Extra Filtration

      Advice on improving dust-collection system effectiveness by adding to filter bags or introducing a pre-separation component. April 17, 2009

Question
I have recently installed an older torrit cyclone collection system and was wondering if replacing the old filter bags with longer bags would help system performance or if there are any negative effects of more filter material.

Forum Responses
(Dust Collection and Safety Equipment Forum)
From contributor T:
I added two extra filter bags on my cyclone to improve filtration and air flow (CFM). Use micron felt bags or cloth. The more filter area the better. It's usually a question of how much space can you afford, how much filter fabric can you justify? I'm sure the tech folks at Torrit can tell you when enough is enough.



From contributor C:
What is the hp of the blower on top of the cone? I may be able to help you with the square footage of cloth. Aside from having a good filter material to handle the fines, an overall air to cloth ratio is important. Assuming the waste created is mostly coarse with some fines mixed in, a 10-1 air to cloth is a good ratio. Example, if we are moving 1000 cubic feet per minute, total filter area would be 100 square feet. This can be achieved by various size bags that equal 100 square feet.


From the original questioner:
HP of the motor is 5. I figured the system CFM to be around 1350, according to Torrit specs. The current bags are about 72 square feet of filter material.


From contributor C:
Torit model 20-5FB 5 hp with after filter shows 70 square feet of cloth (4 bags 11 1/2" diam X 70" long). This unit will deliver 2,000 cfm at 8.4" spwg, which is the external resistance when piped into a typical 40' X 30' shop. At that level, looks like the air to cloth is around 28-1, which is definitely on the high side.


From contributor D:
I do not think you can have too much filter area. The only problem I can think of is that some blowers are overloaded when they do not have some resistance. This is not likely a problem for you but I would advise checking the amp draw after making changes. Also I have some filter material for sale if you are interested.


From contributor B:
It depends on what type of waste you're handling, and how effective your separation is, within the cone. With small industrial single-stage dcs like the Kraemers and Pyradia/Belfabs, you'll see roughly 30-1 air-to-cloth ratio for "general" woodworking applications (coarse/dry waste). The more "fines" you produce however, then the larger that air-to cloth ratio has to be.

Your cyclones' separation efficiency, may depend on how much air you're flowing into the cyclone. This may vary from branch-to-branch, depending on length and configuration of your run.

If you want to avoid sending the bulk of your fines to the dc, try a pre-filtering pre-separator at those machines that may require it, like a drum sander. Itís quite simple to fabricate one. All you need is a drum, then make a plenum and mount it atop your drum. Use a couple of inexpensive cellulose-based filters, mounted horizontally inside the plenum. A flip-top lid will allow access for easy cleaning. That pre-filtering pre-sep will reduce the amount of cleaning required at the central dc, and your other runs won't suffer from pressure-drop due to loaded filters.



Would you like to add information to this article?
Interested in writing or submitting an article?
Have a question about this article?


Have you reviewed the related Knowledge Base areas below?
  • KnowledgeBase: Knowledge Base

  • KnowledgeBase: Dust Collection, Safety, Plant Management

  • KnowledgeBase: Dust Collection, Safety, Plant Management: General


    Would you like to add information to this article? ... Click Here

    If you have a question regarding a Knowledge Base article, your best chance at uncovering an answer is to search the entire Knowledge Base for related articles or to post your question at the appropriate WOODWEB Forum. Before posting your message, be sure to
    review our Forum Guidelines.

    Questions entered in the Knowledge Base Article comment form will not generate responses! A list of WOODWEB Forums can be found at WOODWEB's Site Map.

    When you post your question at the Forum, be sure to include references to the Knowledge Base article that inspired your question. The more information you provide with your question, the better your chances are of receiving responses.

    Return to beginning of article.



    Refer a Friend || Read This Important Information || Site Map || Privacy Policy || Site User Agreement

    Letters, questions or comments? E-Mail us and let us know what you think. Be sure to review our Frequently Asked Questions page.

    Contact us to discuss advertising or to report problems with this site.

    To report a problem, send an e-mail to our Webmaster

    Copyright © 1996-2016 - WOODWEB ® Inc.
    All rights reserved. No part of this publication may be reproduced in any manner without permission of the Editor.
    Review WOODWEB's Copyright Policy.

    The editors, writers, and staff at WOODWEB try to promote safe practices. What is safe for one woodworker under certain conditions may not be safe for others in different circumstances. Readers should undertake the use of materials and methods discussed at WOODWEB after considerate evaluation, and at their own risk.

    WOODWEB, Inc.
    335 Bedell Road
    Montrose, PA 18801

    Contact WOODWEB











  • WOODWEB - the leading resource for professional woodworkers


      Home » Knowledge Base » Knowledge Base Article