SECTION V
UL EX-4510 12-1-01 Page 5-3
Design
APPLICATION METHOD (Continued)
Total Flooding (Continued)
Using these two variables, the INERGEN agent flooding
factor can be calculated in either of two ways:
First: The formula in NFPA 2001 can be used.
X = 2.303
[
V
S
]
Log10
[
100
]
S 100-C
X = INERGEN agent flooding factor
S = 9.8579 + 0.02143 (T)
T = minimum anticipated temperature in the protected
volume (°F)
C = INERGEN concentration, % by volume
V
S
= Specific volume at 70 °F (cu.ft./lb.) = 11.358 cu.
ft./lb.
NOTE: This calculation includes an allowance for the nor-
mal leakage (efflux) from a “tight” enclosure due to agent
expansion.
The second option for calculating the required quantity of
INERGEN agent is to refer to the “Flooding Factor Chart” on
Page 5-18 in to determine the correct flooding factor to use.
To do this, star t by locating the Minimum Ambient
Temperature in the left column, follow this line across until
you reach the column for the Minimum Design
Concentration needed for the design. The number listed
where the temperature line and the concentration column
meet is the Flooding Factor to be used. NOTE: If the mini-
mum temperature, the minimum design concentration, or
both are not listed, interpolation will be required.
Next, to determine the quantity of INERGEN agent, multiply
the Reduced Hazard Volume by the Flooding Factor deter-
mined from the table.
Complete this step for each area protected by the system.
NOTICE
The actual design concentration of
INERGEN agent cannot be less than the
concentration selected in Step No. 4.
Example
Minimum Ambient Temperature = 60 °F.
Flooding Factor = 0.427
Computer Room
• 2,500 ft
3
x 0.427 = 1067.5 ft
3
INERGEN Agent Required
Subfloor
• 250 ft
3
x 0.427 = 106.8 ft
3
INERGEN Agent Required
Step No. 6 – Adjust Quantity of Agent with Altitude
Correction Factor
It may be necessary at this point to adjust the required ini-
tial INERGEN agent quantity for altitude effects. An
increase in altitude or pressure causes a gas to expand and
occupy more space, which will lead to a higher concentra-
tion if the agent quantity is not reduced accordingly. A
decrease in altitude will cause the opposite effect, increas-
ing the quantity of agent required. This same effect will
apply to increases or decreases in the ambient pressure as
could be caused by ventilation systems designed to main-
tain a positive or negative pressure within the enclosure. To
apply the proper adjustment, first look up the altitude or
pressure of the hazard on the “Atmospheric Correction
Factors Chart” on Page 5-20 in this section.
Determine the total INERGEN agent required by multiplying
the initial INERGEN quantity by the Altitude Correction
Factor. If the altitude is between 3000 ft. below seal level
and 3000 ft. above sea level, use of the altitude correction
factor is optional. Interpolation of the table may be neces-
sary if the actual altitude or pressure is not listed.
Example
The hazard altitude is 4000 feet. Referring to the chart on
Page 5-20, the altitude correction factor of 4000 ft. is 0.86.
Computer Room
• 1067.5 ft
3
INERGEN Agent x 0.86 = 918.1 ft
3
Required
Agent
Subfloor
• 106.8 ft
3
INERGEN Agent x 0.86 = 91.8 ft
3
Required
Agent
STEP NO. 7 – Determine the total system INERGEN
agent quantity required
Add quantities from all areas to determine the minimum
total agent quantity required for the entire system.
Example
918.1 ft
3
+ 91.8 ft
3
= 1009.9 ft
3
Total Agent Required
