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The Performance Of Sprinklers For Tunnel Protection Essay

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One of the early test programs to study the performance of sprinklers for tunnel protection was conducted in the Ofenegg tunnel in Switzerland in 1965. The tunnel was an old single track railway tunnel, 4 m wide at the base and 6 m high. Three fire sizes obtained with aircraft petrol fuel were used in the test with following specifications: (a) 100L and 6.6 m2 pool size; (b) 500 L and 47.5 m2 pool size; and (c) 1000 L and 95 m2 pool size. Two lines of sprinklers were installed on the ceiling of the tunnel. The water capacity was 19 L/(min m2). There was no information on the sprinkler system activation time.
The fires developed very quickly during the tests and the maximum temperature was reached 1 to 2 minutes after ignition. Temperatures in the tunnel were quite high with maximum temperatures near the ceiling ranging from 1200 degree Celsius to 1400 degree Celsius prior to sprinkler activation.
The sprinklers were able to extinguish all of the fires within a short period of time. But, a significant quantity of hot steam was obtained during fire suppression. Visibility was found to decrease because of hot steam and cooling of the smoke layer by the sprinklers’ discharge. Smoke and hot steam were pushed a considerable distance from the fire site, resulting in higher temperatures than without sprinklers at some locations in the tunnel.
After the fire was extinguished, the fuel continuously evaporated with the vapour spreading along the tunnel. The vapour was re-ignited in the

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