Photo by Michal Matlon on Unsplash
When I first started my darkroom it was in the spare bathroom and I had to take it out every Friday night and pack it up Sunday evening. It was small, dark and had running water but the best part was that it has a good extractor fan. I spent hours in that bathroom making all kinds of mistakes but the air was always pleasant. Subsequent darkrooms lacked running water but I tried to ensure they all had proper ventilation. Here is what I have learned and how I built it into my purpose built darkroom in Houston.
The Why:
Simply put, our bodies are not prepared to inhale fumes for extended periods of time. Sometimes the reaction is quick, developing a quick but sharp headache and other times it can take years to develop into an allergy that would prevent you from enjoying anytime in a darkroom. For health and enjoyment reasons you NEED to have good air circulation.
The warmer darkroom chemicals become, the more they evaporate and the greater the levels of fumes. In my darkroom in England I had a much easier time with fumes than I did when living in Jakarta. The temperature of London was cool enough to keep the amount of fumes low while in Jakarta the higher temperature caused more evaporation. Keep this in mind when designing your own.
When I was building my darkroom in Argentina, I built it in winter. I used a single large extractor fan over the chemicals and it worked. I could not smell the chemicals and felt fine operating there for hours. In summer, I began to get a headache and quickly realized that the air circulation was not sufficient. I doubled the extraction and it worked...barely. So in my new build, I wanted to be sure I got it right.
The Details:
Generally speaking, when it comes to air ventiatilataion you can never have too much. So the good news is that you cannot really overdo it so best to err on the side of caution. The challenge is finding a way to get the fumes out without too much noise and still keep the room cool (or warm depending on the climate). My solution was to overdo both the ventilation and the heating/cooling. But don't take my word for it...do your own math and lets see what the experts say....
Ilford has this to say in their FAQ:
Smells and fumes from darkroom chemicals and heat from enlargers and lamps are best eliminated by some sort of extract in the room OR by opening the room up between processes.
If you are going to be in a darkroom for longer lengths of time it is useful to set up an extract fan with some sort of light proofing (baffles/black drapes, long duct) which still allows airflow. Also, cover your photo chemicals when not in use (trays/tanks etc.).
With these precautions, you will be able to remain safe and comfortable within the darkroom.
All of this is a bit qualitative but Ilford goes on the share the following (this is mostly focused to commercial darkrooms but it is a good reference).
2.3.24.4 Darkrooms (photographic)
Small darkrooms for occasional use or for purely developing processes may often be ventilated naturally
with a suitable light trap, although consideration should be given to providing mechanical extract using an air
change rate of 6 to 8 air changes per hour. For general purpose darkrooms, however, the air change rate should
be ascertained from a consideration of the heat gain from the enlarger, lights etc. plus the occupants, on the basis of
a temperature rise of 5-6 K. In industrial and commercial darkrooms that have machine processing, the machines
will very often have their own extract ducting, the air supply being drawn from the room itself. It will usually be
necessary to provide a warmed and filtered mechanical inlet in such cases. In special cases, involving extensive
washing processes, the humidity gain may be significant and require consideration."
So here the UK code asks for 6-8 changes per hour. Kodak asks for 10 changes per hour.
My Calculations:
My darkroom is 9.5ft x 9.5ft and it 8.4ft tall. This gives me 758 cubic feet of air in my darkroom. In order for my darkroom to meet the UK code for a commercial darkroom space, I would need to move 101CFM (Cubic Feet per Minute) giving me 6,064 cu ft per hour. This is the advantage of having a small space, the air you must move is considerably smaller.
If I used Kodaks more conservative 10 changes per hour I would need to move 7,580 cu ft per hour or 126 CFM.
I purchased a AC Infinity Cloudline S6 (AI-CLS6). It is rated at 402 CFM (Cubic Feet Per Minute) air flow, but this is at its highest setting. I use it a bit above 50% giving me around 200 CFM that achieves both UK and Kodak recommendations.
The Why:
Simply put, our bodies are not prepared to inhale fumes for extended periods of time. Sometimes the reaction is quick, developing a quick but sharp headache and other times it can take years to develop into an allergy that would prevent you from enjoying anytime in a darkroom. For health and enjoyment reasons you NEED to have good air circulation.
The warmer darkroom chemicals become, the more they evaporate and the greater the levels of fumes. In my darkroom in England I had a much easier time with fumes than I did when living in Jakarta. The temperature of London was cool enough to keep the amount of fumes low while in Jakarta the higher temperature caused more evaporation. Keep this in mind when designing your own.
When I was building my darkroom in Argentina, I built it in winter. I used a single large extractor fan over the chemicals and it worked. I could not smell the chemicals and felt fine operating there for hours. In summer, I began to get a headache and quickly realized that the air circulation was not sufficient. I doubled the extraction and it worked...barely. So in my new build, I wanted to be sure I got it right.
The Details:
Generally speaking, when it comes to air ventiatilataion you can never have too much. So the good news is that you cannot really overdo it so best to err on the side of caution. The challenge is finding a way to get the fumes out without too much noise and still keep the room cool (or warm depending on the climate). My solution was to overdo both the ventilation and the heating/cooling. But don't take my word for it...do your own math and lets see what the experts say....
Ilford has this to say in their FAQ:
Smells and fumes from darkroom chemicals and heat from enlargers and lamps are best eliminated by some sort of extract in the room OR by opening the room up between processes.
If you are going to be in a darkroom for longer lengths of time it is useful to set up an extract fan with some sort of light proofing (baffles/black drapes, long duct) which still allows airflow. Also, cover your photo chemicals when not in use (trays/tanks etc.).
With these precautions, you will be able to remain safe and comfortable within the darkroom.
All of this is a bit qualitative but Ilford goes on the share the following (this is mostly focused to commercial darkrooms but it is a good reference).
2.3.24.4 Darkrooms (photographic)
Small darkrooms for occasional use or for purely developing processes may often be ventilated naturally
with a suitable light trap, although consideration should be given to providing mechanical extract using an air
change rate of 6 to 8 air changes per hour. For general purpose darkrooms, however, the air change rate should
be ascertained from a consideration of the heat gain from the enlarger, lights etc. plus the occupants, on the basis of
a temperature rise of 5-6 K. In industrial and commercial darkrooms that have machine processing, the machines
will very often have their own extract ducting, the air supply being drawn from the room itself. It will usually be
necessary to provide a warmed and filtered mechanical inlet in such cases. In special cases, involving extensive
washing processes, the humidity gain may be significant and require consideration."
- ACH = Air changes per hour.
- Calculate this my multiplying HxWxD for the room in metres to give m3.
- Measure airflow of extract vent in m/second.
- Multiply by Vent HxW in metres to give m3 per second.
- Multiply that by 3600 to give m3 per hour.
- Divide flow volume by room volume to give ACH.
So here the UK code asks for 6-8 changes per hour. Kodak asks for 10 changes per hour.
My Calculations:
My darkroom is 9.5ft x 9.5ft and it 8.4ft tall. This gives me 758 cubic feet of air in my darkroom. In order for my darkroom to meet the UK code for a commercial darkroom space, I would need to move 101CFM (Cubic Feet per Minute) giving me 6,064 cu ft per hour. This is the advantage of having a small space, the air you must move is considerably smaller.
If I used Kodaks more conservative 10 changes per hour I would need to move 7,580 cu ft per hour or 126 CFM.
I purchased a AC Infinity Cloudline S6 (AI-CLS6). It is rated at 402 CFM (Cubic Feet Per Minute) air flow, but this is at its highest setting. I use it a bit above 50% giving me around 200 CFM that achieves both UK and Kodak recommendations.
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Here is the Cloudline fan that is connected straight to the wall on the top shelf of a storage rack that I have. It is secured with tie wraps to the shelf and is very secure.
There is a hose (that came with the kid of the pump) that goes from the fan, through the shelf to a PVC pipe above the sink. I decided that I wanted this to be 6inch in diameter and bought the pump accordingly. From there it goes to a vent that closes when not being used. As a general rule, the more changes you have to the dimensions of the air vents the more efficiency loss you will have and the greater the chance for noise. I could have gone with a 4inch and almost did but opted for the larger diameter. |
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Here is a shot of the pipe and the connection. I have a rubber connector from the PVC pipe to the flexible ventilation hose and I have secured this with...what else....white duct tape.
I then drilled two sets of holes on the underside of the PVC pipe. The area of the holes adds up to slightly larger than a six inch diameter hole. Again, I am working to keep things nice and simple and felt this was a good way to keep the ventilation even. It is not an exact science, nor did I spend much time worried about it but back of the napkin calculations was sufficient. In terms of the sound, it is not noticeable at this setting. If I put it to the max setting I would be bothered by the sound and there is a frequency in there that gives me a whistle sound at times. |
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Cloudline does sell a sound insulator to dampen the sound further but I opted not to get it and frankly do not need it. My lesson here is to buy a larger fan then you need, this allows you to run it at a lower setting reducing overall noise.
Conclusions:
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