External and internal fire water supply: standards.
External and internal fire water supply: standards
External fire water supply
For the most convenient and safe water supply to the source of fire, an external fire water supply device is used., which is the source of water for fire-fighting equipment. According to SNiP 2.04.02-84, the procedure for designing permanent external water supply systems is established, and requirements for the parameters of such systems are established. External fire water supply systemsare used for water supply in settlements with a population of up to 5 thousand people; for extinguishing detached public buildings with a volume of up to 1000 m3, as well as industrial buildings with production categories B, G and D with a water consumption of 10 l/s for external fire extinguishing; warehouses for roughage with a volume of up to 1000 m3. When using water for external fire extinguishing, it is important to take into account and control the water consumption parameter. This parameter is as important as the general calculation of the fire safety risk in the building. Water consumption for external fire extinguishing — per one fire-fighting operation — for residential and public buildings for calculating connecting and distribution lines of the water supply network, as well as the water supply network inside a microdistrict or block is taken for a building requiring the highest water consumption — from 10 to 35 l/s depending on the number of floors and the volume of the buildings. The volume of water consumption for external fire extinguishing for buildings of industrial and agricultural enterprises for one fire should be taken for the building requiring the highest water consumption — from 10 to 40 l/s depending on the degree of fire resistance of the structure. Another important parameter is time. The average time spent on extinguishing a fire until the combustion stops is 3 hours; for buildings of I and II degrees of fire resistance with non-combustible load-bearing structures and insulation with production categories G and D — 2 hours. The minimum free pressure in the water supply network of a populated area with maximum domestic and drinking water consumption at the inlet to the building above the ground surface should be taken for single-story buildings at least 10 m, with a higher number of storeys, 4 m should be added to each floor. The level of free pressure in the low-pressure fire-fighting water supply network during fire extinguishing must be at least 10 m. Free pressure in the network must ensure a compact jet height of at least 10 m with full water consumption for fire extinguishing and the location of the fire nozzle at the level of the highest point of the tallest building. The maximum free pressure in the water supply network is no higher than 60 m.
Internal fire water supply
SNiP 2.04.01-85 regulates, in particular, the design of internal fire water supply systems under construction and reconstruction. Water consumption and the number of jets for internal fire extinguishing in public and industrial buildings (regardless of category) with a height of over 50 m and a volume of up to 50,000 m3 should be 4 jets of 5 l/s each; for larger buildings — 8 jets of 5 l/s each. When using internal fire water supply, the minimum water consumption for residential buildings is 1.5 l/s, provided that there are fire nozzles, hoses and other equipment with a diameter of 38 mm.
Internal fire water supplyIt may not be provided: in buildings of small height and volume (specified according to the table provided in SNiP); in buildings of comprehensive schools, except for boarding schools, including schools with assembly halls equipped with stationary cinema equipment, as well as in baths; in buildings of seasonal movie theaters for any number of seats; in industrial buildings in which the use of water may cause an explosion, fire, or the spread of fire; in industrial buildings of fire resistance grades I and II of categories G and D regardless of their volume and in industrial buildings of fire resistance grades III-V with a volume of no more than 5000 m3 of categories G, D; in industrial and administrative and household buildings of industrial enterprises, as well as in premises for storing vegetables and fruits and in refrigerators not equipped with a domestic and drinking water supply or industrial water supply, for which extinguishing fires from containers (reservoirs, reservoirs) is provided; in some warehouse buildings.
Testing the internal fire water supply
In order to control the uninterrupted and correct functioning of the internal water supply, during the examination, testing of the internal fire water supply is carried out. Tests are carried out in order to determine the operability and technical characteristics of the fire water supply used to ensure the proper level of fire safety of buildings. In accordance with established standards, testing of the internal fire water supply is carried out at least twice a year. The test results show the suitability/unsuitability of the facility's water supply system to ensure the supply of the required amount of water when extinguishing a fire. In addition, during the tests, the actual water consumption and its compliance with the established standards are determined. During the test, the main parameter that must be recorded is the pressure indicator of the main fire hydrant. The test results are recorded in the form of an act and test protocol.