CXS490 New Technology
Inert Gas Fire Extinguishants
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Introduction
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relevant standard is NFP-A2001
At least four inert gases or gas mixtures commercialized
clean total flooding fire suppression agents
design concentrations of 35-50% by volume
reduces ambient oxygen concentration
14% to 10% by volume
agents mixed with air - extinguish by physical mechanisms
agents consist of nitrogen, argon & blends of these
One blend contains 8% carbon dioxide.
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Inert Gases
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Not liquefied gases like Halocarbons
stored as high pressure gases
require high pressure storage cylinders
may have storage volume and weight impact.
use pressure reducing devices
at or near the discharge manifold
reduces the pipe thickness requirements
alleviates concerns regarding high pressure discharges.
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Inert Gases
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Discharge times - one (typical) to two minutes
limit some applications - rapidly developing fires
(explosions)
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Not subject to thermal decomposition
form no byproducts.
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electrically non-conductive
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Physiological Effects
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Primary health concern
effect of reduced oxygen concentration on occupants
reduced oxygen extensively researched & studied
Many countries granted health & safety approval for
use of inert gases in occupied areas in the workplace
One product contains 8% carbon dioxide
intended to increase blood oxygenation &
cerebral blood flow in low oxygen atmospheres
Physiological Effects
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Inert gas agent IG-541 (Inergen)
contains 8% carbon dioxide &
approved by the U.S. EPA SNAP rules
safe alternative to halon 1301 - total flooding systems
At elevated concentrations
carbon dioxide not safe for human exposure &
lethal at fire extinguishing concentrations
Physiological Effects
Generic
Name
IG-01
IG-55
IG-100
IG-541
Maximum
Maximum
Maximum
Exposure
Trade
Exposure
Exposure
Concentration
Name
Concentration Concentration
Above 53%
5 minutes
3 minutes
(Volume %)
Argotec
43
52
(*4)
Argonite
43
52
(*4)
NN-100
43
52
(*4)
Inergen
43
52
(*4)
Notes
1: Nominal maximum discharge time is 60 seconds in all cases
2: Inert gas systems designed to concentrations below 43 percent (corresponding to an
oxygen concentration of 12 percent, sea level equivalent of oxygen) shall be
permitted, where means are provided to limit exposure to no longer than 5 minutes.
3: Inert gas systems designed to concentrations between 43 and 52 percent
(corresponding to between 12 and 10 percent oxygen, sea level equivalent of oxygen)
shall be permitted, where means are provided to limit exposure to no longer than 3
minutes.
4: Inert gas systems designed to concentrations between 52 and 62 (corresponding to
between 10 and 8 percent oxygen, sea level equivalent of oxygen) shall be permitted
given the following:
(a) The space is normally unoccupied.
(b) Where personnel could possibly be exposed, means are provided to limit the
exposure to less than 30 seconds.
(c) Inert gas systems designed to concentrations above 62 percent (corresponding
to 8 percent oxygen or below, sea level equivalent of oxygen) shall only be
used in unoccupied areas where personnel are not exposed to such oxygen depletion.
Environmental Factors
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Inert gas agents are neither
ozone depleting substances nor
greenhouse gases
pose no risk to the environment
Environmental Factors
Generic
Name
Trade
Name
Ozone
Depletion
Potential
IG-01
IG-55
IG-100
IG-541
Argotec
Argonite
NN-100
Inergen
0
0
0
0
Global
Warming
Potential
(100 year)
0
0
0
0
10
Physical Properties
Generic Name
IG-541
IG-55
Trade Name
Inergen Argonite
IG-01
IG-100
Argotec
NN100
Agent Composition
Nitrogen
52%
50%
-
100%
Argon
40%
50%
100%
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Carbon Dioxide
8%
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k1 (m3/kg)
0.65799
0.6598
0.5612
0.7998
k2 (m3/kg)
0.00239
0.00242
0.00205
0.00293
Specific Volume (m3/kg)
0.697
0.708
0.602
0.858
Gas Density
20oC, 1 atm kg/m3
1.434
1.412
1.661
1.165
Properties
Physical Properties
Generic Name
IG-541
IG-55
IG-01
IG-100
Trade Name
Inergen Argonite Argotec NN100
Extinguishing Design Concentration
(% Vol.)
Minimum Class A fire (% Vol.)
36.7
41.1
39.9
39.0
13.3
12.3
12.6
12.8
Class B Heptane (% Vol.)
31.7
36.5
39.3
33.6
Minimum Class B fire (% Vol.)
41.2
47.5
51.1
43.7
12.3
11.0
10.2
11.8
47.3
*
61.4
41.7
11.0
-
8.1
12.2
Oxygen (% Vol.)
Oxygen (% Vol.)
Inerting - Methane/Air (% Vol.)
Oxygen (% Vol.)
* Not Reported
Flooding Factor Calculation
(X)
X - volume of inert gas ONLY added at 14.7 psia, 70oF
(1.013 bar, 21oC) per volume hazard space (ft3/ft3 or m3/m3)
VS - specific volume at 70oF (21oC) at 14.7 psia (1.013 bar)
(ft3/lb or m3/kg)
sV - specific volume at lowest temperature at 1 atmosphere
(ft3/lb or m3/kg)
t - minimum anticipated temperature (oF or oC)
c - inert gas design concentration (%)
Specific Volume
Inert gas
k1
k2
k1
k2
Unit type
SI
SI
English
English
IG-01 (Argotec
0.5612
0.00205
8.40299 0.018281
IG-55 (Argonite)
0.65979 0.001207
9.8809
0.021496
IG-100 (Nitrogen)
0.7997
0.00293
11.973
0.0261
IG-541 (Inergen)
0.659
0.0024
9.858
0.0214
Flooding Factors (X)
The calculation result in a series of flooding factors
required to achieve various inert gas concentrations.
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Flooding Factors (X)
36
0.446368
37
0.462119
38
0.478122
39
0.494385
40
0.510918
41
0.527728
42
0.544825
43
0.562220
44
0.57992
45
0.597945
46
0.616297
47
0.634993
48
0.654044
49
0.673466
50
0.693272
51
0.713478
52
0.734101
36.1
0.447932
37.1
0.463708
38.1
0.479736
39.1
0.496026
40.1
0.512586
41.1
0.529424
42.1
0.546551
43.1
0.563976
44.1
0.581711
45.1
0.599765
46.1
0.618151
47.1
0.636882
48.1
0.655970
49.1
0.675429
50.1
0.695274
51.1
0.715522
52.1
0.736187
36.2
0.449498
37.2
0.465299
38.2
0.481354
39.2
0.497670
40.2
0.51426
41.2
0.531124
42.2
0.548280
43.2
0.565736
44.2
0.583501
45.2
0.601588
46.2
0.620008
47.2
0.63877
48.2
0.657899
49.2
0.677396
50.2
0.69728
51.2
0.717569
52.2
0.73828
36.3
0.451067
37.3
0.46689
38.3
0.482973
39.3
0.499316
40.3
0.515931
41.3
0.532826
42.3
0.55001
43.3
0.567498
44.3
0.585295
45.3
0.603415
46.3
0.621869
47.3
0.640670
48.3
0.65983
49.3
0.679367
50.3
0.699291
51.3
0.719621
52.3
0.740372
36.4
0.452638
37.4
0.46849
38.4
0.484596
39.4
0.500966
40.4
0.517608
41.4
0.534532
42.4
0.551747
43.4
0.569264
44.4
0.587093
45.4
0.60525
46.4
0.623733
47.4
0.642570
48.4
0.661768
49.4
0.681341
50.4
0.701306
51.4
0.721677
52.4
0.742471
36.5
0.45421
37.5
0.470088
38.5
0.486221
39.5
0.502617
40.5
0.51929
41.5
0.536240
42.5
0.553485
43.5
0.571032
44.5
0.588893
45.5
0.607079
46.5
0.625601
47.5
0.644473
48.5
0.663708
49.5
0.683320
50.5
0.703324
51.5
0.723737
52.5
0.744575
36.6
0.45579
37.6
0.471690
38.6
0.487848
39.6
0.504272
40.6
0.520970
41.6
0.537951
42.6
0.555226
43.6
0.572804
44.6
0.590697
45.6
0.608916
46.6
0.627472
47.6
0.646380
48.6
0.66565
49.6
0.685302
50.6
0.705347
51.6
0.725801
52.6
0.746682
36.7
0.457367
37.7
0.473294
38.7
0.48948
39.7
0.505929
40.7
0.522655
41.7
0.539665
42.7
0.556970
43.7
0.57458
44.7
0.59250
45.7
0.610756
46.7
0.629347
47.7
0.648291
48.7
0.667600
49.7
0.687289
50.7
0.707374
51.7
0.727870
52.7
0.74879
36.8
0.458949
37.8
0.474901
38.8
0.491111
39.8
0.50759
40.8
0.524343
41.8
0.541382
42.8
0.558717
43.8
0.576357
44.8
0.594314
45.8
0.612600
46.8
0.631226
47.8
0.65020
48.8
0.669551
49.8
0.68928
50.8
0.709404
51.8
0.729943
52.8
0.750912
36.9
0.460532
37.9
0.476510
38.9
0.492747
39.9
0.509252
40.9
0.526034
41.9
0.543102
42.9
0.560467
43.9
0.57814
44.9
0.596128
45.9
0.614447
46.9
0.633107
47.9
0.652123
48.9
0.671507
49.9
0.691274
50.9
0.711439
51.9
0.732020
52.9
0.753033
Sample Calculation - Inert Gas
Room houses electronic equipment
Ambient temperature is 70° F
Room Dimensions are:
Length: 40 feet
Width: 20 feet
Height: 10 feet
Room Volume = L x W x H
= 40 x 20 x 10
= 8000 cubic feet
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Amount of Agent
A=VxX
where
A is amount of agent (m3 or ft3)
V is volume of space (m3 or ft3)
X is flooding factor of space from calculation or chart
(m3/m3 or ft3/ft3)
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Sample Calculation - Inert Gas
Using IG-541 Inergen
Class A design concentration is: 39.9%
Maximum Human Exposure Concentration for 5 minutes is: 42.8%
Maximum Human Exposure Concentration for 3 minutes is: 52.3%
Available cylinder sizes for Inergen are:
205 ft3, 266 ft3, 355 ft3 and 439 ft3
Flooding factor for 39.9% concentration is: 0.509252
Amount /Volume of Inergen required to create a 39.9%
concentration in an 8000 ft3 enclosure is:
A = V x X = 8000 x 0.509252 = 4074 ft3 of Inergen
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Sample Calculation - Inert Gas
Cylinder Selection
Round up to 10 439 ft3 cylinders
AACTUAL = NumberCYLINDERS x CylinderSIZE
= 10 x 439 = 4390 ft3
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Sample Calculation - Inert Gas
Check to determine the actual concentration that will be achieved, by
looking at “Flooding Factors for Inert Gases @ 70° F for selected
concentrations.
0.54875 relates to a concentration of ≥ 42.2% but ≥ 42.3%.
This is < maximum allowable concentration of 42.8%
for 5 minute human exposure & > Class A design concentration 39.9%
The quantity of Inergen is acceptable.
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