Beyond norms, the key is not to have turbulence. Air has to flow laminar from the emision sources to the extraction, in that way fumes are never breathed. If we have turbulence we always breath some fumes, and we need a lot of air changes to keep fumes concentration low, but it will never be zero. With a properly designed system we breath zero fumes.
A properly designed system is essential when we use some kind of chem.
I am out as Pere and Drew tango
Make up air is important and can be very cold or hot depending on location, climate
Tin Can
No dancing? It's Hell-O-Ween!
Old threads on DR ventilation found on bottom of current page, some go back 20 years.
https://www.largeformatphotography.i...l=1#post709987
https://www.largeformatphotography.i...l=1#post583499
https://www.largeformatphotography.i...ll=1#post81143
https://www.largeformatphotography.i...ll=1#post30262
https://www.largeformatphotography.i...ll=1#post16335
Tin Can
A computer fan????? That's like a mouse dueling a mountain lion. Wrong Holiday. This is Halloween, not April Fools Day.
I was reading Tim Rudman's toning book last night and he also recommends a minimum of 10 ACH.
You don't know what you're talking about, Tin Man, or I am confusing you with a character in Wizard of Oz? If you take 240CFM, factor in hydrostatic pressure outside on a rainy day, or even in a humid climate, and then air friction from ductwork that cannot be straight because it has to prevent light entering and may very well be corrugated for ease of installation, the real world capacity is about half that air volume at best. Then one always needs a boost factor, even if ordinarily running it at lower volume, in case there's a spill of something you want rapidly exhausted, or during mixing of some concentrated chemical. So a fan of at least 180 cfm is called for, or even better, 240 because there's such an excellent in-line option in that case. That would be the routine specification for even a bathroom that size, where mainly just water vapor is involved, unless the climate is routinely arid. What one doesn't want is a cheap ceiling-mount propeller-style fan that is as noisy as a gas lawn mower.
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