User's Manual

September 2013 A-4 P/N 81-CO2MAN-001
An 8% safety factor is usually applied to the quantity calculated in Equation A.5, and thus the
required flooding factor to create a 30 percent concentration is:
The quantity (per cubic foot) calculated in Equation A.5 must be delivered within two minutes,
so the system discharge rate is obtained by dividing this quantity by 2. Thus the discharge rate
required to attain a 30 percent carbon dioxide concentration within two minutes is:
Equation A.6
The rate calculated in A.6 must be checked to ensure that it is high enough to attain the design
concentration is seven minutes. In general, the seven minute constraint will be satisfied if the
rate calculated in Equation A.6 is high enough to discharge at least 28.6 percent (2/7) of the
required quantity of carbon dioxide in the first two minutes. The maximum carbon dioxide
concentration that can be attained in seven minutes by a total flooding system discharging at
the rate calculated in Equation A.6 can be calculated by the following formula.
Equation A.7
Where:
= minimum concentration at two minutes, 0.30
= maximum concentration at seven minutes
= natural logarithm
Solving Equation A.7 for
Equation A.8
Where:
= exponential function
= 1 - EXP (ln (1-0.3)/(0.286) = 1 - 0.287 = 0.713 or 71.3%
Thus the discharge rate calculated in Equation A.6 will be adequate to attain all design
concentration less than 71.3 percent within seven minutes after the start of carbon dioxide
discharge. This rate will be insufficient to attain design concentrations in excess of 71.3 percent
within seven minutes, and thus the required discharge rates for these systems shall be
calculated by dividing the required quantity of carbon dioxide by seven minutes.
W
V
-----
1.080.0396 lb./ft.
3
0.0428 lb./ft.
3
==
R 0.0428 lb./ft.
3
/2 minutes 0.0214 lb./ft.
3
min==
1 C
1
–ln
1 C
2
–ln
-------------------------
0.286=
C
1
C
2
ln
C
2
C
2
1 EXP 1 C
1
–0.286ln==
EXP
C
2