Dust extraction duct size?

[Julesbarn]

Hi all.
I really tried not to ask.. I'm sure it can be a tedious subject that has been much discussed but I've been going round in circles and can't decide! So some advice pleeese.

I have a 2hp HVLP blower venting to outside. It has 5" in and out ports so i have been looking at what 5" pipe and fittings are cheap and available online. All i find is extractor fan duct (rigid and flexi), and a very limited range of fittings.
It seems the easy and cheap option is to use 110 soil pipe and fittings (really cheap from jtm plumbing,by the way), but after reading tons about DE design including Bill Pentz, perhaps bigger ducting would pick up fine dust better.
6" seems too big for my small and simple design, but 110soil might be a bit small!?
It is worth noting that from DE port to TS port is only 2metres (under the floor) same for the 16" bandsaw. The thicknesser is a bit further from the DE, bur i find 4" flexi pulls the shavings well.

So heres my question..
Do you think it is worth using 5" for such short runs? (With limited fittings and more need to use flexi)
..or use 110 soil pipe (with large choice of fittings so a more slick efficient design)?
5" looks a lot bigger than 4" : )

Many thanks,
Jules

 

[heronviewer]

Use 110mm drain pipe fittings - you'll get a faster air flow with a slightly smaller pipe diameter.

 

[Julesbarn]

Thanks robert.
My research shows me,though, that with 110 I'll get more velocity (good for shavings/chips)
And larger pipe I'd get higher flow rate (m3/min...good for fine dust)

 

[MattRoberts]

Hi, afraid that is incorrect. You will get faster airflow using a 125mm system than a 110 or 100m system.

I have a 2hp extractor and have used an anenemoter to test. I've installed a 125mm ducting system reducing to 100mm right at the very end of the run when attaching to the machines.

There's a balance to be found with HVLP extractors between the HP / impeller size and the ducting size, and for a 2hp extractor 125mm is that balance. Any less starts to state the impeller and reduces airflow quite considerably.

I bought pvc ducting from ebay, do a search for 125mm ducting.

I bought the straight pipe, connectors, 45 degree elbows and aluminum blast gates (from axminster) and probably spent about £200 in total, so not too expensive in my book.

 

[Julesbarn]

Matt roberts thanks , just what i needed to hear! My gut feeling has been 125 as far as poss (as the DE ports are 125 and seemed daft to immediately restrict to 100/110) it's just the lack of 125 fittings options that made me doubt...

That has really helped me with my decision
Cheers

Jules

 

[will1983]

Just for the record 110mm soil pipe is 110mm OD, ID is only about 101mm.

 

[sunnybob]

Any sized flexible pipe is much more restrictive than the next size down rigid.
The corrugated sides are a HUGE drag on air flow. Even worse if it goes slightly oval on tight curves.

 

[miffy]

I have 110 mm soil pipe fitted in my workshop, no problems at all, built my workshop in 2000,

 

[MattRoberts]

Just to clarify - 110 / 100mm pipe is just fine for 1hp systems, but if you have a 2hp or more you get better results from 125mm or bigger. The rule of thumb is to look at the inlet diameter on the extractor, and use the same size for the ducting

 

[Yojevol]

I set up my present workshop some 10 years ago using an Axminster 2200 extractor. My main m/c is a Felder combo with 5" ports so I installed 5" metal duct, about 6m, between the two. It has many branches off using 4" plastic soil pipe to other m/c's. Short runs of flexible are used where necessary particularly when switching from one function to another on the combo. I had no problem in buying 5" pipe components. It has worked well over the years.

 

[Julesbarn]

Thanks for your thoughts. As my DE has 5" ports, i wont be going smaller than that for my ducting, except to reduce to 4" at the machine. I can however stay at 5" for my TS as i am able to make a 5" port to replace the 4" it came with. The only challenge is to find some streamlined Y's , and minimise the amount of flexi used.

Jules

 

[gregmcateer]

Thanks for your thoughts. As my DE has 5" ports, i wont be going smaller than that for my ducting, except to reduce to 4" at the machine. I can however stay at 5" for my TS as i am able to make a 5" port to replace the 4" it came with. The only challenge is to find some streamlined Y's , and minimise the amount of flexi used.

Jules

Jules,

I haven't investigated thoroughly, but here in the west midlands there are quite a few metal fabricators - if you are struggling for swept curves, etc, it may be worth a quick google for companies, then give them a call. small engineering places can be surprisingly cheap.

hth

Greg

 

[Julesbarn]

Thanks for that greg. I've found nice 125 Y's from charnwood or poolewood, rigid pipe, not so good Y's,and 45's from fantronix. Bit of flexi and I'm good to go! My system will have really short runs and only a little bit of flexi so should work very well. Thanks anyway

Cheers

Jules

 

[MattRoberts]

Jules, I got my Ys from here if it helps: https://rover.ebay.com/rover/0/0/0?mpre ... 1725443482

 

[Julesbarn]

Thanks matt, but i want to stick with plastic (cheaper and easier to modify). I am considering butchering two Y pieces to make a 3-way splitter to connect to the blower inlet which will point downwards, each with a blast gate. This will suit my pipe run directions really well and allow for gentle bends and minimise flexi. I have piles of sketches on my desk from trying to work out the best design! Hopefully I'll get it right : )

Cheers

Jules