Centralized gas fire extinguishing systems.

Centralized gas fire extinguishing systems.

Centralized gas fire extinguishing systems

         Automatic fire extinguishing systems began to appear in Russia at the turn of the 19th and 20th centuries and began to be widely used starting from the 1930s. Today, it is difficult to imagine a modern, more or less complex facility without the use of automatic fire extinguishing systems of some kind for its protection. Of all the variety of automatic fire extinguishing systems, which differ mainly in the type of extinguishing agent used in them, this article will discuss gas fire extinguishing systems.

      Making up about 15% (according to 2003 data) of the total number of automatic fire extinguishing systems, automatic gas fire extinguishing systems (AGFS) have continued to confidently increase this figure in recent years, as evidenced by the steady demand for these systems and the annual increase in the volume of production by many domestic manufacturers of such equipment.

     AUGPs used in various areas of modern production are provided mainly in cases where the conditions of fire development, as well as the properties of substances and materials participating in combustion, exclude the use of other fire extinguishing agents. In the presence of an alternative possibility of using various fire extinguishing agents, the choice may be dictated by the desire to reduce possible damage from the effect of water, powder, aerosol or foam on the protected object. The main objects of application of AUGPs are: energy facilities, oil cellars of metallurgical enterprises, turbo generators of thermal power plants, state district power plants, paint shops and chambers, warehouses of valuable materials, premises of computing centers, various equipment rooms, archives, museums, libraries, etc.According to the storage conditions of the gas fire extinguishing agent (GFEA) and the functional feature, AUGP are divided into centralized and modular. Unlike a modular installation, in which the gas fire extinguishing modules (GFEM) can be located both in the protected room and next to it, centralized installations (CI) are located in specially equipped fire extinguishing stations at the facility. CI represents modules or batteries of GFEM connected to a common manifold, on which distribution devices (DD) are located, ensuring the supply of GFEA in various directions. In the event of a fire alarm triggering in one of the protected rooms, the signal from the starting device goes to the CI starting module and the corresponding DD, which, having opened, ensures the supply of GFEA through the main pipeline to the room from which the fire signal came. As a rule, the need for CI arises when the task of protecting AUGP of several rooms at one facility arises. In this case, equipping each such room with a separate modular unit will certainly lead to a significant increase in the cost of the project. The use of the central control unit allows for some savings and optimization of the integrated solution. In the practice of our enterprise, there were cases of designing central control units for 30 directions when rooms are located on several floors of the building.

       The quantity of GOTV and, accordingly, the quantity of MGP for its storage are calculated in order to ensure the creation of the standard fire extinguishing concentration in the largest volume of the protected premises. Moreover, to protect smaller volume premises, it is possible to provide a system for triggering in a given direction only that quantity of MGP from the CU that will ensure the creation of the standard fire extinguishing concentration in this room.
The control unit must ensure the supply of 95% of the mass of the GFTS required to create a fire extinguishing concentration in a time not exceeding 15 seconds for installations using liquefied gases (except CO2) and 60 seconds for installations using CO2 and compressed gases. These intervals are determined by the standards for vessels with GFTS when stored at a temperature of 200 C.

Unlike modular installations, for which 100% of the GFFS reserve in modules can be stored in the enterprise warehouse or at the service organization, for the CU, the standards prescribe the presence of 100% of the reserve, located in the fire extinguishing station. Joint storage of the estimated amount and reserve of GFFS in an isothermal tank is allowed, provided that the latter is equipped with a reversible drive and technical means for its control. The vessels for storing the reserve must be connected and in the local start-up mode. In case of failure to supply the main calculated amount of GOS, it is envisaged to switch these vessels to remote or automatic start mode.

Despite the fact that modern MGP can provide the supply of flammable liquids over a considerable distance, the standards require that fire extinguishing stations be located as close as possible to the protected premises. The fire extinguishing station premises must be separated from other premises by type 1 fire partitions and type 3 ceilings. It is prohibited to locate fire extinguishing station premises under and above premises of categories A and B (premises with explosive materials, flammable gases and substances). The standards recommend placing fire extinguishing stations in basements, ground floors and first floors of buildings. However, it is also permissible to place stations above the first floor, provided that it is technically possible to deliver the equipment to the installation site and perform operational work. The exit from the station should be provided outside, to a stairwell that has an exit to the outside, a vestibule, or a corridor. In this case, the distance from the exit from the station to the stairwell should not exceed 25 m. and there are no exits from the rooms of categories A and B into the corridor. When placing modules and batteries of the GP in the fire extinguishing station, its height must be at least 2.5 m. The temperature in the fire extinguishing station room must be from 5 to 350 C, relative air humidity no more than 80% at 250 C, lighting no less than 100 lux. with fluorescent lamps or no less than 75 lux. with incandescent lamps. The entrance to the station must be marked with a light board «Fire extinguishing station».

         In addition to automatic start-up, the control unit must be equipped with a local start-up device. If there are several directions for supplying the GFFS, the starting elements of the local start-up devices for batteries and modules and the switchgear must have signs indicating the protected room (direction).

One of the important elements of the control center is the distribution devices (RD) that provide the supply of GOS in different directions. Technos-M+ has developed and uses distribution devices of the RUE-25-150 and RUE-32-150 types in its systems. Each of these devices provides the supply of GOS in one direction. To supply GOS in two or more directions, the required number of devices are installed on the AUGP pipeline. Unlike many analogues that use a pyropatron as a starting element, RUE devices are equipped with two types of starting: electric (initiating element — electromagnet (solenoid) and manual. Almost all GOTV permitted for use in the territory of the Russian Federation are used as GOTV that can be passed through the devices. A special feature of the RUE design is that they are opened using a built-in pneumatic chamber and the effect of compressed gas (nitrogen) on the stem of the shut-off element. This design provides up to 5 activations without recharging the pneumatic chamber.

At the international salon «Integrated Security-2008», the Technos-M+ enterprise was awarded the «National Security-2008» medal for the development and production of RUE-25-150 and RUE-32-150.

Grinin V.V.
Head of Marketing Department «Technos-M+»

Literature used in preparation of the article:
1. GOST R 50969-96 Automatic gas fire extinguishing systems. General technical requirements. Test methods.
2. Sobur S.V. Automatic fire extinguishing systems.-M. Pozhkniga, 2008
3. Baburov V.P., Baburin V.V., Fomin V.I. Automatic fire extinguishing systems. Yesterday. Today. Tomorrow. -M. «Pozhnauka», 2007