Quick Dips

Furnishing Fire Risk

Scientists at the Wool Research Organisation of New Zealand (WRONZ) are adding their voices to concerns being expressed in the wake of recent tragic house fires, pointing to research undertaken 15 years ago which demonstrate the danger of flammable materials.

Dr Peter Ingham, head of Chemical and Product Innovation at WRONZ, says that they are concerned that the current emphasis on new building materials could sidetrack attention from the real culprit -- furnishings.

"We have extensive evidence that it is the contents of buildings that both start and spread fires," Ingham says. "The traditional furniture and mattress fillings, such as horsehair and kapok, were relatively fire resistant. However, today the majority of homes are full of polyurethane foam, which is both highly combustible and produces thick smoke and toxic fumes. Combine this with the commonly used and highly flammable polypropylene covers and you have what virtually amounts to a very dangerous fire bomb right there in the middle of your lounge."

Ingham says thatWRONZ has carried out considerable research on furnishing flammability, including full-scale burning experiments in houses scheduled for demolition. This involved dropping a lighted match on to a couch covered in polypro-pylene, probably the most common domestic upholstery fabric.

A video taken at the time is called Four and a Half Minutes -- that's the point the fire brigade took over because they were concerned for the safety of adjoining properties due to the intensity of the fire. Flashover actually occurred three and a half minutes after the match was dropped.

"Smoke detectors in an adjoining room went off approximately two minutes after the match ignited the couch, and within another 40 seconds, visibility in this room was effectively zero. The rest of the house would have been smoke-filled inside another minute, making the rescue of children and invalids difficult, if not impossible," says Ingham.

"Given that the New Zealand Fire Service aims for a turnout time in urban areas of less than six minutes, you can see the problem."

When the experiments were conducted in the early 1980s, WRONZ argued for the introduction of regulations to control the fire resistance of home furnishings. The UK has regulations requiring the use of non-combustible foams and protective upholstery fabrics. Wool fabrics pass these standards easily, according to Ingham, and most synthetics can be economically treated with a fire retardant backcoating to comply. Such protective fabrics protect even the most flammable foams from ignition by lighters, matches and cigarettes, thus markedly improving fire safety.

Other experiments showed that polyurethane- filled furnishings covered with cotton and other cellulosic fabrics compounded the problem.

"A cigarette falling on to such furniture can smoulder virtually unnoticed for hours. Then all at once flaming ignition occurs and whoosh, seconds later the flames will be licking the ceiling."

A typical lounge suite contains around 18 kilograms of foam, which has a calorific value equivalent to about 15 litres of petrol. Polyurethane foam is the greatest danger in the home, as it ignites easily, and flame spread can be extremely rapid.

"We have conducted experiments on different bedding materials, in which we ignited a cotton sheet laid over a polyurethane mattress. The results were really quite frightening."

With an acrylic blanket, the bed was completely engulfed in flames within seven minutes, while with a synthetic duvet, the same point was reached in only five. However, when a pure wool blanket was used, after 10 minutes only a small area was burning, and even after half an hour, only one side had burnt, with very little flame involved, because of wool's natural charring effect.

"We believe that it is vital that more urgent consideration be given to what goes into our homes when it comes to fire protection," says Ingham.

"The cost of treating synthetic and cotton fabrics is not high and its technically quite standard. Therefore, why haven't regulations been introduced in New Zealand to reduce the flammability of furnishings?"

A wool-filled overlay and blanket provide excellent protection with very slow combustion. After five minutes the flame continues in the polyester/cotton sheeting, but the overlay and blanket remain relatively unscathed.

A polyester-filled duvet bursts into fast-burning flames only six minutes after a simulated cigarette sets the sheets alight.

Photos courtesy of Wool Research Organisation of New Zealand