Winter time etching

[CodeMonk]

This is a yet another thread about etching PCB's. Sort of.
(Yet another mini novel from me   Sorry about that  .

So in the Northern Hemisphere, Fall is here and Winter will be here soon enough.
My outdoor workshop has one door and one louvered window similar to this:


Each at opposite ends of the room.
I'll often put a small cheap fan pointing out at the window, plus the wind blows here all the damn time.
So I get pretty good ventilation in there.
During Spring/Summer and sometimes early Fall, we have moderate temperature (Although we do get into the 100+ range during parts of the summer, sometimes for a feww weks at a time).
Late Fall and winter, things get rather cold, sometimes going below Zero Degrees F and sometimes staying there for several weeks
And my workshop is very well insulated (It used to be a small dog kennel for my mom's dogs. Hell, I can close the window and door and heat the room up in about 5 minutes with just a heat gun).

Now onto my problem...
While working there during the colder times of the year, I prefer keeping the door closed and maybe the window open just a crack for a little ventilation.
This isn't going to work so well when I need to etch though.

So I came up with this idea that probably won't work all that great, as is, but its at least a start.
Now I'm sure most of you have some sort of hood and ventilation system over your cooking stove.
Based on that design, I drew this up as a rough idea to try to come up with some sort of inspiration/solution to get adequate ventilation via some kind of vacuum when I am etching:



I want to build this with the stuff I that I already have available here.
As for the hood part and the conduit, I have loads of scrap plywood, particle board, cardboard and probably some other stuff.
I was going to give the inside surfaces a coating with some rubberized or paint infused with plastic (Or whatever the equivalent of something like that would be).

I have the fans in there to try to create a vacuum at the hood.
Although I don't think they will be enough to generate an adequate vacuum.
I have 13 fans (12 and 24 Vdc), (and probably more somewhere) with CFM rating of 14 up to 105 (14, 16, 27, 27, 33. 38.6. 46. 93, 105, according to the datasheets at least), with an average of 48.2 CFM.

Now I could just stick the strongest fan right inside the conduit, but experience tells me that that fan would not last long...
(After etching one night a few years ago, I screwed up and left the etching tub open and the next morning, my nice and shiny drill press looked like this after only 10 - 12 hours of exposure):


Now I'm pretty sure that this isn't going to create enough of a vacuum at the hood to be of much use so I am looking for suggestions to make this work.
Or a better idea to vent the etchant fume to the outside.

BTW, I live in a rural area ( https://www.google.com/maps/place/Stagecoach,+NV+89429/@39.3738036,-119.3740567,2372m/data=!3m2!1e3!4b1!4m2!3m1!1s0x8098fdb286736f79:0x77b8d2ed31e13902 ) so annoying nearby neighbors with fumes isn't an issue because there are no nearby neighbors (But hey, I can crank my amp at 3am there is no one close enough to complain   ).


So yeah improvements on this design or even a whole new design that I can hopefully build with the crap I have laying around.



Thanks.

[thelonious]

Something like that might work, but probably the straight pipe won't do. You would need a shape that would create a venturi effect when air blew across it. It might take a powerful fan, though. Another thought- some vent hoods use a water curtain, falling water or whatever, to neutralize the vapors. But then you have to deal with disposing of the drainage. And in NV, I'm guessing water is not cheap!

Edit:
I wonder if there could be a simplified, homebrew version of this (PDF)?

[Quackzed]

why not just one fan stuck into the end of the 'outside' part of the pipe blowing 'outside' and sucking air in from 'inside'?

[thelonious]

why not just one fan stuck into the end of the 'outside' part of the pipe blowing 'outside' and sucking air in from 'inside'?

I think he's worried about corrosion of the fan from the vapor passing straight through it.

[PRR]

> worried about corrosion of the fan

But he's got _Thirteen_ fans!!

Rot one, swap another, repeat. Unless you get to mass production, it could be a long time to rot 13 fans.

I don't think the venturi effect will be strong without complex duct shapes and fans to work against more pressure head than PC fans are.

I think with a hood, one 20-100CFM will clear fumes.

I do wonder about "fumes". With Ferric Cloride, I didn't snort the stuff, but I was never too worried. Would be good to use a lid when not etching.

> there are no nearby neighbors

Dunno, looks crowded to me.

Population Density
Your place: 220/sq mi
My place: 81.5/sq mi

The water in my town is bigger than your whole town (which has no water).

[CodeMonk]

> worried about corrosion of the fan

But he's got _Thirteen_ fans!!

Rot one, swap another, repeat. Unless you get to mass production, it could be a long time to rot 13 fans.

I don't think the venturi effect will be strong without complex duct shapes and fans to work against more pressure head than PC fans are.

I think with a hood, one 20-100CFM will clear fumes.

I do wonder about "fumes". With Ferric Cloride, I didn't snort the stuff, but I was never too worried. Would be good to use a lid when not etching.

> there are no nearby neighbors

Dunno, looks crowded to me.

Population Density
Your place: 220/sq mi
My place: 81.5/sq mi

The water in my town is bigger than your whole town (which has no water).

Fan sizes range from around 3 inches to about 8 inches.



All are 12 or 24 VDC except the one at the lower right, which is 115 and feels like in the neighborhood of 30CFM
I probably have more fans around here somewhere.
I do have a 20 inch box fan that has a VERY high CFM, bit it started squeaking pretty badly the other day.

There are density variations around here.
I live in one the the lower density areas.
From 1 foot to 10,000 feet either East or West of that marker and from 1 foot to 10,000 feet either north or south of the marker.
But you can see my house in that picture.

Something like that might work, but probably the straight pipe won't do. You would need a shape that would create a venturi effect when air blew across it. It might take a powerful fan, though. Another thought- some vent hoods use a water curtain, falling water or whatever, to neutralize the vapors. But then you have to deal with disposing of the drainage. And in NV, I'm guessing water is not cheap!

Edit:
I wonder if there could be a simplified, homebrew version of this (PDF)?

We get all of our water from our well.

why not just one fan stuck into the end of the 'outside' part of the pipe blowing 'outside' and sucking air in from 'inside'?

I think he's worried about corrosion of the fan from the vapor passing straight through it.

Yes I am.

Now I'm trying here to not sound like I'm irresponsible when It comes to the environment (I got a little tree hugger in me), but my main
concern is removing the fumes from my workshop.




BTW...Off Topic...
Zoom in really close on that marker.
See the house just the the left of the marker?
That house was built in like 3 days.
It was built on that TV show "Extreme Makeover: Home Edition"
They had all kinds of problems with that house.
And the family that lived there eventually got screwed over since the value of the new house/property went way up
and the family could not afford the new tax bills.

[Arcane Analog]

Purchase a high CFM bathroom ceiling fan. Place it over top of the tank mounted in a "hood" setup as yo have shown and have the dryer vent hose terminate at a piece of plywood and/or rigid foam that has been cut to fit snugly into a slightly open window. You can hard wire the fan into a plug or use a standard switch to turn it off and on. Plenty powerfull to extract the fumes and no need to run a hose or venting outside. This works great mounted horizontally to vent solder fumes too.

[KazooMan]

The bathroom ceiling fan concept works great.  I have posted pics of my soldering fume hood, and I will post another here.  I was having really bad problems with lung inflammation and was actually prescribed a steroid inhaler.  I finally realized the problem was worse after spending some time soldering.  Flux fumes are nasty.  I made the exhaust hood and the lung problem went away.  No more prescription meds.  

What you really need is a good volume of air flowing, more than a good head of vacuum.  Designing some sort of containment to keep the fumes in the air stream will help a lot.  If the corrosive fumes are too hard on the fan, you might be able to design a system that encloses the etching tank and pushes the air past it and out the exhaust, thus sparing the fan.

One final word of caution (on a humorous note), my fan exhausts through a 2 1/2" flexible plastic pipe and out through a plywood fitting I made to replace the pane of glass in the basement window.  One day I turned the fan on and there was a loud grinding sound.  I opened it up and found a ton of seeds from my bird feeders.  I discovered that an industrious chipmunk had decided that the nice warm pipe was a great place for a winter home.  There is now a hardware cloth grille over the exhaust.

Here's the pic.

[PRR]

> (on a humorous note)... an industrious chipmunk had decided that the nice warm pipe was a great place for a winter home.

Not funny. At the last house we had Radon fans clearing the Radon from the basement. Quite large fans. One day I noticed a fan had stopped. Wires looked fine.

I got the fan out and gagged from the smell. There was a squirrel-tail visible and a lot more "stuff" inside the fan housing.

A new fan was $180, but I could not bear trying to clear the mess. Double-bagged it and put it out to trash. The replacement fan got a screen.

I was thinking of this on my new furnace. "Smoke pipe" is 2" PVC through the side wall. And my squirrels here are small (the size of chipmunks, but not shy). As soon as I poked that pipe out I had the image of chop-meat inside my furnace.

Between condensation and cold, I figured a flat screen might ice-up.

Found "bird feeders" which were wire-mesh with end-caps. Took off one end and jammed them over the pipes. The screen area is 6X the pipe area so it can ice a lot without problem.

[Arcane Analog]

I simply use a dryer exhaust vent. The flaps open when the fan is turned on and close automatically when it is shut off. When the extractor is not in use I simply remove it from the window and close the window. Using rigid insulation means it is rather air tight around the otherwise open window. In the winter, air is forced out but the cold stays out.

One final word of caution (on a humorous note), my fan exhausts through a 2 1/2" flexible plastic pipe and out through a plywood fitting I made to replace the pane of glass in the basement window.  One day I turned the fan on and there was a loud grinding sound.  I opened it up and found a ton of seeds from my bird feeders.  I discovered that an industrious chipmunk had decided that the nice warm pipe was a great place for a winter home.  There is now a hardware cloth grille over the exhaust.