53
Rev.12/31/97
Same condition as previously mentioned except that the battery is located in
a general control room area of 15 by 7 by 5 meters with one air change per
hour:
a general control room area of 15 by 7 by 5 meters with one air change per
hour:
Hydrogen production rate per hour:
(50 amps)(60 cells)(0.000453) = 1.353 m
3
H
2
/hour
Critical volume based on 0.8 percent:
(0.008)(15 m)(7 m)(5 m) = 4.20 m
3
H
2
Hours to produce critical level of 4.20 cubic meters of hydrogen:
4.20 ÷ 1.353 = 3.10 hours, or 3 hours and 6 minutes
Because one air change occurs per hour, the critical concentration would
not be reached with continuous operation of the ventilation system and with
adequate air movement over the battery to ensure diffusion of generated
gases.
adequate air movement over the battery to ensure diffusion of generated
gases.
Example 3
Example 3
Same condition as example 2. Determine fan size for room with no natural
circulation.
circulation.
Hydrogen production in cubic meters per hour:
(0.000453 m
3
/hour)(50 amps)(60 cells) = 1.35 m
3
/hour
Because fans are rated in cubic feet per minute, cubic meters per hour must
be converted to cubic feet per minute:
be converted to cubic feet per minute:
(1.35 m
3
/hour)(35.31 ft
3
/m
3
) = 47.67 ft
3
/hour H
2
production
Divide by 60 minutes per hour to change 47.67 cubic feet per hour into
cubic feet per minute.
cubic feet per minute.
47.67 ÷ 60 = 0.794 ft
3
/min H
2
production
A safety factor of 5 (0.8 percent by volume) is required. With 0.794 cubic
foot per minute
foot per minute
hydrogen production, the hydrogen must never reach 0.8
percent of the total volume of the room. Total volume of the room is (15
m)(7 m)(5 m) = 525 m
m)(7 m)(5 m) = 525 m
3
.
(525 m
3
)(35.32 ft
3
/m
3
) = 18,538 ft
3
total volume of the room
0.8 percent of 18,538 ft
3
= 148.3 ft
3