Thread: Flow loss using a Dust Deputy

Originally Posted by BobL

... I leave the filters in place and just shake the outsides of the filter bags a few times and about half a bucket of fine dust falls into the collection bags. Then I wait for the dust to settle and repeat that a few times and that's it. Emptying the dust collection bag is no more effort or dirtier than emptying a cyclone bin.

Originally Posted by BobL

Then I wait for the dust to settle and repeat that a few times and that's it.

Originally Posted by BobL

Then I wait for the dust to settle and repeat

Originally Posted by BobL

Then I wait for the dust to settle

Originally Posted by BobL

Then I wait

Originally Posted by BobL

Then I wait

Originally Posted by BobL

Then I wait

Originally Posted by BobL

Then I wait

Yep, and by the time you have waited I have already emptied the cyclone collection drum once and dressed another cubic metre of timber and getting ready to empty it again.

Tell me again BobL how many times a year do you empty your dusty? Was it twice? . .

Originally Posted by doug3030

Yep, and by the time you have waited I have already emptied the cyclone collection drum once and dressed another cubic metre of timber and getting ready to empty it again. Tell me again BobL how many times a year do you empty your dusty? Was it twice? . .

Anyone using a chip collector connected to their DC wanting max flow through their DC should be doing exactly the same to their DC filter EVERY time they empty the chip collector.

FWIW the waits are ~10s long at most, Shake one bag - then the other - then go back to the other, 1 min max - I'd like to see anyone thickness a cubic metre in that time.

Last year I indeed emptied only twice but usually I would empty about 3 times a year. MY DC has twin bags that are abut 50% bigger that the volume of 2HP DC bag each so I am emptying the equivalent of about 9 , 2HP DC bags a year.

I understand that devices like a dust deputy are not intended to filter out fine dust but I was interested to know if they did any filtering at all of fine (0.3 - 5 micron) dust because I have seen a lot of fine dust in the bottom of the DD bucket.

To do this I put a 600 mm long x 100 diameter test duct in between the DD and a sucking point.
Into the sides of this test duct I inserted an anemometer and the particle counter probe.
Using residual shed dust levels - which is the same as the dust levels in the back yard - I measured flow in the duct, and particle counts into and out the DD .

After a lot of measurements I detected a 3% removal of fine dust by the DD at 90 CFM.

At half that flow rate (45 CFM or the sorts of flows obtained using a VC and a small hose) I measure a 1% removal, but bear in mind the uncertainty/tolerance of the measurement is about +/- 1% so may not be removing any fine dust.

This highlights two things, one is the need for a good filter on a VC, and the other is regular maintenance and cleaning of the VC filter.

I did loads of other measurements across different particle size ranges, most were difficult to make sense of but some were quite curious.
Like - at 90 CFM, for particles between 3 and 5 microns, the DD made about 50% more dust than it collected, while at the slower flow rate (45 cfm) the reverse applied.
It could be the higher air speeds are breaking up the even bigger dust particles into smaller ones, which is something I have seen before with VCs but why only more 3-5 micron particles and not the others?
The result for the slower air flow could be due to the particles having enough time inside the flow to be more efficiently filtered out.
However, overall the higher air speed seems to be a little bit more efficient at removing most of the fine dust.

Very interesting Bob.

Plus, many thanks for doing this and other tests, with equipment many of us have no access too.

Mick.

Originally Posted by BobL

I understand that devices like a dust deputy are not intended to filter out fine dust but I was interested to know if they did any filtering at all of fine (0.3 - 5 micron) dust because I have seen a lot of fine dust in the bottom of the DD bucket.

To do this I put a 600 mm long x 100 diameter test duct in between the DD and a sucking point.
Into the sides of this test duct I inserted an anemometer and the particle counter probe.
Using residual shed dust levels - which is the same as the dust levels in the back yard - I measured flow in the duct, and particle counts into and out the DD .

After a lot of measurements I detected a 3% removal of fine dust by the DD at 90 CFM.

At half that flow rate (45 CFM or the sorts of flows obtained using a VC and a small hose) I measure a 1% removal, but bear in mind the uncertainty/tolerance of the measurement is about +/- 1% so may not be removing any fine dust.

This highlights two things, one is the need for a good filter on a VC, and the other is regular maintenance and cleaning of the VC filter.

I did loads of other measurements across different particle size ranges, most were difficult to make sense of but some were quite curious.
Like - at 90 CFM, for particles between 3 and 5 microns, the DD made about 50% more dust than it collected, while at the slower flow rate (45 cfm) the reverse applied.
It could be the higher air speeds are breaking up the even bigger dust particles into smaller ones, which is something I have seen before with VCs but why only more 3-5 micron particles and not the others?
The result for the slower air flow could be due to the particles having enough time inside the flow to be more efficiently filtered out.
However, overall the higher air speed seems to be a little bit more efficient at removing most of the fine dust.

Saw an advert for a cyclone connected to a 2" hose and VC which claims, from Independant medical school testing, that it takes out 99.9% of dust 5 microns and above and 80% of fine dust down to 0.5 microns.
Interesting.

Originally Posted by Lappa

Saw an advert for a cyclone connected to a 2" hose and VC which claims, from Independant medical school testing, that it takes out 99.9% of dust 5 microns and above and 80% of fine dust down to 0.5 microns.
Interesting.

References? Enquiring minds want to know.

Regards from Perth

Derek

Originally Posted by derekcohen

References? Enquiring minds want to know.

Regards from Perth

Derek

Here is the site:

CV06 Mini System - Clear Vue Cyclones

Its a Clearvue mini designed by the great man himself Bill Pentz.

They must be selling like hotcakes because they are temporarily out of stock.

Originally Posted by Lappa

Here is the site:
CV06 Mini System - Clear Vue Cyclones
Its a Clearvue mini designed by the great man himself Bill Pent.

Ah , , , , I don't think so, specifically it is

The Mini CV06 is a scaled version of the Bill Pentz Cyclone design

It's clearly not even a scaled down BP design because it does not have a ramped inlet like the BP design.
BP goes out of his way to say that small inappropriately cyclones are very poor at fine dust control because they rob flow from small system.
That is why BPs design starts at 4HP with a 15" impeller.

If someone has a CV06 in Perth I am more than happy to test it.

Originally Posted by BobL

Ah , , , , I don't think so, specifically it is



It's clearly not even a scaled down BP design because it does not have a ramped inlet like the BP design.
BP goes out of his way to say that small inappropriately cyclones are very poor at fine dust control because they rob flow from small system.
That is why BPs design starts at 4HP with a 15" impeller.

If someone has a CV06 in Perth I am more than happy to test it.

Hmmmm - Interesting statement that I have highlighted in red.

Statement from Bill's website:

"My Cyclone Sizing
Another very positive benefit of this design is it ends up being scalable. Innumerable people have built and purchased little 6" diameter cyclones to use with their 2.5" heavy duty shop vacuums. The medical school testing on these smaller units ends up being just as impressive than the separation on the larger units. These small 6" versions provide 99.9% separation efficiency on particles sized under 5-microns versus the closest competitor providing only 99.9% separation on 25-micron and larger particles"

Originally Posted by Lappa

Hmmmm - Interesting statement that I have highlighted in red.

Statement from Bill's website:

"My Cyclone Sizing
Another very positive benefit of this design is it ends up being scalable. Innumerable people have built and purchased little 6" diameter cyclones to use with their 2.5" heavy duty shop vacuums. The medical school testing on these smaller units ends up being just as impressive than the separation on the larger units. These small 6" versions provide 99.9% separation efficiency on particles sized under 5-microns versus the closest competitor providing only 99.9% separation on 25-micron and larger particles"

Interesting, but whatever BP says - the CV06 is not a scaled down version of the Bigger BP cyclone.

BPs statement is either written incorrectly or bollocks.

provide 99.9% separation efficiency on particles sized under 5-microns

Not even the big Clearvue gets this sort of separation. I think BP means OVER 5 microns.
No conventional dust collector or HEPA filter gets this sort of efficiency.
Under 0.3 microns the dust is like a gas and goes straight though just about every sort of filter.

Clearvue state that the CV06 is a Bill Pentz design and endorsed by Bill Pentz.