The spray system is an active fire protection method, comprising a water supply system, providing sufficient pressure and flow to a water distribution piping system, where a fire sprayer is connected. Although historically only used in factories and large commercial buildings, systems for houses and small buildings are now available at cost-effective prices. The fire sprinkler system is widely used around the world, with over 40 million sprinkler heads installed annually. In buildings that are fully protected by fire sprinkling systems, more than 96% of fires are controlled by fire sprinklers only.
Video Fire sprinkler system
Histori
Leonardo da Vinci designed a sprinkler system in the 15th century. Leonardo automatically protects his kitchen with a super oven and conveyor belt system. In the comedy of errors, everything was all right when the big party, and the fire broke out. "The sprinkler system works really well, causing a flood that wipes out all the food and good kitchen parts."
Ambrose Godfrey created the first successful automatic sprinkler system in 1723. He used gunpowder to release the fire extinguisher tank.
The world's first modern recognizable sprinkler system was installed in Theater Royal, Drury Lane in England in 1812 by its architect, William Congreve, and protected by patent No. 3606 in the same year. This equipment consists of a 400 hogsheads (~ 95,000 liter) airtight cylinder reservoir fed by a 10-inch (250 mm) main water that branches out to all parts of the theater. A series of smaller pipes fed from the distribution pipes are pierced with a series of holes 1 / 2 -inch (13 mm) that pours water in case of fire.
Merit Sprinkler Company states history as:
From 1852 to 1885, hollow pipe systems were used in textile factories throughout New England as a means of fire protection. However, they are not automated systems, they do not light themselves. The first inventors began experimenting with automatic sprinklers around 1860. The first automated sprinkler system was patented by Philip W. Pratt of Abington, MA, in 1872. Henry S. Parmalee of New Haven, Connecticut was considered the inventor of the first practical automated sprinkler head. Parmalee improved Pratt's patents and created a better sprinkler system. In 1874, he installed a fire sprinkler system to his piano factory.
Frederick Grinnell refined the Parmalee design and in 1881 patented an automated sprinkler that bears his name. He continued to improve the device and in 1890 created a disc glass disc, essentially the same as that used today.
"Until the 1940s, sprinklers were installed almost exclusively for the protection of commercial buildings, whose owners were generally able to cover their expenses with insurance cost savings.For years, sprinklers have become mandatory safety equipment" in some parts of North America. , in certain occupations, including, but not limited to, newly built "hospitals, schools, hotels and other public buildings" subject to local law and enforcement. Outside the US and Canada, however, sprayers are rarely mandated by building codes for normal hazard dwellers that do not have large numbers of occupants (eg factories, process lines, retail outlets, gas stations, etc.)
Sprinklers are now generally installed in other buildings including schools and residences. This is largely as a result of lobbying by the National Flush Network, the European Flame Network and the British Flood Enginer Association.
Building codes in Scotland and the UK require a fire sprinkler system to be installed in several types of properties to ensure residents' safety.
In Scotland, all new schools are protected by sprinklers, as are new care homes, sheltered housing and high rise buildings. In the UK all buildings higher than 30 m should have watering protection. In 2011, Wales became the first country in the world to make installing sprinklers in new homes mandatory. The law will apply to newly built houses and blocks of flats, as well as home care and university dormitories. This law will take effect from September 2013.
Maps Fire sprinkler system
Usage
Sprinklers have been used in the United States since 1874, and are used in factory applications where fires at the turn of the century often cause disasters in both human and property losses. In the US, sprinklers are currently required in all new high and underground buildings generally 75 feet (23 m) above or below fire-fighting access, where firefighters' ability to provide adequate flow hoses for limited fires.
Sprinklers may be required to be installed with building codes, or may be recommended by insurance companies to reduce potential property losses or business interruptions. Building codes in the United States for hangout, generally more than 100 people, and places with overnight sleeping accommodation such as hotels, nursing homes, dormitories and hospitals usually require sprinklers either under local building codes, as a condition for receiving State Section and Federal funding or as a condition for obtaining certification (essential for institutions wishing to train medical staff).
Rule
United States
Although there are very few federal laws specifically regarding building codes, which are generally left to local jurisdictions, the federal government has used its funds and monetary powers to encourage fire safety standards under construction.
In 1990 the US Congress passed PL-101-391, better known as The Hotel and the Motel Fire Safety Act of 1990. The law requires every hotel, meeting hall, or similar institution to receive federal funds (ie for an overnight stay for a government tourist, or a conference, etc.), must meet fire and other safety requirements. The most visible of these conditions is the implementation of sprinklers. As more hotels and other public accommodations improve their facilities to allow for the reception of government visitors, this type of construction becomes the de facto industry norm - even when not directly mandated by local building codes.
If the building code does not explicitly order the use of fire sprinklers, the code often makes it very profitable to install it as an optional system. Most US building codes allow for cheaper construction materials, greater floor space constraints, longer exit paths, and fewer requirements for construction with fire ratings in structures protected by fire sprinklers. As a result, total development costs often decrease by installing sprinkler systems and saving money in other aspects of the project, compared to building non-sprinklered structures.
In 2011, Pennsylvania and California became the first US states to require a water spraying system in all new residential constructions. However, Pennsylvania withdrew the law the same year. Many cities now require housing sprinklers, even if they are not needed at the state level.
Europe
New interest and support for sprinkler systems in the UK has resulted in a more sprinkler system installed. In schools, for example, the government has issued recommendations through Building Bulletin 100 that most new schools should be built with sprinkler protection. In 2011, Wales became the first country in the world where sprinklers are required in all new homes. This law applies to newly built houses and apartment blocks, as well as university care and dormitories. In Scotland, all new schools are sprayed, as are new care homes, sheltered housing and high rise buildings.
In Britain, since sprinklers of the 1990s have gained recognition in Building Regulations (England and Wales) and Scottish Building Standards and in certain circumstances, the presence of a sprinkler system is considered to provide an alternative form of compliance for some parts of the code. For example, the presence of a sprinkler system would normally allow doubling the size of the compartment and increasing travel distance (to fire exit) and allowing a reduction in the internal compartment wall fire rating.
In Norway in July 2010, all new housing with more than two floors, all new hotels, hospices and hospitals should be sprayed. Other Nordic countries need or soon will need sprinklers in new nursing homes, and in Finland in 2010 a third of nursing homes are installed with sprinklers. The fire at the illegal immigrant detention center at Schiphol airport in the Netherlands on October 27, 2005 killed 11 prisoners and caused retrofitting sprinklers in all similarly designed prisons in the Netherlands. The fire at Dösseldorf Airport on 11 April 1996 that killed 17 people caused sprinklers to be installed in all major German airports. Most European countries also need sprinklers in shopping centers, in large warehouses and in high-rise buildings.
Operation
Each closed sprinkler is sealed either by a heat-sensitive bulb or a two-piece metal connection held together with a fusible alloy. The bulb or link applies pressure to the pipe cap that acts as a connector preventing water from flowing until the ambient temperature of the sprinkler reaches the activation temperature of the individual sprinkler head design. In a standard wet pipe sprinkler system, each sprinkler is active independently when the specified heat level is reached. So, only a spray near the fire will operate, usually only one or two. This maximizes water pressure above the fire point, and minimizes water damage to buildings.
The sprinkler activator will reduce water damage compared to the fire hose flow, which provides about 900 liters/minute (250 US gallons/min). Typical sprinklers used for industrial manufacturing occupants dispose of about 75-150 liters/minute (20-40 US gallons/min). However, the Initial Suppression Fast Response (ESFR) sprinkler at 50 psi pressure (340 kPa) will output about 380 liters per minute (100 gallons AS/min). In addition, the sprinkler will usually be activated within one to four minutes from the start of the fire, whereas it usually takes at least five minutes for the fire department to register the alarm and drive to the fire location, and an additional ten minutes to prepare the equipment and apply the flow of the hose to the fire. This additional time can produce a much larger fire, which requires more water to be extinguished.
Type
Wet pipe system
With wide margins, wet sprinkler pipe systems are installed more frequently than all other types of fire-fighting systems. They are also the most reliable, because they are simple, with only the operating components being an automatic watering and (usually, but not always) automatic alarm valves. Automatic water supply provides water under pressure to system piping.
Dry pipe system
The dry pipe system is the second most common type of sprinkler system. A dry pipe system is installed in a room where the ambient temperature may be cold enough to freeze water in the wet pipe system, so the system can not operate. Dry pipe systems are most commonly used in unheated buildings, in parking garages, in outdoor canopies attached to heated buildings (where wet pipe systems will be provided), or in cooled coolers. In areas that use NFPA regulations, the wet pipe system can not be installed unless the ambient temperature range remains above 40 Â ° F (4 Â ° C).
Water is not in the piping until the system operates; on the contrary, piping is filled with air under pressure under water supply pressure. To prevent greater water supply pressure from improper water imposition into the piping, the dry pipe valve design (special type valve) produces greater strength above the concave valve clamps by using larger valve valves. areas exposed to piped air pressure, compared to higher water pressures but smaller surface clapper surfaces.
When one or more of the auto sprinkler heads are triggered, it opens allowing air in the pipe to vent from the sprinkler. Each sprinkler operates independently, as the temperature rises above the trigger threshold. As the air pressure in the piping falls, the pressure differential across the dry pipe valve changes, allowing water to enter the piping system. The water flow from the sprinkler, required to control the fire, is suspended until air is released from the sprinkler. In areas that use NFPA 13 regulations, the time it takes water to reach the sprinkler away from the activated sprinkler is limited to a maximum of 60 seconds. In industrial practice, this is known as "Maximum Water Delivery Time". The maximum water delivery time may need to be reduced, depending on the hazard classification of the area protected by the sprinkler system.
Some property owners and building occupants can see dry pipe sprinklers as an advantage for the protection of valuable collections and other water sensitive areas. This perceived benefit is due to the fear that the wet pipe system can slowly leak water without attracting attention, while the dry pipe system may not fail in this way.
Disadvantages of using a dry pipe sprinkler fire system include:
- If the sprinkler shares the same standpipe system as the standpipe system supplying the fire hose, then the water supply to the fire hose will be greatly reduced or even restricted.
- Increased complexity - Dry pipe systems require additional control equipment and air pressure supply components that increase system complexity. This places a premium on proper maintenance, as an increase in the complexity of this system produces an inherently less reliable (ie more single points of failure) single inherent system than the wet pipe system.
- Higher installation and maintenance costs - Additional complexity impacts overall dry pipe installation costs, and increases maintenance expenditures primarily due to additional service labor costs.
- Lower design flexibility - Regulatory requirements limit the maximum permissible size (ie 750 gallons) from individual dry pipe systems, unless additional components and design efforts are provided to limit the time from sprinkler activation to water discharge to less than one minute. This limitation can increase the number of individual spray zones (ie from a single riser) that must be provided in the building, and affect the owner's ability to make system additions.
- Increased fire response time - Due to the empty piping at the time the sprinkler operates, there is a time delay inherent in water delivery to the sprinkler that has operated as water moves from riser to sprinkler, filling some piping in the process. A maximum of 60 seconds is usually permitted by regulatory requirements from when a single sprinkler is open until water is discharged to a fire. The delay in these fire fightings resulted in larger fires before being controlled, increasing property damage.
- Increased corrosion potential - After surgery or testing, the piping of the dried sprinkler pipe system is dried, but residual water accumulates at low pipe points, and moisture is also retained in the atmosphere in the piping. This humidity, coupled with the oxygen available in the compressed air in the piping, increases the corrosion of the internal pipe, which eventually leads to a pin-hole leak or other piping failure. The level of internal corrosion in the wet pipe system (where the pipes are constantly filled with water) is much lower, because the amount of oxygen available for corrosion is lower. Corrosion can be resisted by using copper or stainless steel pipes that are less susceptible to corrosion, or by using dry nitrogen gas to compress the system, rather than air. The nitrogen generator can be used as a permanent source of nitrogen gas, which is useful because the dry sprinkler pipe system requires an uninterrupted supply of the supervisor gas. These additional precautions can increase system upfront costs, but will help prevent system failures, increase maintenance costs, and early needs for future system replacements.
Flood system
The "flood" system is a system in which all sprayers are connected to an open water piping system, where the operating elements of heat sensing are removed, or specially designed as such. This system is used for specific hazards where rapid fire spread is of concern, as they provide simultaneous water applications across all hazards. Sometimes they are mounted on the exit of the vehicle or building openings to slow down the journey of fire (eg openings on walls with fire).
Water is not present in the piping until the system operates. Because the open sprinkler hole, the piping is at atmospheric pressure. To prevent water supply pressures from forcing water into pipes, a "flood valve" is used in the water supply connection, which is a mechanically locked valve. This is a non-reset valve, and stays open after stumbling.
Since the heat-sensing element present in the automatic sprinkler has been released (causing the sprinkler to open), the flood valve should be opened as a signal by the fire alarm system. Types of fire alarm initiation devices are selected primarily on the basis of hazards (eg sprayer pipette, smoke detector, heat detector, or optical fire detector). The initiation device gives a signal to the fire alarm panel, which in turn signifies the flood valve open. Activation can also be manual, depending on the purpose of the system. Manual activation is usually through a tensile or pneumatic electric fire alarm station, which signals the fire alarm panel, which in turn gives flood valve open signals.
Operation - Activate the fire alarm that initiates the device, or the manual pull station, beckons the fire alarm panel, which in turn gives flood valve signals open, allowing water to enter the piping system. Water flows from all sprinklers simultaneously.
Pre-action system
Special pre-action sprinkler systems for use in locations where accidental activation is not desired, such as in museums with rare works of art, manuscripts, or books; and data centers, for the protection of computer equipment from accidental disposal of water.
The pre-action system is a hybrid of wet, dry, and flooding systems, depending on the exact system purpose. There are two main sub-types of pre-action system: single interlock, and double interlock.
Operation of a single interlock system is similar to a dry system except that this system requires that previous "preliminary detection" events, in particular the activation of hot or smoke detectors, occur before the "action" of water introduction into system piping. by opening the pre-action valve, which is a mechanically locked valve (ie similar to a flood valve). In this way, the system is essentially converted from a dry system to a wet system. The goal is to reduce the undesired time delay of sending water to the sprinkler attached to the dry system. Before fire detection, if sprinkler operates, or piping system develops leakage, loss of air pressure in piping will activate alarm problem. In this case, the pre-action valve will not open due to pressure loss, and the water will not enter the piping.
Operation of a dual interlock system is similar to a flood system except that the automatic sprinklers are used. These systems require that both "preliminary" fire detection events, usually activation of heat or smoke detectors, and automatic spraying operations occur before the "action" of water introduction into system piping. The activation of fire detectors alone, or sprinklers alone, without concurrent operations from others, will not allow water to enter the piping. Since water does not enter piping until the sprinkler operates, the dual interlock system is considered a dry system in terms of water delivery time, and also requires a larger design area.
Foam sprinkler system
The foam fire sprinkler system is a special application system, the use of water mix and low expansion foam concentrate, produces sponge spray from sprinkler. These systems are typically used with special hazard dwellers associated with high-fire fires, such as flammable liquids, and airport hangers. The operation as described above depends on the type of system in which the foam is injected.
Water spray
The "water spray" system is operationally identical to the flood system, but the nozzle spray nozzle spray pattern is designed to protect uniquely configured hazards, usually of three-dimensional components or equipment (eg compared to flood systems designed to cover the horizontal floor area of ​​the room). The used nozzles may not be registered with fire sprayers, and are usually selected for special spray patterns to suit three-dimensional hazards (eg typical oval spray pattern, fan, full circle, narrow jet). An example of a hazard protected by a water spray system is an oil-containing electric transformer for cooling or turbo-generator bearings. The water spray system may also be used externally on the surface of the tank containing liquids or flammable gases (such as hydrogen). Here the water spray is intended to cool the tank and its contents to prevent the outbreak of the tank/blast (BLEVE) and the spread of fire.
Water mist system
The water mist system is used for special applications where it is decided that creating a heat-absorbing vapor is the ultimate goal. This type of system is usually used where water damage may be a concern, or where water supplies are limited. NFPA 750 defines water mist as a water spray with droplet size "less than 1000 microns at the minimum operating pressure of the disposal nozzle." The droplet size can be controlled by the exhaust pressure adjusting through the nozzle of a fixed orifice size. By creating a mist, the same water volume will create a larger total surface area that is exposed to fire. The larger total surface area better facilitates heat transfer, thus allowing more water droplets to change to steam faster. The water mist, which absorbs more heat than water per unit of time, because of the exposed surface area, will more effectively cool the room, thus reducing the flame temperature.
Operation - The water mist system can operate with the same function as flood, wet pipe, dry pipe, or pre-action system. The difference is that the water mist system uses compressed gas as an atomizing medium, which is pumped through a sprinkler pipe. Instead of compressed gases, some systems use high pressure pumps to squeeze water so that atomisation comes out of the sprinkler nozzle. System can be applied using local application method or total flood method, similar to Clean Fire Fire Protection System.
Design
The sprinkler system is meant for controlling a fire or for pressing a fire. Control mode Sprinkler is intended to control the rate of heat release from the fire to prevent collapse of the building structure, and pre-wet around combustible fuel to prevent spreading of the fire. Fire is not extinguished until burning is burned out or manual blackout is done by firefighters. The suppression mode sprinkler (formerly known as the Initial Quick Start Emrower (ESFR)) is intended to produce a sudden abrupt reduction of the heat release rate of the flame, followed by fast. with complete outages, prior to manual intervention.
Most installed sprinkler systems are currently designed using broad approach and density. The first use of buildings and building contents is analyzed to determine the level of fire hazard. Usually the building is classified as a minor hazard, ordinary hazard group 1, ordinary hazard group 2, extra hazard group 1, or extra hazard group 2. After determining the hazard classification, design area and density can be determined by referring to tables in the National Fire Standards Protection Association (NFPA ). The design area is the theoretical area of ​​a building that represents the worst case area where a fire can burn. Design density is the measurement of how much water per square foot of floor area should be applied to the design area.
For example, in an office building classified as a minor hazard, the typical design area will be 1,500 square feet (140 m 2 ) and the design density will be 0.1 US gallons per minute (0.38 l/m) per 1 (0.093 m 2 ) or a minimum of 150 US gallons per minute (570 μm/mnt) applied over 1,500 square feet (140 m 2 ) design area. Another example would be a manufacturing facility classified as a normal hazard group 2 in which a typical design area would be 1,500 square feet (140 m 2 ) and the design density would be 0.2 US gallons per minute (0.76 l/min) per 1 square foot (0.093 m 2 ) or minimum 300 US gallons per minute (1,100 l/min) applied over 1,500 square feet (140 m 2 ) design area.
Once design and density areas have been determined, calculations are performed to prove that the system can deliver the required amount of water above the design area required. This calculation takes into account all the pressure lost or obtained between the water supply source and the sprinkler that will operate in the design area. This includes pressure losses due to friction within the piping and loss or gain due to differences in elevation between source and sprinkler usage. Sometimes the momentum pressure of the water velocity in the piping is also calculated. Usually this calculation is done by using computer software but before the advent of this computer system the calculations are sometimes complicated done by hand. Sprinkler counting skills by hand is still required training for sprinkler system design technologists who seek senior level certification from engineering certification organizations such as the National Institute for Certification in Engineering Technologies (NICET).
The sprinkler system in the housing structure becomes more common as the cost of the system becomes more practical and the benefits become more obvious. Housing sprinkler systems are usually included in a residential classification separate from the above-mentioned commercial classification. Commercial sprinkler systems are designed to protect the structure and occupants of fire. Most residential sprinkler systems are primarily designed to suppress fire in such a way as to allow a safe escape from building occupants. While this system will often also protect the structure from damage caused by large fires, this is a secondary consideration. In the structure of housing sprayers are often overlooked from cabinets, bathrooms, balconies, garages and attics due to fires in these areas usually do not affect the occupant runaway route.
If water damage or water volume is of particular concern, a technique called Water Mist Fire Suppression may be an alternative. This technology has been developed for more than 50 years. It has not yet entered general use, but gained acceptance on board and in some residential applications. The mist fog system works by using the heat of fire to 'emit' the mist of water mist into steam. This then extinguishes the fire. Thus, the fog system tends to be very effective where there is the possibility of free burning heat. Where there is insufficient heat (as in a fire that sits in as will be found on the stored paper) there will be no steam generated and the fog system will not extinguish the fire. Some tests indicate that the volume of water required to extinguish the fire with the installed system can be considerably lower than that of a conventional sprinkler system.
Cost
In 2008, the cost of installing a sprinkler system ranged from US $ 0.31 - $ 3.66 per square foot, depending on the type and location. The housing system, installed during initial home construction and using the city's water supply, averaged about US $ 0.35/sq. Ft. The system can be installed during construction or installation. Some communities have laws that require a housing sprinkler system, especially if a large urban water supply ("fire") is not available. Nationally in the United States, homes of one and two families generally do not require a sprinkler system, despite the extraordinary loss of life due to fires occurring in these spaces. Inexpensive sprinkler housing systems (roughly the same per square foot as rugs or tile floors), but require larger water supply pipes than are usually installed at home, so retrofitting is usually costly.
According to the National Fire Protection Association (NFPA), fires in hotels with sprinklers averaged 78% less damage than fires in hotels without them (1983-1987). The NFPA says the average loss per fire in buildings with sprinklers is $ 2,300, compared to an average loss of $ 10,300 in non-trimmed buildings. The NFPA adds that there is no death record in a building that is completely dispersed outside the original fire point. However, in a pure economic comparison, this is not a complete picture; total installation costs, and costs incurred from non-fire triggered releases must be a factor.
The NFPA states that it "has no record of a fire that killed more than two people in a completely sprayed building where the sprinkler system operates well, except in an explosion or flash or where industrial brigade members or employees are killed during a fire suppression operation. "
The largest fire sprinkler manufacturer in the world is the Tyco International Fire Protection Products division.
See also
- Active fire protection
- Architectural techniques
- Fire protection
- Fire protection engineering
- Listing and use of approval and compliance
- Passive fire protection
- Sprinkler adjustment
References
External links
- National Fire Protection Association
- The Fire House Sprinkler Coalition
Source of the article : Wikipedia
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