exhaust ducting system design 3

[Q5n8ceVE]

i'm about to upgrade our exhaust system,what items must be considered in installing new exhaust fans?how to compute the losses in ducts due to twists?how to compute air change of the area?any recommended website?thanks...

 

[dino40]

Q5
Here's a start location for you check out Mcmaster-Carr. I just got done doing the same thing at our facility and they helped a bit. The catalog has some starter info on fan cfm rates at differant static rates.
Hope this helps

 

[KiwiMace]

ASHRAE fundamentals handbook 2005 chapter 35 lives and breathes duct design, SMACNA is also a good reference for typical schematics. Air change is simply volumetric flow/volume. If you haven't done any ductwork design before, its like pipes - you draw out the entire system first on paper and calc each component. My rules of thumb are 0.8Pa/m pressure drop in straight duct, 8-10m/s velocity max and a 4:1 ratio on duct dimensions.
Fan choices tend to revolve around your total pressure drop, where this gets >250Pa, centrif fans become the more appropriate choice. Stick to 4-pole (or more) motors for reliability.

 

[Clymber]

Also see the ACGIH Industrial Ventilation Handbook. It has very detailed informationr regarding exhaust system design.

 

[Q5n8ceVE]

Thank you very much for all of your inputs..more power to all..

 

[tomwalz]

Consultants
Most states provide free consulting. If you are in British Columbia then you can contact the Workers’ Compensation Board at (604) 276-3209.

Three Excellent Articles

1. One is by John Ashe of AAF (American Air Filter) International in Louisville, KY. (305) 443-9353. His article is Controlling Welding Fumes in the July, 1997 issue of The Fabricator. Reprints of the article are available by calling (800) 477-1214 and asking for reprint # APC-4-905.

2. Another good article was in the December 1996 issue of the same magazine. It was written by Joe Topmiller who is Director of Technical support for United Air Specialists at (800) 551-5401 in Cincinnati, Ohio. The article is Addressing Air Quality Issues in the Workplace.

3. The third article is on new respiratory standards by Jay G. Mears in Modern Woodworking. (248) 244-6439. It was called: Intelligence Report: Getting Ready for 42 CFR part 84 call MSA and is available at (888) 867-0602.

Equipment Suppliers:

1. AAF International (American Air Filters) –(305) 443-9353 – small line but appropriate for most shop applications – great technical support – (see articles section above). Excellent technical advice.

2. Abicor Binzel (301) 846-4196 Frederick, MD - They only supply fume extraction guns for welding. Great product if you need it.

3. Airflow Systems (214) 503-8008 Dallas, TX – wide variety of units, overhead units, downdraft tables, and portable units – “Dust and fume Exhaust” pamphlet has good technical information. Recommended for literature.

4. Coppus (508) 756-8391 Millbury, MA – unique, portable dust collection systems – also employee coolers for hot areas. Unique products.

5. Dust Vent, Inc. (630) 543-9007 Addison, IL. – Wide range of equipment and good literature. Recommended for literature.

6. Eurovac (905) 850-9828 in Ontario. –Central vacuum cleaner systems and other dust collection equipment.

7. Farr Pollution Control Products (800) 479-6801 Los Angeles, CA. – Overhead cleaning with or without arms.

8. Gardner Environmental Products (414) 485-4303 Horicon, WI –Ceiling mounted and portable units.

9. Industrial Ventilation Group (800) 610-6010 Harbor Springs, MI –Central and portable units, downdraft tables. Recommended for literature.

10. Lincoln Electric (216) 481-8100 –Offers a central collection system and portable units –just one mention in their catalog.

11. MAC Equipment, Inc. (800) 821-2476 – Huge, complete catalog. Excellent information, great source to build your own system. Recommended for literature.

12. Nederman (313) 729-3344 Westland, MI –Nice literature –looks like nice overhead arm extraction equipment –good information on Do It Yourself. Recommended for literature.

13. Plymovent (732) 417-0808 New Jersey –good equipment –great free booklet “My Pocketguide to Clean Fresh Air”. Recommended for literature.

14. Sly, Inc. (216) 891-3200 Cleveland, OH –Shop size central collection systems to huge industrial systems. Recommended for literature.

15. Trion (800) 421-3956 Greensboro, NC –Overhead units –they advertise a free clean air guide.

16. United Air Specialists (800) 551-5401 Cincinnati, Ohio –Invented the original smoke eaters for bars, etc. –Good equipment –good literature and great technical help. Recommended for literature.




Thomas J. Walz
Carbide Processors, Inc.

http://www.carbideprocessor.com