This could be interesting...

[revchris]

I installed a vent today for the dust collector closet. I got a Broan model 639 wall cap at Menards yesterday. It has a 10" x 3.25" square duct section and an exterior flap with screening (very much like what you'd use on a range hood).

Cutting the holes was no problem, and I even managed to put it right next to one of the secret extra studs in the back wall, so two of the face mounting screws are into the stud, and the other two are only into the exterior sheathing. The inside came exactly flush to the inside wall, and is sealed to the wall with two layers of metal duct tape.

Then I stopped and calculated the airflow.

The dust collector has a peak rating of 1600 CFM. The wall cap has a cross section of 0.226 square feet. This works out to a linear velocity of 7,080 feet per minute. Or, in more common units, 80 miles per hour!

(^{1600 ft3}/_min) / (0.226 ft²) = (^{1600 ft3}/_min) * (0.226 ¹/_ft²) = 7080 ^ft/_min, and
(7080 ^ft/_min) * (^{60 min}/_{1 hr}) * (^{1 mile}/5280 ft) = 80 miles/hour, right?

I'm probably going to need more (or larger) wall caps. I do admit, though, that it would be amusing to watch the wall cap blow right out of the wall, but only until I have to fix the wall (or the inside door on the dust collector closet blows out).

I'm going to have to see if I can get one of these. Adding that as a second vent drops the velocity to 18mph. Replacing the first one with one of the 613s and adding a second drops the speed to 12 mph. First, I need to find somebody who sells them.

Edit: Grainger has them for $53, but I'm still going to wait until I have the dust collector up and running. I'm not sure that I'm going to get the full 1600cfm through the required ductwork, and when I do, I'm going to measure the actual airflow for a short trial run and then see what I want to do.

Comments

[teeka.livejournal.com]

But before you install the second vent opening, can you install a peephole for me, and a remote on/off switch, so I can see if the air shooting out of the venthole will be powerful enough to airlift the neighbor's yappy dog next time it goes ballistic?

Pleeeeeeeeeease?

[misteropinion.livejournal.com]

I think it would be amusing to watch the wall cap blow out, even if I had to fix it afters. Blowouts, maaaaaan! They're the future.

[revchris.livejournal.com]

The trick, though, will be to catch it on video, both from the outside, and from a second camera on the inside, which can also be used to capture the image from the hand-held anemometer I'd need to use to get an accurate windspeed.