All the books about dust collectors stress having ducts with sufficient
air velocity to keep the wood particles in suspension to avoid
blockages. This means the duct should not be "too large." Sandor
Nagyszalanczy, in "Woodshop Dust Control" quotes 3500 FPM as optimum.
On the other hand, duct with too small a diameter will decrease air
flow thereby reducing collection efficiency because of pressure drops
across the ductwork. He quotes 350 -500 CFM flow rates at each machine
for adequate dust control.
Having just bought a used Penn State DC1B dust collector I was
interested in measuring FPM and CFM values so I could size my duct
appropriately. A Google search for anemometers showed mostly $200 and
up units, which would be a no-go for me. However I found a newly
released unit for about $40.00-$50.00 designed for wind speed
measurements. It's a Lacrosse EA-3010U, on Amazon at
http://tinyurl.com/4s5f2 . The Lacrosse link is
http://www.lacrosse-htawi.com/ea-3010u.html . It's a tiny thing, about
1" x 4". It can be set to measure wind speeds up to 67 mph, and can be
set to read out in meters per second, m/s. Actually it also measures
temperatures and wind chills for you weather fans. (BTW, I have no
relationship with the Lacrosse folks.)
Knowing how much I have spent and will spend on DC equipment I figured
$40. was worth it to get some quantitative measurements, so I bought
one. (Plus, like many WW'ers I love gadgets.)
Here are the formulas for FPM and CFM starting with air velocity in m/s
and duct diameter in inches:
Air velocity in FPM = m/s * 197.
Air flow in CFM = m/s * (duct diameter in inches)^2 * 1.05.
My DC1B showed an air velocity of 6107 FPM at the DC with one 4" port
open and no load, decreasing to 3940 FPM with both 4" ports open.
The air flow was 672 CFM with both ports open, decresing to 521 CFM
with only one port open. Penn State advertises about 875 FPM for the
new DC1B-XL model that superseded my DC1B, so my machine is about in
line with what I would expect.
Now to measure the air flow with duct in place, which will no doubt be
depressing.
--
Vince Heuring To email, remove the Vince.
In article <[email protected]>, Bob G.
<[email protected]> wrote:
> So do you think you wasted your money or not....on the anemometer?
No way, for the reason you stated below: data on duct sizing and when I
need a bigger DC. :-)
> I have 2 dust collectors and I really do not mind "wasting" lol 30
> bucks if the anemometer will give me some correct answers... has to be
> more accurate then just sticking my hand in fron of a blastgate and
> judging air flow... which has been my method of choice for the last
> 10-15 years since I installed my first DC.... actually I am more
> interested in seeing just how much a cyclone trash can lid effects the
> machine...My system looses a lot of "suction" when I hook up the
> cyclone using my method..
>
> Bob Griffiths
To answer Dan, <[email protected]>, in this post:
>This sounds great, Vince. But I think maybe I'm doing the math wrong.
>Near as I can figure, you're getting 30 or 40 m/s for those numbers,
>and that works out to more than the meter's capacity of 67 mph.
Yup, bad math. The two figures were 20 and 31 m/s. You're right in
general, though. 31 m/s is just at the maximum measurable wind speed
with this model.
Regards, Vince
--
Vince Heuring To email, remove the Vince.
On Tue, 30 Nov 2004 03:44:22 GMT, Dan <[email protected]> wrote:
>
>By the way, did you know if you type "40m/s in mph", without the quotes,
>into the google search box, it'll convert it to mph?
COOL!
"Vince Heuring" <[email protected]> wrote in message
news:281120041206335884%[email protected]...
> My DC1B showed an air velocity of 6107 FPM at the DC with one 4" port
> open and no load, decreasing to 3940 FPM with both 4" ports open.
>
> The air flow was 672 CFM with both ports open, decresing to 521 CFM
> with only one port open. Penn State advertises about 875 FPM for the
> new DC1B-XL model that superseded my DC1B, so my machine is about in
> line with what I would expect.
How about replacing the dual 4" ports with one 6" port? That's possible on
my Jet DC1200 and probably on yours as well. Several people have run 6"
pipe for their system and are very satisfied with it. Are you acquainted
with Bill Pence's website on dust control? He has a spreadsheet for doing
the calculations that is very practical to use. By the way, I think, in
general, you need 2 hp or more with a 12" impellor to support a 6" system.
Bob
On Sun 28 Nov 2004 01:06:33p, Vince Heuring <[email protected]>
wrote in news:281120041206335884%[email protected]:
> Knowing how much I have spent and will spend on DC equipment I figured
> $40. was worth it to get some quantitative measurements, so I bought
> one. (Plus, like many WW'ers I love gadgets.)
>
> Here are the formulas for FPM and CFM starting with air velocity in m/s
> and duct diameter in inches:
>
> Air velocity in FPM = m/s * 197.
>
> Air flow in CFM = m/s * (duct diameter in inches)^2 * 1.05.
>
> My DC1B showed an air velocity of 6107 FPM at the DC with one 4" port
> open and no load, decreasing to 3940 FPM with both 4" ports open.
>
This sounds great, Vince. But I think maybe I'm doing the math wrong. Near
as I can figure, you're getting 30 or 40 m/s for those numbers, and that
works out to more than the meter's capacity of 67 mph.
By the way, did you know if you type "40m/s in mph", without the quotes,
into the google search box, it'll convert it to mph?
On Mon 29 Nov 2004 10:00:50p, "Brett A. Thomas" <[email protected]> wrote in
news:[email protected]:
> ObRW: It doesn't do anything useful with "12x6x32 inches in board feet"
> though. :(
Or currency. :-)
I guess they don't feel like keeping the dollar value updated.
On Sun, 28 Nov 2004 12:06:33 -0700, Vince Heuring <[email protected]>
wrote:
>However I found a newly
>released unit for about $40.00-$50.00 designed for wind speed
>measurements. It's a Lacrosse EA-3010U, on Amazon at
>http://tinyurl.com/4s5f2 . The Lacrosse link is
>http://www.lacrosse-htawi.com/ea-3010u.html .
Amazon is currently showing the device as out of stock and a price of $39.99.
Another source ($5.00 cheaper and free shipping) is:
http://www.clorders.com/lacrossespecialty.htm
The same page has a device that looks like it might serve as a remote control
switch for a DC or other appliance. Didn't check the specs, so don't know for
sure.
Standard disclaimers apply.
Tom Veatch
Wichita, KS USA
On Tue, 30 Nov 2004 14:06:50 -0700, Vince Heuring
<[email protected]> wrote:
>In article <[email protected]>, Bob G.
><[email protected]> wrote:
>
>
>> So do you think you wasted your money or not....on the anemometer?
>
>No way, for the reason you stated below: data on duct sizing and when I
>need a bigger DC. :-)
>
Thanks Vince....my wallet will be 30 bucks lighter very shortly...
Bob Griffiths
On Mon, 29 Nov 2004 06:10:41 GMT, "Bob"
<[email protected]> wrote:
|
|"Vince Heuring" <[email protected]> wrote in message
|news:281120041206335884%[email protected]...
|
|> My DC1B showed an air velocity of 6107 FPM at the DC with one 4" port
|> open and no load, decreasing to 3940 FPM with both 4" ports open.
|>
|> The air flow was 672 CFM with both ports open, decresing to 521 CFM
|> with only one port open. Penn State advertises about 875 FPM for the
|> new DC1B-XL model that superseded my DC1B, so my machine is about in
|> line with what I would expect.
|
|How about replacing the dual 4" ports with one 6" port? That's possible on
|my Jet DC1200 and probably on yours as well. Several people have run 6"
|pipe for their system and are very satisfied with it. Are you acquainted
|with Bill Pence's website on dust control? He has a spreadsheet for doing
|the calculations that is very practical to use. By the way, I think, in
|general, you need 2 hp or more with a 12" impellor to support a 6" system.
It's Bill Pentz. http://billpentz.com/
>
>Having just bought a used Penn State DC1B dust collector I was
>interested in measuring FPM and CFM values so I could size my duct
>appropriately. A Google search for anemometers showed mostly $200 and
>up units, which would be a no-go for me. However I found a newly
>released unit for about $40.00-$50.00 designed for wind speed
>measurements. It's a Lacrosse EA-3010U, on Amazon at
>http://tinyurl.com/4s5f2 . The Lacrosse link is
>http://www.lacrosse-htawi.com/ea-3010u.html . It's a tiny thing, about
>1" x 4". It can be set to measure wind speeds up to 67 mph, and can be
>set to read out in meters per second, m/s. Actually it also measures
>temperatures and wind chills for you weather fans. (BTW, I have no
So do you think you wasted your money or not....on the anemometer?
I have 2 dust collectors and I really do not mind "wasting" lol 30
bucks if the anemometer will give me some correct answers... has to be
more accurate then just sticking my hand in fron of a blastgate and
judging air flow... which has been my method of choice for the last
10-15 years since I installed my first DC.... actually I am more
interested in seeing just how much a cyclone trash can lid effects the
machine...My system looses a lot of "suction" when I hook up the
cyclone using my method..
Bob Griffiths
Dan wrote:
> By the way, did you know if you type "40m/s in mph", without the quotes,
> into the google search box, it'll convert it to mph?
You probably know this, but for the edification of others, it'll do this
for just about anything. I was going to calculate the size of a
resistor I'd need recently, and suddenly thought, "Hey, I wonder if
Google could do this?" I "searched" for "9 volts / 45 milliamps" (or
somesuch, don't remember the real exact numbers) and it said, "200
Ohms." I was quite impressed. I do wish they documented that thing
better, tho. I'm sure there are all sorts of cool things it does that
nobody's noticed, yet.
ObRW: It doesn't do anything useful with "12x6x32 inches in board feet"
though. :(
-BAT