Discussion on fire water supply for high-rise buildings?

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The shortage of urban land promotes the development of high-rise buildings to high altitude. The development of modern science and technology and modern industry also provides conditions for high-rise buildings. Since 1950s, many high-rise buildings have been built in big cities in China. Especially since China's reform and opening up in the 1980s, economic construction has changed with each passing day, and high-rise buildings have mushroomed in large and medium-sized cities and even small cities, developing rapidly. According to the statistics of Shanghai in 2002, there are more than 5000 high-rise buildings. The advantages of high-rise buildings in saving land, spectacular cities and improving people's quality of life have been recognized by everyone. But the fire risk of high-rise buildings is much greater than that of ordinary buildings. Water is the main extinguishing agent for high-rise buildings. Whether enough water pressure can be continuously sent to the position of the water gun is directly related to the success or failure of fire fighting.

1. The necessity of water supply for high-rise buildings. The difficulty of fire fighting and emergency rescue in high-rise buildings has become one of the "three difficulties" in fire fighting ("three difficulties" refers to three kinds of fires in high-rise buildings, underground engineering and petrochemical industry), and the fire water supply in high-rise buildings is the basis and difficulty of fire fighting.

1. 1 Although the high-rise building is mainly self-rescue, once the backward self-rescue system fails, or the self-rescue system can work but cannot meet the use efficiency (coverage and water consumption), it must rely on the mobile facilities and equipment of the fire brigade to extinguish the fire. For example, the fire in Harbin Swan Hotel, Guangzhou Culture Building, Beijing Wei Zi Hotel and Lanzhou Lu Si Commercial Building all used a large number of mobile fire fighting equipment and equipment.

1.2 In the high-rise building under construction, the internal fire water supply system has not yet been formed, and the construction water consumption is low. After the fire broke out, the fire site was almost completely guaranteed by the mobile fire water supply facilities of the fire brigade.

1.3 the fire water supply system of some high-rise buildings is not connected with the municipal water supply network according to the original fire audit requirements, and the specification requires a double-loop annular pipe network with at least two water inlet pipes.

1.4 Although the design of high-rise buildings in economically developed countries is mainly based on self-rescue, due to various factors (such as equipment failure, aging, maintenance failure, poor management, design failure, change of use function, etc. ), there is still a certain proportion of fires that need the mobile fire fighting facilities and equipment of the fire brigade to put out. As we all know, the fires in Andras Building in Sao Paulo, Brazil, Jorma Building in Osaka, Thousand Days Department Store and Darange Hotel in Hancheng, South Korea all used a lot of mobile fire fighting power. According to American data, more than 5% of high-rise building fires in the United States need to call the fire brigade to put out the fire at the scene. From the above situation, it is very important to do a good job in high-rise water supply.

2. Possibility of using existing equipment to supply water to high-rise buildings

2. 1 existing fire-fighting equipment At present, the fire-fighting water supply equipment and facilities in China can only be built after the high-rise building itself has developed a "high standard", and the internal fire-fighting water supply system is relatively perfect. Before the introduction of "High Code", the height of buildings was not large, mostly below 50m; After the promulgation of "High Code", the height of most buildings is below 70m.

Judging from the vehicles and equipment of the fire brigade, except for a few special vehicles imported from abroad, all the others are domestically produced.

Judging from the fire protection products of domestic hose lines, it is no problem to meet the compressive strength of 1.7- 1.8 MPa at present, and the compressive strength of high-pressure nylon hoses produced by some enterprises has exceeded 2.5MPa.

From the design point of view, the water supply capacity of domestic Jiefang (Dongfeng) small fire truck can meet the requirements of 1 100 m when the flow rate is 30L/s; The water supply capacity of the Yellow River (medium-sized vehicles such as Rome, Steyr, Jiefang Flat Head and Dongfeng Flat Head) fire trucks can meet 140m when the flow rate is 50l/s ... In actual combat, the flow rate of each fire truck usually does not exceed 15L/s, and when the flow rate does not exceed 8L/s (the water consumption of a sprinkler is19m. According to the high-rise water supply experiment of Shanghai Fire Corps, the Yellow River fire truck uses 80mm hose to ensure that three water guns (17L/s, 100m) with heights of 19mm2, 16mm 1) come out at the same time.

2.2 theoretical basis

The maximum water supply height of fire engines is:

H 1-2 = HB-HD-H gun (where H 1-2 is the water supply height;

HB is the pump pressure;

Hd is the pressure loss of the hose;

Water gun nozzle pressure required for water gun)

A jiefang (Dongfeng 142) fire truck uses 65mm hose (high pressure nylon) and sets 1 19mm water gun to put out indoor fires.

At this time: HB=80mH2O(0.8MPa) (design lift),

H gun = 13.5 H2O( 1.35 MPa).

Hd of each hose (based on hemp hose) =1.81mh2o (0.0181MPa), use 4 hoses and substitute into the formula:

h 1-2 = h b-HD-h gun = 80- 1.8 1×4- 13.5 = 59.26 MH2O =(0.5926 MPa)。

B Yellow River (Rome) fire truck (medium-sized car) uses 65m nylon high-pressure hose 19mm water gun to put out indoor fire. At this point:

HB= 140mH2O( 1.4MPa)，

H gun =13.5mh2o (0.135mpa), HD =1.81mh2o (0.018/MPa), and the number of hoses used is 9.

H 1-2 = H b-HD-H Gun = 140- 1.8 1- 13.5 = 1 15.64 MH2O( 1.65438)。

According to the above calculation, the maximum water supply height of Jiefang (Dongfeng 142 type) and Yellow River (Rome type) fire engines with 75mm water can be obtained respectively, and the calculation is not made here.

According to the formula of the maximum height of the fire truck supplying water to the indoor pipe network through the water pump adapter:

HP = Hb-Hg-HH (where Hb is the outlet pressure of the water pump, Hg is the pressure loss of the pipe network, and the loss is 0.0 16MPa per 10m height).

(1.6mH2O) meters;

Hh is the pressure required by the most unfavorable indoor fire hydrant, which is generally 23.5mH2O；;

Hp is the maximum height for the fire truck to supply water to the indoor pipe network through the water pump adapter)

A. When Jiefang (Dongfeng 142) fire truck supplies water:

Hb = 80mh2o (0.8mpa) Hg = (50/10) ×1.6mh2o The height here is 50m.

Hh = 23.5 H2O(0.235 MPa) into the formula:

HP = Hd——Hg——Hh = 80— 1.6×(50/ 10)—23.5 = 48.5 H2O(0.485 MPa)

B. When the Yellow River (Rome medium-sized) fire truck supplies water:

Hb =140mh2o (1.4mpa) Hg =1.6x (100 ÷10) =16mh2o (0./kloc-

HH = 23.5 H2O(0.235 MPa), and substitute into the formula: HP = HB-Hg-HH =140-1.6× (100/0)-23.5 =/kloc.

2.3 Conclusion

2.3. 1 Jiefang fire truck (Dongfeng 142) When supplying water:

(1) Using 65mm high-pressure nylon hose and setting 1 19mm water gun to put out indoor fire can ensure 60m water supply height;

(2) Use 75mm high-pressure nylon hose, set up water separator on the ground floor, and set up 2 19mm water guns to extinguish indoor fires, which can ensure the water supply height of 50m;

(3) When the water pump adapter is used, the water supply height of 50m can be guaranteed.

2.3.2 When the Yellow River (Rome medium-sized) fire truck supplies water:

(1) Use 65mm high-pressure nylon hose and set 1 19mm water gun to put out indoor fire, which can ensure the water supply height of 100m;

(2) Adopt 75mm high-pressure nylon hose, set up a water separator on the ground of the position, and set up two 19mm water guns to put out indoor fires, which can ensure the water supply height of 100 mm.

2.3.3 In order to solve the pressure and flow of fire water supply for buildings above 100m, the author thinks that fire pumps can be connected in series (the method of coupling water supply is ideal).

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