Keywords: fire hydrant design rich water column
China Library Classification. : TU892 document identification code: a article number:1672-3791(2012) 05 (b)-0056-01building is an indispensable and important place for human life, production, leisure and entertainment. Correctly handling the fire protection problems encountered in architectural design is directly related to the safety of people's lives and property. It is easy for designers who have just entered the fire protection design to ignore some specifications, which leads to shortcomings in fire protection design and hidden dangers in fire protection. At the same time, the reasonable fire engineering design should also consider the investment cost of construction projects, and the fire engineering design should be safe, applicable and economical. This paper discusses the related problems of water gun filling water column in building indoor fire hydrant water supply system as follows.
1 correctly understand the meaning of water gun enriching water column
The water sprayed by the fire water gun must have a certain intensity and compactness in order to effectively extinguish the flame. Therefore, it is stipulated that the time from the length of the jet from the nozzle of the fire-fighting water gun to the time when 90% of the water in the jet passes through a circle with a diameter of 38mm is a full water column (also called effective range), and a section of water meeting the above requirements is used as the fire-fighting water jet in the design (see Figure 1).
2 the provisions of the code for fire protection to enrich the water column:
Article 8.4.3.7 of Code for Fire Protection Design of Buildings (GB 500 16—2006): The layout of indoor fire hydrants should ensure that the full water column of two water guns on the same floor of each fire zone reaches any part at the same time. For multi-storey warehouses with a building height of 24m or less and a volume of 5000m3 or less, 1 water gun can be used to enrich the water column and reach any part of the room. The full water column of the water gun should be determined by calculation, and the number of Class A and Class B workshops, public buildings with more than 6 floors and workshops (warehouses) with more than 4 floors should not be less than10m; High-rise factories (warehouses), elevated warehouses, shops, gymnasiums, theaters, halls, exhibition halls, stations, docks, airport buildings, etc. The volume greater than 25000m3 shall not be less than13.0m; Other buildings should not be less than 7m.
Code for Fire Protection Design of High-rise Civil Buildings (GB50045-95(2005 Edition)) is hereinafter referred to as Article 7.4.6.2 of the High-rise Code: The full water column of the water gun should be determined by calculation, and the height of the high-rise building with no more than 100m should not be less than100m; High-rise buildings whose building height exceeds 100m should not be less than 13m.
Article 7. 1.3 of Code for Fire Protection Design of Garage, Repair Garage and Parking Lot: When high-pressure or temporary high-pressure water supply system is used for outdoor fire water supply, the pressure of fire water supply pipeline in the garage shall be guaranteed, and the water column enriched by water gun at the most unfavorable point shall not be less than 10m.
Article 7.6.2. 1 in Code for Fire Protection Design of Civil Air Defense Engineering (GB50098-2009): The water filling column of the water gun of indoor fire hydrant shall be determined by calculation and shall not be less than 10m.
Article 7. 1.6 of the Code for Fire Protection Design of Railway Engineering TB 10063-2007 J774-2008 (Table 7. 1.6 Fire hydrant water consumption and water gun filling column) gives the starting stations of interval stations, marshalling stations and marshalling stations above regional level; Intermediate stations and cross-country station platforms such as medium-sized and below passenger railway stations; Large passenger train station platform; The water column of the water gun of the platform of extra-large passenger station, bus servicing line (depot), standby bus storage line and mechanical heat preservation vehicle shall not be less than 10m, and the water column of the water gun of tank washing station shall not be less than 13m.
The value of enriched water column given in the above fire protection code is limited to the minimum value, and the reaction force of water gun should also be considered in determining the enriched water column of fire hydrant. The maximum reaction force that trained firefighters can bear is not more than 20kg, and that of ordinary people is not more than 15kg (when the enriched water column is 10m, the reaction force of the water gun is 7.65kg water column 14m, and the reaction force of the water gun is13.80kg; When the water column is 15m, the reaction force of the water gun is15.438+0kg; When the water column is 16m, the reaction force of the water gun is18.42kg; When the water column 17m, the reaction force of the water gun is 20.13kg; When the water column 18m, the reaction force of the water gun is 24.38kg), so the length of the water column commonly used in fire field is generally (10 ~15) m..
3 calculation of enriched water column
Enriched water column Hm is calculated according to the following formula:
Hm=(H 1-H2)/sinα
Where: Hm is the height of water column enriched by fire water gun, m.
H 1 is the height of the highest indoor fire point from the ground, m.
H2 is the height of the nozzle of the fire-fighting water gun from the ground, and m is generally taken as1m..
α refers to the upward inclination angle of the fire water gun, which is generally 45, and the maximum shall not exceed 60.
Four engineering examples
For example, a building in R&D has a fire resistance rating of Grade II, and each floor has a fire zone. The building area is 8349.8 1m2, with six floors above the ground, the building height is 23.40m, the building volume is 35550.68m3, the height of the first floor is 3.9m, and the rest is 3.6m. Let α = 45.
Calculate the full water column: hm = (h1-H2)/sinα = (3.9-1)/sin45 = 4.1m.
Compared with the provisions of Article 8.4.3.7 of the Building Code, the length of the enriched water column is 7m.
The determination of indoor fire hydrant water consumption in Article 8.4. 1 of Code for Fire Protection Design of Buildings (GB 500 16—2006) shall be calculated and determined according to the following provisions.
(1) When indoor fire hydrant system, automatic sprinkler system, water spray fire extinguishing system, foam fire extinguishing system or fixed fire monitor fire extinguishing system are installed in the building at the same time, the indoor fire water consumption is calculated by the sum of the water consumption of the above systems that are started at the same time as required; When the above fire fighting systems need to be started at the same time, the water consumption of indoor fire hydrants can be reduced by 50%, but not less than10l/s.
(2) The water consumption of indoor fire hydrants should be calculated and determined according to the length of the water column filled with water guns and the number of water guns used at the same time, and should not be less than the provisions in Table 8.4. 1.
As the minimum flow rate of a single water gun is 5L/S as stipulated in the specification, the nozzle pressure of the water gun to enrich the water column to ensure this flow rate is about 1 1.4m (see Technical Measures for Design of National Civil Building Engineering-? Water supply and drainage engineering, page 226, table 7. 1.5-2. When the flow rate is 4.9L/S, the water column of the water gun is 1 1m, and the water pressure required for the nozzle of the water gun is 15m. When the flow rate is 5.2L/S, the water column of the water gun is 12m. After interpolation calculation, the water column of the water gun is11.4m. ..
Finally, it is determined that the enriched water column of this project is 1 1.4m, which not only meets the requirements of the specification for the minimum enriched water column of 7m, but also meets the requirements of the minimum flow of a single water gun of 5L/S, and the reaction force of the water gun is also within the tolerance of firefighters.
5 conclusion
The above is an excerpt, induction and summary of some specifications and calculation formulas involved in the design of indoor fire hydrant water supply system. In a word, in order to make the design of indoor fire hydrant system safe, reliable and economical, we should be familiar with relevant laws and regulations. In the design process, we should strictly abide by the specifications, especially the mandatory provisions, carefully calculate the corresponding values and compare them with the specifications. Ensure the safety and reliability of the design project.
refer to
[1] GB 5001616—2006, code for fire protection design of buildings [S]. China Planning Press, 2006.
[2] GB 50045-95, Code for Fire Protection Design of High-rise Civil Buildings [S]. China Planning Press, 2005.
[3] GB50067-97, Code for Fire Protection Design of Garage, Repair Garage and Parking Lot [S]. China Planning Press, 1997.
[4] GB50098-2009, Code for Fire Protection Design of Civil Air Defense Engineering [S]. China Planning Press, 2009.
Tb 10063-2007J774-2008, Code for Fire Protection Design of Railway Engineering [S]. China Railway Press, 2008.
[6] GB 500 15-2003, Code for Design of Water Supply and Drainage in Buildings (2009 Edition) [S]. China Planning Press, 20 10.
[7] National Civil Building Engineering Design Technical Measures-Water Supply and Drainage Engineering [S]. China Planning Press, 2009.
[8] Zhang Ying. Newly compiled building water supply and drainage project [S]. China Building Industry Press, 2002.