One coolstore burns every month – study

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Thousands of coolstores and other industrial buildings around New Zealand are likely to continue to go up in flames at the rate of one a month.

In little more than three months since the April 5 inferno at the Icepak coolstores at Tamahere two more coolstores have caught fire – at Katikati on June 10 and Hastings last week (July 17) – a frequency anticipated by a 2006 study.

Thousands of mostly industrial buildings in New Zealand have for more than 30 years been constructed using polypanel or EPS (expanded foam polystyrene panel system). Smooth, washable EPS, a godsend for any industry needing hygienic workplaces, is the first choice lining material in controlled atmosphere food processing and storage facilities.

More than 750,000 square metres of EPS is estimated to be produced in New Zealand each year.

And, says consulting engineer Bob Nelligan, “from its earliest days, the use of EPS created a new and dangerous fire hazard. Once the expanded foam was exposed to even a moderate heat flux it ignited and burned with alarming results.”

Using Fire Service records Nelligan has shown that between October 2000 and December 2004 there were at least 56 fires in buildings using EPS – an average of more than one fire every month for four years.

He notes that in many of the fires the EPS panelling “has directly contributed to losses of the building and its contents.”

The major causes of the fires are consistent: electrical faults, heating from solid fuel equipment, and usually when facilities are being renovated, welding, gas cutting and braising.

An examination of 26 fires showed that an electrical cause occurred twice as much as any other.

In 2006, Nelligan wrote a 79-page report on EPS and its fire risk as part of his studies for a Masters degree in fire engineering at Canterbury University.

His aim was help designers, builders and facility operators identify fire issues with EPS panels. He suggested a range of guidelines designed to help avoid fires or, should they occur, to limit their potentially devastating effects.

But as he told the NZ Herald two years later on April 12 – after the Icepak coolstores fire claimed the life of firefighter Derek Lovell and injured seven others – the guidelines were not being adopted as quickly as the Fire Service and insurance industry would like.

Nelligan also notes in his report that “despite the urgings of insurers and the Fire Service, a large number of food factories, cool and cold stores have been built in New Zealand in the past 20 years without sprinkler protection.”

He cited a UK study that concluded that “the plant rooms in cold stores require special consideration, particularly when ammonia refrigerant is used. Ammonia is flammable and can be explosive at 15-28% by volume [in air] … Explosion venting of plant rooms should be considered.”

At Tamahere, another more highly flammable refrigerant, HyChill-50, was in use. Its flammability occurs at a much lower volume in air – just 1.9%.

Nelligan’s report also includes an example of a fire in the USA that is chillingly similar to the Tamahere blaze.

In 1991 in Madison, Wisconsin, two coolstores in a five building complex were destroyed together with their contents, 13 million pounds of butter, 15.5 million pounds of cheese and other foods. The loss was estimated at US$100 million.

All the stores were of polypanel construction, a single ammonia system serviced all the coolers and product was stored on pallets and metal racking.

“Despite arriving on the scene within two minutes of the alarm, and observing that sprinklers were activated, fire officers determined that it was too dangerous to enter the burning freezers due to a layer of heavy black smoke and the sound of creaking metal.

“Plastic strips over doorways could be seen being drawn into the freezers indicating a large inflow of air, suggesting that the fire had vented through the roof but this could not be confirmed because of the smoke. Despite mounting an external attack, fire fighters saw the fire spread to other freezers as the first fire-affected freezer walls collapsed and the ceiling fell. The fire continued to burn for over 24 hours and still contained deep-seated interior burning areas four days later. The fire was finally declared to be out eight days after it was first discovered.

“While the damage was so extensive that a cause could not be established beyond doubt, an electric fork hoist was considered to be a primary suspect.”

In 2006 Nelligan noted that “what is clear is that as it is presently used in New Zealand, EPS presents a far greater fire hazard than is generally appreciated by engineers and architects who specify its use.”

Tamahere, Katikati, and Hastings people could add that it is also a far greater hazard than they appreciated too.

Bob Nelligan’s full report is here (pdf) rnelligan06

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