TNT Equivalency of Unconfined Aerosols of Propylene Oxide

  • A. Apparao High Energy Materials Research Laboratory, DRDO, Pune
  • C. R. Rao ACRHEM, University of Hyderabad, Hyderabad
Keywords: Aerosol, propylene oxide, TNT equivalency, blast data, positive impulse


The unconfined aerosols of propylene oxide (PO) are formed by dispersing the fuel in air. These aerosols undergo detonation by suitable initiation and produce high impulse blast. Tri-nitro Toluene (TNT) equivalence is an important parameter used to represent the power of explosive materials and compare their relative damage effects wrt TNT. The parameters commonly used for estimation of TNT equivalency are total energy of explosive source and properties of resulting blast wave, viz., blast peak overpressure and positive impulse. In the present study, the unconfined aerosols of 4.2 kg PO were formed by breaking open the cylindrical canister with the help of axially positioned central burster charge and then detonated using a secondary explosive charge after a preset time delay. The resulting blast profiles were recorded and the blast parameters were analysed. Being a non-ideal explosive source, the TNT equivalency depends on fraction of total energy utilised for blast formation, the rate of energy release, cloud dimensions, and concentration of fuel. Hence, various approaches based on energy release, experimental blast profiles, triangulated blast parameters, and ground reflected blast parameters were considered to determine the TNT equivalency of unconfined PO aerosols. It was observed that the TNT equivalency is not a single value but vary with distance. The paper provides various options for weapon designer to choose a suitable approach for considering TNT equivalency. The scaling laws established from the experimental data of unconfined aerosols of PO for blast peak over pressure and scaled impulse help in predicting the performance for different values of fuel weight and distance.

Defence Science Journal, Vol. 64, No. 5, September 2014, pp.431-437, DOI:

Author Biographies

A. Apparao, High Energy Materials Research Laboratory, DRDO, Pune
Dr A. Apparao is presently working at High Energy Materials Research Laboratory (HEMRL), Pune. He has been responsible for establishing various technologies, viz., Fuel-air Explosive (FAE), Explosive Reactive Armour (ERA), thermobaric explosive and explosive metal welding technologies. He has 51 research publications and 78 technical reports to his credit. He is recipient of many awards and honours and DRDO Scientist of the Year (2009) is one of them.
C. R. Rao, ACRHEM, University of Hyderabad, Hyderabad
Prof. C. Raghavendra Rao, obtained his PhD (Statistics) and MTech (CS & Engineering) from Osmania University. Presently he is Professor in the School of Computer and Information Sciences, University of Hyderabad. He is a Associate Faculty at ACRHEM, Center for Earth and Space and Center for Health Phycology. His current research interests are simulation and modeling, rough sets, and knowledge discovery. He guided 8 PhD, 40 MTech, 8 MPhil students. Nearly he has 55 journal and 70 proceeding papers to his credit.
How to Cite
Apparao, A., & Rao, C. (2014). TNT Equivalency of Unconfined Aerosols of Propylene Oxide. Defence Science Journal, 64(5), 431-437.
Chemical Science & Technology