H2S is slightly heavier than air, but I vent with the inlets on line with the tops of the battery, and the outlet at the highest point. If there is a lot of space around the bottom of the batteries, I might lower the inlets some, but not enough for the airflow to contribute to much cooling effect. (I'm in the Rockies)
All these stories make even more of a stickler about having my crews wear safety glasses. R. Walters r...@solarray.com Solar Engineer On Dec 15, 2010, at 12:08 PM, Jonathan Hill wrote: > Ray- > Is H2S lighter or heavier than air? Should it be vented from the top or > bottom of the enclosure? Thanks. > > Jonathan Hill, solar applications engineer > Sierra Solar Systems > 563C Idaho Maryland Road > Grass Valley, CA 95945 > Celebrating our 30th year in solar! > tech info and foreign orders: (530) 273-6754 > order line: (888) ON-SOLAR (US only) FAX: (530) 273-1760 > e-mail: <mailto:solar...@sierrasolar.com> > world wide web: <http://www.sierrasolar.com> > <att6eade.png> > > On Dec 15, 2010, at 10:48 AM, R Ray Walters wrote: > >> I really think the real venting issue is H2S (hydrogen sulfide) gas, which >> is deadly at high enough concentrations, causes head aches at lower >> concentrations, and is just awful to smell at any concentration. >> I think you would have to literally design a battery box to explode to ever >> get to the 4% concentration necessary. It would consist of a large battery >> bank, ridiculously oversized charge source, >> the enclosure lid would be barely above the terminals, and the enclosure >> would be a refrigerator, or ice chest with excellent seals and gaskets all >> the way around. >> Hydrogen is tough to contain, it can permeate right through many plastics, >> metals, sheetrock, etc. >> Again despite article 480, the issue of venting is the H2S danger, and >> accelerated corrosion, not explosion. >> I too, have had a hydrogen explosion, ( and cool colorless fire after!) but >> it wasn't due to the enclosure venting at all. (short circuited battery, >> lead terminal melted through battery case, ignition of hydrogen inside of >> battery, boom, then jet whistle sound of fire burning through the hole) >> Article 480.9A should be revised from "explosive" mixture to "dangerous" >> mixture. H2S above 10ppm? >> I copied some toxicity info if anyone wants to see. >> >> R. Walters >> r...@solarray.com >> Solar Engineer >> >> Long-term, low-level exposure may result in fatigue, loss of appetite, >> headaches, irritability, poor memory, and dizziness. Chronic exposure to low >> level H2S (around 2 ppm) has been implicated in increased miscarriage and >> reproductive health issues among Russian and Finnish wood pulp workers,[11] >> but the reports have not (as of circa 1995) been replicated. >> >> 0.00047 ppm is the recognition threshold, the concentration at which 50% of >> humans can detect the characteristic odor of hydrogen sulfide,[12] normally >> described as resembling "a rotten egg". >> Less than 10 ppm has an exposure limit of 8 hours per day. >> 10–20 ppm is the borderline concentration for eye irritation. >> 50–100 ppm leads to eye damage. >> At 100–150 ppm the olfactory nerve is paralyzed after a few inhalations, and >> the sense of smell disappears, often together with awareness of >> danger.[13][14] >> 320–530 ppm leads to pulmonary edema with the possibility of death. >> 530–1000 ppm causes strong stimulation of the central nervous system and >> rapid breathing, leading to loss of breathing. >> 800 ppm is the lethal concentration for 50% of humans for 5 minutes exposure >> (LC50). >> Concentrations over 1000 ppm cause immediate collapse with loss of >> breathing, even after inhalation of a single breath. >> >> >> >> On Dec 15, 2010, at 10:21 AM, Kent Osterberg wrote: >> >>> Sounds like, in general, that the off-grid industry has been fortunate to >>> not have hydrogen explosions. That's good. No explosions here either. >>> But one shouldn't take that as evidence that it couldn't happen. I don't >>> believe this is a circumstance where it is better to be lucky than good. >>> That's why I recommend doing the calculations. >>> >>> Kent Osterberg >>> Blue Mountain Solar >>> >>> >>> >>> Dana wrote: >>>> >>>> Ken – >>>> >>>> To meet the flow have run 2 and 3 fans to meet the flow. 2” output from >>>> the fan into a 4” header with a matching 2.5” inlet as far away on the >>>> lowest portion of the battery box. >>>> >>>> >>>> In 22+ years in off grid installations I have yet to see or even hear of >>>> one hydrogen explosion. I get repeatedly asked why we have to go to the >>>> efforts we go to for box and venting. I am not able to provide even one >>>> incident that I have heard rumor of. >>>> >>>> Q - How many battery based hydrogen incidents have happened in our >>>> collective experience? >>>> >>>> >>>> >>>> Dana Orzel >>>> Great Solar Works, Inc >>>> E - d...@solarwork.com >>>> V - 970.626.5253 >>>> F - 970.626.4140 >>>> C - 970.209.4076 >>>> web - www.solarwork.com >>>> >>>> "Responsible Technologies for Responsible People since 1988" >>>> Do not ever belive anything, but seriously trust through action. >>>> >>>> From: re-wrenches-boun...@lists.re-wrenches.org >>>> [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Kent >>>> Osterberg >>>> Sent: Tuesday, December 14, 2010 12:07 PM >>>> To: Wrenches >>>> Subject: [RE-wrenches] Battery Venting >>>> >>>> Fellow Wrenches, >>>> >>>> The discussion about battery venting reminds me of a useful and >>>> inexpensive program, BattMV, for determining ventilation requirements per >>>> EN-50272. EN-50272 is a European standard used to determine how much air >>>> flow is needed for a room, I don't know of a equivalent standard used in >>>> the U.S. It takes a surprising amount of ventilation. For a 400-AH >>>> 48-volt L16 bank charged at 57.6 volts and 24 amps, it's about 7 CFM just >>>> to keep the %H2 down to 4%. A 12-volt Zephyr vent is good for about 5 >>>> CFM! If you think you are venting enough, take some time and study this >>>> issue. >>>> >>>> Kent Osterberg >>>> Blue Mountain Solar >>>> >>>> _______________________________________________ >>>> List sponsored by Home Power magazine >>>> >>>> List Address: RE-wrenches@lists.re-wrenches.org >>>> >>>> Options & settings: >>>> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org >>>> >>>> List-Archive: >>>> http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org >>>> >>>> List rules & etiquette: >>>> www.re-wrenches.org/etiquette.htm >>>> >>>> Check out participant bios: >>>> www.members.re-wrenches.org >>>> >>>> >>> _______________________________________________ >>> List sponsored by Home Power magazine >>> >>> List Address: RE-wrenches@lists.re-wrenches.org >>> >>> Options & settings: >>> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org >>> >>> List-Archive: >>> http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org >>> >>> List rules & etiquette: >>> www.re-wrenches.org/etiquette.htm >>> >>> Check out participant bios: >>> www.members.re-wrenches.org >>> >> >> _______________________________________________ >> List sponsored by Home Power magazine >> >> List Address: RE-wrenches@lists.re-wrenches.org >> >> Options & settings: >> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org >> >> List-Archive: >> http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org >> >> List rules & etiquette: >> www.re-wrenches.org/etiquette.htm >> >> Check out participant bios: >> www.members.re-wrenches.org >> > > _______________________________________________ > List sponsored by Home Power magazine > > List Address: RE-wrenches@lists.re-wrenches.org > > Options & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > List-Archive: > http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org > > List rules & etiquette: > www.re-wrenches.org/etiquette.htm > > Check out participant bios: > www.members.re-wrenches.org >
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