Loss of CFM?

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Forum topic by newwoodbutcher posted 06-28-2017 07:41 PM 914 views 0 times favorited 9 replies Add to Favorites Watch
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817 posts in 3658 days

06-28-2017 07:41 PM

I’m considering a DC upgrade to a Cyclone machine I have a 1200 cfm delta machine with a Super Dust Deputy and a canister filter It performs “ok”. I read somewhere that the Super Dust Deputy causes a drop in CFM. Does anyone know how to calculare the CFM loss? I can’t really compare a new cyclone to my current setup without that info. My question is should I spent $1000- $1700 on a 1345 – 1400+ cfm machine or Would it be more economical/sensible to replace my blowe with a 3HP single stage unit and use the SDD and cartrige I all ready have? I’m sure this info is out there somewhere but my head is starting to hurt from all the choices and data. A specific machine recomendation would also be helpfu. Your advice will be appreciated

-- Ken

9 replies so far

View Ripper70's profile


1378 posts in 1717 days

#1 posted 06-28-2017 10:07 PM

There’s a YouTube video from Guy’s Woodshop that shows his process of rebuilding and upgrading his DC system and how he calculates the CFM differences before and after. Maybe you’ve seen it but, if not, it might be worth checking out.

He runs through the numbers and formulas to calculate the CFM based on hose diameter, motor rating, etc. and he seems to have a similar setup to yours. That is, he uses a cartridge filter with a Super Dust Deputy and shows how he maximizes the CFM from his setup.


Dust Collector Upgrade - Pt 1 - Upgrading to HEPA Cartridge Filter

Dust Collector Upgrade - Pt 2 - Complete System Rebuild

-- "You know, I'm such a great driver, it's incomprehensible that they took my license away." --Vince Ricardo

View pintodeluxe's profile (online now)


6181 posts in 3621 days

#2 posted 06-28-2017 11:01 PM

Not sure how the converted systems compare, but my factory built cyclone is head and shoulders above my old single stage collector.

Saying that a cyclone causes CFM loss is kind of like saying HSS bits are sharper than carbide bits. Yeah… they are, for about ten seconds. Then carbide wins hands-down.

I understand a cyclone uses some CFM, but if it keeps your filter clean when you’re busy in the middle of a project, then it will translate to improved real-world performance.

I’m sold on cyclones. Any way you can get your hands on one, do it.

-- Willie, Washington "If You Choose Not To Decide, You Still Have Made a Choice" - Rush

View Carl10's profile


115 posts in 1265 days

#3 posted 06-29-2017 02:02 AM

It is hard to advise with such little information. Can you post a pick and model of DC setup? For instance some people mount their blower right on the SDD and exit right into canister. Others take a 4” port on the DC and run flex hose to a reducer to the SDD and leave the the DC stock. The first will gain significant improvement with the current hardware. The second (easiest) approach will greatly reduce performance (even though you will have a cleaner filter). The links to Guy’s videos above are a good example of improving what you have. FYI your Delta DC will never produce 1200CFM. I am not aware of any single stage DC that provides accurate CFM data (usually it is rating only the blower…on a good day). Whereas cyclone data is a little closer to reality (apples and oranges)

Regarding SDD loss, I have seen several people post losses between 30-35% using a SDD. A trash can separator or Thien baffle are even higher (these were all done with handheld meters).

Hope that helps,


View newwoodbutcher's profile


817 posts in 3658 days

#4 posted 06-29-2017 03:09 PM

Thank you all. Ripper, I watched both videos this morning, very helpful and just the data I was looking for. I’m going to modify my system eliminating all bends and hose between the SDD and the blower. If I get anywhere close to the improved performance of the guy in the video, I’ll be happy. It will take a few weeks to get to it but I’ll post with pics when it’s done. Thank you all again.

-- Ken

View magaoitin's profile


249 posts in 1758 days

#5 posted 06-29-2017 06:46 PM

This is a very open ended question, and there are a lot of variables you need to be able to calculate static pressure loss.

With what you have so far, a 1200 cfm Delta blower (sounds like their 1.5 hp model) with a Super Dust Deputy, I doubt that the issue is with the blower. a 1200 cfm blower is big enough to use 6” ducting to its potential

6” ducting requires at least 800 CFM air flow through vertical runs in order to maintain 4000 ft/min minimum velocity, and is well-matched to 18” cyclones.

First question is are you using the maximum inlet size for your ducting? I think the Deputy has a 5” inlet. If for example you have a 4” duct/pipe hooked up to this you are probably loosing/reducing your available CFM by +30% Most of the time doesn’t really matter if you use a 3 HP, 3000 cfm blower or a 1.5 hp 1500 cfm, if you are forcing that through a 4” duct the static pressure loss is going to appear like both blowers are working the same.

How much of your ducting is vertical vs horizontal? What is your duct size from your equipment? is it 6” or 4”

From the website Clean Shop Air:

“4000 feet per minute minimum air velocity is required for ducts with air flowing vertically upward (only 3000 ft/min is needed in horizontal runs) to prevent plugging and keep dust dispersed in the flowing air. Do not use 4” or 5” ducting because the static pressure loss is too high, and will degrade cyclone performance and micro-fine dust separation. To maintain the required 4000 ft/min in vertical 6” ducts, minimum air flow through the duct must always be at least 800 CFM, regardless of what the tool itself actually requires. “

-- Jeff ~ Tacoma Wa.

View Redoak49's profile


4809 posts in 2797 days

#6 posted 06-30-2017 12:56 AM

If it is a 1.5 hp Delta DC, you will only get 609-700 cfm from it based on Wood Magazine Testing.

Whatever the OP decides to do, it should be based on some real numbers and not exaggerated claims by a mfg.

View josephf's profile


217 posts in 2905 days

#7 posted 06-30-2017 03:03 AM

i really saw no difference with my cyclone in vrs bypassing it . i did get a great improvement by venting it outside . could you just bypass the cyclone and see if it has an visible difference in suction .
i have a 1 1/2hp with an ebay cyclone .i go direct to the machine i am using with a flexible hose .
oh it did seem to do better with propeller/motor on top of cyclone rather then in serious ,though just seemed to .

View newwoodbutcher's profile


817 posts in 3658 days

#8 posted 07-19-2017 10:39 PM

Holy Cow! What a difference


I don’t have a way to measure the improvement but just putting my hand near the open pipe at the end of a run feels like 4-5x more suction.

Thank you all for your advice and guidance.

-- Ken

View Ripper70's profile


1378 posts in 1717 days

#9 posted 07-19-2017 10:43 PM

Nice going, Ken! Breathe easier.

Plus, you’ve got some more space to fill with tools! ;-)

-- "You know, I'm such a great driver, it's incomprehensible that they took my license away." --Vince Ricardo

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