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A new principle of development of automatic fire protection systems based on the conception of the underground fire as a controlled system with certain parameters (temperature, heating, velocity of propagation along the mine working) that predetermine selection of methods and combinations of fire–fighting means guaranteeing the maximum possible fire–extinguishing efficiency for each concrete fire. Technical characteristics of the newest systems intended for fire protection of the mine workings and the mining equipment are substantiated. Analysis of constructions of the existing home and foreign fire–fighting means is fulfilled. It is shown that in spite of the rather wide stores of the modern mine be brought to the common not complicated block diagram that includes sub–system of monitoring the environmental parameters, sub–system of fighting the fires, lock and starting valves, distributing pipe-line with sprinklers as well auxilliary monitoring and measuring devices. The principal parameter that is controlled by the mine fire-fighting systems is the temperature. It is checked by means of the mine heat fire detectors that are intended towarn about elevation of the air temperature in the mine working being protected. Besides the heat fire detectors the smoke detectors of various construction can belong to the complete set of the mine automatic systems.
The underground fires remain one of the most complicated and hazardous kinds of accidents at present that devastate entrails of the earth, destroy mine workings and expensive equipment, do enormous moral and material damage to coal enterprises and are frequently accompanied by victims. In the mines of Ukraine 160…200 underground fires occur on the average every year, 50…70 % of which are the open ones (figure 1).
Fighting the developed underground fires is one of the most complicated and actual scientific and technical problems of coal industry. Two ways of solving this problem exist: the first way is wide use of the scientifically grounded preventive measures that exclude possibility of ignition and following fire development, and the second one is creation of methods and means of fighting the developed fires.
Practice shows that now against a background of slackening the centralized control financing the programs directed to modernization of mines, industrial safety measures and guaranteeing fire safety was reduced considerably. This circumstance complicated carrying–out the preventive measures considerably and influenced upon the level of coal output as a whole negatively. The share of damage stipulated by the underground fires in coal industry of Ukraine mounted to 27 % from the total volume and became dominating among all kinds of damage because of accidents in mines (figure 2).
State of fire protection of overwhelming majority of the Ukrainian mines is non–adequate to their fire hazard. Situation arisen in the coal branch is redoubled with low production efficiency and fabour discipline, sharp reduction of quality of materials being delivered into the mine especially conveyor belts, which inflammation results in grave consequences quite often. And so, it is necessary to carry–out thorough scientific investigations of the processes of development of the underground fires and to create high–efficient technical means and methods of fighting the fires side by side with realization of preventive measures.
The scientific–research and project and development works in the sphere of prevention and fighting the open fires are directed to development of the high–efficient fire–fighting equipment with use of water, air-mechanical foam, inert gases, fire-extinguishing powders, aerosols as well their combinations as fire0fighting substances. Water remains the most widespread and cheap fire-fighting means on account of its unique physical properties. Automatic plants that are possible to protect the mine workings and technological equipment against the underground fires effectively are of the greatest interest.
The basis of conception of creation of the modern mine automatic fire-fighting systems is the principle based on idea that the underground fire is a controlled system with certain parameters (temperature, heating rating, velocity of propagation along the mine working) predetermining selection of methods and combinations of fire–fighting means guaranteeing the maximum possible fire–extinguishing efficiency for each concrete fire. In spite of this the automatic system realized steady monitoring of the environment checking its parameters and comparing them with regulated values for the purpose of producing the control signal to switch on the fire–fighting plants.
The principle parameter that is the temperature. It is checked by means of the mine heat fire detectors that are intended to warn about elevation of the air temperature in the mine working being protected. Besides the heat fire detectors the smoke detectors of various construction can belong to the complete set of the mine automatic systems.
One of the most significant aspects of creation of the mine automatic fire–fighting systems is scientific substantiation of selection of type and construction of the fire detector depending on its purpose and service conditions.
The fire detectors with the operation temperature of 72 oC are used in the constructions of the modern mine fire–fighting systems.
In spite of the rather wide stores of the modern mine fire–fighting systems their structure can be brought to the common not complicated block diagram that includes sub–system of monitoring the environmental parameters, sub–system of fighting the fires, lock and starting valves, distributing pipe–line with sprinklers as well auxilliary monitoring and measuring devices and devices for preparation and technical maintenance of the system. The powder systems that can efficiently fight the fires of the A, B, C classes, as well ignition of the electrical equipment at a voltage up to 1140 V are most universal from the point of view of various classes of the underground fires. The typical block diagram of the mine dry–powder fire–fighting system is presented in figure 3. As a rule, the parts of the system are: automatic fire-fighting plant, ÀÓÏÏ type (or its modifications) with starting units (mechanical and electrical switching on), light and audible warning devices, distributing pipe–lines (perforated or with sprayers), fire-alarm station, ÑÖ-1, ÑÖ-2, ÑÏ-types (or their modifications) with the set of fire, heat or smoke detectors signalling stabs and switching elements.
The dry-powder fire-fighting systems operate as follows. The fire detector that is the nearest one to the ignition source operates by the fire in the zone being protected. The electric signal from it comes to the fire-alarm station that switches on the light and audible alarms and begins realization of logical estimation of the arrived pulse determining its value and nature of origin.
In this case the station checks integrity of stabs uniting the detectors with each other, determines availability of short circuit current in their circuit, integrity of the detectors and “de-excitates” the diagnostics results on the control panel.
In the case of operation of the second detector the station produces the control electric signal to start the fire-fighting plant. The automatic plants are started by means of the starting devices (units) which design is determined by the purpose of the system.
Logical processing the signals that arrive from the fire detectors is realized by the ÑÖ station. Principle of operation, design, technical parameters, installation rules and other information about the ÑÖ station are presented in the specifications.
The ÑÖ station is supplied by the power unit, to which input a voltage of 220 V, 50 Hz is applied. By accidental switching-off the voltage the station turns to the own reserve supply of 24 V d.c. automatically.
The principle of development of the mine automatic fire-fighting systems based on presentation of the underground fire as the controlled system with certain parameters (temperature, heating rating, velocity of propagation along the mine working) that predetermine selection of methods and combination of the fire-fighting means guaranteeing the maximum possible fire-fighting efficiency for each concrete fire is worked out.
The modern high-efficient fire-fighting system, ÑÀÏ type, and its modifications are developed, tested and introduced in the industry. The system can “recognize” at the early stage and fight the underground fires of the A, B, C classes and inflammations of the electrical equipment being at the pressure up to 1140 V. Procedure of calculation of the principal parameters of the mine automatic plants forming a part of the fire–fighting systems, ÑÀÏ-1 type, were carried out that confirmed their reliability and high fire-fighting efficiency. They can be used most efficiently and expediently for fire protection of mine electric substations and electric locomotive garages, tower–type headgears and administrative and service centres of the mines. There are more than 50 automatic systems, ÑÀÐ type, in the coal mines of Ukraine and Russia at present in operation.