Page 83 - Dust Explosions in the Process Industries

56 Dust Explosions in the Process Industries
1000 ,

500 -

- 300 -
VI
2a 200 -
-
‘d
r:
I
c
? 100 - MAIZE STARCH
%
50
30 c

1 2 5 10 20 50
CONTENT OF COMBUSTIBLE GAS IN AIR EXPRESSED
AS PERCENTAGE OF MINIMUM EXPLOSIBLE CONCEN-
TRATION OF THE GAS IN AIR ONLY

Figure 1.66 Influence of low concentrations of various organic solvent vapors in the air on the max-
imum rate ofpressure rise during explosions of organic dusts in a 20 liter closed vessel (From Dahn,
1986).

not always easy to achieve in practice, and supplementary means of protection (water
barriers etc.) must be employed.
A useful, more general analysis of the problem of inerting combustibledust clouds by
adding inert dust was given by Bowes, Burgoyne, and Rasbash (1948).
Table A.3 in the Appendix gives some experimental data for the percentages of inert
dusts required for inerting clouds in air of various organic dusts and coals.

1.3.11
CONCLUDING REMARKS

Section 1.3 is included primarily to bring into focus the various important parameters
that influenceignitability and explosibility of dust clouds and to indicate main trends of
their influence.
The extent to which the reader will find quantitativedata that satisfy specific needs is
bound to be limited. In particular, size distributionsand specific surface areas of dusts of
a given chemistry can vary considerably in practice. However, the quantitativeinforma-
tion provided can help in identifying the type of more specificinformation needed in each
case. In many cases, the required data have to be acquired by tailor-madeexperiments.