I will be repurposing an old shed for temporary procession of sheet film. The entire space is 6'x'6 roughly and the roof peaks at about 7' so total volume is approximately 252 sq feet. I am trying to figure out how much ventilation I require to stay on the safe side. I am looking at this fan currently:

6" fan

It ::claims:: to do 240cfm, so from my very poor math that means the fan would circulate 1 shed's worth of air volume per minute. Is this sufficient? I will be using mostly HC110 and standard kodak fixer but I will occasionally use some pyrocat.

The ducting will be placed directly over the developing tray and fixer tray at around waist height so that hopefully most fumes are sucked out before they reach my nose - that's the idea anyway.