Another HF with SDD & Wynn 35A question! how much WC change should I see?

[Carl Kona]

Larry,

You are absolutely correct. You are referring to the chart on page 68 which tests a 5" port. I kept referring to the chart on page 67 which uses a 4" port. So many people downsize to 4" pvc I didn't even think of the context of Lane's setup and the other curve on the next page. I also apologize for my 'extrapolate' comment. Re-reading it comes across the wrong way. What I was trying to say was the chart I was looking at went down to 4.25" (wrong chart) and your chart went lower. I thought it was a factor of the software extrapolating the data to make a longer smoother line. I didn't mean to imply you were making up data points.

Thanks for correcting me.

Carl

[Lane Hardy]

Wow now that we have cleared up�� I did not mean to start a war, just kidding Carl and Larry.
ok let me ask this question! I wil start with my anemic HF modified D.C. system.

stock HF fan: we will call it 10 inch. I not have put my Sarrete micrometer on it.
intake into Fan is now 6 inch dia. Direct connect to Supper Dust Deputy (no bends) (fan shaft is vertical)
exhaust of blower going into stock HF separator with a Wynn 35Anano filter on top and the clear dust bag on the bottom.
for ducting I am using 5 inch HVAC Duct and very short 5 inch flex hose for coupling two different 5 inch blast gates.
of the two fan curves which one should I use to help detrimen performance?
i have been taking the shotgun approach using my DIY Manometer and measuring the SP changes as I add or reconfigure bends and angles on my three drops. One blast gate 5 inches is connected to the bottom of the TS. I am considering an overhead TS pick up. To collect the dust on the table top. I am thinking that I might employ a 5 inch to 4 inch wye one 4 inch connected to the bottom of the TS and the other half of the Wye going to the top collector.
any thoughts on if this is a good idea? Considering the CFM and what ever the velocity of the air actually is?
perhaps a smaller upper collection hose to increase the velocity considering that two four inch exceed the volume of the 5 inch main.

any thoughts?
oh one other! Question, I have read that the Rickon blower fan will fit in the HF housing and another fan that I can not call will fit as well. I do know that I will need to increase the ID on the fan shaft on the Rikon to fit the shaft on the motor that is not a problem.

I am not worried about the current draw I have an amprobe and I am no where near 14 amps.
my altitude is 1900 feet Mean sea level, when yon consider the temperature the density altitude hovers around 2400 or more on 67 degree day. So pulling too much current is not an issue.

Lane

[Carl Kona]

Lane,

It is great you are really stretching that HF DC to get the most out of it! The curve on page 68 will be in the neighborhood but still meaningless to me. Your system left the 'Stock' station awhile ago. If you look at the curve on page 69 of that article you will see various filters attached to the same DC. As you provide more filter area (less motor restriction) your curve chages. As you can see 4 filters, 4 curves 1 blower. The same is true with changes to your opening. If you look at a fan table like this one on page 6 https://www.cincinnatifan.com/catalogs/PBSCatalog.pdf the PBS-14A has several impellers shown in rows with different inlet diameters. As you look at the same impeller in the same housing with 3 different inlet diameters you will see the CFM increase with larger diameters. 3 diameters 3 different curves for the same blower. So can you tell me what a fan curve would look like on your system now? IMO it can't look like the tested unit. Now if you look, still within the PBS-14A rows, at the 12 1/4 impeller vs the 14 you will see significant increases in both CFM but also a couple more inches of SP. If you also look at the same impeller 14x3 1/4 in a different housing PBS-15A you will see even different curves. So your system changed as soon as you changed the filter and lowered the restriction on the output.

Another improvement you can look into fairly easily is to disconnect your output from the filter/separator assembly and measure the SP, then attach the separator assembly without the filter attached to see how much the separator restricts your exhaust air. An improvement would be to exhaust directly into the filter without the baffle (but it may not be enough of an improvement to bother with).

As for your TS connection, splitting your 5 into 2 4s would not be as effective as a 4 and a 3. Look at the area of the 5 (just under 20 sq-in) and a 4 (about 12 sq-in). So you will be going from a smaller area to a larger area.

Hope that helps. Let us know how you make out.

Carl

[David L Morse]

Lane, it seems to me that it would be a lot simpler to just measure your flow instead of trying to guess at fan curves. Use a DIY Pitot tube and your DIY manometer and find out what you actually have. The only "calibration" you need to do is calculating your air density and it sounds like you're already on top of that.

FWIW I'm using two 4" ducts to my table saw and I get enough lift on the topside to keep the duct clear. It's best to minimize the amount of flex in the path because it adds a lot of resistance unless it's pulled absolutely straight. Bends in that stuff cause more pressure drop than I ever expected.
Top TS Dust.jpgBottom TS Dust.jpg

[Lane Hardy]

Carl and David thank you for all the input, for the link to Cincinnati Fan. Wow I wish I had seen this in the begaining of this project. Had I had this information available I would have sold the HF D.C. On Craig's list even thou it was a gift to me. And started with a new 2 stage system and perhaps upgraded the filters if it would have helped.
I feel like I have a well filtered 12 volt portable handheld dust buster when I need a sawmill D.C. System. Well I may not need a Sawmill DC but more CFM would be nice however then I would have to use substantially heavy ducting.as it is
i am a one tool at the time shop as it is. And it is a hobby. Thanks for the idea of going from a 5 inch to a 4 inch to the TS with a 4 x 4 x 3 wye the 3 will go to the overhead drop down. the 5 inch flex is only about 5 inches long to make up couplings. And where possible the couplings ID are smooth and contact each other so the corrigations of the flex pipe is not incountered by the airflow.for the Wye I will have it made locally I will have 5 inches on one end and it will tapper down to 4 inches the 3 inch will be the wye leg. This way there are no sharp steps that will cause a higher SP (parisitic drag)
Again thanks for all the help gentlemen, this weekend I will digest the Cincinnati Fan website.


Lane.

[Lane Hardy]

David thanks for the Overhead layout you have, I hate ask can you give me the details of your D.C. System HP, your Alt I think you said 600 feet. The reason I ask you say you are useing two 4 inch lines one for the over head the other to the TS base, what size main plenum do you have before you split the two 4 inches?

Lane

Lane, it seems to me that it would be a lot simpler to just measure your flow instead of trying to guess at fan curves. Use a DIY Pitot tube and your DIY manometer and find out what you actually have. The only "calibration" you need to do is calculating your air density and it sounds like you're already on top of that.

FWIW I'm using two 4" ducts to my table saw and I get enough lift on the topside to keep the duct clear. It's best to minimize the amount of flex in the path because it adds a lot of resistance unless it's pulled absolutely straight. Bends in that stuff cause more pressure drop than I ever expected.
Top TS Dust.jpgBottom TS Dust.jpg

[David L Morse]

Lane, you can see the DC in the background of the first pic. It's the same HF unit you have, just in the older Green paint. I recently modified the intake so I can use 6" hose. Two 4" hoses were adequate for the table saw but my jointer/planer only has a single port and a single 4" hose wasn't doing the job.

Before I modified the DC I used two 10' hoses connected to it's plastic wye. The hose I have is very flexible so without care in routing it the suction could pull it into odd twists that made an observable difference in flow. The PVC, even with all of the fittings, is a little better than the best arrangement I could get with the hoses and a lot better than the worst. I'm using a 6x6x4 wye with a 6x4 reducer to split into 4" lines. I kept my DC mobile so I use 6" flex to connect the wye to the DC.

I did some testing on a 10' length of my 4" flex. When stretched tight it had a flow resistance equal to 24' of PVC. When compressed to 5' but kept straight it increased to 64'. Stretched tight with 2 90 degree bends is 61' and tied into a random tangle 214'.

My altitude is 670'.

[glenn bradley]

I have witnessed Beranek's Law in action in a previous career; it is so true. I have also noticed that Beranek's Law frequently applies to dust collectors as well.

[David L Morse]

I have also noticed that Beranek's Law frequently applies to dust collectors as well.

I wasn't actually thinking about loudspeakers when I chose that for a sig.