, and 1-inch wide openings should be provided on either side. Grinding and polishing belt hoods shall be constructed as close to the operation as possible. _|_|_įor any wheel wider than wheel diameters shown in Table G-4, increase the exhaust volume by the ratio of the new width to the width shown.Ĥ.5 divided by 4 X 610 = 686 (rounded to 690). Wheel diameter | Wheel width (inches) | Minimum exhaust TABLE G-4 - GRINDING AND ABRASIVE CUTTING-OFF WHEELS The entry loss for the vertical-spindle disc grinder hood is shown in figure G-1 (following 1910.94(b)). The entry losses from all hoods except the vertical-spindle disc grinder hood, shall equal 0.65 velocity pressure for a straight takeoff and 0.45 velocity pressure for a tapered takeoff.
Grinding wheels on floor stands, pedestals, benches, and special-purpose grinding machines and abrasive cutting-off wheels shall have not less than the minimum exhaust volumes shown in Table G-4 with a recommended minimum duct velocity of 4,500 feet per minute in the branch and 3,500 feet per minute in the main. Where flammable or explosive dust mixtures may be present, the abrasive blasting enclosure, the ducts, and the dust collector shall be constructed with loose panels or explosion venting areas, located on sides away from any occupied area, to provide for pressure relief in case of explosion, following the principles set forth in the National Fire Protection Association Explosion Venting Guide, NFPA 68-1954, which is incorporated by reference as specified in § 1910.6. The blast nozzle shall be bonded and grounded to prevent the build up of static charges.
Where flammable or explosive dust mixtures may be present, the construction of the equipment, including the exhaust system and all electric wiring, shall conform to the requirements of American National Standard Installation of Blower and Exhaust Systems for Dust, Stock, and Vapor Removal or Conveying, Z33.1-1961 (NFPA 91-1961) which is incorporated by reference as specified in § 1910.6, and subpart S of this part. Organic abrasives which are combustible shall be used only in automatic systems.
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