EnerSys PowerSafe Data Safe Operation & Maintenance Manual page 55

HYDROGEN FORMULA
Formula for hydrogen evolved evolved—C = FC x AH x K x N
C = Cubic feet (cubic meters) of hydrogen per minute
FC = Float current per 100 AH (temperature compensated) in milliamperes
AH = Ampere hours (nominal 8 hr.)
K = Constant = 0.000267 cubic feet (7.56 x 10
per minute of hydrogen per Ah.
N = Number of cells
EXAMPLE
60 cell GT-41 (3730 AH) near end of life, on equalize at 2.33 VPC at 92
electrolyte temperature
FC = 450 (from table) x 2 for 92
C = 900 x 3730 x 0.000267 cu. ft. (7.56 x 10
1000 100
Hydrogen = 0.538 cu. ft. (0.0152 cu. m.) per minute
Assume a room size of 16,000 cu. ft. (452.5 cu. m.) that is allowed a 2% concentration of
hydrogen or 320 cu. ft. (9.06 cu. m.). At the above hydrogen evolution rate of 0.538 cu. ft.
(0.0152 cu. m.) per minute, it would require 10 hours to reach 2% concentration. Thus with one
air change every 10 hours, the hydrogen concentration could be maintained below 2%.
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1000 100
o o
F (33 C) = 900 milliamperes
-6
cu. m.) x 60
Publication No. US-FL-IOM-002 January 2007 Page
-6
cubic meters)
o o
F (33 C)
47