Page 3 of 4 FirstFirst 1234 LastLast
Results 21 to 30 of 33

Thread: Darkroom Venting

  1. #21

    Join Date
    Feb 2021
    Posts
    1

    Re: Darkroom Venting

    Quote Originally Posted by Drew Wiley View Post
    Bingo. Thanks. Nothing remotely related to true 250 extraction, but evidently useful for simpler applications. I had something similar exchanging air in a makeshift film drying cabinet, with nothing other than basic "permanent" coffee filters glued over the intake and outlet ports to prevent dust.

    Not sure what your "Bingo" point is. I was just mentioning a cheaper source of efficient fans for do-it-yourselfers.

  2. #22
    Drew Wiley
    Join Date
    Sep 2008
    Location
    SF Bay area, CA
    Posts
    18,318

    Re: Darkroom Venting

    Efficient? Not by any HVAC standard by which things are conventionally classified. Useful perhaps under limited conditions, yes, as you have demonstrated, but not realistic under most darkroom circumstances, which necessarily factor ducting, long-term durability, and sometimes, formal building code inspections. Hardly suitable for color darkroom either, where fumes can be distinctly unhealthy. Then there's the hydrostatic weather and humidity issue I noted earlier.

    But I do understand the need of affordable options. My first "darkroom" setup consisted of the enlarger in a bedroom with a blocked out window, and a drum processor in a small adjacent bathroom with the window wide open and an ordinary stand fan next to it. The color drums were light tight and loaded in the bedroom. All the chemistry was done in the bathroom. But even that was better than where I learned to do sheet film development for sake of masking in a filthy furnace closet, which had the necessary legal floor air vent.

  3. #23
    Old School Wayne
    Join Date
    Dec 1999
    Posts
    1,255

    Re: Darkroom Venting

    They may not be for everyone but they are plenty efficient in cost, airflow and power use, and they work just fine for color. They can be a bit noisy, but I like white noise.

  4. #24
    Drew Wiley
    Join Date
    Sep 2008
    Location
    SF Bay area, CA
    Posts
    18,318

    Re: Darkroom Venting

    I have R23 insulation in the sink and film rooms, which makes my darkroom itself the quietest place to be on weekends. I have neighbors over the back fence whose whole point for existence seems to be to get roaring drunk on cheap beer on game days, shout as loud as they can, mostly obscenities, and play loud "music" (also mostly obscenities). Even their cats left and adopted us instead. But now they've got a pet raccoon with a conspicuous beer belly of its own - friendly tubby feller, but probably due for coronary bypass surgery to clear all the french fry grease clogging things up. He's the only member of that group covered with fur instead of tattoos.

  5. #25
    Mike in NY's Avatar
    Join Date
    Sep 2012
    Location
    Hudson Valley, NY
    Posts
    220

    Re: Darkroom Venting

    For fresh air intake I use a light-tight vent installed in one of the darkroom's two doors. For exhaust, I use 6" duct tubing that hovers above the sink where I tend to do my fixing. The duct is positioned in a 6" diameter hole cut into a shelf above the sink. From there it goes straight up, then makes a curved 90 degree turn to the right and runs until it reaches the wall. Then it makes another 90 degree turn and runs down to an outside vent. There are three separate in-line duct fans installed within the tubing: the first one is just inside the opening above the shelf; the second fan is about half way down the first horizontal path; and the third fan is at the vent exit. They are easy to install; you just slice your tubing and fit it onto either end of the fan's housing, and run the cord to an outlet. I got my fans at Home Depot, but they are available from Amazon and other providers. They come in different sizes for 4", 6" or 8" tubing. The 6" fans I use have a speed of 2960 RPM, and a rated air flow of 240 CFM. Is it enough ventilation? I really don't know, but I know that it helps, and the fans are very quiet.

    Click image for larger version. 

Name:	Darkroom.jpg 
Views:	26 
Size:	69.6 KB 
ID:	212976

    Click image for larger version. 

Name:	Fan.jpg 
Views:	11 
Size:	77.1 KB 
ID:	212977

    Click image for larger version. 

Name:	Fan 2.jpg 
Views:	14 
Size:	75.3 KB 
ID:	212978
    Last edited by Mike in NY; 21-Feb-2021 at 10:03.
    I dream in black and white.

  6. #26

    Join Date
    Mar 2005
    Location
    Newbury, Vermont
    Posts
    2,255

    Re: Darkroom Venting

    While these duct-vent "helper" fans might not be powerful enough (for darkroom venting), especially when placed at the beginning of such a long and curvy run, I think the fact that you have three of these in succession would make this sufficiently effective.

    Does this vent to the outside through a weather-head equipped with an aluminum "anti backdraft" flap? If so, how much does this flap deflect upwards when the fans are on? (I'd worry if this deflection, when measured at the bottom of the flap, were less than about one half inch).

    And a test: place a tea-saucer on your sink bottom...maybe about a third of the distance between your faucet and the vent opening - light a match and blow it out...then quickly place it on the saucer - and watch what happens to the smoke. (alternately, use a candle) Then...try the smoke-test from the other end of the sink. If your vented darkroom door is where it should be in this picture (off to the right, furthest from the fan), then the smoke, while it may take awhile to get there...should still be pulled towards the vent.

    You might also want to try taping some very thin strips of tissue to the inside-top of your darkroom door-vent, to see that these deflect enough to give you confidence that your vent system is powerful enough to overcome enough air resistance so this system can be effective.

    A final test: after your darkroom is up and running for awhile, leave it for awhile (lunch break?), then come back and see if you are greeted with a strong waft of fixer. If so, you might need more power in your vent system.

    In any case...I'm also assuming that you arrange your trays to place the fixer closest to the vent, unless your developer happens to be particularly toxic.

  7. #27
    Mike in NY's Avatar
    Join Date
    Sep 2012
    Location
    Hudson Valley, NY
    Posts
    220

    Re: Darkroom Venting

    John, you've made some cogent points. As mentioned above, the first fan is positioned over the space where I perform my fixing. When I set this up, I tested the uptake draw with a tissue held beneath the first fan opening, and it pulled the tissue upwards. (I also lit and blew out a match, but it didn't really produce enough smoke for me to get a good sense of how powerful the intake was.) I haven't tested the strength of the intake flow at the light-tight vent in the door at the other side of the room; that's something I'll try - thanks for the suggestion. The exit vent in the wall does not have an anti-backdraft flap, as it is deeply recessed into the very thick foundation of the home, within a deep 30" x 30" by 60" window well, which is covered by hinged, iron grating (these enormous window wells are a most unusual feature, but our 94-year old home has several of them, all with operating drains in the base of them). So there is no resistance to the outflow of air from a flap, which I agree would have been an impediment.
    I dream in black and white.

  8. #28
    Old School Wayne
    Join Date
    Dec 1999
    Posts
    1,255

    Re: Darkroom Venting

    Quote Originally Posted by John Layton View Post
    While these duct-vent "helper" fans might not be powerful enough (for darkroom venting), especially when placed at the beginning of such a long and curvy run, I think the fact that you have three of these in succession would make this sufficiently effective.

    Does this vent to the outside through a weather-head equipped with an aluminum "anti backdraft" flap? If so, how much does this flap deflect upwards when the fans are on? (I'd worry if this deflection, when measured at the bottom of the flap, were less than about one half inch).

    And a test: place a tea-saucer on your sink bottom...maybe about a third of the distance between your faucet and the vent opening - light a match and blow it out...then quickly place it on the saucer - and watch what happens to the smoke. (alternately, use a candle) Then...try the smoke-test from the other end of the sink. If your vented darkroom door is where it should be in this picture (off to the right, furthest from the fan), then the smoke, while it may take awhile to get there...should still be pulled towards the vent.

    You might also want to try taping some very thin strips of tissue to the inside-top of your darkroom door-vent, to see that these deflect enough to give you confidence that your vent system is powerful enough to overcome enough air resistance so this system can be effective.

    A final test: after your darkroom is up and running for awhile, leave it for awhile (lunch break?), then come back and see if you are greeted with a strong waft of fixer. If so, you might need more power in your vent system.

    In any case...I'm also assuming that you arrange your trays to place the fixer closest to the vent, unless your developer happens to be particularly toxic.

    I was wondering how much resistance the great length of ducting and each successive fan creates. Common sense says it would work fine but common sense is often wrong. You'd almost need an aerospace engineer to figure out the actual efficiency of some darkroom vent systems

  9. #29
    Member
    Join Date
    Jun 2004
    Location
    Port Townsend, Washington
    Posts
    353

    Re: Darkroom Venting

    As a side issue when constructing your exhaust fan system, give consideration to what covers the outside end of your exhaust pipe. Some of these covers include a single round flap that may not close completely when the fan is turned off. I had one of these, and starlings started building a nest inside, which I had to clean out by hand. I replaced that cover with one with multiple louvers that fully closed, and had no more starling problems.

    That darkroom, by the way, was on the plans used by the home builder. Since new homes are more tightly sealed, the building code here requires each house to have a "whole house fan" to prevent the buildup of stale air in the home. I requested the plans for the house to specify a whole house fan for my darkroom that vented outside. The door to the darkroom included a light-tight air inlet from B&H. Once the starling issue was solved, it worked great for the years I owned that home.

    Keith

  10. #30

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

    Re: Darkroom Venting

    Whatever type of fan you use, it will be better than not having an exhaust fan. That's my take on it. If you can get the # of air changes per hour recommended in the Kodak guide, great, if not, it's better than nothing.

Similar Threads

  1. AC, Venting, ideas for a Darkroom Shed?
    By m00dawg in forum Darkroom: Equipment
    Replies: 67
    Last Post: 17-Aug-2023, 07:47
  2. Bad ebay seller (venting)
    By G Benaim in forum Business
    Replies: 40
    Last Post: 4-Sep-2008, 05:59
  3. venting
    By Jack_5762 in forum Darkroom: Film, Processing & Printing
    Replies: 1
    Last Post: 9-Sep-2005, 09:23

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
  •