Hydraulic calculation of automatic firefighting systems
combined with internal fire water pipeline system

Summary

In recent decades the construction of large buildings has risen sharply: shopping and entertainment centers, multifunctional high-rise buildings for residential and public purposes with underground parking lots, storage facilities for the storage of combustible materials. During construction finishing materials are often used that emit toxic substances if ignition occurs. Fires can result in fatalities and substantial material losses. For the fire safety of buildings and structures the use of firefighting water supply – both outdoor and internal is most effective. Due to the inability to provide for outdoor firefighting of a large part of the premises of the upper floors of high-rise buildings, the effectiveness and reliability of internal firefighting systems is of particular importance. Water consumption for fire water supply can be 200 l/s or more. To supply water in such a volume to the fire points, effective internal fire water supply systems are required: automatic firefighting systems (sprinkler and deluge), internal fire water pipelines, deluge water curtains. Combined internal firefighting systems include automatic firefighting installations and internal firefighting water pipeline. The method of hydraulic calculation of each of these systems is available in the regulatory and specialized literature. However, in the process of hydraulic calculations of combined (integrated) firefighting water supply systems, their essential features should be taken into account. In this regard, a mathematical model of flow distribution in automatic firefighting systems combined with an internal fire water pipeline system is considered. The technique of hydraulic calculation of arbitrary combined firefighting water supply systems is given. The proposed model allows you to get an actual value of water abstraction through nozzles (sprayers) and hand control branch pipes.

Key words

pressure , head , hydraulic design , water curtain , automatic firefighting installations , internal fire water pipeline , flow distribution task , variable abstraction

Modeling hydraulic modes of firefighting water system operations in the Internet

Summary

Basic fire protection of industrial and storage facilities, shopping and entertainment centers and other objects is made up of automated firefighting installations, internal fire water pipeline and water curtains. The analysis of the results of hydraulic calculations performed while designing these systems provides for selecting the required equipment composition, evaluating the operation of the systems in different modes etc. Hydraulic calculations are carried out, as a rule, using hand calculation, or a partially automated process. Algorithms are also used that implement numerical modeling procedures involving off-the-shelf software that simplifies compiling a system of equations with the formation of a calculation model from nodes and connecting paths. The software available in the domestic market is either not effective or very expensive, and requires user training. Substantive and mathematical statement of the flow distribution problem with variable nodal flow rates for a random pipeline system including fire protection, is presented. The corresponding modification of the nodal pressure method is given that takes into account the dependence of the flow through the nozzle (sprinkler, fire branch, etc.) on the pressure (head) upstream of it. This task and other ones can be solved using «ISIGR» programming and computing suite developed at the Institute of Energy Systems named after L. A. Melent’ev of the Siberian Branch of the Russian Academy of Sciences. The software is designed for modeling in the Internet the hydraulic modes of the ring systems of water, gas supply and firefighting. The software has an effective, convenient, user-friendly graphical interface that provides for drawing a network layout with minimal effort, performing hydraulic calculations, and interpreting the results in graphical or tabular style.

Key words

water supply , flow distribution , water curtain , mathematical and computer simulation , internal fire water pipeline , automated firefighting system

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Experience of using СP 10.13130.2020 in designing internal fire-fighting water lines for buildings

Summary

Proposals are given for adjusting CP 10.13130.2020 «Fire protection systems. Internal fire-fighting water lines. Design rules and regulations» with account of the experience of designing internal water supply systems for buildings and structures. The need for adjustments is due to the following reasons: the use of new terms in the text of the code of practice instead of the historically established and currently used in other regulatory documents; the presence of erroneous recommendations; the lack of the correct information on the initial pressure value as well as on the type of the diaphragm being calculated with the use of a nomograph (with sharp or thickened edges); the lack of the information on the mutual influence of the valve and the diaphragm being taken into account. It is proposed to replace the new terms included in the code of practice with already known ones (a list of such terms with recommendations for their replacement is given) so that the new terms do not conflict with other regulatory documents. It is proposed to eliminate erroneous recommendations regarding the use of elevated and hydropneumatics water tanks as a means of increasing pressure in the internal fire-fighting water line. It is concluded that engineering calculations based on the nomograph provide for the sufficient accuracy for almost all types of diaphragms 3–4 mm thick. An exception is the diaphragm installed at the outlet of the direct-flow fire valve. For this diaphragm the relative deviation of the results of applying the nomograph and methods known from hydraulics is more than 25% due to the mutual influence of the local resistances.

Key words

set of rules , terminology , terms , internal fire water pipeline , design rules and regulations , medium-flow fire hydrant , diaphragm calculation , nomograph