darkroom ventilation

[Chuck_P]

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 (there was a url link here which no longer exists). It's my solution. You will find a source for components too.

Ulrich

 

[Chuck_P]

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.

 

[sepiareverb]

The drawback to many fans is their sound volume. My last fan worked very well, but was so loud I didn't use it all the time. I've lost a good bit of hearing over the years, and the fans in my darkrooms are likely partly to blame. My current set-up has the fans outside the darkroom and the vents are ducted to the unit. It could likely be stronger, but I don't hear it at all. The upside is I have it on all the time now rather than only when the fumes got to the point that I noticed them. After 30 years in the darkroom I, like Vaughn, don;t notice the fumes much at all- I really don't smell anything but sulfides anymore.

 

[Trond]

I also use a duct fan installed outside the darkroom, and use a duct to suck air from just above the sink. The fan is connected to a variable speed controller. I set it quite high when developing with open trays, and low when developing films etc. Seems to work OK and the noise level is low.

I bought a kit with fan and flexible ducts, I'm sure you can find something similar where you live:
http://www.clasohlson.no/Product/Product.aspx?id=160743266

Trond

 

[grahamp]

Ceiling mounted extraction will also pull heat out of the room. This may be an issue depending on the local conditions. My extract is in the ceiling, but it is offset towards the wet bench so my head is not in the direct line when processing. I have about 72 square feet, around 500 cubic feet. If the room had allowed it I would have gone for a wall mount.

Graham

 

[cgross]

I've used these fans in various home remodels and they really work well. They are very quiet. I've always thought of using them for the darkroom. Maybe it will give you an idea for yours. They have various types of ventilation products.

http://residential.fantech.net/residential-products/inline-duct-fans/inline-exhaust-fans/#FR Series

 

[john_s]

If venting is less than optimum you could consider low odour stop and fixer. Not a complete solution but it helps a lot.

 

[Maris]

I've built two darkrooms with ventilation based on filtered inward blowers rather than extractor fans. The blower fan is mounted anywhere in a back darkroom wall or (inward opening) door and the air outlet is a passive vent in the wall at the far side of the sink. Advantages include:

The fan and its noise are at the back of the room away from your ears.
The darkroom is positively pressurised so dust and fumes leak out rather than being sucked in. The darkroom door is being pushed shut by air pressure and seals better.
Air movement is away from your face, across the trays, and out the vent; no fixer smell.

 

[Vaughn]

I can see where that would work very well, Maris. One would have to be careful that no odors are leaked into any adjacent living areas. With a constant positive pressure, air will try to sneak out anyway it can. The uni darkroom has its own ventilation system from the rest of the building, but since we had a positive pressure situation within the darkroom, fixer fumes were being pushed out into the rest of the building. And you can image what the clerks and professors down the hall think when someone sepia tones! The speed of the intake fans was dialed down a little and it has helped. The exhaust fans were kept the same.

Vaughn

 

[Trond]

I considered a positive pressure ventilation system for my own darkroom, and this is the main reason I decided against it. It would have been very difficult to make the room completely airtight, and the bedrooms are just above the darkroom.

Trond

 

[Chuck_P]

The positive pressure route is not an option for me----the best I think I can do is to install ceiling ventilation above the sink, at least any fumes will tend to be drawn straight up rather than toward my face enroute to the center of the ceiling. Next question is what fan to actually get and what CFM rating it should have, I guess at least 800.

 

[Jon King]

I'm not sure how extensive the remodeling will be, but I put an inline exhaust fan, as Barry suggested, in the attic and put ducts down to the wall along the trays - the fumes get pulled right off the trays and never near my face. I put my ducts in the wall, but they could be on the outside if you aren't modifying the wall.

 

[Chuck_P]

I'm not sure how extensive the remodeling will be, but I put an inline exhaust fan, as Barry suggested, in the attic and put ducts down to the wall along the trays - the fumes get pulled right off the trays and never near my face. I put my ducts in the wall, but they could be on the outside if you aren't modifying the wall.

can you post a picture?

 

[Ulrich Drolshagen]

can you post a picture?

May I help with this one?

 

[Jim Noel]

Two possible solutions.
1. if you have a window, make a plywood cover for the window and put the fan init blowing out.
2. Reverse the direction of the fan and make it blow into the darkroom. This will cause the fumes to blow away from you and out all the unseen cracks in the doors, walls, etc. Clean rooms have always used this type of positive ventilation.
I have used such a system in my 10x10 darkroom for more than 25 years.
3. A third solution which may help is to attach a length of dryer hose to the fan and place the intake near the sink. For this you willlikely need a squirrel cage fan.

 

[Chuck_P]

Two possible solutions.
1. if you have a window, make a plywood cover for the window and put the fan init blowing out.
2. Reverse the direction of the fan and make it blow into the darkroom. This will cause the fumes to blow away from you and out all the unseen cracks in the doors, walls, etc. Clean rooms have always used this type of positive ventilation.
I have used such a system in my 10x10 darkroom for more than 25 years.
3. A third solution which may help is to attach a length of dryer hose to the fan and place the intake near the sink. For this you willlikely need a squirrel cage fan.

I appreciate all the suggestions, the third option that you state here is going to be the most practical for me-----squirrel cage fan?

I googled it, I see what you mean-------can they be wired from a switch or do they just come with a power cord to be plugged into an outlet?

 

[macrorie]

I'm using a bathroom conversion right now with limited possibilities for customizing ventilation, but I once was able to build a darkroom on a first floor that allowed putting an exhaust vent near the floor under the wet bench and sink, so the fumes were pulled off the trays and downward, then exited through an easily strung clothes dryer vent hose in the basement. The fan was in the basement, so noise was not a problem, and I had a filtered, light-proof vent for the make-up air. It worked very well in terms of controlling fumes and dust.