Thread: Clearvue CV1800 / Max Impeller Install - Home Garage Workshop

Originally Posted by BobL

I find this claim hard to believe.
If the 1800 can deliver 1400 CFM through 6" pipe then to get 25% more (i.e. 1750 CFM) through a 6" duct its impeller will have to develop around 20" of WC.
This is a very difficult task for even a 20" impeller.
The Max is supposed to be good for ~2000 CFM in an 8" pipe - that only requires 12" of WC. Completely feasible with an 16" impeller.

You are right if talking about maximum airflow but for a restricted system with say 12" of static pressure drop 20% is not completely unreasonable. Looking at the Cincinnati fan tables gets you;
995 cfm for a 15.5" impeller at 12" of static pressure whilst a 16.5" fan will pull 1219 cfm at 12" w.c., both through 6" inlets. Of course this ignores the fact that you could never have the same static pressure drop at different cfm's for a given system so is a gross simplification. But the performance of a larger impeller for a typical restricted system is clear from this example.

Originally Posted by DomAU

You are right if talking about maximum airflow but for a restricted system with say 12" of static pressure drop 20% is not completely unreasonable. Looking at the Cincinnati fan tables gets you;
995 cfm for a 15.5" impeller at 12" of static pressure whilst a 16.5" fan will pull 1219 cfm at 12" w.c., both through 6" inlets. Of course this ignores the fact that you could never have the same static pressure drop at different cfm's for a given system so is a gross simplification. But the performance of a larger impeller for a typical restricted system is clear from this example.

It sounds like those fans maybe inefficient / poorly designed. 12" of WC should pull 1450 CFM through a 6" pipe but that's it - going to a bigger impeller and staying at the same pressure won't move any more air as the 6" ducting becomes the limiting fact.

Originally Posted by BobL

It sounds like those fans maybe inefficient / poorly designed. 12" of WC should pull 1450 CFM through a 6" pipe but that's it - going to a bigger impeller and staying at the same pressure won't move any more air as the 6" ducting becomes the limiting fact.

I think I didn't do a great job of explaining. In my example using Cincinnati fan data, I was talking about the flow through a ducting system with a 12" static pressure drop, not that the fan is only capable of producing 12" of static pressure. Of course for the smaller fan the same duct system would not have 12" of static pressure drop as the lower airflow would mean that the static pressure drop would also be lower, resulting in slightly higher CFM, hence my statement that this is an over-simplification. Maybe the Clearvue representative did not understand this distinction and made her comments based on a 20% higher CFM at the same System Static Pressure drop. Hope that makes sense.

Originally Posted by DomAU

I think I didn't do a great job of explaining. In my example using Cincinnati fan data, I was talking about the flow through a ducting system with a 12" static pressure drop, not that the fan is only capable of producing 12" of static pressure.

OK I understand now. The Cincinnati fans claim to be moving still moving near 1000 cfm EVEN AFTER there is a 12" pressure drop.
If this is correct then they are indeed very efficient fans.
However I have seen the document that shows the industry standard way of measuring flow so I am wary about published measurements of flow rates.
Most of the DC impellers I have measured have flow rates that are from 50 to 100% over inflated.
Either way the relative difference should still be correct so as you say around the 20% mark which if real is worth having.

Couple of small updates.

1. Measured CFM of my 2HP dusty. With 1 m of 4" flex and an 8" test duct I got; 350CFM. This Dusty is stock-standard except for a pleated filter (no mods) and running through the standard 2 x 4" port (using 1). It shows that in typical use the 1490 CFM claim on the back of this machine is a touch optimistic

2. I redid the ducting to my Bandsaw. I removed the 4" splitter box and ran two reducing Y-juntions to have 3 x 4" ports running to the bandsaw. 2 under the table and 1 overhead as before. Amp output from the VFD picked up from 7.6 Amps (per phase) to 8.7 Amps at this machine. Did a few test-cuts and it works extremely well. Only the tiniest bit of visible dust is left on the table and I assume most of the fine dust is also caught.

20160410_130157_001 (2).jpg20160410_130202 (2).jpg20160410_130208 (2).jpg

Lastly, i put some sound insulation around the impeller housing of the clearvue, as well as the intake, both of which now appear to be the primary sources of noise. Not the neatest looking fix, but the sound pressure level at 1m is now approximately 80-81 dBA and at 3m is around 74-75 dBA. I may still make an enclosure for the top half of the cyclone.

20160410_130806 (2).jpg

3. I'm going to start work on an over-head guard / collector for the Table Saw.

Wrapped the exhaust ducting with another layer of 75mm r2 acoustic insulation. So that makes it about R5 total. Sound levels did not change much but less than 80 dBA at 1m and less than 75 dBA at 3m. Most of the noise appears to be the droning noise from the impeller so would need to build an enclosure to get it any better. Less noisy than my 2HP dusty was though so I'm happy.
20160414_080145.jpg

Also started on my overhead table saw guard today. Used some acrylic sheet to make a guard with sliding sides that move up as wood is fed through to catch dust firing forward from the blade, particularly during side cleanup type cuts or dado cuts. The front will have a segmented rubber lip.

20160416_191030.jpg

20160416_191004.jpg

20160416_191023.jpg

Still to start on the actual structural part.

Looks well made but it would be easier to see the blade if at least the area in blue was a clear flat panel (no seams etc)

BladeGuard.jpg

Yeah you're probably right. I positioned the tube for maximum dust collection at the expense of visibility. If this ends up as a source of frustration I'll make a mkII variant with better visibility.

Originally Posted by DomAU

Yeah you're probably right. I positioned the tube for maximum dust collection at the expense of visibility. If this ends up as a source of frustration I'll make a mkII variant with better visibility.

Yeah no doubt you will find something else to modify. ;-)

The front will have a segmented rubber lip. .

Have you looked at "Truck mudguard bristles?" - these can be added all the way around except for the back.

Made a bit more progress with the overhead collector. I had to brace the aluminium framework a little as it was initially not rigid enough. Also still haven't put any lip on the front edge and need to get some more flexible hose so that I can move the guard up/down easily (the current hose is very rigid, albeit with a nice and smooth bore).

20160423_171430.jpg20160423_202650.jpg20160423_202716.jpg20160423_202740.jpg

Tried a few quick cuts. A few small slices of 35mm blackbutt including an edge trim. The photo below shows how much visible dust this generated. Absolutely none! Really happy. No wood smell either.
20160423_171951.jpg

Put some temporary (poor quality) hose on the guard and did some more test cuts. Seems to do a great job regardless of the type of cut or wood. I just haven't tried cuts with a wide dado-blade yet; that will be the real test I feel. I did notice a decrease in dust collection when I changed back to the zero-clearance insert however, so decided to fit a front-lip after all. This helped prevent stray chips flying forward, although it worked very well without this lip as well; not sure if I end up keeping it.

20160424_190921.jpg20160424_152227.jpg

Guard moves up and down very nicely .

20160424_152237.jpg20160424_152245.jpg

On another matter, I found that after about 30min of continuous running the cable and plug from the point to the VFD was becoming extremely hot; to the point where I couldn't hold the terminals after pulling the plug from the wall. I found that the cable was only 1.5mm^2. I had it changed for 2.5mm^2 wiring and this seems to have resolved the issue. In hindsight I would have had the sparky install a 20 Amp rather than 15 Amp point; just for added piece of mind. I certainly wouldn't run a Clearvue on a 10 Amp point!