New technology for building fire protection systems based on robotic fire extinguishing systems.
Modern development of science and technology allows us to talk about the next step in fire extinguishing. This is the introduction of robotic means, where human intellectual abilities are combined with the technical capabilities of automation. Currently, in Russia, stationary fire robotic systems are increasingly used to protect modern buildings and structures from fires. In robotic fire extinguishing systems, the ability to select plays a certain role, that is, the most optimal system for protecting the object is selected for various fire parameters. In this case, the most important thing is to minimize the supply of fire extinguishing agents with unconditional elimination of the fire. All this led to the improvement of fire robots (PR) in three directions.
Direction one.Initially, fire robots were created on the basis of monitor fire nozzles. The tactical capabilities of modern monitor fire nozzles are limited by the range of the stream they create. For monitor nozzles with a flow rate of more than 20 l/s, the range of water supply for various designs is from 43 to 55 m. An increase in the range of the stream is traditionally achieved by increasing the productivity of the nozzle, which, in turn, significantly increases the requirements for the supply water supply networks. As a result, the design of fire extinguishing systems becomes significantly more complex and the cost of such systems increases. Therefore, the relatively short range of the continuous stream of the monitor nozzles used has reduced the competitive advantages of PR over traditional automatic water fire extinguishing systems.
The solution to this problem was the creation of a special nozzle, which allows the formation of the longest continuous jet. The nozzle design ensures a shock-free flow entry into the nozzle, a uniform increase in velocity along the nozzle profile, and averaging of the velocity over the flow cross-section. The simplicity of the nozzle design allows the creation of PR with a wide range of flow characteristics, which ensures the use of PR for extinguishing fires in all groups of premises according to NPB 88-2001*, cooling building structures and equipment of various buildings and structures. Fig. 1 shows the range of a continuous jet depending on the water flow rate.
When implementing robotic fire extinguishing systems using monitor fire nozzles, practitioners faced the need to regulate water flow depending on the pressure on the supply pipeline, since the length and trajectory of the jet significantly depends on the pressure on the nozzle. The new nozzle allows maintaining the range of the jet after reaching the operating pressure (see Fig. 2), thereby eliminating the need to control the Q-H characteristics on the nozzle, as a result, the reliability of the system as a whole increases.
Thus, for robotic fire extinguishing systems, instead of monitor fire nozzles, it is advisable to use specially designed PR nozzles.
The second direction.Fire is a complex physical and chemical process, the detection of which is determined by the stage, size of the fire, purpose of the protected premises and type of fire load, and since the distinctive feature of the fire extinguishing system is the ability to supply a large amount of extinguishing agent to a given space, robotic fire extinguishing systems impose additional requirements on the fire detection subsystem: high reliability of fire detection, low inertia, accurate determination of the location of the source of combustion. Fire detectors used to ensure fire safety of facilities do not fully meet these requirements.
The search led to the creation of a principle of thermal field control in the IR range, which demonstrated exceptional competitiveness in comparison with other methods of fire detection. The method was called the «Optical Array Method» and consists of the following: the sensors are divided into two sets — sensors responsible for the X and Y axes. For each sensor, its coordinate is specified (usually 0.X or 0.Y). If the sensors (regardless of the axis belonging) have determined the state of the «optical array» zone as «fire», then the sensor readings are approximated for each of the measurements by a polynomial equal to the power of the number of sensors in the measurement. In each measurement, the coordinate of the global maximum is found (0.Xmax or 0.Ymax) — these coordinates determine the point on the P plane. To ensure the required accuracy, this procedure is performed until the difference between Pi does not exceed R (the confidence interval) k times in a row; at this point, Pcp is located. Next, the rotation/tilt angle for the actuators is determined (through the difference between the coordinates Pcp and Execution Device according to the principle of a right-angled triangle). D rotation and D tilt are added (subtracted) to the obtained rotation and elevation angles, resulting in the maximum rotation and tilt angles, which are transmitted to the barrel control controller.
The fire detection subsystem is based on addressable-analog heat flow sensors located in the protected premises. The sensors are installed in such a way that the entire protected premises are divided into zones of the same shape. Each zone has its own coordinates, which are incorporated into the extinguishing algorithm for each robotic fire extinguishing system. Polling of addressable-analog heat flow sensors by the control and addressable module allows for continuous thermal monitoring of the protected premises. The detection algorithm is determined by the technical requirements for software development. Within the framework of the set goal, the following tasks are solved: classification of sensor readings, selection of the optimal distance for placing sensors, determination of the thermal field value.
The task of selecting the optimal location of sensors is defined as a classical optimization problem for a given minimum intensity of the detected source, with the criterion of the minimum number of sensors, taking into account the architectural features of the object and is solved individually for each specific object at the stage of designing the system.
Thus, this method of fire detection allows:
- to avoid constant mechanical scanning of the fire detection system, thereby increasing the reliability of the system and the service life of the fire detection system;
- to reduce the fire detection time to fractions of a second;
- to use the fire detection system without a video monitoring subsystem;
- to monitor the condition of the premises during a fire;
- to significantly reduce the cost of the detection subsystem.
The third direction is control of the robotic fire extinguishing system. From the point of view of hardware implementation, the system must meet two main requirements: on the one hand, it must have a speed sufficient to solve the set of tasks assigned to it in real time, and on the other hand, it must meet typical requirements for fire extinguishing systems, that is, be reliable and easy to maintain.
The requirements for the PR software include: the ability to manufacture and change it relatively quickly, reliability and speed, as well as failure-free operation and safety.
The system includes a fire alarm, a fire extinguishing system and a cooling system for structures based on robotic fire nozzles. (See Fig. 4)
The system must include the following elements:
- Operator workstation;
- automatic installation of a fire alarm and determination of the coordinates of a fire;
- a system of robotic fire extinguishing installations;
- a system for alerting people about a fire;
- a video surveillance system (optional).
Operation of the control system
The control of the robotic fire extinguishing system is carried out using the fire alarm and control receiving and monitoring device by receiving the necessary parameters from the early detection system and further direction of the robotic nozzles to the fire source and cooling zones of building structures. When the system is switched to manual mode, the operator has the ability to remotely control the robotic nozzles, monitoring their position on the monitor screen, and also additionally through the video surveillance system.
Operation of the water supply system
Each of the robotic fire extinguishing units has its own unique addressing, which allows flexible control of the water supply subsystem. In the event of an emergency (smoldering, overheating) or the immediate occurrence of combustion, the system's operating algorithm provides for the launch of at least two robotic fire extinguishing units and their automatic orientation in the direction of the fire source. At the same time, the shut-off valve on this trunk is remotely opened. Both robotic fire extinguishing units are directed in accordance with the adopted water supply algorithm, and if the dispatcher does not respond to the fire warning, automatic water supply is started, taking into account the periodic change in the direction of the trunks.
The system allows:
- to avoid inefficient water consumption when extinguishing a fire;
- to ensure the required intensity of fire extinguishing agent supply at the site of the fire;
- to increase the reliability of fire protection equipment as a whole, which is achieved by ensuring autonomy and reliability of operation from several directions of water supply under fire conditions.