Dust Extraction - When to Step Down Extract Pipe Diameter ?

[Stuartgb100]

Planning to put a 1500kw extractor outside and bring the 100mm pipe into the workshop.
This will be connected to smaller machines - mitre saw, bandsaw etc.
Do i immediately step down to (say 50mm etc) or run with the 100mm pipe right up to each unit before reducing ?
Thanks.

 

[Sachakins]

Run the biggest pipe you can for the longest you can.
Is the 100mm the max inlet on the extractor? Some are 125mm, 150mm.
I would run the biggest pipe diameter that matches the extractor inlet and run it up to as close as you can, stepping down to suit your machine, keeping that length as short as possible.

 

[Sideways]

Excellent advice above.
100mm is too small for a 1.5kW extractor. You should use 150mm.
Aim to use swept T joints to minimise the air resistance and step down after the T. Keep flexible hose short. It has awful airflow properties. 1m of flex hose is as bad as 3m to 10m of smooth bore duct.

Read this article.
It is pretty much describing your 2hp extractor and how a fairly streamlined 6" duct system will give you a usable 800cfm airflow while 100mm ductwork will give you only half that.

https://www.oneida-air.com/blog/how...qzm_nChqHDpTNEvLhAsd85xiWlFPSbN8AWpJdXlDFRfc2

And if you think "6" is too big, I don't have space for that" then ditch the hvlp extractor idea altogether and get a 3 motor camvac. They don't make great airflow but at least they have enough suction that a poorly designed duct won't ruin the performance they do have.

 

[Stuartgb100]

Many thanks both - a big help.
Cheers.