Expert witnesses at yesterday’s coronial inquest suggest the lack of an earth lead and a volatile toluene gas may have been responsible. Static electricity may also have contributed.

An explosion at the petrol station in June 2008 occurred while Mr Nakad was standing on top of his tanker pumping diesel into it from a fuel tanker.

Mr Nakad’s tanker was then engulfed in flames after an explosion.

Mr Nakad was still breathing after the ambulance arrived but died a short time after.

He suffered horrific burns to a large percentage of his body.

First officer on the scene, Senior Constable Damian Kremers, part of Dubbo’s forensic unit, told Coroner Carmel Forbes that there was no earthing wire grounding Mr Nakad’s tanker.

He believes this may have prevented a build up of static energy delivered from the diesel tanker to Mr Nakad’s tanker.

"The movement of fuel from the tanker ... into Tony’s tanker started a charge and that was discharged when he opened the fuel tank," Mr Kremers said.

Mr Kremers also told the inquiry that remnants from Mr Nakad’s shirt from the post mortem may have been polyester, but he couldn’t be certain.

Heath Pryde, the fuel tanker driver who delivered the diesel to Mr Nakad that day, told the inquiry that only wool or cotton clothing should be worn by people working in the fuel industry.

He also said he would have reported to his supervisor any unsafe practices when transferring the fuel to Mr Nakad’s tanker.

Coronial advocate Sergeant Sheldon Korneluk asked Mr Pryde if there was anything he saw occurring that day which he should have reported.

"Maybe the top loading," Mr Pryde said.

Sergeant Korneluk said Mr Nakad had been working in the industry for a number of years and was confident he knew what he was doing.

In giving evidence yesterday Senior Constable Justin Powell of Dubbo police forensic unit also stated that there was no earth wire in use and nowhere for static electricity to go.

Constable Powell was asked by the Nakad family’s solicitor, Karen Robinson, whether there was an earth lead in a rolled up position in Mr Nakad’s truck and whether earth leads "were normally not used in this scenario".

The police officer agreed this was the case. Fire investigation expert, Inspector Bob Alexander from NSW Fire and Rescue, told the inquest that scientific examinations showed there were traces of toluene, a remnant of petrol, in one compartment of Mr Nakad’s tanker. Toluene is used in petrol manufacturing and doesn’t occur in diesel, the inquiry heard.

"When I was informed about the event involving the decanting of diesel I said, ‘are you sure it’s diesel because it’s difficult for diesel to explode’," Mr Alexander said.

"They said, ‘yes they were decanting diesel’, so I thought that maybe there was some other residue that caused the problem." Work Cover solicitor Peteris Ginters asked Mr Alexander whether petrol vapours left in the compartment of the tanker or contaminated diesel could have caused the explosion.

"Vapours versus contaminated fuel," Mr Ginters said.

But Mr Alexander said he couldn’t say either way what may have caused the explosion.

Members of Mr Nakad’s family were present at the coronial inquest, which continues on tomorrow.