Page 169 - CW E-Magazine (7-5-2024)

Special Report

in the case of liquefi ed gas cylinders is kitchen platform (or anywhere inside kitchen or home; and not using a PRV
very high (exponential). the house), that cylinder is likely to on small LPG cylinders.
explode due to overpressure. Kitchen fi res
At the moment of bursting of an are common throughout the world due Although these are well-known and
LPG cylinder, a large quantity of to the presence of high temperatures universally practised safety precau-
superheated LPG suddenly mixes with and/or fl ammable stuff like hot oil/ghee tions, surprisingly both are not prac-
the ambient (hot) air. Propane at 2.15- and/or a leak of any fuel (gas or liquid) tised in India.
9.6% in the air forms an infl ammable and/or the presence of inflammable
mixture. A large cloud of this highly solids like dry food grains, wooden If we wish to reduce and eliminate
infl ammable hot gas explodes sponta- cabinets, etc. frequent explosions of LPG cylinders
neously, or in the presence of any hot in India, the above two universal prac-
surfaces, sparks or fl ame. Proposed action plan for preventing tices may be formulated and imple-
these explosions mented by the concerned authorities as
The devastation caused by any The internal pressure of LPG with soon as possible
chemical explosion is directly propor- temperatures above 130°C rapidly ex-
tional to the heat energy released in ceeds the bursting pressure of domes- REFERENCES
the explosion. That, in turn, is propor- tic LPG steel cylinders. Thus, there is 1. https://data.gov.in/resources/num-
tional to the quantity of the explosive no way to prevent explosions of these ber-lpg-accidents-deaths-reported-
involved. This is why the destructive cylinders, if kept indoors and exposed and-compensation-paid-where-lpg-
power of explosions is labelled in terms to the heat of a moderate home fi re. leakage-primary-cause
of an equivalent quantity of TNT. The These LPG cylinders need to be moved 2. https://ncrb.gov.in/sites/default/fi les/
explosion of one kg of TNT releases the to some outside place, e.g., balconies ADSI2017-FULL-REPORT-2017.
energy of 4.2 Mega Joule (MJ) and one etc., like the practice followed in most pdf [Table 1.10 on page 123].
kg of dry gunpowder (with which one other countries and followed in newly 3. https://www.thehindu.com/news/na-
is more conversant) gives 3-MJ. One kg designed and constructed apartment tional/tamil-nadu/article60409245.ece
of LPG has 46.1-MJ. If we assume buildings in metrocities. 4. https://en.wikipedia.org/wiki/
that an LPG cylinder of 14.2 kg capa- Clausius%E2%80%93Clapeyron_
city was only half full when it exploded, For additional safety, we may fi t relation.
it may suddenly add 7x46.1= 322.7-MJ suitable over-pressure release valves
energy to the mechanical (overpres- (PRVs) on all the existing and new LPG ABOUT THE AUTHOR
sure) explosion. In other words, 7-kg cylinders. This will avoid the buildup Ashok Gupta did
LPG is equivalent to 107.6-kg equiva- of any dangerous internal pressure and his Masters in Physics
lent of dry gunpowder in terms of its explosions. However, unless the LPG and Ph.D. in Elec-
explosive power. This is indeed enough from the PRV is safely let out into the trical Engineering
to bring down an RCC roof slab of a open space, the fi re hazard from the (UK). He has many
typical house, as often observed. LPG from the PRV will remain. Elimi- patents and publica-
nation of the explosions by the addition
Thus, LPG cylinder explosions of PRVs will signifi cantly reduce the tions and has 50 years practical ex-
may fi rst involve an overpressure type loss of lives and property from LPG- perience in many technical fi elds: 12
years at Atomic Energy Labs (now
mechanical explosion, followed by a related home fi res. BARC); 29 years at IBP/IOC as GM
highly exothermic chemical reaction (Engg) and GM (Operations), and
type explosion. In the above energy A committee of safety experts can nine years at Shapoorji Pallonji as
equivalence calculations, the additional be appointed to fi nalise the design and Head, Energy Group. He has studied
mechanical energy of bursting of the implementation details of the above and contributed to many technical
heavy gauge (~ 2.8 mm thick, ~12 kg recommendations as early as possible. fi elds like solar energy, biofuels, etc.
weight) steel cylinder due to overpres- Using basic physics and chemistry,
sure is not considered. CONCLUSIONS he has improvised many innovative
In India, the following two unsafe
We have shown above that in case practices are mainly responsible for solutions to practical problems and
of a home fi re, with the present practice the frequent explosions of LPG cylin- achieved safety, technical and eco-
nomic enhancements.
of keeping an LPG cylinder under the ders: keeping LPG cylinders inside the

Chemical Weekly May 7, 2024 169

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