# Trash can separator CFM measurements



## Chashint (Aug 14, 2016)

Summary of what I have and measured. 
CFM measured with HoldPeak HP -846A anomometer.
Dust collector Delta AP-400 1HP.
New felt filter bag.
33 gallon metal trash can.
90 deg elbow on inlet and outlet of trash can lid.

AP-400 inlet 780 cfm
Trash can inlet 498 cfm
4" x 20' Dust Right hose extended ~10' 270 cfm
4" x 10' clear flex hose. 250 cfm
4" x 13' metal duct and 4' flex hose. 240 cfm



















Long winded version ….
A while back I converted my dust collector to a two stage system with a metal trash can.
I knew that adding a trash can in front of the dust collector had impacted the airflow but it seemed to still work decently enough moving a 10' hose between tools.
I was happy enough not having to wrestle that collection bag.

The garage has always transitioned between woodworking and car parking so I never really developed a shop setup.
Tool placement was most often decided by how easily it could be McGyvered back into storage configuration.

Being newly retired I am now piddling around trying to setup the garage as a more permanent woodworking shop and the plan is to spend a lot more time playing there than ever before.
To that end I would like to improve a few things for the workshop.

The dust collector is as good of a place to start as another so I put a window in my trash can and sealed all the seams with caulk. 
I thought the airflow might improve with only one 90* elbow in the lid so I swapped in a straight hose coupler.
Some observations about the trash can separator.
It separates much better when using two 90* elbows in the lid vs one elbow and one straight coupler.
It doesn't matter if the single elbow is on the inlet or outlet, lots of stuff blows through the trash can.
With elbows on the inlet and outlet virtually nothing of substance blows through.
I doubt that either configuration affects fine dust particles very much.
I put the trash can back to the original two elbow configuration.

Since any new dust collector (that I want) is expensive I thought it would be interesting to record some numbers to see for myself just how much the trash can, hoses, and fittings are affecting me so I got an inexpensive anomometer and made some measurements.

As far as the measured cfm numbers go all I know for sure is the meter is setup correctly and I held the probe the same way for all measured locations.
Is it actually accurate? I don't know.
Comparatively though the measurements should be very accurate to each other so the losses are quantifiable. 
I have no way to know if the numbers would scale on a percentage basis to compare what I have to what someone else has or if they would hold up on a percentage basis if I were to simply replace the dust collector and leave everything else the same.


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## Redoak49 (Dec 15, 2012)

Is the anemometer accurate for this use….No. I wrote a blog about trying to use one and you can get numbers all over the place. A pitot tube or hot wire anemometer give much better data

I do not believe you can get 780 cfm with a 1 hp motor and about a 9" impeller.

While I am always glad to see people trying to measure performance, I do not think your numbers or data are accurate. It is so difficult to get numbers with that type of instrument.

What your numbers do show is that the flex hose dramatically reduces flow.


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## ArtMann (Mar 1, 2016)

The specification on the AP-400 says the maximum flow rate is 650 cfm. That is usually measured at the inlet with nothing connected. I doubt very much that Delta would under rate their dust collector. There is something off about your measuring system. A trash can separator usually cuts air flow by close to half.


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## Redoak49 (Dec 15, 2012)

The best way to measure the effect of various configurations in a cheap and easy way is to use a water manometer to measure static pressure.

If this system works for you, then use it.


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## Chashint (Aug 14, 2016)

I knew the 780 cfm would be the discussion point, I should have left out the raw numbers and just used % drops through the system.
On a comparative basis the measurements should be accurate enough to reflect % change from one location to another.

There are relatively few posts that include any measurements but many people asking indirectly about system losses.
I was surprised by how much loss there is in the trash can and in a 10' section of 4" flex hose.

Redaoak49, I read your dust blog, good job all around on your setup and good documentation on performance.

Like many people I am just trying to figure out what it's going to take to get good two stage dust collection in my 2 car garage workshop.


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## ArtMann (Mar 1, 2016)

You need to read up on the concept of static pressure and dust collector performance curves. Static pressure, or SP for short, is a measure of the resistance of pipes, fittings, devices and end shapes to air flow. If you can get an accurate SP estimation for your system, you can use it and the performance curve of the DC to predict cfm values without making any measurements. You can compare different scenarios on paper before you start assembly. Here are some of the things you will see. A straight pipe has a much lower SP than a curved one. A smooth pipe will have a much lower SP than flex hose. Every "Y" or elbow adds to the SP and lowers the flow rate. The longer the pipe, the higher the SP and the lower the flow. A trash can separator has a high SP value. A cyclone separator, such as the Oneida Super Dust Deputy, has a lower SP but will still cost you some air flow. You can download tables of SP ratings of various components and configurations from many sources on the internet.

I am going to be honest and sorry if it is a little discouraging. A one horsepower dust collector is questionable for any central system. Your machine was designed to be moved and attached to a single tool through a short hose and that is going to be your best configuration.


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## Redoak49 (Dec 15, 2012)

It is understandable trying to make it work but the 1 hp is such low power. As Art says, might work for rolling to one tool at a time. The cheapest solution is the HF dust collector.


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## OSU55 (Dec 14, 2012)

Chas, what is your goal with DC? If you are trying to capture ALL dust so a respirator is not needed, go to proper machine collection design, which will include cfm requirements. Then ducting design, and calculate losses. After determining flow and sp, you can select a dc system. Probably $10k for all the proper collection sustems, ducting, and dc not inlcluding adding electrical to the shop. You also need to invest in a system to test shop air properly to prove the air is clean.

You are probably like the vast majority of us - cant or dont want to go to the trouble and expense, or just overwhelmed with it all. Just view the dc as a "cc" chip collector and wear your respirator. Collect chips, make it easy to dump them, and move on to enjoying wood working. Whether your measurements are right or not, your not even in the ballpark from a health perpective, along with most everyone else. Go to Pentz site if you want to actually commit to doing it correctly.


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## Redoak49 (Dec 15, 2012)

Yes, a dust collection system can be expensive but not anywhere near 10 K.

I have a 5 hp cyclone that cost $2200 with another $250 in 6" PVC pipe and fittings. I built my own blast gates for less than $100. The hoses and other fittings are an additional $200. So, I have a very good system for $3K.

Many on here have built a HF based system with modifications for a lot less and probably about $600"-800.


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## OSU55 (Dec 14, 2012)

So how well does it work Redoak? I take it you have performed particulate tests in accordance with certified methods to determine effectiveness?


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## Manitario (Jul 4, 2010)

Thank you for posting your measurements Chashint. CFM and measurement process aside, it shows that the pre-separator gives a significant hit to the CFM.

Spending $10K for a complete hobbiest DC system seems excessive. I have a Clearvue 5hp cyclone. It's a few years old, so when I got mine it was ~$2K delivered. I went with Nordfab 6" duct, in part b/c I've had 3 shops since the initial install and it's easy to tear down and re-configure. Probably have at least another $1800 in the ductwork. General guess is I have $4000 in the whole system.

As for testing; I measure the CFM several x per year (just because that is the way my brain works) with a Dwyer pitot tube and digital manometer. Also have a particle counter that I use for testing. In my 25×40 shop, my shortest run to my MS (~15') gives me around 950CFM on average and the longest run to my jointer (~35') gives me around 550CFM (jointer only has a 5" port). Particle count while out in the shop and using machines is around 1ug/m3 which is much less than the OSHA standard of <10mg/m3 cumulative exposure over 8h. Amusingly, the air quality in my house is worse ~4ug/m3.


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## Redoak49 (Dec 15, 2012)

OSU55….The answer is no that I do not have a particulate monitor and do not plan to get one. Perhaps you could explain the proper certified method for air quality testing that you have used. I am certain it would be educational.

My point and as backed up by Manitario is that you do not need to spend anywhere near 10K. He has a ClearVue and I have the Oneida. These are similar machines with similar price tags.


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## OSU55 (Dec 14, 2012)

^See Manitario above


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## Chashint (Aug 14, 2016)

Thanks to everyone for participating.

What are my goals for the dust collector ?
This is a very good question, and maybe an even better question is … what are my goals for my woodworking shop ?

I am turning my attached 2-car garage into a full time woodworking shop.
Layout of the tools has actually been much harder than I would have ever imagined …. probably just my OCD kicking my rear.
Before I would move the car out, drag the tools out of the nest and just make do with the clutter.
Now I want it to be a "real" shop. LOL

I have been cleaning things, moving things around, throwing stuff away, relocating stuff to the shed, labeling drawers, and doing a lot of contemplating about everything and nothing.

For Christmas I got the anomometer and a singed felt bag so that was the inspiration to make the cfm measurements.
The trash can was something I have had in place for a couple of years, I knew it really hit the airflow hard but not having to take the bag on/off was worth it to me.
As far as the blast gate manifold goes I wanted to try attaching all of the machines and open/close the blast gates vs moving the flex hose from machine to machine.
Hey, I have looked at hundreds of workshops with awesome dust collection systems and I just wanted to cobble something together from parts mostly on hand.
It sounded a lot better in my head than it actually worked though.
Adding the blast gates was the final nail in the coffin and today I took all that apart and went back to the single hose solution.
The anomometer I have reads 400 cfm at the end of the Rockler Dust Right hose when it's connected directly to the trash can. Not great, but noticeably better than when it read 250 cfm.

I do not know what my goals are for the dust collector. I would like it to work better but I am not even sure what working better means for me either.
What I have does a decent job collecting the shavings and sawdust.
When it comes to fine dust collection if the information published by Pentz is anywhere close to accurate, I don't know if I want a 5hp clearview monster with 6+" pipes all over the garage ceiling, not to mention the noise that much airflow would create on top of the noise a 5hp blower would generate.

At this time I don't know exactly where my woodworking interests will settle in at.
I have really enjoyed building some small boxes and plan to build quite a few more as gifts.
For the workshop I want to build a router table, better bases for the sanders and the planer, and maybe a work bench.
I would like to build a dining table.
The cabinets in the kitchen and one of the bathrooms needs to be updated.
Lots of different projects out there for me.

Sorry for the ramble.
All interest and comments are appreciated.


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## Manitario (Jul 4, 2010)

Building a shop is a process, and making a lot of tool decisions is probably overwhelming to most of us. I started with a small 15×25 shop and a few cheap tools and slowly upgraded as my interests grew. Got a "real" TS to replace my $100 Ryobi TS, then got a jointer and a planer b/c I wanted to make cutting boards. My first DC was a 1.5hp canister DC that I got b/c I was tired of coughing after spending some time in the shop. Moved after a couple of years to a two car garage and upgraded to the Clearvue at that point; realistically would have been ok with a 3hp unit for a 2 car garage but I figured I was spending the money anyways and it would be big enough for whatever size of shop I had in the future.

Essentially the main questions for every ww looking at dust collection are:
-do you want a clean shop and/or clean air
-do you have enough space to move a DC from machine to machine or do you need ducting?

If you want a clean shop, get whatever you want, hook up a trash can separator and you're done. This is what most people do and reason "Well, I have a ___DC and my shop looks clean so I'm happy with it/it must be working". If you want clean air, you are going to want to target at least 600CFM at each machine. This isn't magic, this is just the minimum airflow it takes to capture fine dust. That leads to the second question, about shop space. Most small, 1.5 HP canister DC have more than enough power if they are connected to each machine by a short piece of flex duct, without any sort of separator, ie. wheeled from machine to machine. Most people don't want to do this though (how many people want to have to stop and wheel a DC around between each machine). The problem if you try and add ducting to a small DC is that they just don't have enough power to overcome the resistance (friction) of the ducting and the CFM drops significantly. Therefore, if you want the convenience of not having to wheel a DC from machine to machine, you need to duct it. Generally, in a two car garage, you're looking at a 3hp machine to provide the CFM for the duct runs you'll need (6" pipe with reducing right at the machine and minimal flex duct).

A large DC is noisy, but less so that your other machines. I have my DC in an insulated closet and it's quiet enough that I don't have to wear hearing protection when I'm using my lathe at the other end of my shop.


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## Chashint (Aug 14, 2016)

My oldest tool is a Harbor Freight floor standing drill press. I got it in the early 90's. It does not get much use and is not a very powerful machine.
At that time I had an ancient Craftsman contractor saw and a Delta 9" bench top bandsaw.
I cannot find a date on the Hitachi C10FS miter saw, but when I got that is when I realized just how big a pain in the rear the tablesaw and bandsaw were to use.
I got rid of the tablesaw shortly after getting the miter saw.
In 2004 I got the dust collector and used it inside the house for building RC airplanes.
In 2006 I bought a Delta 36-714 hybrid tablesaw, a Jet 14OS bandsaw, a Ryobi lunch box planer and 4" bench top sander.
In 2016 I got the Ridgid oscillating belt/spindle sander.
This year I got a Ridgid 6" jointer.

More modern times have increased the awareness of dust inhalation and tablesaw safety devices.
I am interested in both.
My tablesaw predates riving knives and my dust collector is very entry level.

I live in Texas and the garage is not temperature controlled.
I have used a respirator in the past when doing power sanding operations and when blowing out the garage with the leaf blower.

Now that I want to setup shop and do woodworking as my go to activity things like dust control and any safety features that can prevent amputation have bubbled to the frontal lobes.

My wife is home 24/7 too and I have some concerns about noise.
Other than being cautious about adding a "huge" machine that would always be used whenever another machine was in use I have no viable ideas for noise abatement.

My initial plan is to try to optimize what I have and see if "full time" woodworking will be my go to activity or do I just want to build the shop because it's something I have always dreamed of and once it's done…will I be done too??

I am very pleased to be retired and mentally I am doing well being at home, having said that this is a new way of life for me and I am in the beginning stage of getting it figured out.


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## Redoak49 (Dec 15, 2012)

I think it is a good idea to see if this is a hobby you will stay with in retirement.

Given your current dust collector, I would have skipped the modifications and just connected it to one tool at a time. This would maximize its effectiveness.

For some of us who have been making sawdust for many years, spending the money to have a powerful system makes sense.


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## Chashint (Aug 14, 2016)

Yes I need to see if I will settle in and really embrace woodworking before spending significant money on replacement/upgrade equipment.

I stopped trying to treat the garage as a factory today and I actually made some noticeable progress on becoming work capable.
There's still plenty of organization that needs to be done but the major horizontal surfaces are clear and clean.
All of the cast iron has a fresh coat of wax and the things that needed lubricant got it.


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