1024 PREVENTION OF TOXIC CHEMICAL RELEASE
(^102030405060708090100)
0
z
100
90 80 70 60 50 40 30 20 10
0
Z
Y
X
100
90
80
70
60
50
40
30
20
10
0
10
20
30
40
50
60
70
80
90
100
20 18 16 14 12 10
8 6 4 2
F 0
D
B
E
21
97.5 %
Y
START
(LEL)
A
Combustible gas (Acetylene per cent by Volume)
Inert gas (Nitrogen) per cent by Volume
(Taking Equipment out of Service)
X
START
(LEL)
Line of LEL’S
C
20%
Lower Limit 2.5 % C
H 2
pure and dry 2
97.5% air dry
0% N
inert added 2
Line of flammabilitylimits from Fig.1
C
H 2
and air only 2 zero inerting
nitrogen
Explosion (2)
range
narrowed
on
addition of
nitrogen
Line of UEL’s
Upper Limit 80% C
H 2
pure and dry 2
20% Air dry
0% N
inert added 2
2.5
4.8
Inert Gas (Nitrogen) per cent by Volume
(Putting Equipment into Service)
Air per cent by Volume
(Equivalents)
Oxygen equivalent in air per cent by Volume
(1)
FIGURE 1
Acetylene-Air-Nitrogen purging chart (atmospheric temperature and pressure).
C016_011_r03.indd 1024C016_011_r03.indd 1024 11/18/2005 1:12:55 PM11/18/2005 1:12:55 P