What's new
What's new

Downdraft fan size question

iuctx

Aluminum
Joined
Jan 24, 2019
Location
Fort Worth, TX
I am trying to find the best type and size fan to exhaust the smoke/fumes/dust from my table. The table is 6x12 and has a v-shaped basin. Suspended halfway between the basin bottom and the cutting surface is a 7" ID steel pipe with 8ea 4" square 'ports'. There is only one outlet on the table located on one end. The table will be situated in my shop in such a way that the outlet of this pipe is 8' from the exterior wall, at 90 degrees from where I need to vent.

I have read good things about backward incline blowers. Any input on what size and type fan as well as connection methods will be much appreciated.

IMG_20200924_113008.jpg

IMG_20200923_155443.jpg

PXL_20200930_120753893.jpg
 
I am trying to find the best type and size fan to exhaust the smoke/fumes/dust from my table. The table is 6x12 and has a v-shaped basin. Suspended halfway between the basin bottom and the cutting surface is a 7" ID steel pipe with 8ea 4" square 'ports'. There is only one outlet on the table located on one end. The table will be situated in my shop in such a way that the outlet of this pipe is 8' from the exterior wall, at 90 degrees from where I need to vent.

I have read good things about backward incline blowers. Any input on what size and type fan as well as connection methods will be much appreciated.

View attachment 303663

View attachment 303664

View attachment 303665

Is this manifold your own design ?
 
It is. This 'design' was on the fly, using leftover materials, and included a lot of "y'all think this will work?" ... and here I am. ;)

Most of what I see of these downdraft tables, use a large volume, low pressure blower.
Several I have seen use older, belt driven furnace blowers.

Me thinks you're going to have to resort to higher pressure (and resulting velocity) blower, and
lose efficiency.
 
Most of what I see of these downdraft tables, use a large volume, low pressure blower.
Several I have seen use older, belt driven furnace blowers.

Me thinks you're going to have to resort to higher pressure (and resulting velocity) blower, and
lose efficiency.

Any idea what type and size? If I need to change the design of the duct then now would be the time. Thanks for your help!
 
If you can manage I'd recommend little automated flaps on each port and baffles around it to only draw air from where you are cutting.

Our laser produces less smoke than a plasma, has 8 baffled regions on a 5x10 table, and has a 10hp dust collector. It is adequate but not overkill. It does have filters which adds an additional 4 inches of water suction to the blower load.

In any case you will need a higher pressure blower due to the restriction of the 7" duct.
 
If you can manage I'd recommend little automated flaps on each port and baffles around it to only draw air from where you are cutting.

Our laser produces less smoke than a plasma, has 8 baffled regions on a 5x10 table, and has a 10hp dust collector. It is adequate but not overkill. It does have filters which adds an additional 4 inches of water suction to the blower load.

In any case you will need a higher pressure blower due to the restriction of the 7" duct.

What brand/model dust collector? Do you have any pictures of the baffles you could share? Thx!
 
What brand/model dust collector? Do you have any pictures of the baffles you could share? Thx!

Dust collector is a $30k+ model with blowoff filters and reverse purge. Not the most small shop friendly. If you intend on building one you can DM me for some technical details about these sorts of systems.

As far as baffles I'm referring to two distinct components, which could have gotten confusing.

The first are stationary baffles which are just vertical pieces of

Out of time I'll finish this later
 








 
Back
Top