While the cause of the explosion that destroyed the BestCare Pet Food Factory has been determined to have been a faulty regulator to the gas supply, the NSW Deputy Coroner concluded the incident could have been avoided if employees had been trained to shut off the main gas supply valve when the plant was not operational. Alternatively, he said if a system existed whereby Origin Energy had been informed of the proposed closure of the factory for an extended period it could have terminated the gas supply. NSW Deputy State Coroner Carl Milovanovich yesterday released the findings of a coronial inquest at the Westmead Coroner's Court which concluded earlier this month.

Mr Milovanovich found evidence clearly demonstrated no such shutdown system or understanding between the company and the gas supplier existed.

He, therefore, found the explosion and subsequent fire was as a consequence of the failure of the first stage regulator, which allowed high pressure LPG gas to escape unregulated into the facility.

The BestCare Foods Limited facility in Borthistle Rd, in the town's industrial hub, was decimated and reduced to little more than a smouldering skeleton of twisted metal after the enormous explosion on Saturday, January 25.

The blast, just after 7.45pm was felt, heard and seen up to 20km away, severely damaging structures of homes and businesses within a 1km radius of the facility including the Namoi Division State Emergency Service (SES) headquarters.

Residents living near the plant reported seeing a mushroom cloud over the site and small explosions and debris flying through the air shortly after the initial blast, which lifted houses and businesses from their foundations, shattered windows, bent industrial roller doors and ripped air conditioning units from roofs.

The inquest heard evidence from a number of expert witnesses, including WorkCover district inspector Russell Webb and independent mechanical and metallurgical engineer David Corderoy.

Mr Webb, in his investigations, found the explosion was due to the loss of containment of propane and its subsequent ignition.

He found the ignition could have been attributed to any number of factors within the factory premises including static electricity, dust explosion or electrical activity from the switchboard.

The loss of the containment of the propane gas was found to be due to the failure of the first stage-reducing regulator.

Mr Corderoy expressed the same view after undertaking an independent examination commissioned by the coroner on the remains of a number of pieces of equipment including disc holders, the dryer filter boxes and gas filters on the LPG gas tank.

He found the regulator failed owing to the fracture of the low strength cast aluminium disc holder, the manufacture of which was of inadequate strength and fracture toughness for the circumstances.

In handing down his findings Magistrate Milovanovich said secondary factors in the failure were the brittle fracture of the rubber nitrile-sealing disc owing to freezing of the disc from the escaping gas.

"Another factor ... was the manufacture of the filter boxes and tanks in an unmodified aluminium silicon alloy which was of inadequate strength and fracture toughness," he said.

"... that opinion in placing the primary cause for the fire/explosion on the failure of the first stage regulator is from an evidentiary

viewpoint.

"There is no doubt other factors contributed or played a part in the fire/explosion."

He found more frequent maintenance checks may have detected the need to replace parts within the first regulator.