×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Battery Room Venting
2

Battery Room Venting

Battery Room Venting

(OP)
Can anyone give me a quick rule of thumb method/ formula to calculate the minimum safe (below the lower explosion limit LEL) ventilation rate required to ventilate a battery room whilst boost charging both valve regulated and lead acid batteries?

RE: Battery Room Venting

CFM given off by battery at maximum charge rate= (Amps x # of Cells x 0.000269 CFM/amp-cell).

From IEEE 484 "Recommended Practice for Installation Design and Installation of Large Lead Storage Batteries for Generating Stations and Substations."

That formula gives the amount of H2 the battery releases during an overcharge. Use the current limit setting of the charger for the amps.

Size ventilation rate for the maximum H2 release to be conservative.  Then talk to someone who knows more about HVAC than me.

RE: Battery Room Venting

Some of the battery manufacturers have a handy Excel spreadsheet for this.

Alan
----
"It's always fun to do the impossible." - Walt Disney

RE: Battery Room Venting

The pertinent Australian standard for this states that to keep the hydrogen concentration below 2% in a battery room or enclosure the following equation should be used:

qv = 0.006nI

Where qv = minimum exhaust ventillation rate, in litres per second.

n = number of battery cells

I = charging current.

RE: Battery Room Venting

U.S. code is 1%. 4% is the lower explosive limit.

Alan
----
"It's always fun to do the impossible." - Walt Disney

RE: Battery Room Venting

I had developed a simple spreadsheet which calculates the Hydrogen volume generated by GU-9 Enersys Wet cell battery. The no. of hrs required for the dangerous built-up is calculated. The sheet is attached for your use. The hydrogen evolution figure should be taken from the battery vendor.

Another method used in the IEC regulated countries, is the one given in IEC 60079-10. See the document at:http://www.tchouvelev.org/Documents/UpdatedDocs/HazLocs_Code_Requirements_Comparison.pdf. Here a hypothetical volume is calculated and then the correct conclusions are drawn.

The LFL of Hydrogen is well known at 4%. The restricted concentration of 1% comes from NFPA 30. In IEEE 418, is is in Sec 5.4 Ventilation that a value of less than 2% is mentioned.

One useful article is located at:http://www.battcon.com/PapersFinal2008/ODonnellPaper2008PROOF_6.pdf

RE: Battery Room Venting

(OP)
Many thanks to you all. All comments, formulae and links are very helpful.

Regards
peterp.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources