Your postings target extremes which we will never experience in our darkrooms.Originally Posted by Drew Wiley
Back to your bubble, boy.
Your postings target extremes which we will never experience in our darkrooms.
Back to your bubble, boy.
hmmmm, Drew, please see this HEPA manual: https://www.honeywellstore.com/store...ier-manual.pdf
In this case, Honeywell says:
THE DOCTOR’S CHOICE
TRUE HEPA
ALLERGEN REMOVER
AIR PURIFIERS
If they are lying then somebody suffering severe asthma can die. This would be very expensive for a company....
Do you think they are lying ?
My bet is that they fulfill EU HEPA H13 level and US DOE HEPA specs.
HEPA ratings regulate filters, sealed systems are regulated by ISO 14644-1 and 14698 or by US FED STD 209E that's a bit obsolete but still in wide usage.
Bingo. Not an item there is remotely HEPA by EPA spec. I'm not implying those kinds of cheap devices are not useful in darkroom spaces or for home dust control, and I do know a thing or two about allergies. I had life-threatening allergies as a child, and my wife works in an allergy clinic. I use an even cheaper portable filter for the intake air on my film dryer cabinet; but it's in a room quite clean to begin with. But you plainly do not have a clue what you are talking about, Pere. I am making a distinction quite important for those who might opt someday to work with HAZARDOUS metal salts in alt processes, or who are thinking about leasing a darkroom space in a converted industrial building possibly having toxic compounds in walls or in use in adjacent studios, or toxic mold situations possible in semi-tropic environments. That could potentially include quite a number of photographers dreaming about being able to do their own printing. Some of the art collectives in this general area have proven themselves to be downright deadly, i.e., fatal. Painters, photographers, and sculptors take out leases on those spaces without understanding the risks. And those risks can be extreme. Not everyone has space in their home per se. Some alt processes use highly flammable solvents, or they might be in use by someone else in a craft studio nearby. All it takes is a single spark from a non-registered air extraction device or ungrounded duct line (that has to be factored in too, in the design of legal equipment, or even in common-sense fume hood ducting; even an ordinary clothes dryer duct hose requires it). Many others of us need not worry about such technicalities, and nitrile gloves and a simple ventilation system might be enough. But you need to know how to ask the right questions first. Don't assume.
Ugh! Can we just get back to darkroom ventilation solutions?
--- Steve from Missouri ---
Drew, let me add that HEPA qualitification was issued for the Manhattan project, A-Bomb, so to arrest radiactive particles. I guess because of that it was regulated by US Dep of Energy (nuclear section). Initial meaning was "high-efficiency particulate absorber", later a bit changed.
"The original HEPA filter was designed in the 1940s and was used in the Manhattan Project to prevent the spread of airborne radioactive contaminants. It was commercialized in the 1950s, and the original term became a registered trademark and later a generic term for highly efficient filters"
But "true HEPA" in the USA is H13 HEPA in the EU.
IMHO we ended that debate yet, http://www.largeformatphotography.in...=1#post1464123
but if you have something to add, please don't hesitate...
This IS about ventilation solutions!! Is your fume duct grounded or otherwise static-resistant? Does your intake air need HEPA filtration due to adjacent atmospheric conditions otherwise beyond your control? - which might include pesticides in farm
communities, and not just urban hazmat issues. Do you work with hazardous powders? Not every darkroom is limited to Dektol and D76. I can think of at least thirty "artistes" in this immediate area who were alive two years ago, but are not today, simply because they did not ask such questions in advance. Or maybe someone might like to build in extra features right from the start, when it is easiest to remodel, just in case they want to step up to color printing or alt processes, or even mix their own pyro from powder instead of buying it liquid A&B like me. I've got all kinds of nasty chem in my lab for specialized incidental rather than daily purposes that I'd hate to spill. ... But gosh, Pere, I'm tired of talking about it to you. Just turn in your job application at the one of the Fed Rad Labs here - either Lawrence Berkeley or Lawrence Livermore. I'm sure they'll be quite impressed. They use water-filtered vacs, of course, not HEPA. But you already knew that.
It depends on if one likes dealing with dust or not !!!
In the simplest terms: if you want to work safely in the longer-than-very-short-term with dichromates or much of the wetplate chemistry, you should not be doing so without appropriate (ie chem lab standard) ventilation, especially if you're working in close proximity to other people, animals etc.
A cleanroom would be most useful for dealing with any cold mount processes - they are a magnet for dust!
Last edited by interneg; 11-Oct-2018 at 15:44.
I would like to have my darkroom with positive pressure that is filtered air being pulled in from my house. Due to where my water lines are for where my sink will go, I may need to have a vent hood that has a separate fan/filter that draws the air over the sink and vents to the outside. I may install a separate filtered vent with a valve that allows the incoming air from house to vent out when the vent hood over the sink is not on, while maintaining a small positive pressure to keep out the dust. In essence, like a big version of a table top clean room. I think the only thing I would want is explosion proof fans if they are not too expensive. Will also need to have a vent line that is filtered to the outside for the enlarger/s.
I am keeping this simple, but at the same time, I want to keep any chemical vapors I vent to the outside to a minimum (no need to add to the pollution if I don't have too. Not that the amount or type I would be venting is that harmful)
You could supplement a serious fume hood fan with a simple low-pressure automated "attic fan" if necessary, which would allow for modest exhaust even when you're not there. For the latter, a simple dryer duct flap hood on an outside wall would work in lieu of a fancy valve. The ideal configuration with a sink allows air to be drawn past you over the sink, then up into the hood. I periodically tweak my own system, which began with a bunch of big components salvaged free from local industrial lab renovations. Doing it "perfectly" from the start would have been way beyond my budget.
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