Is it better to reduce 4" port to a 2-1/2" hose, or run a 4" hose to a 2-1/2" port?

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Forum topic by Winny94 posted 08-18-2021 05:00 PM 458 views 0 times favorited 8 replies Add to Favorites Watch
View Winny94's profile


110 posts in 1726 days

08-18-2021 05:00 PM

Insert obligatory “far from ideal” “will upgrade when funds allow” etc. I know neither option is good, but for the time being: Is it better to run a 4” hose from my saw to a reduced 2-1/2” port, or reduce a 4” port to a 2-1/2” port and run through a 2-1/2” hose?

8 replies so far

View Ocelot's profile


3563 posts in 3923 days

#1 posted 08-18-2021 05:15 PM

How long is the hose?

What kind of tool is it?

-- I intended to be a woodworker, but turned into a tool and lumber collector.

View Winny94's profile


110 posts in 1726 days

#2 posted 08-18-2021 05:17 PM

How long is the hose?

What kind of tool is it?

- Ocelot

About 5’. Table saw to Dust Deputy.

View Bill_Steele's profile


779 posts in 3016 days

#3 posted 08-18-2021 06:07 PM

I’m not sure if there would be a lot of difference.

View therealSteveN's profile


9230 posts in 1859 days

#4 posted 08-18-2021 06:13 PM

I’ve always heard for improved flow to keep it the biggest size for as long as you can. So I would 4” up to the port, and use a reducer to hook up. Someone will come along soon with Math, and machines to state what is best though.

-- Think safe, be safe

View controlfreak's profile


3055 posts in 886 days

#5 posted 08-18-2021 06:22 PM

Smaller hose = more static pressure but as said over a 5’ distance not a huge deal breaker.

View EarlS's profile


4805 posts in 3633 days

#6 posted 08-18-2021 07:14 PM

I’m not going to do the math, but 4” pipe has a lot less pressure drop than hose because the inside of the pipe is smooth while the hose obviously is not. The larger diameter also has less pressure drop. Tapered reducer have less pressure drop than a dutchman style reducer which is basically a cap with a smaller diameter connector on it.

The problem with 4” pipe is the velocity if you are hooked up to a shop vac. Not enough velocity and the dust falls out of the airstream and plugs the pipe.

You might be better off with 2.5” pipe if you have a shop vac set up with a Dust deputy

-- Earl "I'm a pessamist - generally that increases the chance that things will turn out better than expected"

View bigblockyeti's profile


7750 posts in 3005 days

#7 posted 08-18-2021 07:29 PM

4” pipe (or flex corrugated hose) better with a high volume, low pressure DC. 2.5” pipe or hose better with a low volume, high pressure vacuum.

-- "Lack of effort will result in failure with amazing predictability" - Me

View Fred Hargis's profile

Fred Hargis

7296 posts in 3778 days

#8 posted 08-18-2021 08:40 PM

I’m with Bill Steele, do which ever is easiest because there won’t be much difference.

-- Our village hasn't lost it's idiot, he was elected to congress.

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