Dust Extraction-external venting

[WoodyMcWoodFace]

Hi All,

I've been a UKWorkshop member for a while, but this is my first post so I'm hoping I'm not asking a question that's already been covered.

I've read a lot of posts about dust extraction, and read the Bill Pentz stuff that's been referred to, and it leaves me with a question/solution that I'm wondering if someone can clarify.

Simply put - can you use the CamVac accoustic outlets to pipe fine dust outside?

I have very limited workshop space and was looking to upgrade my wall mounted CamVac to service my new Hammer A3-31 PT (and other, more fine dust producing machines), but the more I read into this, the more getting a HEPA (i.e. sub 0.5 micron) rated extractor seemed the best option. However, that takes you into the c£3K Laguna PFLUX type of machines which, along with the hefty cost, just takes up too much space.

So it occurred to me that as the Camvac is a closed system, then the only apparent way for air (and hence any fine dust that's got through the 0.5 micron filter) to get out would be via the acoustic outlets. Since these outlets can have pipe attached to them, and I have a convenient hole in my workshop wall, putting the end of the pipe through the wall "should" vent all remaining fine dust outside (under an outbuilding).

Is there a flaw in this thinking? I realise the current Camvac is a bit underpowered for the job, but it's not at all bad, and if I were to upgrade to the e.g. CGV386-6, that would actually save me some space and increase my air flow from 108 l/s to 162 l/s - still a bit low for the Hammer I know, but I could wheel it right next to the machine, limit flexi pipe etc. and get a big improvement on the already pretty good 286-3-wall one.

Ultimately, this is all about space and fine filtration for me. Whilst spending lots on dust extraction is not great, I'd be prepared to do it for the good of my health, but I'm just struggling to find anything small that will do the job. I can't house a traditional vortex 2 stage outside and I want to capture the dust at creation, not filter it out once its in the air. I also realise that venting air outside on a cold day will make my workshop cold, but since I don't usually heat it anyway, an extra layer of clothes is the solution there.

Any thoughts would be very welcome.

Steve.

 

[Myfordman]

If you heat your workshop with paid for energy then it is madness to vent dust extraction outside.
1) unless you open a door or window, the your extractor will be strangled by the lack of air.
2) your expensively heated air will be sucked outside to be replaced by cold air from outside.

after adequate filtration return the air to the workshop. If you want to place the extractor outside the envelope of the workshop but still return the air to the workshop, then this will reduce noise of the motors and baffles can reduce the noise of the airflow. Make sure you have something to indicate when the collection bin is full though. Capacitative proximity detectors can work quite well wired to an alarm inside the shop.

 

[WoodyMcWoodFace]

If you heat your workshop with paid for energy then it is madness to vent dust extraction outside.
1) unless you open a door or window, the your extractor will be strangled by the lack of air.
2) your expensively heated air will be sucked outside to be replaced by cold air from outside.

after adequate filtration return the air to the workshop. If you want to place the extractor outside the envelope of the workshop but still return the air to the workshop, then this will reduce noise of the motors and baffles can reduce the noise of the airflow. Make sure you have something to indicate when the collection bin is full though. Capacitative proximity detectors can work quite well wired to an alarm inside the shop.

Thanks for your reply, but perhaps I didn't word my question clearly. I have no problem venting to the outside. As I said, I don't heat the workshop, so that isn't an issue.
My question is simply, will the fine dust that gets through the filter be vented outside, thereby removing my need for a sub 0.5 micron filer?

 

[Jameshow]

Could you simply vent using a tumble dryer hose? You would just need a way to fit over the motor vents.

So long as the area of the hose was well above that of the suction hose then you won't loose much performance...

 

[WoodyMcWoodFace]

Hi Jameshow.

There are already hoses available to fit over the acoustic ports. These come as standard to allow you to direct the sound of the motors away. What I'm trying to determine is whether this would also divert the finest of the dust which isn't trapped by the filter.

I can't see why it wouldn't, but I haven't read anywhere anyone suggesting this, so I'm wondering if it's too good to be true?

 

[stigg]

Have you seen this? .
Similar but without the external vent.

 

[WoodyMcWoodFace]

Hi Stigg.

Yeah, I've seen this, but unless it's been updated since I watched it, he is venting into an acoustic box to act as a further sound reducer, not to vent dust.

 

[stigg]

There is a section in it where he talks about the amount of dust caught in the acoustic box. He claims not very much at all.
Venting to outside would eliminate any dust as you suggest (unless the wind blows it back through your open window)

 

[Inspector]

Hi Jameshow.

There are already hoses available to fit over the acoustic ports. These come as standard to allow you to direct the sound of the motors away. What I'm trying to determine is whether this would also divert the finest of the dust which isn't trapped by the filter.

I can't see why it wouldn't, but I haven't read anywhere anyone suggesting this, so I'm wondering if it's too good to be true?

I don't have a Camvac but if the hoses carry all the air from the machine and exhausts it outside you will not be getting any dust inside the shop as long as the intake to the building is far enough away. Any leaks in the vacuum or worn out filters letting dust over the .5 micron size will also be vented out. You could even get by with the minimum in filters rather than a HEPA as long as the air that cooled the motors is clean enough for them. In other words if you vent all the air outside you breath the cleanest air. Now if not all the dust is picked up by the Camvac at the machine then you have that to contend with. A Clearvue Cyclone (Bill Pentz design) when vented outside doesn't show any signs of dust in the air or on the surfaces surrounding the outlet. Most of the Aussie sold ones were without filters and are vented directly outside. I, standing at the bar and pounding my fist, yell "Blow the sucker outside if you like!". Sending the exhaust air out through bigger hoses will reduce the back pressure aiding a little in the suction.

Pete

 

[HamsterJam]

Short answer - yes, venting outside will take any remaining fine dust outside too.
However, I think the filtering on the Camvac is already quite good (1 micron?) and I just baffle mine and exhaust it to the workshop as an additional heat source. I sometimes vent outside in the summer to keep things cooler.
As an alternative have you considered discharging the vent into a HEPA filter? Bit belt and braces and requires a decent filter area so it doesn’t rob you of too much suction power. I have considered simply attaching a HEPA vacuum cleaner bag over my baffle outlet.

 

[WoodyMcWoodFace]

Thanks Everyone for your replies.

Stigg - apologies, I've not had chance to watch the vid again, but I do recall now something around the lack of dust caught in the box. I guess my thought on that is that Bill Pentz' points out that it's the really small (sub 0.5 micron) dust that's problematic, and I'd perhaps question if the acoustic box would capture that, or if the lack of seeing it just means that it's 'left the building'.
HamsterJam - that's really helpful thanks, and I love the idea of just putting a HEPA bag onto the outlet hose if I don't want to vent outside. That opens up a whole new world of warm woodworking. Imagine!
Pete - you of course touch on the elephant in the room when you say "Now if not all the dust is picked up by the Camvac at the machine", and I think that boils down to what the Camvac itself is capable of. Whilst the biggest Camvac's published extraction rate is 162l/s (345cfm; 583m3h) that's still lower that the Hammer's "requirement" of around 814m3h and also lower than Bill Pentz's recommendation of 800cfm (471m3h). So whilst I'm seeing (visually, I don't have a way of measuring air quality) good results from my existing (smaller=108l/s) Camvac, hoping that switching to the larger one will capture everything is perhaps naive from the figures above.

I think I'll probably get the larger Camvac for now, but probably continue to spend countless hours staring at the tiny patch of workshop floor that hasn't been filled with machinery, wondering if I can fit a bigger unit in. Maybe I need to make a full sized mock-up? Bit nervous about cutting up the MDF to make it with though, since I don't have adequate dust extraction............

Thanks everyone for your input.

Steve.

 

[Jaydee]

You could make your mock up out of old cardboard boxes to give you an idea of size and sighting. Just a thought.

 

[Keith 66]

Venting dust outside is all very well if you are a long way from any neighbours. Years ago i had a workshop on a farm, I had a 28ft yacht in for major fibreglass repairs, now when you are grinding grp with a heavy grinder for hours at a time the amount of dust produced is huge. I rigged up a big centrifugal extractor fan with a 9" outlet it was about 1.5hp. Duct was run outside round the corner into the bottom of a huge patch of brambles. A week later it looked like it had snowed heavily, Needless to say i lived in a respirator. I doubt i would get away with that today!