Ideas for Light Proof Vent Hole Between Wall?

[SourSmoke]

Greetings ALL I am looking for ideas on creating a simple 6 inch venting passthrough between my veg and bloom room. 2x4 walls. One hole will have an inline fan for circulation between rooms and the other hole will be passive air transfer. I can't have light passing through the holes. THANKS!

 

[paper thorn]

6" pvc and two 90* elbows flat black on the inside.

 

[Granger2]

^^^^yes. The flat black on the inside makes the difference. I would direct the 90's down so direct light isn't shining into them. Sometimes you may get a glow. You can always add a 3rd 90. Not unless you have to cuzza the added static pressure. Good luck. -granger

 

[intotheunknown]

orrr.....

check these out. expensive but kick major ass.

http://www.adorama.com/DKL8.html

 

[Granger2]

into,
How about air flow on those. I've been interested in them, but can't find anything on air flow. Thanks. -granger

 

[sub]

I've actually been building my own light-proof vents. I don't have the room for a bunch of 90 degree PVC elbows, so basically here's what I'm doing:
Got a big stack of these aluminum drip caps from home depot for 99 cents each (almost 4' long), cut them up, gorilla glued them together with 1/8" wooden spacers between them, like this:

Gonna paint them all black then frame the whole unit in a mountable box. Much smaller that PVC and all that other stuff, plus those darkroom vents have awful air flow and you would need a lot of them.

Check out this thread for more DIY ideas along the lines of mine

For my passive intakes, which are in my mother/clone chamber, I am only doing one layer of drip caps (so it's shaped like a V instead of an N)

still pretty light proof, but might let a little glow in, which doesn't matter for my veg chamber, but the doubled up stack should be 100% light-tight

 

[RB56]

I do this by having the intake hole low on the exterior wall and the intake high on the inside wall. Paint drywall facing inside the wall flat black. Put a register cover on the outside wall with the fins pointing down, if you like.

 

[Bulldog420]

Is this kind of like a glory hole?

 

[sub]

A glory hole for Gumby maybe
I think what he is describing is called a baffle? Think of a periscope shape.
I did that on my last box, but it was this ugly cardboard box on the outside of my cab.. looked ugly (my box was small, though) - and this new one is also small so I am pretty excited to get these DIY light-vents in there!

 

[RoadRash]

There's this book by a guy named Scott, last name.

He spent his career at Varian as a mechanical engineer, cooling various kinds of high-power tubes, like radar amplifiers, travelling wave tubes, etc.

He took meticulous notes, and did thousands of pressure drop measurements.

Then he boiled all his observations down into formulas.

Basically, on how the shape of a plenum affects the air-flow through it. For example, comparing a 180 degree bend to a 90 degree bend, comparing a 4 inch diameter straight section to a 6 inch diameter straight section.


Long story short, a tight bend radius is harder for the air to go around than a sweeping bigger bend radius.

I would buy the 4 inch or 6 inch ducting elbows with the least tight bend, & paint the inside black.

Also, something simple, like covering the inlet with a piece of wood to block the sun-light or a room lamp.

OTOH that Adorama product looks pretty functional.


I have stuck an 80 mm AC fan in a piece of 4 inch laundry hose before, and that worked for air inlet. That would be a 'cheap & dirty & quick' solution.

 

[sub]

Yeah that DIY thread has some calculations for airflow, I think something like mine I might expect to see 60% efficiency, but I would love some proper calculations! I have been going with 60% just to be safe, better to have passive vents larger than needed than too small!

RoadRash, do you happen to know the formula for figuring out how much airflow loss you would see in 90 degree bends?

 

[sub]

Also keep in mind those Adorama vents are not 100% light-tight - probably not a good option between veg and flower chambers, maybe if you doubled them up. I believe you would need a lot of them, though.. I can't find the CFM rating on these, but other similar ones were very low and people who have used them said they had to buy a lot of them, kind of a waste of money personally, but I like to DIY stuff anyway.. if you aren't a tinkerer or enjoy making things it may be worth the money, but just be sure to calculate the CFM you need and how much air can pass through these vents.

Although this one seems to be 400 CFM, nice! - bit pricey, though. Would be nice to have for passive intakes on the veg chamber, though!