Planning my darkroom ventilation system

For your sink area, have you considered kitchen stove hoods? They might come with exhaust fans, charcoal filters, etc. If you could find them second hand or surplus, they might be affordable.

Does the outside wall have a window? For periodic cleaning and freshening the air, I would consider at least one which can open to the outside. If it can double as an emergency exit, so much the better.

Mike

 

I have a simple bathroom ventilator connected to a ventilation shaft. It does a pretty reasonable job, even though it's located a meter or so above the trays on the wall. Still manages to supply enough fresh air, in combination with a door with secured, light safe, air inlet.

 

I like the system of the PCV pipe behind the sink -- but perhaps with hort. slots cut cut in them instead of holes? Can you cut a vent hole in the outside wall, or perhaps go straight up thru the ceiling?

Another thought I had was a fan and PVC pipe for each sink (but could have a common exhaust pipe)...or the ability to close the vent/pipe behind one of the sinks. That way you could concentrate the pull over the sink with the noxious fumes.

Vaughn

 

Pressurize your darkroom. Instead of sucking the air out, blow filtered air into the space from the intake vent and have it exhaust naturally out the exhaust vent. The positive pressure will keep out dust.

 

I have my wet area (someday a full sink, for now a slop sink and a table) along one wall with 3 rectangular vents spaced along the wet area, about 18 inches(45cm) above the table/sink surface. these vents are ducted to a fan in the attic, then to the outside. My thought was to keep the fumes away from my nose, and it seems to work well.

 

Any reason (plumbing, etc.,) why the sinks couldn't be along the outside wall? That would cut down on the amount of ductwork. Have the ventilation drawing from tray level in the sinks with the intake high on the opposite wall. This helps keep you from breathing any fumes. A kitchen fume hood overhead will likely draw the fumes up towards your face and you don't want that.

Personally, I'd keep the NuArc out of the darkroom. While it is running you won't be able to coat or dry alternative process prints or do any silverprinting if the exposure unit is in the same room. Loading the NuArc under incandescent lamps in another room won't present any problems with alt prints. So unless your plan is to expose Lodima or other factory silver print materials I'd put the NuArc elsewhere.

 

Filter the air coming in through a high quality furnace filter or you will have lovely little white spots on your prints.

I like Panasonic whisper fans. The only noise I hear is air in the pipes. They have worked well for four years now.

John Powers

 

http://www.eepjon.com/Drvent.htm

 

I used a 36 inch SS unit from Braun. I had it left over after a kitchen upgrade so it was an easy choice for me as it was surplus, but the truth is it has worked out great,it has built in lighting that I can just reach up and turn on for print inspection. it runs quite and moves plenty of air to keep fumes down.
The thing I missed in my design (I am presently correcting) was air intake, the fan would try to pullair but the light sealed door in the room would not let in makeup air. I plan to add ducting to let n fresh air and a furnace filter to keep down dust.

 

They are simple to make out of wood with even the most modest of carpentry skills.

Budget a $150 or so for a 500-1000 CFM fan. These can be bought cheaply from indoor garden supply stores with the appropriate adapters.

 

I use an exterior kitchen vent fan, ducted to a plenum over my sink. I think this would be very similar to the PVC pipe you suggest.

I would punch a hole through the wall above the film dryer, mount the exhaust fan outside (which would be much quieter), and duct this to your PVC.

Just for reference, my exhaust fan can pull about 600 cfm, and I have it on a rheostat to further cut down noise.

 

Also take a look at the sink drain, 1 ½” pvc pipe, that runs 36 feet to the sump from the bottom of a waist high sink. The liquids flow like a torrent. You may be able to have your sinks anywhere you want them.

John

 

I would be concerned that the pvc pipe might not have enough volume for airflow (it will be relatively low pressure) - unless it's fairly large diameter (6-8 inches). I would consider rectangular aluminum duct (3.25x12 or 14) with 4" round vents cut in every 2 feet over the sink. All "off the shelf" stuff. Then, you could transition to 6" round duct and an inline fan (placed in the darkroom or outside).

 

Skip the fluorescent lights as they keep glowing for a while after you turn them off. The darkroom is one room where I'll gladly waste a bit of electricity so I don't waste my film or paper.

 

A couple of random thoughts:

Anything but fluorescents. LEDs are low electrical usage if carbon footprint is your concern.

There are PVC landscape drainage pipes made with thin walls that can be purchased in largish sizes without busting the budget so you can get quite a few CFM venting your space. Pressurizing the darkroom is better than sucking air out - you will push dust out - rather than sucking it in. Filter your air source.

 

Having watched and heard the Bickersons set up a tent across the pond from our house, I want to sell tickets to watch & listen to you two patient people wait five minutes every time you turn on that light.

John

 

I have used 4" PVC pipe quite happily the last four years connecting to two Panasonic whisper fans that sit in the rafters. The 4" pvc come down from the rafters and pick up at the side of the trays away from me.

As mentioned earlier if you have "vents cut in every 2 feet over the sink." the fumes are drawn up past your nose. That is what you are trying to avoid. If you have them across the sink from you the fumes are drawn out of the trays away from you and out.

It also helps to have the input air coming from behind you so that the flow goes from behind you, around you, across the trays and out.

John

 

May I read this to her when you guys visit the 21st?

John