Industrial Exhaust Fans: Exhaust Volumes & Pipe Sizes

Exhaust Volumes and Pipe Sizes: This list of recommended exhaust volumes and pipe sizes for average sized metal working and woodworking machines is based on many years of experience and the work of many people. Some modern high speed or extra large machines will require higher velocities than shown. Smaller machines may use less air than shown. The air volume required to capture the dust at the machine will vary with each operation. Particle size and hood type must be considered. The following charts will provide an excellent guide to determine your total air volume requirements. Please note that these charts are only guides and you should contact a Murphy representative if you require more information or assistance.

Other factors to be considered:

  1. Correct and efficient hood design
  2. Correct conveying velocity
  3. Efficient duct design and layout
  4. Properly balanced system
  5. Properly located cleanouts

Caution: One of the most important factors in an efficient dust collection system is proper hood design. Hoods must be designed so that the dispersed particles are thrown or deflected directly into the hood opening. The large heavy particles thrown out by the cutting heads or wheels have such a high speed that their trajectories cannot be altered by a vacuum system regardless of its velocity. In addition hoods should be placed as close to the source of dust contamination as possible since the effectiveness of an exhaust hood decreases very rapidly as it is moved away from the source. The following recommended pipe sizes are based on the use of reasonably good hoods.

Wide belt and abrasive sanders, moulders and shapers with high R.P.M. spindles often call for higher duct velocity (through hoods supplied by manufacturers) than those indicated on the charts. In these cases caution must be used. Contact the fan experts at N.R. Murphy for further assistance.

The following charts are recommended for machines with good hood enclosures. (Also check with the machine manufacturer for their recommended velocities.)

Recommended Exhaust Volumes and Pipe Sizes:

  1. Moulders, Matchers & Sizers
  2. Double Surfacers
  3. Single Surfacer
  4. Jointer
  5. Grinding Wheels
  6. Buffing & Polishing
  7. Turning Lathes
  8. Circular Saws
  9. Band Rip or Resaws
  10. Horisontal Belt Sander
  11. Single Drum Sander
  12. Floor Sweep
  13. Gang Rip Saws
  14. Disc Sander
  15. Multiple Drum Sander
  16. Spindle Shaper
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