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Helpful Member!  wendee (Electrical) (OP)
31 Aug 06 0:10
hello,

I am just new on my job and I usually deal with batteries.
I hope you can help me on this situation.

There's a battery room that will be designed to have a forced ventilation ( using exhaust fan ) and air-conditioned to maintain the temperature within the room and to exhaust H2 gas.

The battery is an AGM type. I already computed the hydrogen concentration in the room based on EN standard and it shows 0.04% hydrogen concentration. And the time for the critical hydrogen concentration to accumulate (without ventilation) is within 6 hours. The room is to have 3 ACH (air-change per hour). (Actually, 1 ACH is enough but owner wants it to have 3 ACH.)

The problem is that the design for the battery room is having its exhaust air, 80% of it, will be recirculated through ducts as an input for A/C, while the remaining 20% of exhaust air will be drawn out from the room. Is there any standard that allow this kind of design?
Is it possible?

There's a tendency that some H2 gas (80%)will go through ducts and accumulate inside the ducts. If I will provide hydrogen gas sensor inside the ducts to monitor the percent concentration, I still doubt if recirculation is permitted for battery rooms.

Please advise me. Thanks!   :)
pauljohn (Marine/Ocean)
19 Dec 06 13:50
Hi wendee

it was my understanding (from battery salesman mind you!) that AGM batteries along with Gel cells don't gas when charged properly. Is this information wrong?
stevenal (Electrical)
19 Dec 06 15:20
Not wrong. Room design should not be based on the no contingency situation, though.
peebee (Electrical)
26 Dec 06 14:29
Not sure if this helps you or not:

Per IBC 608.5, "Ventilation shall be provided in accordance with the IMC and ...  shall be designed to limit the maximum concentration of hydrogen to 1 percent of the total volume of the room....".  See also IBC 609.6.
avijo (Electrical)
10 Jan 07 16:13
hi, i think that this information can helps, this is only informative.

http://www.bhs1.com/batteryroom/ventilation.htm

so long
bertramh (Electrical)
28 Mar 07 18:57
Wendee,

Could you shed some loght on how you computed the hydrogen concentration in the room based on EN standard? I have some battery rooms and there is this question that keeps poping up as to weather we need to put hydrogen sensors that activates the exhaust fans.

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