Thanks Thanks:  0
Needs Pictures Needs Pictures:  0
Picture(s) thanks Picture(s) thanks:  0
Results 1 to 8 of 8
  1. #1
    Join Date
    Feb 2015
    Location
    Indiana, US
    Posts
    46

    Default Small duct Measurement

    I recently saw a video where a guy tried measuring the flow of shop vacs and extractors by using a vane anemometer at the end of 1.5 and 2.5" hoses. Does look accurate.

    What is a reasonable method to measure flow from small hoses ?

  2. # ADS
    Google Adsense Advertisement
    Join Date
    Always
    Location
    Advertising world
    Posts
    Many





     
  3. #2
    Join Date
    Jun 2005
    Location
    Helensburgh
    Posts
    7,333

    Default

    Read the sticky posts directly above yours for more information but the short answer is no, a total waste of time. The bigger question is what are you wanting to measure the airflow for? The information in the stickies should answer most questions about ducting and DE in general.
    CHRIS

  4. #3
    Join Date
    Jun 2005
    Location
    Helensburgh
    Posts
    7,333

    Default

    As an aside from your question 99.9% of information concerning dust extraction on YouTube is simply wrong and should not be relied on. Do some reading here and gain some knowledge and you can then begin to weed out the misleading information from the occasional snippet of useful stuff.
    CHRIS

  5. #4
    Join Date
    Feb 2006
    Location
    Perth
    Posts
    27,084

  6. #5
    Join Date
    Nov 2016
    Location
    USA, Indiana, West Lafayette
    Posts
    188

    Default

    Quote Originally Posted by Chris Parks View Post
    As an aside from your question 99.9% of information concerning dust extraction on YouTube is simply wrong and should not be relied on. Do some reading here and gain some knowledge and you can then begin to weed out the misleading information from the occasional snippet of useful stuff.
    fixed
    Dave

  7. #6
    Join Date
    Feb 2015
    Location
    Indiana, US
    Posts
    46

    Default

    Thanks for the responses...but I think I phrased it not clearly.

    What type of setup is needed to measure the cfm of shop vacs? No doubt that you need to use a much larger test duct. How big a test duct and how long? It would seem that if too large the velocity would drop to low.

  8. #7
    Join Date
    Feb 2006
    Location
    Perth
    Posts
    27,084

    Default

    Quote Originally Posted by Maple71 View Post
    Thanks for the responses...but I think I phrased it not clearly.

    What type of setup is needed to measure the cfm of shop vacs? No doubt that you need to use a much larger test duct. How big a test duct and how long? It would seem that if too large the velocity would drop to low.
    Its not that difficult to work it out for yourself.

    The flow rate for a typical vac is ~0.06 m^3/s
    A 30mm diam hose has a cross sectional area of 0.0007 sqft
    This means the air speed is notionally 0.06/.0007 = 85 m/s
    Now unless you have an air flow device that uses something like a "pitot tube" there is no way you can measure this air speed.
    At this nominal flow rate the air speed is also not uniform across this duct so it has to be slowed right down/\.

    This is done by increasing the cross section of the pipe so the ai speed comes into the range of the air flow meter you are going to use.
    If you can't work it out then ask and I'll step through it for you.
    For that I will need to know the range of air speeds your air flow meter can cope with.
    It will also help to know the type of meter you have.

    The rest is in this post. DRAFT: FAQ - Dust Extraction (Practical Aspects)

  9. #8
    Join Date
    Feb 2015
    Location
    Indiana, US
    Posts
    46

    Default Apology

    Deleted

Similar Threads

  1. Replies: 17
    Last Post: 11th January 2020, 07:07 AM
  2. Beyond Tools - Flexible Anti Static Duct Duct
    By DeeSki in forum DUST EXTRACTION
    Replies: 1
    Last Post: 21st March 2019, 02:56 PM
  3. Small angle measurement??
    By TTIT in forum WOODWORK - GENERAL
    Replies: 17
    Last Post: 29th May 2012, 08:53 PM
  4. New Units of Measurement
    By WoodGirl in forum WOODIES JOKES
    Replies: 0
    Last Post: 11th May 2008, 12:04 AM
  5. rpm measurement?
    By Slow6 in forum WOODTURNING - GENERAL
    Replies: 24
    Last Post: 20th November 2006, 12:46 AM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •