Ph.D., CEO of JSC "NPO" Sopot "(St. Petersburg),
Vice President WASCS GN KUPRIN
One of the most important criteria for survivability multifunctional skyscraper is the ability of its own integrated security system to counter fire hazards and the consequences of it.
As a result of fire and action to combat it identifies all the disadvantages and advantages of the regulatory and project-accounting framework, implemented in the construction of multi-functional high-rise buildings, as well as the effectiveness of the alternate (compensating) events.
This article shows examples of some of the contradictions between the rules of fire safety and the reality of their implementation.
General Plan and Fire
Primary condition of building, usually a master plan for compliance with regulatory requirements. For example, according to the design standards, construction of high-rise buildings is not allowed if there is no development in the area of the fire station at a distance of no more than 2km for buildings up to 100 meters, no more than 1 km - height of more than 100m.
Suppose that, in accordance with the development plans of Moscow and St. Petersburg in the city will be built over 200 high-rise buildings. But even with free areas for the construction of such buildings and within a radius of 1-2 km from the existing fire stations, require either a radical reconstruction of the past, or the creation of new fire stations with the appropriate equipment to modern fire appliances (avtonasosami, ladders, lifts, elbow height not less than 50m). Accordingly, it is necessary to fire department staffing by qualified personnel in an amount in the thousands people.
However, even if this requirement is met, with great confidence we can say that it will not yield the desired result, as the timely arrival of the fire brigade to the fire in Moscow, St. Petersburg and other large cities is a process unlikely.
In addition, the use of ladders or lifts to evacuate people from a height of 50 meters or more is ineffective, and the efforts of fire departments MOE m MIA associated with trying to provide easy access and placement of fire fighting equipment in high-rise buildings, required for evacuation or extinguishing of the zone burning, lead often to useless (ineffective) waste of time, both for direct fire and rescue.
Thus, trnebovaniya regulations of the presence in the area of building fire stations within a radius of 1-2 km from the mandatory staffing their ladders, avtonasosami high pressure car lifts are nothing more than a proof of the complete dependence of integrated security systems, high-rise buildings from external forces and means Rescue and fire fighting. In the opinion of the author, it is this relationship is one of the major flaws ensure survivability of high-rise buildings.
Further evidence of this dependence are the requirements of regulations to ensure the fire resistance of structural elements of buildings, space planning solutions, including defining and dividing buildings into compartments.
Standards provide fire resistance of fire walls at least REI 180 for buildings up to 100 meters, REI 240 - higher than 180 meters Here in Germany, for example, fire resistance structures of buildings 60 meters high is 90 minutes, over 60 m - 120 min . Thus, in Russia trebovaniyaik fire safety, particularly regarding fire resistance of structures, inflated by more than 2 times. This indicates a pre-planted in the rules, so to speak, "the ratio of engineering uncertainty" about the reliability of organizational and technical measures aimed at preventing and extinguishing fires.
By the way, the statistics of fires in tall buildings confirms the objectivity of this "uncertainty." Indeed, most of the measures taken to extinguish fires as regular internal technical resources, as well as by outside forces (ie, involving urban forces and means of fire protection) are not sufficiently effective. This indicates a lack of confidence in the possibility of designing organizations to provide fire suppression process vystonyh buildings within 180-240 min.
Thus, it is logical to assume that the requirements for fire-fighting in the Russian Federation is an understatement.
External and internal firefighting
Analysis of technical solutions based on internal and external fire fighting MGSN and TSN, shows complete dependence provide firefighting capabilities of fire departments outside the high-rise building. The author's view, this dependence is also flawed, particularly because it lies in the requirements of the rules. This suggests a certain degree of shifting the responsibility for the process of fire on foreign forces and, consequently, a decrease in the vigilance of its own forces in a complex security plan to prevent fire spreading to a critical size.
Consider, for example, design for fire protection multifunctional skyscraper "Krylatskie hills" of Moscow.
Paragraph 12 of the "Fire Protection" in accordance with the design flow to provide water for external firefighting within a 100 l/s with a duration of 3 hours extinguishing (MGSN 1.01-99 "Norms and standards for design and construction of Moscow").
Requirements MGSN 4.04-94 "Multifunctional buildings and complexes," MGSN 5.01-01 "parking cars" and SNIP 2.04.01-85 * "Domestic water supply and sewerage of buildings" is defined to ensure total water consumption 14.4 l/s in a sprinkler system and 40 l/s (8 jets at a rate of 5 l/s each) - at the waterfall, the fire. Thus, the total water consumption for internal firefighting in public office area amounted to 54.4 l/s.
For internal fire in the premises parking for a sprinkler system provides flow 28.8 l/s, the internal fire water supply - 10 l/s) 2 jets by 5 l/s each). In addition, the parking lot is provided by the work of deluge water curtains with a flow rate of 5 l/s. Thus, the total flow of water to extinguish a car park is 43.8 l/s.
Maximum total water consumption for internal firefighting amounted to 54.4 + 43.8 = 98.2 l/s, ie, it is approximately equal to the total consumption of water in the external firefighting.
External firefighting should be provided with an increasing effect with fire trucks arriving at the fire place and installed on fire hydrants, according to the project located at the distance of 150 m These vehicles are able to pump water through the building suhotruby tip within the 9th floor at work conventional pumps that effectively.
The use of fire jets outside the building to extinguish the fire within him above the 9-12th floors of the author is not considered due to the limited efficiency of the fire.
Technical analysis of this solution shows that the outdoor fire may be able at least 1080 m3 of water (about 18 tank wagons), for internal fire of public office - about 587.5 m3 (9-10 tank wagons), and with the fire in indoor parking - additional 587.5 m3 of water. Thus, the external and internal extinction within the normative duration of fire (3 hours) will require about 2160 m3, or about 36 wagons.
Tactics of fighting the fire to date is based on the use of a significant amount of water, which, as we see, built into the regulatory framework. Therefore, fire departments fully exercise their right to use the water, despite the fact that experts know more than 90% of water used (in our case, it will be almost 2,000 m3 or about 33 railway tanks) will not participate in fire fighting, and in fact will be used the destruction of the building, since the consequences of over-spilled water are usually fatal.
Fatality water use is not so much that the water destroyed the underlying floors, property, equipment, machinery, rendering useless condition of the building, especially in fire-fighting in the winter, but in the fact that the 10% of water that is actually involved in fighting fire, not enough to create the required intensisnosti fire on the floor on fire.
For example, if we consider that to extinguish the fire in the fire compartment area of about 12,000 m3 provided to ensure total water consumption 54.4 l/s, which is the basis of a three-hour fire fighting will be 587,000 liters, the specific consumption of water is equal to approximately 50 l/m2. In this case, based on the same claim three hours extinguishing the flow rate of fire extinguishing be only 0.0045 l/(s*m2), which is more than 100 times lower than that required for suppression of solid fuels.
The calculation of the intensity of the water supply for fire on one floor at a rate of 10 l/s (2 streams of 5 l/s each) also gives lower results on this parameter.
Thus, on the one hand, the rules stipulated (by indirect indicators) there is a huge supply of water, the use of which can lead to damage, more than from the fire itself, on the other hand, just to fight a fire of this amount is not enough.
This contradiction can only be solved with the application of new technical solutions to ensure instant response capabilities, including embedded project to eliminate a fire and prevent its development to the size of a room, in the worst case - one floor. Therefore, in my opinion, the design of the high-rise building fire should not be construed as a high fire resistance of structures and duration of fire, how fast (speed) the elimination of burning at the same time increasing the efficiency of the water (fire extinguishing). In this regard, the best favor a proposal to use in fire public office, industrial, manufacturing and warehouse buildings and the more parking water and foam fire fighting equipment, including foam medium and high multiplicity.
Foam multiplicity 100-200 characterized by low water content and high utilization of a fire, as in fire solid fuels surfactants, which are the basis of fire extinguishing foam, contribute a higher wettability of these materials, rather than just water. Foams have good insulating and cooling capacity for fire flammable liquids than water, through which the liquid to put out such unacceptable. The last of these is especially important when making a decision to protect parking lots, transformer substations, diesel generator or helicopter pads located on the roofs of tall buildings.
Problems of water delivery and placement of pump stations
Another problem is the delivery of internal fire fire water to the upper floors of high-rise buildings. The higher the building, the more complex system of transportation and provide pressure on the overlying floors, including a heliport.
According to MGSN and TSN in high buildings may provide some independent pumping stations.
For example, the design for fire protection multifunctional skyscraper "Krylatskie hills" to optimize the internal fire provides for the use of four independent pumping stations:
MSP-1 - for an automatic sprinkler fire extinguishing 1st and 2nd public areas of the office part of the building;
PNS-2 - Automatic sprinkler systems and deluge curtain parking;
MSP-3 - for internal fire line (fire hydrants) public office part;
PNS-4 - for pumping station internal fire line parking.
Task PNS-1, MSP-2 and MSP-3 - providing water supply to the overlying floors inclusion of independent pump groups, each of which consists of two (primary and backup) with a multi-stage pumps with suction and discharge nozzles two.
Each pumping station shall be equipped with two independent sources of the 1st category of power supply reliability with automatic transfer switches (points 14.1 and 14.5 NPB 88-2001 * "Setting fire and alarm systems. Standards and design rules").
Electrical control of pumping stations is provided in accordance with paragraph 5.11 NPB 88-2001 * and includes a kompaleks problems, namely:
selection of operating pumps and rezervonogo;
automatic start working pump;
automatic start standby pump failure or absence from duty pump operating mode for the specified time;
switch back when you stop the pump working;
switch valves with electric;
local and remote control of pumps cabinets fire hydrants (for pump stations that have them on the distribution network) and the central control system of fire protection (CPU SDR);
automatically turn on and off booster pump (jockey pump) to maintain the design pressure in the supply and distribution pipelines;
disable the automatic starting of pumps;
automated functional testing of electrical devices, recording the control and operation of the command pulse shaping the automatic starting of pumps;
Automatic control of the alarm level in drainage pit;
functional testing of the light and sound alarm;
disable audible alarm.
The inclusion of pumps and their work is a complex technical process, the implementation of which in a state of emergency in case of failures in the supply of electricity, even when the system backup is problematic.
Given the above, it is advisable to find a radically new solution to a certain stage of fire, especially at the beginning, to have backup power, little to do with energy supply and building a system of automatic control. According to the author, the source may be placed on the top floor (or roof) autonomous modular water and foam fire fighting (a more detailed description of the system and the initial requirements to create it are described below.)
Parking: sprinkler and deluge fire extinguishing
In accordance with the NPB 110-2003 "The list of buildings, structures, facilities and equipment to be protected by automatic fire suppression and automatic fire alarm," MGSN 4.04-94 and other documents protection sprinkler fire extinguishing systems required for all rooms in the building, except for the bathrooms, showers, stairwells, cooling and ventilation chambers, electrical, transformer, etc.
Paragraph 3.9 MGSN 5.01-01 provides independent sprinkler system to protect the premises parking and public office part of the building.
In addition, the parking area at the entrance to the platform lift-gate, and at the output of floor on the ramps provided deluge water curtains that are managed automatically remotely.
The design of the automatic fire protection project authors do not consider some important factors related to the dynamics of fire. For example, a fire in the car park which has arisen from any statistically known cause (eg, terrorism) may fuel spreading within one or two storage compartments of cars on the square as provide authors of about 240 m2.
Quenching fuel spillage in reality can not be achieved by any flow of water at any intensity, as the use of water in this case, even the spray is ineffective.
Furthermore, when using a sprinkler system may fuel spreading over a large area. A deluge of work contributes to the development of fire due to the active oxygen supply to the premises of the building. In addition, the development of a fire in the car park will promote the inclusion of smoke.
An alternative is to use water and foam fire fighting, the description of which is given below.
Fire protection helipad
Most of the design decisions usually involves placing a roof of tall buildings helipads. For example, the complex "Moscow-City" is expected to build at least four of these areas.
The main objective of helipads - providing rescue people with cabins and rescue helicopters.
In recent years, examines the use of helicopters to transport passengers and cargo, and for other purposes, using helipads skyscraper.
Takeoff and landing of the helicopter are extremely hazardous processes and are always accompanied by a flight accident risk associated with fire and explosion. Thus he speaks helicopter fire and explosion hazard object. He, as a rule, since a lot of fossil fuels, which is a rough landing can spread over a large area and burn.
Helicopter design made of fusible and combustible materials, as it has blood vessels and equipment under high pressure (landing gear, air and oxygen tanks). Perhaps the presence of cargo, which has a higher risk of explosion, it is possible the presence of chemical and biological hazardous cargo, whose behavior as post-emergency fire difficult to forecast.
These components cause high transience and dynamism of the combustion process, which is accompanied by explosions, followed by a spread of the fragments and the airframe to the site, increasing the area of combustion with subsequent complete destruction of the helicopter, the death had not managed to flee from the scene of the crew and passengers. All of this occurs within 1-2 minutes after the fire started.
Thus, a helipad requires special treatment for protection against fire.
Unfortunately, in many projects fire protection (sprinklers) helipads or not at all, or do not take into account the dynamics of the fire, the specific design features of the helicopter and its behavior in the fire, the direction and strength of the wind, which is always present on top.
MGSN 4.19-05 "All-rise buildings and complexes" provide the necessary equipment pads fixed foam fire automatic installation. In accordance with these regulations space measuring 20x20 meters with a blind parapet height of not less than 0.1 m should be filled with foam for 1.5 min. In this case, the foam solution flow rate should be 6.3 l/s. However, the study of physical and chemical processes of combustion and end the practice of extinguishing by helicopter indicate that the elimination of fire on this site even if the regulatory intensity of 0.14 l/(m2 * s) will take about 50-60 l / foam solution that is is almost 10 times more than the stipulated norms.
Given the dynamics of the fire and the available facts demolition operations helicopter in the combustion process must be extinguished in less than 30 seconds. after exposure to flame design of the helicopter. Consequently, the rate of elimination of burning must be at least 13 m2 / s.
The current practice and tools of fire with this problem practically managed. In order to improve fire protection helipads "NPO" Sopot "has developed an autonomous system using fire extinguishing systems combined" Purga "(for more information see" Journal of Fire Safety in Construction "№ 3 in 2010).