Thanks: 0
Needs Pictures: 0
Picture(s) thanks: 0
Results 1 to 8 of 8
Thread: Small duct Measurement
-
13th May 2022, 09:59 AM #1Intermediate Member
- Join Date
- Feb 2015
- Location
- Indiana, US
- Posts
- 46
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 ?
-
13th May 2022 09:59 AM # ADSGoogle Adsense Advertisement
- Join Date
- Always
- Location
- Advertising world
- Posts
- Many
-
13th May 2022, 11:18 AM #2GOLD MEMBER
- Join Date
- Jun 2005
- Location
- Helensburgh
- Posts
- 7,696
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
-
13th May 2022, 11:41 AM #3GOLD MEMBER
- Join Date
- Jun 2005
- Location
- Helensburgh
- Posts
- 7,696
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
-
13th May 2022, 11:57 AM #4.
- Join Date
- Feb 2006
- Location
- Perth
- Posts
- 27,788
-
13th May 2022, 09:19 PM #5Senior Member
- Join Date
- Nov 2016
- Location
- USA, Indiana, West Lafayette
- Posts
- 188
-
13th May 2022, 11:48 PM #6Intermediate Member
- Join Date
- Feb 2015
- Location
- Indiana, US
- Posts
- 46
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.
-
14th May 2022, 08:45 AM #7.
- Join Date
- Feb 2006
- Location
- Perth
- Posts
- 27,788
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)
-
14th May 2022, 12:11 PM #8Intermediate Member
- Join Date
- Feb 2015
- Location
- Indiana, US
- Posts
- 46
Apology
Deleted
Similar Threads
-
Testo 405i Hot Wire Anemometer inappropriate for small (150mm) duct
By dmorse in forum DUST EXTRACTIONReplies: 17Last Post: 11th January 2020, 07:07 AM -
Beyond Tools - Flexible Anti Static Duct Duct
By DeeSki in forum DUST EXTRACTIONReplies: 1Last Post: 21st March 2019, 02:56 PM -
Small angle measurement??
By TTIT in forum WOODWORK - GENERALReplies: 17Last Post: 29th May 2012, 08:53 PM -
New Units of Measurement
By WoodGirl in forum WOODIES JOKESReplies: 0Last Post: 11th May 2008, 12:04 AM -
rpm measurement?
By Slow6 in forum WOODTURNING - GENERALReplies: 24Last Post: 20th November 2006, 12:46 AM