Post B5rSl5IQEB3XXGAbXU by SRLevine@neuromatch.social
 (DIR) More posts by SRLevine@neuromatch.social
 (DIR) Post #B5rSl4r7rfDoAbOnzc by Canageek@wandering.shop
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       I made mistake of complaining today was going to be a boring day at work. I just had to send out an email declaring a lab closed, because due to the wild under pressure inside that room there's a decent chance you wouldn't be able to open the door if there was a fire. You can see how well that boring day is going. #RealTimeChem
       
 (DIR) Post #B5rSl5IQEB3XXGAbXU by SRLevine@neuromatch.social
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       @Canageek Don't you love when the HVAC goes haywire in a building with fume hoods!
       
 (DIR) Post #B5rSl5cH2Mw4WpSSTw by azonenberg@ioc.exchange
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       @SRLevine @Canageek My fume hood is ductless so no issues there, but when the overhead room exhaust system kicks in it under pressures the lab by enough the door is noticeably more difficult to open. You can still get in and out just have to push a little harder.
       
 (DIR) Post #B5rSqoiwkuCxsKJIfY by Canageek@wandering.shop
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       @azonenberg @SRLevine We got -125 Pa this morning
       
 (DIR) Post #B5rTc6P8pyVcJxasrY by azonenberg@ioc.exchange
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       @Canageek @SRLevine I measure 1014 mbar with the exhaust fan off and 1013.65 on, so -35 Pa.Which only increases the force needed to open the door by 12 pounds. You'll notice it, but it won't damage the door frame or stop you from getting out in an emergency.
       
 (DIR) Post #B5rWjjLgk1uKzhJ8gy by Canageek@wandering.shop
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       @azonenberg @SRLevine -35 Pa is about our target as well
       
 (DIR) Post #B5rZFXRijMXHFmQMEq by Canageek@wandering.shop
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       @azonenberg @SRLevine I've also never understood the point of ductless fume hoods, if you've got a toxic gas release, you want to get that out of the room as fast as possible
       
 (DIR) Post #B5racs9vzB806nnMae by azonenberg@ioc.exchange
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       @Canageek @SRLevine the point is when you're working with small quantities of known materials that you can safely treat with a filter, and you're not in a room that's set up with an exhaust stack for a normal fume hood.Your options are either to go to a different lab, drill a bunch of holes in the walls and roofs, or use a ductless.Also it completely avoids the issue of where the exhaust goes... For small companies in office parks and other less industrial locations there may be problems with zoning, complains from neighbors, etc. if you filter you may have to dispose of the filter as hazmat depending on what's in it, but there's no uncontrolled exhaust.In my case one hood is functioning as a scrubber for exhaust of a soldering oven, so just dealing with smoke and flux volatiles. Easily handled by a HEPA + carbon stack.The other one is used for microscopy sample prep so various acid etches, solvent cleans, and epoxies but all at single digit ml scale. Low volumes, known reagents. That one has an alkaline doped carbon filter for acid gases and solvent fumes, paired with a HEPA mostly just to catch any carbon dust the filter would otherwise exhaust into the lab.If your experiment has the potential to release large amounts of gas it's probably not something you should be doing in a ductless.