Document 1qz45NNaLR9kN51MBB0vQQGX

1050 CHAPTER 46 1956 Guide Table 5. Exhaust Requirements for Woodworking Operations*1 (Air Velocity: 4000 fpm in all branches unless noted otherwise) Self Feed Table Rip Saw Use 1-5 in. branch at bottom pulley; 1-4 in. branch at saw head. Lane Self Feed Rip Saws Other Than Table Saws Use 1-6 in. branch at bottom; 1-5 in branch at top. Swing Saws Up to 20 in. use 1-4 in. branch; over 20 in. use 1-4)4 in. branch. Circular Saws Up to 12 in. diam............................................................................................ Over 12 in; diam............................................................................................. Dado head saws............................................................................................... ................................. 1-4 in. branch Gang Circular Saws . .Ventilation rate depends on effectiveness of hood and maximum number and diameter of saws. Disc Sanders Up to 12 in. diam................................. ........................................................ 12 in. to 18 in. diam..................................................................................... 18 in. to 26 in. diam........................................................................................ 26 in. to 32 in. diam.......................... ......................................................... 32 in. to 38 in. diam....................................................................................... ... 1-4 in. branch and 1-5 in. branch 38 in. to 48 in. diam....................................................................................... ... 1-5 in. branch and 2--4 in. branch Multiple Dnim Sanders (over the table) Up to 31 in. wide........................................................................................... ........................ 5 in. branch (see note) 31 in. to 49 in. wide................................................................... ................. ....................... 6 in. branch (see note) Over 67 in. wide....................................................................................................................... 8 in. branch (see note) Note: One branch of size indicated required for each drum. Fewer branch pipes may be used as long as total branch pipe cross sectional area is not reduced. Some manufacturers use I extra branch of equal size on feed side. 1-4 in. branch may be required for exhausting bed rubber cushions or mechanically operated brush. Single Drum and Spindle Type Sanders ' Up to 50 sq in; sanding surface............................................................. ...................................... 1-3 in. branch 50 to 200 sq in. sanding surface...................................... ..................... 200 to 400 sq in. sanding surface........................................... ............... ...................................... 1-5 in. branch 400 to 700 sq in. sanding surface......................................... .................... 700 to 1400 sq in. sanding surface......................................... ................. 1400 to 2400 sq in. sanding surface.............................................................. Horizontal Belt Sander or Edge Sander (see note) Drive Pulley Idler Pulley Up to 6 in. wide................................................................................................. .: 1-4)4 in. branch 1-4 in.branch 6 in. to 9 in. wide......................................... ..................................................... .. 1-5 in. branch 1-4 in.branch 9 in. to 14 in. wide.......................... ............................................................. .. 1-6 in. branch 1-4 in.branch Over 14 in. wide...................... ................................................ ........... .. 1-7 in. branch 1-5 in.branch Note: Where more than one belt is used, the pipe sizes specified shall be required for each belt. Where a common hood is used for more than one belt, a single pipe of an area not less than the sum of the areas of the pipes specified may be used. .. Where belt is reversible, pipe at idler pulley shall be the size specified for the drive pulley.' Vertical Belt Sanders (rear belt and both pulleys enclosed) Up to 6 in. wide................................................... .......................................... ......... ........ 4)4 in. branch on bottom 6 in. to 9 in. wide........................................................................................... ....... ........5 in. branch on bottom 9 in. to 14 in. wide......................................................................................... Over 14 in. wide.............................................................................................. Band Saws and Resaws Bottom Up to 2 in; wide................................................. ................................ ....... ___ 1-4 in. branch 2 in. to 3 in. wide................................ ;....................... ................................. .... 1-5 in. branch 3 in. to 4 in. wide;...................................-........................................................ 1-6 in. branch 4 in. to 5 in. wide........................................................................ ....................___ 1-7 in. branch Over 5 in. wide.................................................................................. ............ .... 1-8 in. branch Top 1-4 in. branch 1-4 in. branch 1-5 .in.branch 1-5 in. branch 1-5 in. branch Jointers Up to 6 in. knives......................................................................................... 6 in. to 12 in. knives.................................................................................... 12 in. to 20 in. knives................ :................................................................. Over 20 in. knives.......................................................................................... Industrial Exhaust Systems 1051 Table 5. Exhaust Requirements fob Woodworking Operations (Concluded) (Air Velocity: 4000 fpm in aU branches unless noted otherwise) Single Planers or Surfacers t_ Up to 20 in. max. working width..................................................................................................... 1-6 in. branch 20 in. to 26 in. max, working width................................................. 1-7 in. branch 26 in. to 32 in. max. working-width......................................................................... 1-8 in. branch 32 in. to 38 in. max. working width................................................................................................ 1-0 in. branch Over 38 in. max. working width.................................................................................................. ... 1-10 in. branch Double Planers or Surfacers Upper head Up to 20 in. max. working width..................................................................... 1-6 in. branch 20 in. to 26 in. max. working width................................................................. 1-7 in. branch 26 in. to 32 in. max. working width.......... ................................................... 1-8 in. branch 32 in. to 38 in. max. working width................................................................. 1-9 in. branch Over 38 in. max. working width....................................................................... 1-10 in. branch Lower 1-5 in. branch 1-6 in. branch 1-7 in. branch 1-8 in. branch 1-8 in. branch Moulders, Matchers, Sizers' (see Note) Matcher head Top Bottom Up to 4 in........................................................................ 2-4 in. branch 1-5 in. branch 1-6 in. branch 4 to 6 in............................................................................. 2-5)4 in. branch1-6 in. branch , 1-6 in. branch 6 to 8in................................................................................ 2-6 in. branch 1-7 in. branch 1-6 in. branch 8 to 18 in............................................................................ 2-6 in. branch 1-8 in. branch 1-8 in. branch Note: Where profiler is used, provide additional pipe not lessthanthatspedfiedfortop head. Wood Shapers 1-4)4 to 10 in. branch for each spindle according to size and character of work. Tenoner ------- -- For cutoff saws: Up to 12 in. diam.................................................................................................... Over 12 in. diam.................................................................... ............................... Use 1-5 in. branch minimum for each top and bottom tenon, cope and dado head. 1-4 in. branch 1-5 in. branoh Automatic Lathes Use 1-3 in. to 1-10 in. branch according to work length. Hogs ... .. Air volume based on 50 cu ft per lb of refuse conveyed. Use 4500 fpm minimum oonveying velocity. Floor Sweeps Use 6 in. branch for fine dust to 8 in. branch for coarse material. Mouth at floor, 10 X 4 in. to 12 X 5 in. Note: Area of floor sweep pipe need not be included in computing main pipe area. Miscellaneous Equipment Pulley pockets and chain mortises-3 in. branch; dovetail and lock corner machines, dowel machines, duplex molding sanders, forming lathes, panel raisers (each head), ploughs, rail shears, routers, sash stickers (each head) 4 in. branch; pulley stiles-5 in. branch; glue jointer-6 in. branch. can be adjusted to required airflow rate, cfm, by use of a blast gate or orifice plate in such stub branch. 2. Arranging system layout so future points can be picked up by a separate main which will run directly to the fan or air cleaning equipment inlet. CALCULATION OF SYSTEM PRESSURE LOSS The pressure loss of the system includes entrance loss37 as air is accelerated through the hood to a branch duct connection, resistance loss of ducts,38 elbows, and junctions, and acceleration or deceleration losses from velocity changes within the system. Chapter 32 includes data on duct resistance and on resistance of elbows, and provides sample calculations. In exhaust sys tems, either the equal friction method (illustrated in Chapter 32) or the use of blast gates in the branches to equalize pressure loss of all runs is em ployed.8' 11 13-18 Data on losses for hood entrance and branch entry, transitions and weather hoods-are given in Fig. 2. The static pressure in branch ducts close to the hood connection is frequently referred to as hood suction. It is the sum of the velocity pressure in the branch and the hood entrance loss.