5" or 6" flex for portable DC

[Jonathan Wicks]

Hi,

I've got a Delta 50-760 1.5HP DC that I wheel between tools. It's got a 5" main port with a 4" wye connector and comes with 6' of 4" flex tube that I've been using to connect to the tool ports. I only ever use one tool at a time so the other side of the wye is capped.

From what I can gather from reading many posts I would get higher CFM if I use a 5" or 6" pipe. Here is what I am considering (avoiding changing the tool hoods for now):

1) Get a 5" flex tube, get rid of wye, and step down to 4" at the tool.
2) Get a 5" to 6" fitting (do they make a fitting like this in PVC?) and run 6" flex then step down from 6" to 4" at the tool.

The flex's 5" or 6" would be short, probably the 6' like I have now.

So which would get me higher CFM at the tool option 1 or 2?
I've heard the going from a 6" to 4" will add a lot of SP and hurt CFM...BUT...will it hurt CFM enough to undo the benefit of the 6" diameter pipe?

Thanks,
Jon

[Victor Stearns]

Jonathan,
Greetings. You are limited by the use of a 4-inch fitting. It does not matter if you have 5 or 6-inch flex to your DC when you neck down to the 4-inch machine connection. A 4-inch line will only flow 300-cfm, while a 5-inch goes up to 475cfm. Now if you make the next step to 6-inch, 675cfm!!
I would suggest that you replace the machine connections with largest size based on how much cfm each machine requires. A table saw for example will need 350-500 cfm while a router table needs 200-350 cfm.
Good Luck
Victor

[Jonathan Wicks]

Thanks for the reply.

Duh, I guess that makes sense that the airflow is limited by the surface area of the intake. So I guess 6" lines make sense only when you have a 6" port at the tool or a wye (like 6-4-4) that can get close to 6" of surface area. But in the case of the wye I assume you still are only getting the 4" amount CFM (you quoted ~300) from each 4" port...

[Jim Becker]

I'll play devil's advocate and suggest to you that running the larger hose with a reducer right at the tool will still give you a little more performance than using a 4" hose. You'll get a little bit of "venturi effect" at the reducer...some acceleration of the air flow at that point that you will not get with just the 4" to 4" path. But I do agree that the greatest increase in performance is going to come if you can up-size the port in the tool hood.

[jason lambert]

Everything I read is in line with what Jim said. Even when you have a pro like oneida or someone lay out duct work it is alwas bigger, 5 or 6" to the machine to 4" in the machine. Try to get the flex with a smooth inside flex will also kill your cfm so use as little as possable.

[Jim Becker]

Jason, the only reason that most of us use 4" connection to the machine is that many machines are a pain to make it larger. Ideally, a 5" or 6" hood connection would be much better on many tools....such as a table saw. But they don't come with one and modification can be real work.

[Chris Padilla]

I'm still waiting for the day when these tool manufacturers give us an option for a larger dust collection port on their machines....