Role is to prevent external flame there is flammable gas fleeing into the equipment, pipe or prevent fire in the equipment, the spread between the pipes.

作用是防止外部火焰窜入存有易燃易爆气体的设备、管道内或阻止火焰在设备、管道间蔓延。阻火器机理是通过传热作用和器壁效应将火焰被熄灭在管道中。

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The fire service said the workers tried and failed to extinguish the blaze and it spread behind the external cladding "extremely quickly due to the dry nature of the material".

BBC: The damage to the roof