[RE-wrenches] Explosion proof ceiling fan

[Ray Walters]

Putting the fan on the intake causes the battery box to be at higher 
pressure.  You don't want the pressure in the battery box to be higher 
than the surrounding room, or it will push the H2S into the room through 
any cracks.   You want to create a vacuum (lower pressure) in the 
battery box, so that the H2S is less likely to enter the room, and is 
drawn out.  That's why we always put the fan on the exhaust side.

Ray Walters
Remote Solar

On 5/6/2025 1:20 PM, Bradley Bassett wrote:
> Put the fan at the intake near floor level and a passive vent at the 
> ceiling
>
>
>
> On Tue, May 6, 2025, 12:09 PM Ray Walters via RE-wrenches 
> <re-wrenches at lists.re-wrenches.org> wrote:
>
>     Hi William;
>
>     Poor ventilation could be part of it, but I've also seen corrosion
>     problems from:
>     clients over filling the cells,
>     EQing to often,
>     absorption voltage set too high and for too long,
>     too high a charge rate, (too large an array)
>     too high a temperature, due to floor heating and/or insulated
>     battery box.
>
>     my best systems seem to be on the lower side of array size
>     relative to battery size, with batteries in a basement or garage
>     that stays above freezing, but below 60F most of the year.
>
>     Sorry I don't have a line on explosion proof fans, but I have a
>     client with a 120 vac radon blower for the battery exhaust that
>     seems to do much better than the traditional DC battery fans. 
>     (Not my install.)
>
>      I've only seen batteries blow twice:
>     1) Idiot was arc welding next to a HUP battery and multiple large
>     sparks went right on to a cap; result: blew the top off the cell.
>     He had been told to construct a battery enclosure around the
>     batteries, but never did.
>     2) a loose connection at a battery terminal arced, melted the lead
>     until the molten lead melted through the top of the case and
>     ignited the hydrogen, result: burned a clear flame for a few
>     seconds and went out without any major damage.
>
>     So my take away is that unless the ignition source is in the cell
>     or within an inch of the cap, the hydrogen is too low a
>     concentration to ignite.  Actually, are lead acid battery internal
>     plates and their external connections considered "explosion proof"?
>
>     Ray Walters
>     Remote Solar
>
>
>     On 5/6/2025 12:20 PM, William Miller via RE-wrenches wrote:
>>
>>     Friends:
>>
>>     I have two flooded battery arrays that have steel cases that are
>>     corroding.  I am sure poor ventilation is the issue even though
>>     we have passive vents high and low.  I think I need active
>>     ventilation.
>>
>>     Does anyone have knowledge of a 120VAC explosion proof ceiling
>>     mounted exhaust fan?
>>
>>     Thanks in advance.
>>
>>     William
>>
>>     Miller Solar
>>
>>     17395 Oak Road, Atascadero, CA 93422
>>
>>     805-438-5600
>>
>>     www.millersolar.com <http://www.millersolar.com/>
>>
>>     CA Lic. 773985
>>
>>
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