Protecting wine assets

A vast amount of wine spends much of its time stored in wooden barrels or stainless steel tanks wrapped in highly combustible expanded polystyrene (EPS) foam insulation to maintain an even temperature.

What would happen to these valuable and appreciating assets if fire broke out in a wine barrel storehouse or in a wine tank farm?

Australian scientists were asked this by Fosters Group Limited and Beringer Blass Wine Estates through consultants FM Global, who developed the protocol on which the tests were based.

"The conclusions of the test program for wooden barrels showed they did not induce a self-sustained fire spread and growth in the dry barrel stack. The minimum ignition source size that would induce self-sustained fire growth on the indoor dry barrels arrangement is between 80 and 1000 kW."

Dr Vivek Apte, Project Leader of CSIRO's Fire Science & Technology Laboratory, says, "A major purpose of the two streams of testing was to discover at what level an ignition source, accidental or intentional, would lead to a self-sustained fire."

The barrel testing program set out to investigate whether and how a large ignition source would induce self-sustained fire spread and growth on the external surface of wooden barrels placed in portable racks and stored in a three-dimensional array. Whether fire would continue to spread and grow along the width, depth and height of the barrel stack even after the ignition source had burned out.

The ignition source represented a fire that was accidental or deliberately started.

The objective of the tank tests was to examine whether a large ignition source, such as a pool fire with its flames impinging on the source tanks, would induce self-sustained fire spread in the EPS insulation on the surface of the source tanks.

Dr Apte says, "The intention was to investigate whether the fire would continue to spread and grow on the EPS insulation after the burnout of the ignition source."

'The ignition source represented burning of a fuel spill from a truck or from a mineral oil-filled transformer.'

The wooden wine barrels were placed in the normal storage position - horizontally in portable racks - and a large ignition source in the form of a pool fire was located on the ground in the flue between the two central columns of barrels.

The stainless steel wine storage tanks were covered on the top and the sides with insulating EPS cladding. Two vertical source tanks erected close to each other were directly exposed to the flames from a pool fire located between the two tanks. Parallel to the source tanks was a row of two vertical target tanks, each fabricated as a one-third arc of a full tank, with EPS cladding.

The barrel tests were conducted with different ignition sources, using both dry and wet barrels. Two tank tests were conducted: one with a separation distance of 0.5 m between the source and target tanks, and the other with a separation distance of 2 m.

The conclusions of the test program for wooden barrels showed they did not induce a self-sustained fire spread and growth in the dry barrel stack.

The minimum ignition source size that would induce self-sustained fire growth on the indoor dry barrels arrangement is between 80 and 1000 kW.

Dr Apte says, "It was most interesting to note that a small water leak from the barrels is highly effective in rapidly arresting and preventing fire growth under a 550 kW ignition source."

A separation distance of 0.5 m between source and target tanks will not provide adequate fire safety. In this test, aluminium sheets covered the EPS, and the bottom edge of the EPS insulation was uncapped. Under these conditions, fire will rapidly spread vertically and laterally on both the source and target tanks.

CSIRO found that: a separation distance of 2 m between the source and target tanks, with sealed bottom edges of EPS on the source and the target tanks, would minimise the chance of ignition of the target tanks. In the test, the EPS on the target tanks did not ignite, but underwent partial softening and shrinkage. Dr Apte says that the most significant information for use in assessing the test results against the performance criteria came from the video records and visual observations, while temperature and heat flux measurements were made wherever possible.