Extraction, when to reduce the pipe diameter

[LarryS.]

Hi,

I've bought myself a record dx5000 which has a 100mm outlet, one of the tools I want to connect to it is a tablesaw with a 40mm Pipe connection.

So do I put a 40mm connector on the end of my 100mm 3m flexible Pipe, or put a 40mm connector at the extractor end and buy a 40mm Pipe?

I'm presuming the choice could affect performance hence the question

Thanks for any advice


Paul

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[Brandlin]

yes, what you choose will effect performance. whether it effects itenough to matter is dependent on a lot of factors.

but, in general you want to keep the widest diameter pipe you can until as close to the tool as you can.

also, reduce the sharp turns as much as you can, and use smooth bore pipe rather than flexible ... anything to keep your airflow as smooth and uninterrupted as you can.

 

[Mike Jordan]

The shorter that you keep the 40mm pipe the greater wil be the efficiency. It would be better in my opinion if you find a way of converting the saw outlet to 100mm and allowing the extractor to move plenty of air.

 

[MattRoberts]

Reducing from 100mm to 40mm is way too much - you're going to starve the impeller and dramatically reduce the airflow, as well as risk burning the motor out.

As Mike suggests, you're much better off cutting a 100mm hole and fitting a 100mm spigot.

The alternative (less effective) option would be to have a branch in your line with a blast gate on which is partially open, to allow additional air to flow into the pipe in addition to the 40mm port

 

[LarryS.]

Thanks all, sounds a bit more involved than I thought (isn't thsat just always the way!).

One the record site they sell a kit for the dx which is straight down to 35mm at the unit then a long pipe, could this be possible because the unit has two motors which can be turned on separately?

Thanks

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[cammy9r]

The dx5000 is a HPLV extractor, a vacuum rather than an air mover. I would reduce at the saw. It will work well as the impeller on these is not really effected in the same way as the big chip extractors (HVLP) impellers. I use both types of extractors. This info comes from me doing rather than reading, you could try both ways of what you are thinking and see the results first hand.
You could read siggy's technical thread on extraction.