Would anyone care to recommend a supplier of ducting suitable for a small woodworking shop? I have the extractor and bagging system but now need the central spine, branches, gates and flexible pipe to connect up the machines.
Google throws up endless possibilities with wildly varying prices.
regards
Axminster stock of lot of this stuff.
HTH
Cheap solution is soil pipe, but I'm told that transparent rigid tubing is a huge advantage when you get a blockage.
Cheap flexi tends to encourage blockages too - I tend to use a loose
100mm hose to clear up, and keep telling myself to upgrade.
Nordfab QF Duct.
a downloadable brochure.
Contact is
They can also supply flexible hose and large Jubilee clips to fix it as well as being able to fabricate particular combinations of outlets - I needed a couple of those - very inexpensively. Their blast gates are excellent, made by sandwiching a metal sheet between nylon components to seal. Hint. Ask for a discount.
Felder also sells a good range of flexible hoses.
I have an American manufactured cyclone extractor which has a 7 inch intake duct. This is transitioned immediately to proper metric sizes (140mm to begin with) using a short length of flexible hose. After a couple of metres this splits into two 160mm branches and these then go to 120mm closer to machine connecion points. My combination machine needs 120mm for the saw, the spindle moulder and the planer/thicknesser and then additionally 80mm for the spindle moulder and 50mm for the saw guard extraction. I've implemented three wall positions plus a ceiling one which each have 120mm gates and then there are 80mm gates for the rest. The bandsaw also needs 120mm.
All of this works very well indeed - extraction is good and no blockages, so no design errors.
Another advantage of the Nordfab QF is that it can be demounted and modified very easily. So for example, I've added an additional 120mm connection point for a downdraught table for sanding.
A completely alternative approach is to just use flexible hose for the lot. If that's done, then it's important to buy decent industrial hose because it's smoother internally. The cheap stuff, apart from being flimsy tends to have ridges inside and will impede air flow.
Don't be tempted to buy cheap airconditioning grade duct. A half reasonable extractor is perfectly able to collapse it. As a minimum, extraction grade duct must be used even if you decide to go for a type that is taped together at the joints.
There is a small risk of static build up, and with fine dust, explosion with soil pipe. As a minimum, if it must be used, it should be sprayed with a metallic paint and grounded.
100mm pipe over more than a very few metres, even if connected to a 100mm extractor, will have too much internal resistance and spoil air flow. If the extractor has a good enough pressure/flow curve, it's better to go for 125 or 150mm duct. However, 150mm soil pipe is getting expensive.Industrial grade is far better and also tends to be static treated which avoids catching of dust etc on the sides.
In message , Tim Lamb writes
Plenty to be going on with:-)
I had found Felder which seems an up-market product.
My extractor came second hand with a burned out single phase motor so I don't have technical info on flow/pressure curves. I have fitted a 3 ph. motor which should survive over loading better. (I suspect the previous user had forgotten to empty the collecting bags and stalled the fan).
I had been comparing prices with ventilation duct and take the point about collapsing the walls.
The whole building is only just over 12m long so 100mm duct may do. I will look out for design info.
Thanks.
regards to all
Absolute and utter bolllocks.
Ah, Governments, we all believe them then. Wonder which pipe manufacturer took who on holiday?
Not to say you aren't right Andy, but this ain't proof.
R.
Made me think of this:
Odd to see that the State of California is in league with the Health and Safety Executive.
Maybe they threatened to set the Governator on our HSE boys if they didn't go along with perpetuating this myth.
What else are they lying about? Is asbestos dust actually good for you?
I wasn't setting out to provide *proof* as such, only to say that it is considered that there is a risk.
For the sake of a small cost saving from using proper metal duct, vs. plastic, the prospect of a fire isn't worth the saving even if the risk is small
One should also point out that when using extractors, it's important to watch out for metal items being cut or sparking if they contact a moving part and ending up in the waste bin. I always make a point of checking that before leaving the workshop for the day. Other issues are to keep the place as clean as possible and to store solvents sensibly.
This has bee covered before:
IME safety standards can sometimes be fairly arbitrary rather than based on proper risk analysis or rationale.
cheers, Pete.
explosion in wood dust?
The UK advisory sheets don't claim this. One of them advises bonding, which is reasonable advice for a staff comfort PoV. The Califonian code requires bonding, but doesn't say why.
No-one disputes that dust flow causes static discharges. These are an annoyance.
However:
"Static discharge causes wood dust explosions" is a red herring. It doesn't happen. It's not hard to show that it _can't_ happen (the available energies are simply too low). In particular it's an FAQ to most of those bits of usenet associated with either wood, dust, safety or electrostatics.
Worry about the real stuff. Smouldering embers going up the pipe is what's going to get you, not static discharges. Or else using toluene.
Reasons can be this, charge build up on machines or deposition on duct eventually causing blockages. Perhaps there are others.
Since one can and should ground machines, I am not sure where comfort would enter into it.
I don't have evidence that this is impossible.
Agreed
Also agreed.
This all seems to be based on an article by one Dr Rod Cole a maths PhD and meteorologist
Given even that scenario, and being faced between the choice of using PVC and doing the job properly with metal duct, to me the choice is clear. If risk can be reduced reasonably, then reduce it.
Notwithstanding this, 100mm soil pipe is too small to use for any reasonably sized duct system and 150mm and fittings costs as much as or more than using metal. That's before one considers the lack of suitable fittings.
All of this is real stuff. The question is the degree of risk.
I would agree that risks associated with embers, bits of metal and solvent are higher, but don't exclude others than can be reasonably reduced.
of doing risk analysis for chem / pharm labs, but let's not let that get in the way of citing a few random web links instead 8-)
Rod Cole's page is a good one, and his explanation of discharge types is clear and useful (although 'merkins count 6 here and non-meteo Europeans generally only count either 4 or 5). "Spark" vs. "Discharge" is a significant distinction worth drawing. If there's one thing worse than a plastic duct, it's a mixed metal and plastic duct.
If you don't want to believe random webbage, then try reading the electrostatics literature. If you search news:rec.woodworking, you ought to find literature reviews that I've posted there myself. Be warned though, you'll need a uni library or similar as most of this stuff isn't found on the free sections of general reference shelves.
DC fans shouldn't be that class of jobs where a 3 phase motor has a great deal to offer over a single phase. They must have _really_ screwed things up!
Only time I've ever seen a stalled fan on a DC was when someone left the ring clamp from the filter wedged in it.
The trouble is that the web sites and newsgroups are littered with conflicting information.
Cole appears to have some level of credibility, I agree, but still does not definitively and wisely say that it's impossible for an explosion to happen as a result of static. It also represents one perhaps reasonable (or not) set of data among a volume saying the opposite. Then we have H&S recommendations not to use plastic duct.
As you say, to research that properly and to form an opinion would require a trip to the unversity library and quite a few hours of research and maths.
That would still only take one to the point of reasonable doubt.
Since 100mm plastic soil pipe is unsuitable for dust extraction on all but the smallest systems anyway, and larger sizes are as or more expensive than the proper metal stuff, then the point is academic anyway and I decided not to waste time on it.
You can't afford Encyc. CPD (two dozen volumes, hundred quid each) and you won't find a copy of Glor as it's OOP and scarce. Luttgens' "Electrostatic Hazards" is the only one that's even vaguely affordable. That's also a bit qualitative, not quantitative, so I doubt you'd be convinced by it anywayy
Exactly, so cutting it short and taking the pragmatic approach of using metal duct is the thing to do, for other reasons as well.
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