A grieving relative of one of the victims outside the school. Picture by SS Sundaram

New Delhi, Jan. 28: The technology for gas-run vehicles in India is mature but a tendency to cut costs can lead to tragedies like the one in Mumbai today, according to experts.

If customers decide not to use liquefied petroleum gas (LPG) kits that cost below Rs 20,000 apiece, such accidents can be avoided, they added.

The switchover to either LPG or compressed natural gas (CNG) is taking place in an environment where adequate quality and safety checks on components are non-existent in some cities and not enforced in others.

“We’re virtually sitting on bombs,” said H.B. Mathur, former professor of mechanical engineering at IIT Delhi. Mathur is also an internal combustion engine expert and member of a panel looking at safety aspects of the CNG-powered public transport buses in Delhi.

“There can only be two reasons for a fire in such a vehicle — bulk leak of gas and leak of current,” Mathur told The Telegraph. “And the flames can cause the petrol tank to catch fire.”

Both events — the leak of gas and current — can occur through faulty components, piping or wiring used in the vehicles.

“We’re probably looking at a case of either substandard fittings or faulty retrofitting and poor maintenance,” Mathur said.

The Automobile Research Association of India and the Bureau of Indian Standards have notified the quality of material that should go into the pipes and valves used in any gas conversion kit. But automobile engineers point out that it is up to state transport authorities to enforce these standards.

Automobile engineers said they were worried not about buses or vans from original manufacturers but those which have been converted using special “kits”.

“Vehicles converted to run on CNG and LPG through kits supplied by private entrepreneurs are among those most vulnerable to problems,” said a senior engineer specialising in fuel systems.

Private entrepreneurs offer to convert cars to run on LPG for amounts ranging from Rs 6,000 to Rs 20,000. Automobile engineers point out that LPG, which is 1.5 to 2 times heavier than air, tends to flow downwards and accumulate in floor-level depressions.

“Low-cost conversions are likely to compromise on safety,” said Narendra Pal, deputy manager at the research and development centre of Indian Oil Corporation, Faridabad.

Mathur said a conversion system for LPG should cost about Rs 20,000 but competition is forcing some to cut corners and costs.

A leak by itself wouldn’t lead to a fire, experts said. But faulty wiring in the vicinity of the engine could lead to a leak of current that could in turn set the gas aflame.

During an inspection of a fleet of 6,000 public transport buses in Delhi, engineers were surprised to find that nearly half had faulty wiring susceptible to leaks.

In a CNG-powered bus, there are between 50 and 70 joints between the fuel cylinder and the engine where the gas is burnt with air. Most of these joints were a potential source of a leak, Mathur said.

A CNG-powered vehicle uses a petrol engine to burn air and gas. The CNG is maintained at a pressure of about 200 atmospheres and a series of pressure reducers located between the cylinder and the engine scale down the pressure before it enters the engine.