Inflatable Tunnel Plugs

Lindstrand Technologies Ltd created a new approach to fight tunnel fires by designing an inflatable tunnel plug: a structure which seals the tunnel, thus cutting off the flow of air to the fire and depriving it of the oxygen it needs to burn. Moreover, this device also inhibits the spread of smoke and, in the case of potential terrorist attack, any other harmful agents in the air.

When not in use, inflatable tunnel plugs (in a deflated state) are pre-positioned at 100m intervals in the tunnel and, in the event of a fire, are inflated by remote control using encrypted high frequency transmissions. Therefore this system has the added advantage that all operations can be handled at a distance from the fire, and with much less danger to the firemen’s lives.

Inflatable tunnel plugs have a zip in the centre allowing human passage through the plugs from both sides so that a person caught on the wrong side can easily escape.

Inflatable tunnel plugs are manufactured from a medium weight glass fibre fabric, coated with specially formulated solvent free silicone rubber with aluminium flakes added for pigmentation. Inorganic fillers and a relatively low add-on weight enhance fire retardant performance of the silicone rubber. The material is temperature resistant up to 450C°, and if the temperature exceeds that level the fabric will turn into sand thus releasing no toxic gasses while burning.

Inflatable tunnel plugs provide an affordable and effective solution for fire extinguishing in tunnels. They can be installed in the shortest time with minimum tunnel preparation. Inflatable tunnel plugs function independent of other tunnel services and can be automatically deployed quickly when necessary.

Currently London Underground Victoria Line has installed Lindstrand inflatable tunnels plugs.

Full scale tunnel fire testing has been conducted at the Brenner Pass in Italy and in the Hague in Holland. Both tests proved the ability of the plug to extinguish the fire in minutes with no damage to the tunnel.