work shop ducting

[the sheep lover]

Hi Guys, i'm new to the forum so be patient , I have recently bought a dust extractor for my work shop/shed for my wood turning, its not a large space and was wondering if i can get away with using rectangular ducting as this would sit closer to the walls. i was wondering has anyone used rectangular ducting instead of the traditional round?

 

[Random Orbital Bob]

I've not seen any I must admit. Whatever you do...make sure you get that fine dust out when you're power sanding or your health will be at extreme risk. The flexible 100mm hose can get into pretty tight spaces because it flexes into gaps.

 

[Ian down london way]

Having just bought one of those bargain shop vacs from Lidl, I must say that whilst built in extraction is great, and necessary, you still get a fine dust which is not picked up (and I've a room extractor too). A simple mobile shop vac to get the dust once it has settled is needed, to avoid what I did for way too long, which was sweep the dust off surfaces with a hand brush, onto the floor to then sweep up - putting dust into the air all over again.

I like having clear tubing for my extraction. Partly, I just love to see it whizzing along, but also I like to see where there may be build ups / blockages. especially as I sent the piping over the ceiling, with drops to fixed tools, and you can get some strange effects when drawing from the furthers machines, where the dust drops down the tubes drawing from nearer ones.

 

[Reggie]

axminster appear to have some new clear extraction tubes for sale.
http://www.axminster.co.uk/page/find/?n ... 0hose&page

 

[Random Orbital Bob]

Ian's comments about dust settling on surfaces and remaining a hazard is right on the money. The real trick to effective LONG TERM DX is to remove it at source. We're less worried about the big chips but more so about the fine particles of less than 5 microns in size. When I'm powersanding a bowl, there's a lot of that stuff coming off!! Even offering a gouge to very dry wood creates pretty fine dust. That's the stuff you need to extract before its either gone into the air or settled on another surface (for later entry into the air when you're not taking precautions).

Three measures should in my view be seriously considered:

1. make sure your extractor has a fine filter that caters for 5 micron and less dust
2. vent the extractor outside your actual workshop so the blowing effect doesn't re ignite all the dust around it
3. get a decent hood that connects the business end of your hose so you can effectively shroud the turning wood to capture as much of that fine dust as you can. And wear a mask when powersanding or doing any extreme fine sanding operation IN ADDITION to the DX machines.

People always under-estimate proper DX....if its a very part time basis the risks are lower of course because your exposure is less but small workshops are at much greater risk than industrial sites because the dx isn't generally properly considered. My father was a home wood worker and died of lung cancer. He worked in a regular sized garage workshop with zero dx!!

 

[Random Orbital Bob]

By the way....the belt and braces approach (which isn't nice but I do myself) is to wear a trend power'd full face mask when doing those very dusty operations (again as well as all the machine dx running simultaneously)

 

[Random Orbital Bob]

a final yes and......

If your throats tickling or you have a persistent frog in your throat type cough after dusty wood work, you know you've inhaled a ton of fine dust and your bronchiole system is reacting to it. Do that after using man made boards with resin in ie ply or mdf etc and you're heading for trouble.

 

[Baldhead]

The sheep lover I assume you mean using these,

http://www.screwfix.com/p/manrose-recta ... 00mm/14118

Instead of these,

http://www.axminster.co.uk/axminster-10 ... rod803512/

Apart from the fact that, as you say they take up less room, there is also a considerable difference in price!

Although I do have a wet/dry vac and a chip collector I don't have fixed extraction facilities, so I can't answer your question, however it may have something to do with the volume of the pipework and corners creating a greater resistance, this is all just guess work on my part.

I will follow this thread with interest as I too want to install something a 'bit more permanent' than I have at present.

BH

 

[MARK.B.]

As far as i know (dont quote me on this ) the rectangular ducting you are thinking of using is used for air extraction from things like cooker hoods or bathroom extraction fans.

 

[Phil Pascoe]

This is a subject about which I know little, but I'd have thought you could use anything you could get to fit where you wanted it - as long as all the fitting are air tight, what difference does the shape of the pipework make? Also, I assume you could use soil pipe as long as you could get the fittings for the ends?

 

[Jamesc]

Dredging back to when I was taught ventilation design manu more years ago than I care to admit (even to myself) rectangular ducting is not suitable for extracting solids. It is all to do with maintainig sufficient aire velocity to keep the solid particles moving. Rectangular ducts particularly when they have bends have great differences in air speed accross their width, this can lead to in this case sawdust getting deposited and clogging up the duct.
Stick to circular ductwork and keep the duct size the same as the inlet of your extractor. If you increase it the air velocity drops and so will the sawdust. If you decrease it the air velocity will go up but the volume will likely drop and the motor will have to work harder and possibly burn out.

Regards

James

 

[the sheep lover]

Cheers Jamesc thats pretty much answered the question for me, i didnt know if i could drop the size down, it would be more powerful but motor could be working harder! just with 100mm ducking all over my already packed out shed would mean even less room for me or my lovely home brew!

and yes Bald head that was the ducking i was looking at as it would take up less room and would save me a few bob too! surely there has to be a cheaper place to get clear ducting from out there? or the normal waste pipe?

Ben

 

[Random Orbital Bob]

Well, normal soil and waste is 4" so why wouldn't that confirm to the specs desired here without changing the dynamics if either air flow or motor wear? It's also much cheaper than the dedicated stuff

 

[Tim_H]

I have seen quite a few examples of dust collection on the tube using and internet using soil pipe but I understand it is slightly bigger than 100mm which is what a lot of machines are made to accept, so duct tape seems to be the order of the day for those joints. Although I note the Axminster do a converter joint for soil pipe.

 

[pip1954]

hi thats what i use 4" soil pipe works a treat, i use flexi pipe with soil pipe cut to fit inside flexi pipe and soil just cut a slice out of the side wall and you have a connector to fit flexi to solid pipe.
pip

 

[Jamesc]

No problem Ben I new those years of studying wierd calculations would finally come in usefull one day

James