Environmental Engineering Reference
In-Depth Information
miscellaneous elements and metal powder [
1
,
2
]. Regardless of the composition, the
oxygen balance can be calculated based on the four elements of C, H, O, and N.
The universal formula of explosives can be written as C
a
H
b
O
c
N
d
, wherein C and H
are
flammable agents, and O is an oxidizer. During the explosion, the explosive
molecules are broken, new stable products are formed through the redox and
reforming reactions with a large amount of heat released. These products are mainly
CO
2
,H
2
O, CO, N
2
,O
2
,H
2
, C, NO, NO
2
,CH
4
,C
2
N
2
,NH
3
, and HCN. Types and
quantity of explosion products are not only affected by pressure and temperature
during the explosion, but also related to the amount of its
fl
fl
flammable agents and
oxidants. Generally, oxygen balance and oxygen coef
cient are used to express the
relative content of oxygen and
flammable elements.
The oxygen balance of explosives is the excess or insuf
fl
cient oxygen compared
to that completely oxidizes carbon and hydrogen in the explosive to CO
2
and H
2
O.
If the explosive contains other combustible elements, such as aluminum, the cal-
culation should be done based on that aluminum is completely oxidized to Al
2
O
3
.
The oxygen balance (%) of explosive C
a
H
b
O
c
N
d
can be calculated as the following:
2
c
2a
þ
16
Oxygen balance
¼
100
ð
3
:
1
Þ
M
where,
16
atomic weight of oxygen;
M
molecular weight of explosive.
According to the explosive formulation, oxygen contents of different explosives
will be different, and there are three kinds of oxygen balance as the following:
With c
[
2
0, there is excess oxygen after oxygen in the explosive to
oxidize all combustible elements completely, which is called as positive oxygen
balance. And this explosive is called oxygen-positive explosive.
With c
2a
þ
¼
2
0, the oxygen in explosive is just enough to oxidize all
combustible elements completely, which is called as zero oxygen balance. This
explosive is called oxygen-zero explosive.
With c
2a
þ
0, the oxygen in explosive is not enough to oxidize all
combustible elements completely, which is called negative oxygen balance. This
explosive is called oxygen-negative explosive.
For example, in nitroglycerin (C
3
H
5
O
9
N
3
), its oxygen balance is:
2a
þ
2
\
5
2
9
2
3
þ
16
Oxygen balance
¼
100
¼þ
3
:
5
%
227
and it can also be expressed as +0.035 g/g explosive.
In PETN with formula of C
5
H
8
O
12
N
4
, its oxygen balance is the following:
