Battery-type in Class 1, Div 2 Area

[scopi]

Could someone please provide me with a reference/standard for use of batteries (12VDC) in a Class 1, Div 2 area - specifically what limitations there might be for placement of a battery within a NEMA 8 enclosure at an outdoor facility? The battery would be powering an intrinsically-safe sensor.

 

[peebee]

My main concern would be if you were using a battery type that off-gassed hydrogen. I would do anything in your power to avoid that situation, select some battery type that won't give you that problem.

My next concern would be that sooner or later, you'll need to replace the battery. That will mean repetetive opening and closing of your enclosure, which can often lead to poorly sealed enclosures, missing bolts, etc. Also, you would want to make absolutely sure that there were no hazardous fumes around when you changed the battery.

Is there any chance to relocate the battery to a GP location, and avoid the issue entirely?

Also -- the intent of Article 501 is generally to protect against sparking equipment only in Div 2 areas (that's not entirely true -- surface temperatures are an issue too) -- maybe a GP enclosure would make more sense than a NEMA 1 (Div 1) enclosure?

As a side note -- there's certainly plenty of small battery operated portable equipment available, including flashlights, pagers, clocks, etc. . . Generally, they seem to do little or nothing to seal the small batteries (double-A, C, D, etc) used in those devices. Are you talking a battery like a disposable double-A, or something more like a lead-acid battery?

 

[scopi]

Peebee,

Thanks for your input. The client, as a matter of standard procedure, is going to require the NEMA enclosure.

The technicians at the site monitor the air for hazardous conditions before doing maintenance, so changing the batteries will be a pain from the perspective of undoing all 12 bolts on the enclosure, but all other safety concerns would be addressed through standard maintenance procedures.

The battery will be powering a signal strobe light (12VDC, 0.4 amps). Based on the site conditions, the signal light will need to be powered for 12 to 18 hours (interval between routine site inspections); therefore, the capacity of the battery will need to be around 7 amp-hours.

I was contemplating a sealed-lead acid battery for the capacity rating, but now I am considering other batteries because of the off-gassing issue. Are there off-gassing issues associated with Ni-Cad or NiMH batteries?

 

[peebee]

I'll defer to the battery experts.

I didn't make clear in my last post, I was referring to XP rated flashlights, etc.

I realize the following is rather off-topic, but maybe it will be of some help to you. . . . I have a Rayovac Model IN2-MS flashlight, rated for Class I Gr C&D and Class 2 Gr G. It looks like a fairly standard flashlight, it's plastic & runs off 2 D batteries. It does have the note 'Use PR2 or PR6 bulbs and 2 "D" size non-rechargeable Carbon-Zinc or Alkaline batteries (3 volts max.) only' on it. It's apparently listed to UL870A, and it seems to have an MSHA (Mine Safety and Health Administration) approval #106-630-0 (MHSA tested in Methane-Air mixtures only).