【 Weak current College 】 skyscraper fire water tank roof installation should pay attention to the issue of

High-rise building due to limitations in existing fire equipment, fire protection design should be based on self-help, and should be based primarily on indoor fire facilities. Water, as the principal extinguishing agent has been widely used, especially for automatic sprinkler system due to its fire-extinguishing with high efficiency, small secondary water hazards and by General designers alike.
In order to achieve the purpose of rapid fire, the relevant specification on the indoor fire service water and water pressure are made clear. In urban water supply, as most of the urban network is branched, and life, fire use combined, fires, municipal pipe pressure and accident point outlet water is difficult to meet the high-rise building construction design of pressure and flow, on the other hand, even if the municipal network to meet the requirements of their water consumption, under normal circumstances do not allow water drawn directly from the network, so as to avoid the negative pressure occurs in water supply piping, affecting around other users, therefore, generally, the design of high-rise buildings, fire water tank or water use and water wells, natural, through the pumps and other equipment for water supply pressure. Specification of requirements, regulators pumps, pressure tank, variable speed pump water supply equipment are temporary high pressure water supply system, and the temporary high pressure system fire water tank should be set to ensure the most negative point of indoor hydrant and automatic sprinkler system in the early days of fire extinguishing water quantity and necessary to achieve the rapid water pressure in the early days of fire fighting purposes.
1. fire water tank volume calculations
The need for fire water tank of the system, its container quantity first meet fire 10min (minutes) indoor water use. For ease of maintenance, management, design practices is to life, fire and water tanks. For combined with water tanks, the effective volume should meet: V = Vt + Vs + Vf + Vx, Vt (3 m ＾) for domestic water consumption, Vs (m ＾ 3) water for life adjustment, Vf (m ＾ 3) water reserves for peak load, Vx (＾ 3 m) of water for fire fighting, Vx = q600/1000, q-indoor hydrant or sprinkler system design for water consumption (litres/second). If indoor hydrant and automatic sprinkler systems tanks individually set, its capacity to meet the respective requirements. When indoor hydrant and automatic sprinkler systems share a fire water tank, under the automatic sprinkler system design specifications (GBJ84 — 85) specification, its fire water may not be less than 18 m. Because in the same building, fire, usually put into use in indoor hydrant, automatic sprinkler systems starts fire nozzle, if each nozzle by flow 1.331/s calculation for 23 sprinkler fire water consumption, or 10min 2 pistol 15 jets of water, extinguishing 10min initial fire requirements. For water supply of the system partition, and parallel mode, each district water tank fire water volume shall be calculated on the type; for in-line water supply system, water tanks, in addition to guarantee low fire 10min water consumption, mainly on a should also be a central pool of water, the fire service should meet local fire duration in water consumption, Q = (q1t1 + q2t2)-q3t3, (q1, q2, q3-indoor hydrant, automatic sprinkler systems design flow and water tank fill water flow, t1, t2, t3 in order to regulate the provision of fire-water supplement the duration and time), at the same time, it should meet the water needs of the area. In order to ensure that fire not be diverted its water consumption, water tank outlet to adopt certain technical measures, General, life, fire water pipe should set up a separate, and in domestic water outlet on the destruction of the siphon and control the water level. As shown in the figure. For the construction of a height exceeding 50m, indoor fire service in each of the two water tanks, yishe and connecting pipe connection. As a pond of water tank should be divided into a grid, for cleaning and maintenance is not shut off.
2. fire water tank piping layout
According to the specification requirements, fire water tank should be set into the water pipes, water pipe, overflow signal pipe, snorkel, etc., in order to ensure that water is not contaminated and periodic discharge water sediments and contaminants, fire water tank venting tube should also be set. For the outlet pipe diameter, designed to determine the volume and flow, that is, d (m) = (4q/3.14v) ＾ (1/2) (q:m ＾ 3/sv: m/s). On fire hydrant system, water tank, water pipe with booster (of water height can not meet the requirements of the hydraulic calculation), you can connect directly with the fire hydrant pipeline network, and the automatic sprinkler system, must be approved by the wet alarm valve before and sprinkler riser, but never touch without wet alarm valve is connected directly with the network, because alarm valve of the water hydraulic motor alarm is to alert the impulse, without alarm valve, fire, pressure water into alarm channel, causing pressure switch, hydraulic alarm not action, not to fast signals start spraying pump so that the water pipe network is not fully guaranteed. To avoid fire pumps after the opening of the Park's water distribution network into the fire water tank, fire water tank outlet check valve must also, in order to prevent water entering the fire water tank and fire pump to maintain pressure on network.
3. pressure measures
According to the specification requirements, high fire water tank of the set height should meet most negative points in the system required pressure requirements, the most negative point fire hydrant hydrostatic pressure not less than 7m water column (more than 100m is hydrostatic pressure of not less than 15m water column), the most negative point the nozzle pressure should not be less than 5m water column, and along and local head loss, fire water tank level lowest point and the most negative point of geometric height at least 20m around, not only affects the appearance of buildings, but also on structural design and construction has caused certain difficulties, therefore, is located in the top of the skyscraper fire water tank is not for the most negative point fire hydrant or water pressure sprinkler equipment requirements, shall be charged. Commonly used devices are the air pressure tank or regulators pumps. Design time, if a separate in-tank outlet pressure pump on the set, because the network is not available to adjust the volume of water, once the pipeline leakage phenomenon, the pressure inside the pipe network will rapidly decline, make frequent opening and closing pressure pump, affect its service life. For separate use pneumatic supply design, in a real project of many. In my city had put into use in engineering, designers often use pumps andPressure tank series of pressure, after the practice has proved that good effect. Normally, a small pressure tank pressure to maintain the network, its main role as water, water pumps to trap a small flow, low lift. Pump is started, the roof of the Park's suction pipe, pumps into the fire pipe network, at the same time, the water entered the pressurized tank part by tank pressure gauge control pump on the opening and closing. Because the system has an adjustable pump water, you can avoid frequent start. Its relatively simple equipment structure, small floor area, and in radio, also water fire extinguishing.

5. all pneumatic tank instead of fire water tank

Some of the multi-storey building roof load bearing members for steel structure, setting fire water tank is hard, designers typically consider pressure tank instead. But for serious danger level of the building is not allowed, can only rely on the early fire fire water tank with water supply.