The blast at the Indian Institute of Science (IISc) on December 5 that killed an engineer and injured three others was caused by the explosion of a cylinder containing a hydrogen-oxygen mixture, according to Vikram Jayaram, the head of IISc’s internal investigation team.
The incident, which occurred in the Laboratory for Hypersonic and Shockwave Research (LHSR), puts the spotlight on safety practices at the campus. Hydrogen-oxygen mixtures are highly flammable, and can be ignited easily, S. R. Chakravarthy, a professor at the National Centre for Combustion Research and Development at the Indian Institute of Technology, Chennai, said over the phone. This is why it is not a common practice to store such mixtures, and the gases are typically stocked separately and only mixed at the point of use. “When they are mixed together, you have to be very, very careful,” said Dr. Chakravarthy.
Set up in the 1970s, researchers at the LHSR study shockwaves, or pressure waves that move faster than sound. The four researchers, including the deceased engineer, were employees of SuperWave technology, a start-up co-founded by G. Jagadeesh, a professor at the lab. The gases were being combusted to produce shockwaves to study applications like fracking.
The IISc lab in Bengaluru where an explosion took place on December 5. Special Arrangement
In 2016, a similar explosion at the University of Hawaii, Manoa, resulted in a post-doctoral researcher losing her arm. She had been using hydrogen, oxygen and carbon dioxide to create bioplastics. In June 2016, a report based on an investigation by the University of California Centre for Lab Safety (UCCLS) identified multiple safety lapses. One finding said that the researchers had been storing the gas mixture without assessing its hazards. At a ratio of 70:20:10, the three gases were in a highly flammable range. Such a cylinder ought to have been grounded because even an electrical charge as low as 0.02 millijoule (mj) could have set it off. A static discharge lower than 1 mj cannot be perceived by humans. The UCCLS investigation concluded that the mixture was likely ignited when static electricity from the researcher travelled via the cylinder’s metallic pressure gauge and set off the gases. The force of the explosion was calculated to be the equivalent of a blast generated by 70 g of TNT.
Dr. Jayaram told The Hindu that the IISc had, however, been using the cylinders for long, with no problem. “They are stored and transported in lorries on normal roads,” he added. Also, he said, there was no preliminary indication that safety precautions were skipped. However, the cylinder debris is with the police and unless the investigators examine it, they cannot confirm what caused the blast.
Other researchers said the explosion should ideally be investigated by experts from outside IISc.
Anant Bhan, a Bhopal-based bioethicist, said in a text message that an independent investigation would make the findings credible.
Craig Merlic, executive director of UCCLS and the lead investigator into the Hawaii blast, said there was a case for an independent probe into IISc’s safety practices. “An internal investigation could suffer from internal pressures to avoid serious criticisms and changes,” he said via e-mail.
