Document yrVVOvYJym0rnOJD9gDR0D5jX

American Society of Heating and Ventilating Engineers Guide, 1928 Table 1. Size of Connections for Wood-Working Machinery Type of Machine Diameter of Connections in Inches Circular Saws, 12-in. diam--................................................ Circular Saws, 12-24-in. diam.......................... ................... Circular Saws, 24-40-in. diam............................................. Band Saws, Blade under 2 in. wide................. ............... Band Saws, Blade 2-3 in. wide....... .................................... Band Saws, Blade 3-4 in. wide--....................................... Band Saws, Blade 4-5 in. wide........................................... Band Saws, Blade 5-6'in. wide.......................................... Small Mortisers..................... ................................................. Single End Tenoners............................................................ Double End Tenoners.......................................................... Double End, Double Head Tenoners............................... Planers, Matchers, Moulders, Stickers, Jointers, etc.-- With Knives, 6-10 in.................................................. With' Knives, 10-20 in........................................-......... With Knives, 20-30 in.--..... ........................................ Shapers, Light Work.......................................... .................. Shapers, Heavy Work................................;.......................... Belt Sander, Belt less than 6 in. wide...... ...................... Belt Sander, Belt 6-10 in. wide....... ................................. Belt Sander, Belt 10-14 in. wide........................................ Drum Sander, 24 in......................................................-....... Drum Sander, 30 in------- ,....................... .......................--- Drum Sander, 36 in..................-..........-............................... Drum Sander, 48 in.......................................... ............-...... Drum Sander, over 48 in..................................................... Disc Sander, 24 in. diam................................. -.................. Disc Sander, 26-36 in. diam................................................ Disc Sander, 36-48 in. diam--.......................................... Arm Sander.............i.............................................................. 4 5 6 4 5 6 7 .8 6 6 7 10 5-6 6-8 6-10 4-5 8 5 6 7 5 6 7 8 10 5 6 7 4 Table 2. Size of Connections for Grinding and Buffing Wheels .. . . _ a Diameter of Wheels Grindings 6 in. or less, not over 1 in. thick.-...... 7 in. to 9 in., inclusive, not over 1XA in. thick...... 10 in. to 16 in., a " " 2 in. a ...... 17 in. to 19 in., " " " 3 in. " 20 in. to 24 in., " " " 4 in. " -..... 25 in. to 30 in.,! " 5 in. a ...... Buffing-- 6. in. or less,, not over 1 in. thick......... 7 in. to 12 in.,'inclusive, not over \x/i in. thick...... 13 in. to 16 in., " " " 2 in. " ...... . 17: in. to 20 in., . " " " 3. in. " ...... 21 in. to 27 in.,. " 4, in. u.' ...... 27 in. to 33 in., " " . 5 in. " ...... Max. Grinding Surface Sq. In. 19 43 101 180 302 472 19 57 101 189 338 518' Min. Diam. op Branch Pipes in Inches 3 4 4 Vi 5 6 3'A 4 5 .6 7 Chapter XXVI--Dust, Exhaust and Collecting Systems Table 3. Suctions Required at Hoods For Connections of Usual . Proportions Work Static Suction in In. of Water pvhaiistin^ from grindine and huffing wheels. Fvh;i listing from wood-working machinery--light duty Exhausting from wood-working machinery--heavy duty................... Sbrv* machinery exhaust. ............. ........ ......... . Fyhansting from rubber manufacturing processes Flint grinding exhaust...................................................... ....... Fxhaustine from Dotterv processes I.ead dust and fume exhaust................................... ... Fur and felt machinery exhaust. ................................................ F.xhausting from textile machinery................................... Exhausting from elevating and crushing machinery. ............ Conveying bulky and heavy materials............................................ 1-2 1-2 1-2 2-4 2-3 1-2 1-2 19 1-4 2-3 13 1-2 3-5 Velocities commonly employed are: 2,500 to 3,000 ft. per min. for light dusts, cotton, shavings and sawdust from dry wood, and similar substances. Heavy dusts, wool, shavings and sawdust from wet wood, rags, waste paper and similar materials 3,000 to 4,000 ft. per min. Lead dust, hog waste, pulp chips, etc., 4,000 to 6,000 ft. per min. In choosing the pipe sizes consideration must be given to the way and manner in which the machines will be operated, as in case a considerable number of machines, all discharging into one main, should be shut off at the same time, the velocity in the main might easily be lowered to the point where it would not be sufficient to carry the material from the machines still in operation, and thus result in clogging the pipes. Ac cordingly, it is sometimes desirable to use velocities higher than the mini mum to allow a factor of safety to cover this contingency. The resistance of a round pipe to. the flow of air is inversely proportional to the fifth power of the diameter of the pipe. Therefore, handling a given quantity of air through a larger pipe at a lower velocity decreases the frictional resistance very materially and correspondingly decreases the horse-power required at the fan, and thus it is very desirable to keep the air velocities throughout, the system as low as possible, consistent with the major requirement that the material must be taken away as fast as made, without clogging the pipes, under the varying operating conditions met with from day to day in the plant. The static suction required at the hood connections varies from 1 to 5 in. of water. The suction required depends upon many factors such as the relative size of the hoods and connections, kind and quantity of material handled; as well as its physical condition. In some states codes have been issued specifying suctions to be maintained for the more common dusts. A suction standard should always be considered in conjunction with the shape of hood, and size connection, as these factors together determine the volume of air exhausted and its velocity which in turn are a measure of the effectiveness of the exhaust system. 345