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Battery Trays for VRLA Batteries in UPS

Battery Trays for VRLA Batteries in UPS

Battery Trays for VRLA Batteries in UPS

(OP)
I have an application using a 10kVA UPS in 208/120V in an electrical room. The batteries specified are VRLA batteries. The UPS is being placed in an electrical room along with (3) MCC's, VFDs, and panel boards and transformers. The equipment is all low voltage (480V) and below and there is a air conditioner rated for 10 tons to condition this space.

According to what I've found from the UPS company APC, there is no need to worry about venting a "VRLA" battery as it is considered sealed.

Having said that, one of the text books I have from IEEE associated with DC power systems notes that if a VRLA battery fails, it can put out hydrogen.

Here are my concerns:

a) Do I want to ensure that relief valves are specified for the VRLA battery selected?
b) Do I need to follow any form of air change per hour criteria in my location (say 1-2 ACH per NFPA 110) even though APC notes that air change per hour associated with human occupancy should be adequate?
c) Do I need any form of containment for the battery itself? I would think not because a VRLA battery is sealed.

I thank you in advance for any comments you have on this matter.

RE: Battery Trays for VRLA Batteries in UPS

The letters stand for valve regulated lead acid. This valve is a relief valve, closed normally (sealed) and open when pressure exceeds its threshold (no longer sealed.)
I would provide air changes sufficient to avoid combustible levels of H2 from accumulating under any condition.
VRLA batteries have either a gelled electrolyte, or one absorbed in glass mats. Containment should not be needed.

RE: Battery Trays for VRLA Batteries in UPS

I agree with stevenal.  Some ventilation should be provided, but the ventilation requirements for batteries are often greatly overestimated.  The need for forced ventilation will depend on the installation location and battery size.  In many instances, the natural ventilation will be more than adequate.  Problems generally occur when someone feels the need for a special battery room that is only big enough for the batteries.  Then forced ventilation is probably necessary.  

Also, hydrogen gas is much lighter than air and all it wants to do is get out of the building, if given much opportunity.  

I see no need for containment.   

David Castor
www.cvoes.com

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