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How to Evaluate Air Flow w/o Instrumentation
Posted: Sat Jul 03, 2021 10:01 am
by dusty
There has been discussion about the DC-3300 Motor Upgrade Kit. The primary purpose of this upgrade is to increase air flow in the dust collection hoses.
I placed an order for that upgrade kit. I'm not absolutely certain why because I have been satisfied with my DC-3300. Nonetheless, I am waiting for the upgrade kit.
Now I am faced with evaluating it's performance without instrumentation. A subjective evaluation at best.
Any suggestions on how I might do this will be greatly appreciated.
Re: How to Evaluate Air Flow w/o Instrumentation
Posted: Sat Jul 03, 2021 11:16 am
by garys
Your own subjective evaluation is likely what matters. If it works better for you after the upgrade, you win.
Airflow has different characteristics. You have volume, you have pressure/vacuum, and probably more things to consider.
If you change your dust chute from 2.5" to 4", you should get more flow, but less pressure/suction. With larger wood chips, more suction on the smaller line might work better while fine dust should work better on the larger line with more airflow.
If you are fairly familiar with the machine now, you will be the best judge of the performance increase. In the end, the numbers probably don't matter.
Re: How to Evaluate Air Flow w/o Instrumentation
Posted: Sat Jul 03, 2021 11:23 am
by dusty
garys wrote: Sat Jul 03, 2021 11:16 am
Your own subjective evaluation is likely what matters. If it works better for you after the upgrade, you win.
Airflow has different characteristics. You have volume, you have pressure/vacuum, and probably more things to consider.
If you change your dust chute from 2.5" to 4", you should get more flow, but less pressure/suction. With larger wood chips, more suction on the smaller line might work better while fine dust should work better on the larger line with more airflow.
If you are fairly familiar with the machine now, you will be the best judge of the performance increase. In the end, the numbers probably don't matter.
I don't disagree at all but I have put myself in a pickle. I have been using the DC-3300 for years and I have always be satisfied with its performance. The only time it lets me down is when I fail to hook it up or use it. But, I have the Motor Upgrade Kit on order and I am sure I will be satisfied. I would just like to be able to say why it was a wise decision. Being able to say it produces twice the airflow would be great.
Re: How to Evaluate Air Flow w/o Instrumentation
Posted: Sat Jul 03, 2021 11:47 am
by algale
I think the answers you are searching for are there in that document you posted on the other thread about the DC6000 and the upgrade kit. Before the upgrade, you could only get 200 cfm from a DC3300 with one hose at a time and additional hoses decreased cfm in each hose. After the upgrade, you can get 200 cfm simultaneously with all three hoses. This assumes use of 2.5 inch hoses.
Re: How to Evaluate Air Flow w/o Instrumentation
Posted: Sat Jul 03, 2021 12:52 pm
by edma194
This would be quite difficult to determine without instrumentation. You can look at how well, how fast, or perhaps how far away the intake hose can pick up a measured amount of sawdust or similar material. Simply timing it or measuring the distance breaks your 'no instrumentation' rule though.
It's probably easier to just feel how much air is coming from the outlet. Of course you won't have two of these machines side by side with the different motors for comparison so you'll have to rely on your memory and a very crude measure.
If you were willing to get a little technical a mass air flow sensor from a car could be adapted for use. And maybe something as simple as a DC box fan put inline as a turbine generator could produce measurably different outputs.
Re: How to Evaluate Air Flow w/o Instrumentation
Posted: Sat Jul 03, 2021 1:15 pm
by dusty
algale wrote: Sat Jul 03, 2021 11:47 am
I think the answers you are searching for are there in that document you posted on the other thread about the DC6000 and the upgrade kit. Before the upgrade, you could only get 200 cfm from a DC3300 with one hose at a time and additional hoses decreased cfm in each hose. After the upgrade, you can get 200 cfm simultaneously with all three hoses. This assumes use of 2.5 inch hoses.
Thank you. This post led me back to the input from Jim McCann. When I read it before I did not pick up on those details. I'm kinda slow on the uptake these days.
Re: How to Evaluate Air Flow w/o Instrumentation
Posted: Sat Jul 03, 2021 2:50 pm
by RFGuy
dusty wrote: Sat Jul 03, 2021 10:01 am
Now I am faced with evaluating it's performance without instrumentation. A subjective evaluation at best.
I haven't seen any good test methods for evaluating airflow without a test instrument. If anyone has a method, I would be interested to learn it. The instrument used to measure it is called an anemometer, but you have to get one with a high enough range to measure very fast airspeeds such as a dust collector can provide. Mine cost about $130 and has come in handy for HVAC adjustments as well as evaluating dust collector performance in the shop, but not a tool most woodworkers need or will want to purchase.
It would be useful if anyone has an anemometer and purchases the new DC-3300 upgrade to have them measure airflow both before and after the upgrade. From the other thread, I do believe the airflow numbers that Jim McCann quoted are design numbers so actuals could be quite a bit different. I am surprised by the numbers he quoted though. Supposedly the impeller is a new design which you would think would yield a higher airspeed which should translate into a higher airflow (for the same port size). IF the DC-6000 still only delivers 200CFM into a single 2-1/2" hose (same as the DC-3300) then that implies the impeller airspeed is the same between both of them, but we expected more since the impeller design changed.
I would also argue that most of us only use one 2-1/2" port at a time on our DC-3300's so if there is no increase in airflow on a single port, then what exactly are customers going to gain by using the new DC-3300 upgrade? I mean the airflow through a single port is the same between the DC-3300 (old), DC-3300 (new - upgrade), and the DC-6000. Unless you are planning on running multiple tools at the same time thus using more than one 2-1/2" hose on the DC-3300 (new) or DC-6000, then what is the benefit of this new dust collector or the upgrade?
Re: How to Evaluate Air Flow w/o Instrumentation
Posted: Sat Jul 03, 2021 2:57 pm
by algale
RFGuy wrote: Sat Jul 03, 2021 2:50 pm
I would also argue that most of us only use one 2-1/2" port at a time on our DC-3300's so if there is no increase in airflow on a single port, then what exactly are customers going to gain by using the new DC-3300 upgrade? I mean the airflow through a single port is the same between the DC-3300 (old), DC-3300 (new - upgrade), and the DC-6000. Unless you are planning on running multiple tools at the same time thus using more than one 2-1/2" hose on the DC-3300 (new) or DC-6000, then what is the benefit of this new dust collector or the upgrade?
This^. I kinda of said this in the other post. With one hose, there's no improvement in cfm per McGann. You have to have at least two hoses going at once to see an improvement (or rather no drop off) in cfm. I never use multiple hoses, so the upgrade is not for me. I would be delighted if someone showed that there really is an improvement. Maybe it's got enough oomph to put a Dust Deputy or other cyclonic separator in-line without losing cfm? I tried a Dust Deputy with my DC3300 but perceived a loss of cfm (indicated by partial deflation of my hood).
Re: How to Evaluate Air Flow w/o Instrumentation
Posted: Sat Jul 03, 2021 3:51 pm
by dusty
RFGuy wrote: Sat Jul 03, 2021 2:50 pm
dusty wrote: Sat Jul 03, 2021 10:01 am
Now I am faced with evaluating it's performance without instrumentation. A subjective evaluation at best.
I haven't seen any good test methods for evaluating airflow without a test instrument. If anyone has a method, I would be interested to learn it. The instrument used to measure it is called an anemometer, but you have to get one with a high enough range to measure very fast airspeeds such as a dust collector can provide. Mine cost about $130 and has come in handy for HVAC adjustments as well as evaluating dust collector performance in the shop, but not a tool most woodworkers need or will want to purchase.
It would be useful if anyone has an anemometer and purchases the new DC-3300 upgrade to have them measure airflow both before and after the upgrade. From the other thread, I do believe the airflow numbers that Jim McCann quoted are design numbers so actuals could be quite a bit different. I am surprised by the numbers he quoted though. Supposedly the impeller is a new design which you would think would yield a higher airspeed which should translate into a higher airflow (for the same port size). IF the DC-6000 still only delivers 200CFM into a single 2-1/2" hose (same as the DC-3300) then that implies the impeller airspeed is the same between both of them, but we expected more since the impeller design changed.
I would also argue that most of us only use one 2-1/2" port at a time on our DC-3300's so if there is no increase in airflow on a single port, then what exactly are customers going to gain by using the new DC-3300 upgrade? I mean the airflow through a single port is the same between the DC-3300 (old), DC-3300 (new - upgrade), and the DC-6000. Unless you are planning on running multiple tools at the same time thus using more than one 2-1/2" hose on the DC-3300 (new) or DC-6000, then what is the benefit of this new dust collector or the upgrade?
Very interesting.
Re: How to Evaluate Air Flow w/o Instrumentation
Posted: Sat Jul 03, 2021 3:52 pm
by dusty
algale wrote: Sat Jul 03, 2021 2:57 pm
RFGuy wrote: Sat Jul 03, 2021 2:50 pm
I would also argue that most of us only use one 2-1/2" port at a time on our DC-3300's so if there is no increase in airflow on a single port, then what exactly are customers going to gain by using the new DC-3300 upgrade? I mean the airflow through a single port is the same between the DC-3300 (old), DC-3300 (new - upgrade), and the DC-6000. Unless you are planning on running multiple tools at the same time thus using more than one 2-1/2" hose on the DC-3300 (new) or DC-6000, then what is the benefit of this new dust collector or the upgrade?
This^. I kinda of said this in the other post. With one hose, there's no improvement in cfm per McGann. You have to have at least two hoses going at once to see an improvement (or rather no drop off) in cfm. I never use multiple hoses, so the upgrade is not for me. I would be delighted if someone showed that there really is an improvement. Maybe it's got enough oomph to put a Dust Deputy or other cyclonic separator in-line without losing cfm? I tried a Dust Deputy with my DC3300 but perceived a loss of cfm (indicated by partial deflation of my hood).
Very interesting