Howdy, I am setting up a home shop and in the process of designing the
dust collection system. My location is at 7000 ft elevation so the
question is, what efficency drop will the duct collector suffer due to
the altitude? Anyone ever dealt with this issue? I called Jet tech
support and they didnt have an answer. The books I have read dont even
mention effects of altitude on DC performance..... anyone have any
input?

TIA, of course

Even without knowing the power of your DC, any minor loss of air
pressure-density will be offset by the ability of the impeller to spin
a _bit_ more rapidly. I'll bet that you'll hardly notice a difference,
if at all. Tom

Figure your CFM requirements as 'sea level' and then add 25% as an
altitude adjustment. That will get you close enough.

Woody

Not quite.... the static pressure will be less, but the air density is
also less.... at 8,000 ft the air density is down 26% from that at sea
level.

"Spamless" wrote in message
...
Howdy, I am setting up a home shop and in the process of designing the
dust collection system. My location is at 7000 ft elevation so the
question is, what efficency drop will the duct collector suffer due to
the altitude? Anyone ever dealt with this issue? I called Jet tech
support and they didnt have an answer. The books I have read dont even
mention effects of altitude on DC performance..... anyone have any
input?

TIA, of course

What could you do about it anyway? Just buy a 25% larger DC that you think
you need.

Dave

Higher the altitudes the bigger the impeller needs to be.

check out this
http://billpentz.com/woodworking/cyclone/Index.cfm

no simple answer with any vacuum system.

Initially, I was considering using a 4" main line with 4" legs to the
machines. According to the book, that works (presumably at sea level).
I wonder if going to a 6" main with 4" legs would make up for the
altitude factor? I already have the DC, a Jet 1100 so really need to
make that work if possible. Wish money was no object.....

On Tue, 23 May 2006 16:45:48 -0700, "Teamcasa"
wrote:


"Spamless" wrote in message
.. .
Howdy, I am setting up a home shop and in the process of designing the
dust collection system. My location is at 7000 ft elevation so the
question is, what efficency drop will the duct collector suffer due to
the altitude? Anyone ever dealt with this issue? I called Jet tech
support and they didnt have an answer. The books I have read dont even
mention effects of altitude on DC performance..... anyone have any
input?

TIA, of course

What could you do about it anyway? Just buy a 25% larger DC that you think
you need.

Dave

On Tue, 23 May 2006 11:50:14 -0700, Spamless
wrote:

Howdy, I am setting up a home shop and in the process of designing the
dust collection system. My location is at 7000 ft elevation so the
question is, what efficency drop will the duct collector suffer due to
the altitude? Anyone ever dealt with this issue? I called Jet tech
support and they didnt have an answer. The books I have read dont even
mention effects of altitude on DC performance..... anyone have any
input?

TIA, of course


There won't be much difference. But I recommend getting more HP than
you think might need for other reasons that have a much larger impact.
Like curves, turbulence, length of piping, leaks, adding a drop box,
exaggerated HP claims, etc. I have a 1.5 HP and really can really use
a 2HP, but I use what I got.

About 4in vs 6in. If you want the best i would go with 6in. Just
remember you want to move mass of air and your not trying to lift
water. The larger the pipe the smaller dust particles you will catch. I
just got the jet 1100rck put up my 6in pipe for main line then ran
shorter smaller pipe to equipment. I can say my router table is 99%
dust free when using.

Spamless wrote:
Initially, I was considering using a 4" main line with 4" legs to the
machines. According to the book, that works (presumably at sea level).
I wonder if going to a 6" main with 4" legs would make up for the
altitude factor? I already have the DC, a Jet 1100 so really need to
make that work if possible. Wish money was no object.....

On Tue, 23 May 2006 16:45:48 -0700, "Teamcasa"
wrote:


"Spamless" wrote in message
.. .
Howdy, I am setting up a home shop and in the process of designing the
dust collection system. My location is at 7000 ft elevation so the
question is, what efficency drop will the duct collector suffer due to
the altitude? Anyone ever dealt with this issue? I called Jet tech
support and they didnt have an answer. The books I have read dont even
mention effects of altitude on DC performance..... anyone have any
input?

TIA, of course

What could you do about it anyway? Just buy a 25% larger DC that you think
you need.

Dave