PREVENTION OF TOXIC CHEMICAL RELEASE 1027
X A line and UEL line intersect Acetylene 19%, air 29%,
O 2 6.09%, 52% inserting nitrogen. This is a borderline case
and safely assume nitrogen is explosive. Dilute with acetylene
of nitrogen to render mixture non-explosive.XB On dilution of mixture X with nitrogen, new mixture
will fall along XB and remain non-explosive. In this process,
per cent O 2 will continue to drop below 6.4%. Dilution with
acetylene would effect the same results.When shutting down Add N 2 until acetylene reaches 25%
of experimentally determined lower limit. Thus, 0.25
4.8 1.2%.When starting up Add N 2 until O 2 reaches 0.25 6.4
1.6%. When purging with any gas allow from 6 to 10 volume
space changes before testing for concentrations. The Design
Institute for Emergency Relief Systems (DIERS) Users
Group, which is an affiliate of the American Institute of
Chemical Engineers, has developed some methodology to
design emergency relief systems.^8 The DIERS study was
very extensive and complicated. It involved significant devel-
opments and applications of complex theories and experi-
ments. Some aspects were reaction kinetics under runaway
conditions and multiphase critical flashing flow for viscous
and nonviscous systems. A number of DIERS users have
attempted to simplify the DIERS technology. 9,10,11REFERENCES- Prevention of Acetylene–Air Explosions by Addition of Carbon Dioxide
or Nitrogen. Dr. W. Gliewitzky, Berlin Autogene Metall bearbeitung,
1940, No. 1, 2–5.
2. Bureau of Mines Bulletin 279 (1938). Limits of Inflammability of Gases
and Vapors. H.F. Coward and G. W. Jones.
3. Theoretical and Practical Considerations in Purging Practices.
S. S. Tomkins, A.G.A. Proceedings (1934), pp. 799–828.
4. Precautions in High Pressure Acetylene Work. B.I.O.S. Final Report
No. 1162. Item No. 22, London—H.M. Stationary Office. S.O. Code
No. 51–1275–62. Tests conducted during years 1940, 1941 and
1944.
5. Industrial Explosion Prevention and Protection, Bodurtha, Frank T.,
Engineering Department, E.I. du Pont de Nemours & Company, Inc.,
1st Ed. 1980, McGraw-Hill Book Company, New York City.
6. Kemp Gas Generator Technical Manual, The C.M. Kemp Manufac-
turing Company, Engineered Gas Systems Division, Glen Burnie,
Maryland 21061.
7. Gascope Combustible Gas Indicator, Models 60 and 62, Mine Safety
Appliances Company, 600 Penn Center Boulevard, Pittsburgh, PA
15235.
8. H.G. Fisher. DIERS Research Program on Emergency Relief Systems.
Chem. Engr. Prog., 81 (8), 33–36 (August 1985).
9. H.K. Fauske, G.H. Clare, and M.J. Creed. Laboratory Tool for
Characterizing Chemical Systems. Proceedings of the International
Symposium on Runaway Reactions, Cambridge, MA, March 7–9,
1989. Center for Chemical Process Safety/AIChE, New York, 1989,
pp. 372–394.
10. J.A. Noronha, R.J. Seyler, and A.J. Torres, Simplified Chemical and
Equipment Screening for Emergency Venting Safety Reviews Based on
the DIERS Technology. Proceedings of the International Symposium
on Runaway Reactions, Cambridge, MA, March 7–9, 1989. Center for
Chemical Process Safety/AIChE, New York, 1989, pp. 660–680.
11. D.P. Mason. Highlights of FM Inspection Guidelines on Emergency
Relief Systems. Proceedings of the International Symposium on Run-
away Reactions, Cambridge, MA, March 7–9, 1989. Center for Chemi-
cal Process Safety/AIChE, New York, 1989, pp. 722–750.
12. Chatvathi, Kris, and Richard Siwek. Suppression Systems Mitigate
Explosions, Chem. Eng. Prog. Vol. 92, March 1996.
JOHN D. CONSTANCE (DECEASED)
Consultant, Cliffside Park, N.J.C016_011_r03.indd 1027C016_011_r03.indd 1027 11/18/2005 1:12:56 PM11/18/2005 1:12:56 P