darkroom ventilation

[CPorter]

I've searched a while in the archives, but not finding a scenario that seems to fit my situation. It seems right now that my only choice for placement of the ventilation is to install some type of fan with light where the current light is located (center of the 8 ft.ceiling in a 10 ft. x 10 ft. room; 800 cu ft), intake will be a light tight louver in the door. As I see it, this places me in the direct path of the fumes as they move from the wet side of the room toward the center ceiling and I know that is not ideal. I've read that it is most efficient to provide ventilation from the sink near tray level, don't think that is possible in this situation, unless someone has an idea that I'm not aware of at the moment. The only other option it seems, is to try and move the installation of the light/fan from the center ceiling to the ceiling directly above the sink area. Doesn't look like there is a real question in here, but more or less just my preliminary thoughts on the subject; any of your thoughts would be appreciated.

[Bob-D659]

Don't forget the optimum placement of ventilation is just that, optimum. How long do you plan to be in there with your head over the trays. 1,2,5,10 hours per day? If you or a paid employee is in there for 8 hours a day, 5 or 6 days a week, it would be worth your while to move the fan. Way less exposure time probably means you can have your exhaust point in a less than optimum place. If it's easy to move it, do it, but you could always run some duct work across the ceiling and down the wall.

Also I'd be tempted to just install a fan, not a combo unit. Someone is going to turn that white light on at the absolute wrong time.

[Robert Hall]

Any ventilation is better than none. I have an 800 sq ft darkroom and have 2 600 cfm fans place opposite the fresh air entry. It works quite well but I had to have 2 8" holes cut in the cement wall for the vents. Well worth it. I tell anyone who wants to have a darkroom that you have to have at least ventilation and a drain. Everything else is optional.

[Trond]

Do you have some photos of the room?

Trond

[Vaughn]

Leave the light where it is and drop some new ventilation straight down to the back of the sink.

I will disagree with Robert's "Any ventilation is better than none." But not in its spirit, only in that I can imagine there are situations that the system is as bad as no ventilation, so I am picking nits. I have worked in the same darkroom since 1978, the last twenty years actually getting paid (university darkroom). Over that time I have seen the ventilation go from poor to a little bit better than poor, then to fairly reasonable. Nineteen enlarger stations, two sets of 11x14 trays. It can be big and roomy, or when all stations are in use, it can be small and cramped. About 75 hours of open lab a week -- so students should be able to plan and find time to work...but on the eve of critiques, the darkroom gets busy and the ventilation seem to be able to keep up.

The fellow that had my position before me conducted a health survey of the darkroom users in a successful effort to show that the poor ventilation was causing headaches. The old system had the exhaust vent in the ceiling drawing the intake air straight to it -- above everyone's heads and by-passing the chemicals. There was a steady exchange of air happening, but it was all happening up by the ceiling: not where the students' heads were at -- which was in the middle of the fixer fumes!

Ventilation systems that draw the air from over the trays then past one's head on the way to the exhaust are possibly worse than no ventilation. One might as well stick one's nose in the tray and breathe it in! Feeling the chemically laden air passing one's face does create a pleasant false sense of security that one is protecting oneself! BTDT. Fortunately in those early years of all-night printing sessions it never really bothered me, though my girlfriends knew where I had been all night from the smell of the fixer.

After 30+ years I can not smell fixer in the air. My nose is numb to it. And I seem to be more sensitive to chemicals in general, though I do not do much silver gelatin printing, mostly alt. I have acquired asthma, most likely from blow-drying the platinum/palladium salts on watercolor paper; kicking some of the pt and pd salts into the air. Not a common thing, but so it goes. Belately it has shown me that I should have taken better care and should take better care in handling chemicals and paying attention to ventilation.

That said, I admit I sort of like the smell of acetone in the mornings...

Vaughn

[Rick A]

Buy a cheap range hood and mount it above the sink. You can duct it anywhere from there. The upshot, exhausting fumes where you need, extra light above the sink, plus the benefit of not having to rip out the light in the center of the room.

[bdial]

You could consider an in-line ducted fan. The intake can be placed wherever you need it, and the fan can be located near it's power source.

[Ulrich Drolshagen]

You may be interested in looking here. It's my solution. You will find a source for components too.

Ulrich

[CPorter]

You could consider an in-line ducted fan. The intake can be placed wherever you need it, and the fan can be located near it's power source.

Thanks for the suggestions so far----

bdial,
could you expound on this idea a bit, it may seem obvious, but it's not just yet. Pictures?

BTW, what CFM removal rate would be recommended for this room----I haven't seen a bathroom type fan yet that is over 140 and the Doran / Delta models rated for 12' x 12' room say 400/800 cfm; also, it says it comes with a 3 prong plug, doesn't it come with capability to be wired into an existing junction box?

[DREW WILEY]

Vaughn - don't tell me that "medicinal" palladium salts have been added to your local narco economy
up there! But seriously, any exhaust fan should have about double the pull of the mere CFM recommendation for area. For one thing, you have to move air through some sort of light-tight
ducting maneuver. For another, you have to be able to buck any hydrostatic pressure from air outside. The ideal solution is an inline or exterior fan with variable speed control. Air is much easier
to pull than to push, and it's a lot quieter this way too.