Known extinguishing methods, problem identification. Part 3/8. 1


Introduction of the ISO 14001 to the disaster recovery – part 3/8.

Experiences unambiguously show that the combustion of over 60,000 m3 tanks cannot be extinguished with the most of applied extinguishing methods. What now?

At the present time, the fire prevention strategy used by oil and chemical companies is based on national environment safety laws, the national general and professional laws and standards based on the said laws and the guidelines of professional associations, and primarily relies on the use of mobile and semi-stable extinguishing equipment.

 

extinguishing methods

 

In essence, the former extinguishing strategy is that

  • a person or a sensor detects the fire
  • alarms the fire station
  • the fire brigade gets to the site
  • assembles the devices necessary for extinguishing, and
  • starts and executes extinguishing

extinguishing methods

In the case of fire in small-sized tanks, ideally, the arrival time within the refinery is 10 minutes or less. After the assembly of the light technology, extinguishing can be started within less than 15 minutes from the out-break of the fire.
In the case of large tanks, high-capacity extinguishing equipment must be taken to and set up on the site. In this case, the time taken to arrive is longer, as are the assembly and set-up times.
During this, the fire will reach the stationary combustion stage, and the metal parts of the tank will start glowing.

During the combustion of a 80,000 m3 tank, 14 tons of carbon black is given off into the air every minute.

 

14 tons. Every minute.

 

Outline of the problem with the use of traditional semi-fixed extinguishing equipment

The drawbacks to the former known extinguishing methods and the essence of the problem can be stated as follows:

  • tank fire prevention is principally based on the fire prevention standards, guidelines and semi-fixed extinguishing concept formulated some 40–50 years ago
  • the operating parameters (foam solution intensity, extinguishing time) are prescribed in standards which are constrained by the technical possibilities of the time
  • the plant has the task of assembling the foam jet pipes and foam introduction devices on the tanks
  • the foam generation tools, the foam generators are mounted on the side of the storage tank, at a place that is difficult to access
  • as a narrow nozzle is used, foam generators often do not work and get clogged,
  • traditional extinguishing devices do not operate safely because of the difficulty of maintaining them,
  • a fire fighting water network is necessary to operate this type of extinguishing equipment,
  • devices compulsorily installed in advance are put into operation by the arriving fire brigade,
  • because of the need to call the fire brigade and the time it takes to arrive and assemble the necessary equipment, extinguishing is started with considerable delay,
  • the foam and pump necessary for extinguishing is brought to the site by the fire brigade,
  • any contamination of the fire water network may cause an operating failure,
  • because of the low application intensity value prescribed in the relevant standards, a large amount of extinguishing agent is used and the extinguishing
  • time is long,
  • as the fire continues for a long time, the loss is big,
  • environmental pollution is considerable, and
  • the fire endangers health, life and technique

International experience shows that the combustion of 60,000–80,000 m3 tanks cannot be extinguished with the most of applied extinguishing techniques.

 

extinguishing methods

 

The fire goes on for tens of hours until there is no more combustible material, and then it goes out. During this period, there is enormous environmental pollution.

The repeated failure to put out extensive fire  has triggered research to develop new, effective fire prevention systems.

to be continued…


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