The installation of the foam fire sprinkler system is used to protect from the fire the process equipment, chemical and petrochemical plants, warehouses and bases of oil and oil products, as well as other facilities where in the large quantities are used flammable and combustible liquids.
According to the composition and operation the foam fire sprinkler system in many respects is similar to the water fire sprinkler system. The additional elements in the foam units are devices which make the foam (sprinklers and generators), as well as the systems of storage and dispensing of the foaming agent.
In addition the difference of the foam systems from the water fire sprinkler system is that the source of supply for foam extinguishing systems should be the not drinkable water pipelines, moreover the amount of water needed to produce a foam, must meet the requirements of technical documents for applicable foaming agents.v
By the functional characteristics and design features, the automatic foam fire sprinkler system is classified based on the multiplicity of using foam, the start time, the duration of its work, ways to power up and receiving foamable solution such foaming devices and a method of filling of the pipes.
Depending on how much the volume is increased in comparison with the original, foams are low (up to 20), medium (20 to 200) and high (greater than 200) ratio. Accordingly, the fire sprinkler systems divided into low, medium and high expansion.
By way of influence on the fire, the foam fire sprinkler systems divided into the general-surface, locally-surface, general-volume, locally-volume and combined fire sprinkler systems.
- The general-surface systems – deluge, to protect the entire working area;
- Locally-surface: sprinkler – to protect individual apparatus or individual sections of the premises; deluge – the protection for the individual objects, devices, transformers, etc;
- General-volume – designed to fill the protected volume;
- Locally volume – to fill the volume of the individual processing units, small built-in storage space, etc;
- Combined – the connected circuit units of the locally surface and locally-extinguishing volume for simultaneous supply of foam in the volume or on the surface of the technological devices and the surface around them.
The foamable solution in the fire sprinkler system can be obtained by volumetric method (preliminary preparation of an aqueous solution and the foaming in the tank from which it is fed by pumps into the distribution network); using inkjet devices, automatic dispensers, metering pump systems.
By the method of filling the pipeline the foam fire sprinkler systems may be dry pipe, flood and circulation. The dry pipe installation filled with the foam solution to the stop-starting devices, so during the start of the fire sprinkler system, it takes some time to fill the pipes.
In order to reduce the switching times the foam fire sprinkler systems used a method of filling the pipes before the sprinklers or to the level of distribution in the riser (in the foam fire sprinkler systems of the deluge type).
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