Page 2 of 3 FirstFirst 123 LastLast
Results 11 to 20 of 30

Thread: Darkroom Ventilation advice, please

  1. #11
    wclark5179's Avatar
    Join Date
    Oct 2009
    Location
    Minnetonka, Minnesota
    Posts
    137

    Re: Darkroom Ventilation advice, please

    How long of a duration do you intend to spend in your darkroom?

    In high school and college I don’t recall ventilation being used.

    I would be more concerned about dust with ventilation you describe.

    My wife insisted our basement bathroom, we had it finished in 2017, be made large enough to support my darkroom activities. It does have a fan but I very rarely use it. So far I have no dust issues.

  2. #12

    Join Date
    Aug 2000
    Location
    California
    Posts
    3,908

    Re: Darkroom Ventilation advice, please

    M darkroom has positive ventilation with the intake near the sink,and the outlet at the other end of the sink. Not an ideal placement of vents, but they have worked well for over 30 years. I Have forgotten the brand of the fan, but it is a squirrel cage.

  3. #13

    Join Date
    Jul 2016
    Posts
    4,566

    Re: Darkroom Ventilation advice, please

    Quote Originally Posted by wclark5179 View Post
    basement bathroom ... my darkroom activities. It does have a fan but I very rarely use it. So far I have no dust issues.
    Many bathrooms do nothing if door is closed, if there is no additional air intake then extraction can do nothing


    Quote Originally Posted by wclark5179 View Post
    So far I have no dust issues.
    Also no dust issues if you place filter in the air intake, a bare foam is very good, an HEPA class filter is perfect.

  4. #14
    William Whitaker's Avatar
    Join Date
    May 2002
    Location
    NE Tennessee
    Posts
    1,423

    Re: Darkroom Ventilation advice, please

    David,

    There's not really any correct or incorrect way to do it as long as the air is exchanged in a manner and timeliness that suits the demands made on the room.

    Personally, I have my doubts about the ability of a 400CFM-rated Doran unit to adequately exchange the air in a 1200 cubic foot space. That would suggest an exchange rate of once every three minutes, assuming an 8' ceiling and if everything is working correctly. That may be enough, but for me, I'd rather have a little extra performance built in.

    For the system I installed 20 years ago I built the ventilation around a surplus furnace fan that I mounted outside of the darkroom space. It pushed filtered air into that darkroom space which exited on the other side of the sink. I worked to keep flow paths as straight and smooth as possible to try to keep flow laminar and avoid turbulence as much as possible. The air entered the room behind a cabinet. Part of the laminar flow idea was to provide a clean workspace for loading film holders. Air crossed the room and over the sink to some ductwork which then directed it to the exhaust built into an outside window. The ductwork toward the window was painted flat black inside and a couple of 90º bends all but insured that no daylight could get in. Finally an exhaust vent with a spring-loaded flap kept dust, dirt, small animals, etc. outside where they belonged.

    That system was great. It ran like it had a Hemi in it (which it almost did). I knew when I bought it that the fan would too powerful for the application. And sure enough it was. So I exchanged the driven pulley for one of slightly larger diameter to reduce the fan speed somewhat. It helped, but the fan was still a serious contender for a wind tunnel (which was what I did not want!). Upon turning on the fan, doors would slam shut due to the sudden air flow. And that certainly seems like overkill. But I must add that the exhaust was [necessarily] on the side of the house that was upwind to the prevailing winds in the area and they could be very strong.

    Once the doors to the darkroom were shut (and myself lashed to the ship's wheel) the airflow settled into a well-behaved system. There was a constant exchange of air which felt refreshing on most days. Fumes and dust never seemed a problem.

    I don't think a mass-produced, factory-built fan unit would have done what I needed. And my space was similar in size to yours. Of course, I did have the prevailing winds to deal with. But I was very satisfied with that installation and would do the same thing again if I had the opportunity.

    BTW, the fan was mounted in a coat closet outside of the darkroom (formerly a bedroom) and bolted to the concrete slab floor. The closet door was replaced with a full-size board into which was mounted a 16x20" filter frame. The filter installed therein is what filtered all the air going into the darkroom. After the fan, the air entered the darkroom through a 12x12" duct cut in the wall, thence distributed into the darkroom. That helped, I'm sure, to keep noise to a very tolerable level.

    It was a fun project and it worked very well. I still have recollections of going into the darkroom for an evening's work, Turning on the system and being able to feel right away the change in the atmosphere as the cool evening air pervaded my workspace.

    I'm sure not being married helped.

  5. #15
    Tin Can's Avatar
    Join Date
    Dec 2011
    Posts
    22,387

    Re: Darkroom Ventilation advice, please

    LOL

    Twice


    Quote Originally Posted by William Whitaker View Post
    I'm sure not being married helped.
    Tin Can

  6. #16

    Join Date
    Jul 2013
    Posts
    80

    Re: Darkroom Ventilation advice, please

    Quote Originally Posted by William Whitaker View Post
    David,

    There's not really any correct or incorrect way to do it as long as the air is exchanged in a manner and timeliness that suits the demands made on the room.

    Personally, I have my doubts about the ability of a 400CFM-rated Doran unit to adequately exchange the air in a 1200 cubic foot space. That would suggest an exchange rate of once every three minutes, assuming an 8' ceiling and if everything is working correctly. That may be enough, but for me, I'd rather have a little extra performance built in.

    For the system I installed 20 years ago I built the ventilation around a surplus furnace fan that I mounted outside of the darkroom space. It pushed filtered air into that darkroom space which exited on the other side of the sink. I worked to keep flow paths as straight and smooth as possible to try to keep flow laminar and avoid turbulence as much as possible. The air entered the room behind a cabinet. Part of the laminar flow idea was to provide a clean workspace for loading film holders. Air crossed the room and over the sink to some ductwork which then directed it to the exhaust built into an outside window. The ductwork toward the window was painted flat black inside and a couple of 90º bends all but insured that no daylight could get in. Finally an exhaust vent with a spring-loaded flap kept dust, dirt, small animals, etc. outside where they belonged.

    That system was great. It ran like it had a Hemi in it (which it almost did). I knew when I bought it that the fan would too powerful for the application. And sure enough it was. So I exchanged the driven pulley for one of slightly larger diameter to reduce the fan speed somewhat. It helped, but the fan was still a serious contender for a wind tunnel (which was what I did not want!). Upon turning on the fan, doors would slam shut due to the sudden air flow. And that certainly seems like overkill. But I must add that the exhaust was [necessarily] on the side of the house that was upwind to the prevailing winds in the area and they could be very strong.

    Once the doors to the darkroom were shut (and myself lashed to the ship's wheel) the airflow settled into a well-behaved system. There was a constant exchange of air which felt refreshing on most days. Fumes and dust never seemed a problem.

    I don't think a mass-produced, factory-built fan unit would have done what I needed. And my space was similar in size to yours. Of course, I did have the prevailing winds to deal with. But I was very satisfied with that installation and would do the same thing again if I had the opportunity.

    BTW, the fan was mounted in a coat closet outside of the darkroom (formerly a bedroom) and bolted to the concrete slab floor. The closet door was replaced with a full-size board into which was mounted a 16x20" filter frame. The filter installed therein is what filtered all the air going into the darkroom. After the fan, the air entered the darkroom through a 12x12" duct cut in the wall, thence distributed into the darkroom. That helped, I'm sure, to keep noise to a very tolerable level.

    It was a fun project and it worked very well. I still have recollections of going into the darkroom for an evening's work, Turning on the system and being able to feel right away the change in the atmosphere as the cool evening air pervaded my workspace.

    I'm sure not being married helped.


    In accordance with ASHRAE, the darkrooms required 20-30 cfm of fresh air per person. To have 1 air change per 3 min. giving you 20 air changes per hr. This is craaazy big number and really overdesign. For example the typical hospital patient room for people with EBOLA and other dangerous diseases by the code required only 12, max. 15 air changes per hr. Not many chemical labs having 20 air changes per hr. requirements. And in the labs usually in order to limit amount of exhaust air, special hooded cabinets used and exhaust working only when the cabinet door open and dangerous vapor may enter the room space. The darkroom with 20 air changes /hr. exhaust and direct fresh air intake from outside, without dedicated air conditioning unit specifically provided for that particular room will be hot in summer and cold in winter. Drafting air from the rest of the house also not perfect idea, because the regular home air conditioning system don't have any fresh air intake at all. Standard home air conditioning system designed just to circulate the same air and heating or cooling it. It assumed that in the house fresh air can get through the doors or windows. Removing air from the house will required to kip some window open, and house unit will work more often then usually, and because the fan of the unit designed to circulate the air through the entire house the electrical bill will show some additional charges. If you not trying to design in your house a hospital operating room where you will be printing photographs don't do 20 air changes per hr. exhaust. In order to kip you room clean from the not so dangerous vapors just build a hood above the sink, size the hood opening same as the area of the sink, run the duct from the hood to outside and provide the exhaust fan. If you figure the capacity of the fan as 1.2 to 1.5 or maximum 2 cfm per square ft. of the area of you sink, the room will be free of any chemical contaminations even if you will work there 24/7 without coffee brakes.

  7. #17

    Join Date
    Jun 2011
    Location
    romania/germany
    Posts
    67

    Re: Darkroom Ventilation advice, please

    those are good tips by R.K.
    about dust entering darkroom, think about automotive square filters. they do a great job.
    in any case dont blow air into darkroom, suck it out.
    radial fans do a great job, you can hook them up to pvc pipes with multiple intakes above the wet/chemical area if you have no room for a proper hood. check my post in post-your-darkroom area of forum. i can send additional pics if you need.
    my fan exchanges air volume 10x hour, never smells like chemicals in the room.
    cheers & good luck

  8. #18
    Angus Parker angusparker's Avatar
    Join Date
    Nov 2012
    Location
    San Francisco, USA
    Posts
    936

    Re: Darkroom Ventilation advice, please

    The key as far as I have found is to have the air come in over your head height (preferably across from your trays) and go out at waist height behind your trays. That way you are never breathing fumes because the travel of air direction is downwards away from your nose. This guy makes plastic upside down V shaped vents to uptake the air from just above your trays. http://www.eepjon.com/Drvent.htm Scroll down to see the pictures and read the advice. I have two of them and found they work very well. I filter the air intake and push the air in, then I suck it out and send it to the roof line. That's a bit over the top but I'm in an urban setting and don't want to piss off the neighbours with smells, or send Pt from historical processes anywhere near people (even if its a tiny amount). So abundance of caution.

  9. #19

    Join Date
    Jul 2016
    Posts
    4,566

    Re: Darkroom Ventilation advice, please

    Quote Originally Posted by angusparker View Post
    go out at waist height behind your trays. That way you are never breathing fumes // http://www.eepjon.com/Drvent.htm
    True, this is perfection...

    Click image for larger version. 

Name:	lowprofl.jpg 
Views:	43 
Size:	21.3 KB 
ID:	194433

  10. #20

    Join Date
    Jan 2013
    Location
    Madisonville, LA
    Posts
    2,412

    Re: Darkroom Ventilation advice, please

    It’s not rocket science. Put an exhaust fan over the sink and put a filtered intake grill behind you on the opposite wall. That’s it!! Or you can loose sleep over the details.

Similar Threads

  1. Ventilation Arm
    By Henry Yorke in forum Darkroom: Equipment
    Replies: 7
    Last Post: 30-Jan-2015, 17:30
  2. RED LED for safe lighing in drakroom
    By smithdoor in forum Darkroom: Film, Processing & Printing
    Replies: 22
    Last Post: 4-Oct-2013, 07:20
  3. Ventilation
    By Allen in Montreal in forum Darkroom: Equipment
    Replies: 19
    Last Post: 25-Jul-2013, 09:54
  4. Bad ventilation in darkroom
    By Yaakov Asher Sinclair in forum Darkroom: Film, Processing & Printing
    Replies: 24
    Last Post: 25-Jun-2002, 10:19
  5. darkroom ventilation
    By Raven Garrow in forum Darkroom: Film, Processing & Printing
    Replies: 9
    Last Post: 23-Jul-2000, 21:43

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •