Thread: 2 small dusty or 1 large dusty

Hi Albert,

I am making an assumption that based on the list of top-end, expensive equipment in your signature block, you can afford to buy quality in this instance.

That being the case, I would recommend one large, high-end extractor over two smaller ones. Even at 20m, assuming you use 8" or 9" main lines (in fact even 6" main lines) you aren't going to create that much pressure drop over a 15-20m straight section of smooth ducting that you get better performance from a smaller unit closer to one side of the shop.

I would suggest looking at the Clearvue Max and running 8" diameter main trunk line (or 225mm PVC) and 6" or 7" (if you can afford to go steel) drops to each machine. The Clearvue will draw about 18-20 Amps at 60Hz. With the VFD there is no issue with inrush current as it is programmable for a slow-start and stop. With this you would more CFM at any machine than a smaller 3 HP unit would provide even with minimal ducting IMO. It would also take up less space, be less work to install and plump one machine etc. Plus, I don't know of any smaller machines I would recommend if you actually have the ability to afford a Clearvue level system; and then you would need to locate them outside the shop to minimise dust exposure.

I just want to say I have absolutely zero affiliation with Clearvue, even though I always seem to recommend them, it's just that it's the only system I can see available in Australia that ticks all of the boxes. Another would be Oneida, but they aren't available here. Not sure about NZ.

Actually, the Felder RL200 / RL160 units are also very good by all accounts but I have no experience with them and I believe that they are significantly more expensive than even the Clearvue. Perhaps worth looking into though.

Hi Albert, I agree with DomAU, go for one big unit in middle of shed with runs each way and 225mm main runs with 150mm drops to your machines. You can buy 225mm stormwater pipe and also 225 to 150 wye fittings to get the runs to each machine easily and at a reasonable price.
You can also buy 150mm blast gates from Clearvue I believe but I have been making my own square style ones but find them a bit of a pain up in the ceiling when manually opening and closing them. My latest plan is to replace them all with this design of pivoting gate. The Sketchup link is no longer current for this pin but there are several types on google if you search "pivoting blast gate."

There is plenty of info on these forums under the "dust extraction" section and especially look for input from BobL who is probably the best source of useful info on the subject.

Hope this helps, good luck with your new shed, don't forget there is a section for "The Shed" here also which covers builds where you may find some good info. Don't forget to share some photos with us when you get going.
Cheers, Ian

Originally Posted by DomAU

Hi Albert,

I am making an assumption that based on the list of top-end, expensive equipment in your signature block, you can afford to buy quality in this instance.

That being the case, I would recommend one large, high-end extractor over two smaller ones. Even at 20m, assuming you use 8" or 9" main lines (in fact even 6" main lines) you aren't going to create that much pressure drop over a 15-20m straight section of smooth ducting that you get better performance from a smaller unit closer to one side of the shop.

I would suggest looking at the Clearvue Max and running 8" diameter main trunk line (or 225mm PVC) and 6" or 7" (if you can afford to go steel) drops to each machine. The Clearvue will draw about 18-20 Amps at 60Hz. With the VFD there is no issue with inrush current as it is programmable for a slow-start and stop. With this you would more CFM at any machine than a smaller 3 HP unit would provide even with minimal ducting IMO. It would also take up less space, be less work to install and plump one machine etc. Plus, I don't know of any smaller machines I would recommend if you actually have the ability to afford a Clearvue level system; and then you would need to locate them outside the shop to minimise dust exposure.

I just want to say I have absolutely zero affiliation with Clearvue, even though I always seem to recommend them, it's just that it's the only system I can see available in Australia that ticks all of the boxes. Another would be Oneida, but they aren't available here. Not sure about NZ.

Actually, the Felder RL200 / RL160 units are also very good by all accounts but I have no experience with them and I believe that they are significantly more expensive than even the Clearvue. Perhaps worth looking into though.

Hi Dom

Thanks for the advice, my main trunk is 8" steel ducting with quick release system at the moment, I have considered Clearvue before, at the time I didnt give it much 2nd thought because it is too noisy, the bin is too small, no warranty within NZ and there is a bit of DIY involved with MDF. my sander's spec says it needs 6320m3/hr (2 x 160mm and 2 x 140mm) at 28m/s, pressure drop is 2313Pa through the machine. this requires something like 5-10 hp extractor. The RL300-RL350 will work but I dont need them inside the workshop.

If I am going cyclone it may have to be one of the industrial cyclone say the likes of from Donaldson Torrit. but they are very high, over 4m.

I still lean towards either Donaldson Torrit Unimaster or Nederman's Auto MZ baghouse system, but would need to know if one big extractor is better or 2 smaller, with 1 large extractor, I can use VFD to dial down the motor speed but not sure if this is any good to the motor if done over prolonged period of time.

Originally Posted by Albert

Hi Dom

Thanks for the advice, my main trunk is 8" steel ducting with quick release system at the moment, I have considered Clearvue before, at the time I didnt give it much 2nd thought because it is too noisy, the bin is too small, no warranty within NZ and there is a bit of DIY involved with MDF. my sander's spec says it needs 6320m3/hr (2 x 160mm and 2 x 140mm) at 28m/s, pressure drop is 2313Pa through the machine. this requires something like 5-10 hp extractor. The RL300-RL350 will work but I dont need them inside the workshop.

If I am going cyclone it may have to be one of the industrial cyclone say the likes of from Donaldson Torrit. but they are very high, over 4m.

I still lean towards either Donaldson Torrit Unimaster or Nederman's Auto MZ baghouse system, but would need to know if one big extractor is better or 2 smaller, with 1 large extractor, I can use VFD to dial down the motor speed but not sure if this is any good to the motor if done over prolonged period of time.

OK. Big stuff! Out of my zone of experience. However, I would still suggest that 1 large system should be far better than 2 smaller ones. The pressure drop over long sections of straight, smooth pipe is fairly minor compared with any bends, machine resistance etc so I assume you would get better overall airflow using one larger system and at a cheaper overall cost as well.

I'll be interested to hear what you end up doing and seeing some pics etc. Keep us updated.

Originally Posted by DomAU

OK. Big stuff! Out of my zone of experience. However, I would still suggest that 1 large system should be far better than 2 smaller ones. The pressure drop over long sections of straight, smooth pipe is fairly minor compared with any bends, machine resistance etc so I assume you would get better overall airflow using one larger system and at a cheaper overall cost as well.

I'll be interested to hear what you end up doing and seeing some pics etc. Keep us updated.

Will do, Will do.

I agree 1 big dusty probably works better than 2 smaller ones too... unless someone comes up with something we havnt thought about...

Here is my existing workshop anyway

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Under those circumstances I'd look at a single large extractor, probably a shaker type seeing it's going outside. Something like a DCE uma250, or Micronair VC4. But that's in the vicinity of 5.5 to 7.5kW which brings up the power question. A 7.5kW compressor is in the vicinity of 30cfm FAD, that's not a small amount of air. What's the duty cycle like? Would an electric start diesel compressor be a viable option if you are limited in power, or would the run time make it cost prohibitive?

Hi Albert

I think you will agree that your current setup is closer to medium scale industrial than a home workshop.

I don't think I've ever seen an industrial setup that used two small units when one larger one would do. As Dom mentioned the pressure drop over the extra length of ducting -- which would probably only be 5 metres -- is negligible compared to other issues.

If you, can mount the extractor near the centre of the portion of the shed that you use for machining.
Based on other posts, I'm guessing that one end of the new shed will likely contain a spray booth.
Conventionally you would divide your shed into zones based on the dust generating potential of the machinery in each zone, which might reduce the total run of ducting to less than 10 metres.

Depends what you means by small DCs.
Given the air flow requirements for your machinery then you are going to need either 2 x Cleavue Max Cyclones (4+4 HP) or a 7+ kW single unit.

Originally Posted by Albert

One of the limiting factor I have on the proposed site is that I only have 63 Amp total supply. same as my current workshop. at the moment the worst case loading is when the WBS(11kW)+Compressor(7.5kW)+Extractor(4kW) working at the same time. I had to put a VSD on the WBS to limit the inrush current.

How often do you need the compressor running continuously as the DC system?
You could lock out the compressor when the DC is running and VV.

2 x 4HP Cleavues could be viable because running one of those is probably not going to burst the power limit.

Hi Bob

I recall that Albert's "problem" is that his 11kW belt sander needs both the extractor and the compressor running at the same time.
The extractor to pull the dust away, and the compressor to inject high pressure air into the belt cleaning system.

Originally Posted by ian

Hi Bob

I recall that Albert's "problem" is that his 11kW belt sander needs both the extractor and the compressor running at the same time.
The extractor to pull the dust away, and the compressor to inject high pressure air into the belt cleaning system.

Yeah I now remember.

flamin 'ell now thats a workshop! and he's getting something bigger

Originally Posted by ian

Hi Albert

I think you will agree that your current setup is closer to medium scale industrial than a home workshop.

I don't think I've ever seen an industrial setup that used two small units when one larger one would do. As Dom mentioned the pressure drop over the extra length of ducting -- which would probably only be 5 metres -- is negligible compared to other issues.

If you, can mount the extractor near the centre of the portion of the shed that you use for machining.
Based on other posts, I'm guessing that one end of the new shed will likely contain a spray booth.
Conventionally you would divide your shed into zones based on the dust generating potential of the machinery in each zone, which might reduce the total run of ducting to less than 10 metres.

Thanks Ian, agreed and agreed, I have not seen an industrial setup with 2 small dusty rather than one large dusty as well

For the spraybooth. I've sort of parked this idea for now - too busy marketing and manufacturing stuff. its too big of a learning curve and the fumes probably not good for kids/children - yes I am gonna be a dad soon

If the spray booth does go ahead, I also needed a display room as well. so its probably not too bad.

Originally Posted by BobL

Depends what you means by small DCs.
Given the air flow requirements for your machinery then you are going to need either 2 x Cleavue Max Cyclones (4+4 HP) or a 7+ kW single unit.



How often do you need the compressor running continuously as the DC system?
You could lock out the compressor when the DC is running and VV.

2 x 4HP Cleavues could be viable because running one of those is probably not going to burst the power limit.

the compressor comes online intermittently, my worst case air usage meant the duty cycle is ROUGHLY 60% with my 10hp compressor

I can lockout the air jet on the sander, this reduces the air usage from a whopping 44m3/hr(26CFM) to a negligible 1.8m3/hr (1CFM or thereabout). the pneumatic system on the sander doesnt use too much air.

I am still not a fan of the Clearvues....

Silly question - your 63A power supply - is that single phase only?

I only ask because a 3ph 63A supply won't care about the 3 pieces of equipment you mentioned in your first post - that's still at only 50% utilisation. Provided you've got breakers with motor (and not general use) curves, they'll handle the start up current from each device without tripping (they're basically just slow acting on a certain grade of overload). Of course, if you have a main breaker, you may need to get that changed as well. In Aus we still normally have service fuses as the main protection for residential supplies, which is great because they take heaps of overload before even thinking of blowing D.

Bear in mind of course that those power ratings are only with the motors working as hard as they can. For the dusty that is all the time (or should be if you've got a nice free-flowing system). For the compressor that is in the last bit of the cycle where it's almost up to pressure. For your sander, well, that depends on how the machine loads up the belt. You may find that the average power requirements aren't that bad and you only really get into trouble if everything turns on at once.

A single phase 63A supply, well, you're cooked.