Darkroom Exhaust Fan(400 CFM) For Positive Pressure, Plus DR Design?
Hello everybody,
Thanks so much for providing your input.
This project is so important to me, appreciate all help in this matter.
Details:
I'm in the process of transfer to a new darkroom.
Just contemplating to fit two(2) exhaust fans, REVERSED, in the door of the darkroom, to create positive pressure. Each will be connected to a separate one(1) "On/Off" switch. Door will use the Automatic Closing Mechanism.
The other side of the door, is leading to a small corridor that leads to the rest of a very big apartment(house).
Will use another two(2) fans as exhaust(not inverted), above each other, separated by 30 inches, on the other side of darkroom, but on the other extreme of the same wall of the positive pressure fans.
Hope the drawing(below) is easier to understand.
One exhaust fan is equivalent to one of the positive pressure fans(400 CFM). The other is bigger(may be 1200 CFM). The bigger exhaust fan will be at bout 60" above the ground level, at the end of my sink.
Exhaust fans are pulling air into a vertical vent area inside the building(not house), that open at the top of the building.
Exhaust fans will work as a passive louvers when they are "Off". Both will be connected to one(1) "On/Off" switch.
Positive Pressure Fans, will work permanently. Or at least one of them.
Please assume every thing is light/air tight.
The room has two(2) windows, but will close them to prevent dust, unless it is seriously needed(do not know, so far).
I'm afraid of pressure gradient to be effective enough to do the job?
Room area: 21 ft X 15 ft X 9 ft(6.5mX4.5mX2.8m). BTW, 9 feet = 108".
Capacity of each each regular fan(2 positive pressure & 1 exhaust): 400 Cubic Feet Per Minute(400CFM).
Capacity of the bigger fan(1 exhaust): 1200 Cubic Feet Per Minute(1200CFM). But, I think this will effectively be 800CFM after making an efficient light tight hood around it.
Room Volum: 2835 Cubic Feet.
Which theoretically means, 7 exhaust fans Plus 7 positive pressure fans(or louvers), of the same capacity.
The original two(2) windows of the room(for air and light), will be closed, to be air/light tight, to prevent any possibility of dust accumulation. Any louvre or fan there, will destroy the shape of the building from outside.
Photos before summary:
Room Design including Inlet and Outlet of Air:
.
Positive Air Fans & one Exhaust Fan Model:
.
Tried to be organized, My apologies being long.
Summary:
So, I'm describing a darkroom design providing fresh air from inside house air(house is designed to provide maximum air/light ventilation, on demand), minimal or no dust could inter the darkroom.
And ventilating safely to a vertical vent area that connected at the top with air above the whole building. No other air ventilation leads to that same vent area in the building.
My query:
Drawback, potential problems, that I may missed?.
Or it's just a crazy idea?
Really wish to know how it will work, before doing more destruction.
Appreciate any input.
Best.