VRLA or GEL Batteries in sealed environment
VRLA or GEL Batteries in sealed environment
(OP)
Does anyone have any background with using VRLA or GEL style 12V batteries in a Class I Div I area? This NEMA 4x sealed mobile system is protected with a Y Purge and a non-incendive enclosure and contents and has its own mobile pressurized air supply. but I can't get a straight answer out of any battery makers on the outgas of the battery (excess of H production that can't recombine) in a scenario where it could possibly fail catastrophically. It doesn't seem that the minimal air vented to the outside in a typical purge system would truly address venting the H to outside the unit, and I can't crank the air up with the limited on-board air supply.
It makes me think the only suitable application of a battery in such an environment is to apply it in its own explosion-proof (ugly) enclosure.
Thanks for any and all advice.
It makes me think the only suitable application of a battery in such an environment is to apply it in its own explosion-proof (ugly) enclosure.
Thanks for any and all advice.






RE: VRLA or GEL Batteries in sealed environment
I can understand you might not get an answer about gassing from a 'catastrophic' incident with the batteries. Why is that a particular concern? That would not normally be covered under the definition of hazardous locations.
Keep in mind pressurized and purged enclosures are acceptable code-wise only if 'approved for the location' and provided with clean air.
RE: VRLA or GEL Batteries in sealed environment
In normal situations the GEL Cell batteries don't generate any appreciable gases. Otherwise they would dry out and fail. So the out gassing comes with overcharge situations.
This is why you are getting null responses from suppliers. The batteries essentially don't out gas unless they are being hammered. Gas evolution is a function of HOW much abuse is being dished out. So they have no way of guessing the gas evolution.
I suspect any purging is plenty but check the calcs.
We enclosed a group of Gates cylindrical cells in a light stainless steel box, potted them in epoxy and ran them thru a highly incendiary environment by the dozen daily.
Two important points:
1) The units were never charged in the environment.
2) The batteries had tygon ribbon running from the
venting area out of the potting in case charging generated any gas.
RE: VRLA or GEL Batteries in sealed environment
Do you think the fact that they will be cycled down twice daily and charged in the sealed environment adds to the minimal if any H concerns in the system? It's about 18" x 24" x 12" with an upper minor enclosure 18" x 19" x 4"
RE: VRLA or GEL Batteries in sealed environment
And since these kind of devices can cause BIG LOUD energenic problems, could you clarify what you mean by "cycle down"?
And next you say, "charged in the sealed environment", but you said this was a "purged" environment not a sealed environment. I'm confused. Sorry.
RE: VRLA or GEL Batteries in sealed environment
By cycle down, basically discharging the battery most of the way.
Gel battery reps and VRLA reps keep green lighting charging in the hazardous sealed environment, and I keep reading the label off of their battery and MSDS sheet that says "wll-ventilated" and all I keep getting back is resounding "duhs" - I'm finding it hard to quantify the difference between truly sealed and purged as far as the TRUE continual air movement & replacement in the unit. It has a standard mechanical purge vent on top.
RE: VRLA or GEL Batteries in sealed environment
RE: VRLA or GEL Batteries in sealed environment
Mike
RE: VRLA or GEL Batteries in sealed environment
RE: VRLA or GEL Batteries in sealed environment
Using lead-acid batteries in non-purged hazardous locations is not without precedent. For example,
http://www
Perhaps the fixture is sufficiently rugged that a battery explosion is not a concern.
As a side note, you mention Gel and VRLA as two types of batteries being considered. Technically gelled electrolyte cells are actually a type of VRLA. I assume you are thinking of Gel vs. absorbed electrolyte?
RE: VRLA or GEL Batteries in sealed environment
Thanks again to everyone for their responses. I've read code over and over and over, and that's good to a point, since every company likes to provide a certain standard of system - in our case we are looking for a perfect system (or close to), due to the extreme hazardous environment these will be used in.
RE: VRLA or GEL Batteries in sealed environment
RE: VRLA or GEL Batteries in sealed environment
Of course, in all reality the probability of violent battery failure is rare, we just want to play it on the extra safe side...
RE: VRLA or GEL Batteries in sealed environment
Extra safe is extra good.
Old Dave