Thread: Advice

Originally Posted by hughie

I 'm in need of good dust extraction, more along the lines of scrubber that I can hang in the centre of the room to scrub the atmosphere. At this point in time I'm not looking for anything like a generic/low cost and it would be nice if it has a capability of at least 1 micron, 240 volt. It has to handle wood dust and general house construction dust ie floor sanding, Gyprock dust to some extent as well.

A figure like 1 micron is not very useful. It is like saying I would like to move at a speed of 100 km (time factor deliberately omitted). The missing factor is the filter efficiency. The correct way to specify a rating would be e.g. "99% at 1 micron or greater". This means it will remove 99% of all particles bigger than 1 micron.

Only when the efficiency is included in the rating can any sort of accurate recommendation be made.

Hospital grade HEPA air scrubbers are typically 99.95% efficient at 0.3 microns or greater. The standard CT room air filter is only about 50% efficient at 1 micron or greater. Well maintained and seasoned needle felt or Pleated filtered DCs are about 97% efficient. The elephant in the room for all scrubbers is that they dump their exhaust back into the shed so any leaks will be a problem so any leaks will be far more of a problem than their efficiency. All hobby level gear (eventually) leaks at the 1 micron level.

In theory 100% efficiency can be obtained by simply venting shed air to the outside of the shed. This is by far the simplest way to deal with this issue.

While 1 micron is in the lower end of the health concern range, the sub micron particles should also not be ignored.

Originally Posted by hughie

It has to handle wood dust and general house construction dust ie floor sanding, Gyprock dust to some extent as well.

Gyprock dust is a filters worst enemy (so too is concrete dust). Unless you install a sophisticated device with an auto clean function your filters will quickly clog, put excessive load on fan motors and will soon or eventually kill them.

It sounds like you are doing some renovations. My advice, based on my experience, would be to place an industrial type fan just inside the door of the room you are working in and point it at an open window. Creating a strong draft stream to expel the dust out of the room as quickly as possible is your best bet.

Craig.

Originally Posted by CMB

Gyprock dust is a filters worst enemy (so too is concrete dust). Unless you install a sophisticated device with an auto clean function your filters will quickly clog, put excessive load on fan motors and will soon or eventually kill them.

Yep I agree. When I recently resurface down the bench tops in my kitchen I used a blower vac connected to a belt sander. I then connected the blower end to a 2" hose and hung this out a window. to strip the old epoxy off I used a 40 grit but for the 80 and 120 grade sanding I took the filters off the vac otherwise the fine stuff would block the flow within a few minutes. This solution is fine for small areas but not really suited for major renos.

It sounds like you are doing some renovations. My advice, based on my experience, would be to place an industrial type fan just inside the door of the room you are working in and point it at an open window. Creating a strong draft stream to expel the dust out of the room as quickly as possible is your best bet. .

Just pointing a fan at a door or window is likely to stir up dust inside a room and will not be as effective as placing it at the actual door or window.

Hi Hughie

If this is for your shed I would start with a whirlybird in the roof, then a fan pushing out the door.

Another possibility is - Ezi-Duct have a couple of roof ventilator fans page 29 http://www.eziduct.com.au/pdf/cat12.pdf .

In my shed, 6m x 6m x 2.8m, I have the whirlybird in the roof and 2 Jet room filters with Wynn after market filters and of course the DC60 (1 micron) with a drop box collecting shavings, chips and dust at the machinery.

This works for me.

Ross

Originally Posted by Ross

Hi Hughie
If this is for your shed I would start with a whirlybird in the roof, then a fan pushing out the door.

Whirly birds only work when there is a breeze or significant temperature differentials between internal and external air. Extensive tests around Australia found a wide variation of wind speeds with average extraction by small whirlybirds being about about 100 cfm which is about the same as a computer fan. They may work for temperature control but the average flow rates are not a dust extraction solution.

Originally Posted by BobL

Whirly birds only work when there is a breeze or significant temperature differentials between internal and external air. Extensive tests around Australia found a wide variation of wind speeds with average extraction by small whirlybirds being about about 100 cfm which is about the same as a computer fan. They may work for temperature control but the average flow rates are not a dust extraction solution.

Hi Bob

You are right on its own it is not a solution but for the very fine air born dust above the Jet filters it helps. When I first built the shed I installed a smoke detector which went off whenever I made dust, since fitting the whirlybird I does not trigger it.

Every little bit helps.

Ross

Originally Posted by Ross

Hi Bob

You are right on its own it is not a solution but for the very fine air born dust above the Jet filters it helps. When I first built the shed I installed a smoke detector which went off whenever I made dust, since fitting the whirlybird I does not trigger it.

Every little bit helps.

Yep - every bit helps.
My smoke detector does not trigger with wood dust unless the wood has been burnt or charred in some way such as when I push the wood too fast through my TS. It does trigger with metal cutting and of course welding which I now do under a dedicated metal work fume hood. If anyone has a DC, one of the best ways to ventilate a shed is to vent the DC outside since the high flows possible with DC can vent a shed fairly quickly.

It sounds like Hughie is about to do some renovation and is looking for ways to manage the dust inside the rooms he is working on.

What I am looking for is the removal of residual dust after a clean up on a reno

Originally Posted by hughie

What I am looking for is the removal of residual dust after a clean up on a reno

Has the reno already happened?

If so the reno dust will have a similar residence time in air to fine/invisible dust from a sander but within a day or so most of it will have settled out on surfaces and no amount of air scrubbing will pick it up off these surfaces so you are going to need some sort of vacuum cleaner. The problem with most (even expensive ) vacuum cleaners is they will fluff some dust off surfaces before they grab it and some of what goes into a VC will go straight through the filters. On top of that the motor cooling loop will mince finer dust into even finer dust and re-suspend this in the air again. Multiple passes of a VC will eventually get more of it. A blower vac that you attach an exhaust pipe to the blower and hand out a window will get around the fine dust getting through the filter but won't cure the motor cooling loop issue. The way around that is to put the whole VC outside but then you will need a really long hose and that means reduced flow.

If the reno has not happened then big volume air flow with the DC outside, One such item worth considering is one of those axial flow fans in a tube that sit on a floor and has a 300+ mm diameter 10 m log flex hose on the end of it - that will vent any room pretty quickly. Its the sort of thing that painters and asbestos removalists use.

H&F have this one
F050 | AF-30 Industrial Axial Flow Fan | machineryhouse.com.au on special for $150
And the 5M lengths of hose are F051 | DH-30 Air Duct Hose | machineryhouse.com.au

The spec claimed is 1680 cfm and even allowing for the x 2 markup it's still pretty good!

Originally Posted by BobL

If the reno has not happened then big volume air flow with the DC outside, One such item worth considering is one of those axial flow fans in a tube that sit on a floor and has a 300+ mm diameter 10 m log flex hose on the end of it - that will vent any room pretty quickly. Its the sort of thing that painters and asbestos removalists use.

This is my experience too. I now use my cyclone (vented outside) to clear the shop not only of dust, but also of lacquer (etc) fumes. After spraying, the cyclone clears the shop quite quickly. The axial flow fans Bob mentions would do a similar job.

Originally Posted by John Samuel

This is my experience too. I now use my cyclone (vented outside) to clear the shop not only of dust, but also of lacquer (etc) fumes. After spraying, the cyclone clears the shop quite quickly. The axial flow fans Bob mentions would do a similar job.

Just be very careful with inflammable fumes they do not mix too well with electric motors. My mother scorched the floor by sucking up a cockroach and spraying fly killer into the bag.

Originally Posted by shedman

My mother scorched the floor by sucking up a cockroach and spraying fly killer into the bag.

Originally Posted by shedman

Just be very careful with inflammable fumes they do not mix too well with electric motors. My mother scorched the floor by sucking up a cockroach and spraying fly killer into the bag.

Good to see you have your mother cleaning up your shed

Originally Posted by shedman

Just be very careful with inflammable fumes they do not mix too well with electric motors. My mother scorched the floor by sucking up a cockroach and spraying fly killer into the bag.

Just had a vision of my Clear Vue exploding ... not pretty.

Should not be an issue. The fuel/air ratio in the system would likely be below ignition point, and the air flow would be more likely to direct the fumes away from the motor and out of the exhaust than it is to put it near a source of ignition.

At least I hope so.