Video: Stadium roof material fire test


Housed as it is on the Otago harbour waterfront, the Forsyth Barr Stadium's roof may seem threatened more by winds, flurries of snow and the odd hail storm than by the ravages of fire.

But the safety of the ethylene tetrafluoroethylene (ETFE) covering in the event of a fire has continued to exercise the minds of the project's opponents.

The debate reared its head most recently on the Otago Daily Times' website comments section, a site where readers get the chance to respond to stories.

The story in question told of Dunedin City Council chief executive Jim Harland's return to Dunedin with offcuts of the material, after a recent visit to the Beijing factory where it was being joined.

The ETFE was manufactured by Vector Foiltec in Singapore and Germany, before being shipped to the factory in Beijing and welded into 1.5m by 5m pillows secured against sections of rope, Mr Harland said at the time.

One respondent asked "how flame-resistant is ethylene tetrafluoroethylene?".

"Can it withstand fireworks or flares?"

Another said information he had found showed "ETFE can burn, produces highly toxic gases when it decomposes from heat or burning, and in a fire, molten ETFE can stick to skin causing burns".

To get to the bottom of how ETFE responds in a fire, the newspaper - literally - applied the blowtorch to ETFE.

Samples of the material were taken to the Dunedin Central Fire Station, and under the supervision of Deputy Chief Fire Officer Trevor Tilyard, burned.

What was instantly noticeable was that the material refused to burn unless a flame was being held directly to it.

The material disintegrated when the flame was applied, but immediately stopped burning when the flame was removed.

Vector Foiltec advertises the material as "self extinguishing", and says drops of molten ETFE will not burn.

That appeared to be the case.

One piece dropped away from the main sheet being burned, but was not alight when it hit the ground about a metre below, and could be picked up straight away.

"I think that's performing very well," Mr Tilyard said.

On the question of fireworks or flares, Carisbrook Stadium Trust chief executive Malcolm Farry said they would not be used at the new stadium.

"We won't be setting off fireworks," he said.

Instead, laser light shows, which had been used "to huge effect" at events worldwide would be used.

"They are the next generation beyond fireworks," he said.

 

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