Fire- and Extinguishing Tests at Cooling Tower Fixtures Made of PVC/PP/PE Materials as well as Wood

Project Number 289

So far, rare cooling tower fires always resulted in complete destruction. In particular for larger buildings, such loss is always followed by a longer plant shutdown. Cooling towers with a concrete shell should be so impaired in their stability that repair will not be an option.

Fire hazards in cooling towers mostly occur during maintenance and repair works owing to forbidden smoking as well as during works were hot particles leave the working area uncontrolled (i. e. cutting and welding works with spark emission).

Today, cooling tower fixtures mostly consist of wood or man-made materials, i. e. burnable materials. Besides, there are also concrete-like materials. In mostly all cases, surfaces are covered with moss/lichens, which in dry condition have firing characteristics similar to those of nitro-cellulose. Due to this covering by biologic material, partly already in the original condition, cooling tower fixtures cannot be moistened with extinguishing water and consequently an occurring fire is difficult to fight.

Due to the cooling tower thermal conditions the fire is fanned so strong that already in the early stages of its development it cannot be fought. The extremely fast heat production corresponding to the fast fire development leads to high heat stress, considerably impairing the strength of the concrete building.

The aim of the scheduled tests is to determine which preventive measures could avoid a fire development and/or at what time extinguishing measures must be taken at the latest to be successful.

The fire fighting measures to be investigated are based upon modern extinguishing agents forming isolation layers; these also have a positive effect on the moistening characteristics of surfaces.

Test realisation is to be observed and evaluated by experts of the power plants’ fire brigades. Consultation of the Technical Committee “Fire Protection”, the VGB Working Group “Fire Protection in NPP” as well as interested fire protection representatives is planned.

The project is realised by the DMT-Centre for Fire Protection and Safety, Dortmund, headed by Heinrich Petersmann. The final report is expected in spring 2007.