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What are sprinklers?An automatic fire sprinkler system is one of the most effective methods of controlling or suppressing a fire.Sprinkler systems are made up of a network of pipes in the walls and ceilings that have sprinkler headsproviding protection to hallways, rooms, stairways and other areas of a building. In most systems, the pipesare always filled with water under pressure; the system is ready to do its job of putting out a fire quickly!Sometimes sprinklers are concealed behind small metal plates in the walls and ceiling. Even though you can'tsee the sprinkler head, they are still there andable to spray water on a fire.

Why are sprinklers important for life safety?Sprinklers do not rely upon human factors suchas familiarity with escape routes or emergencyassistance. They go to work immediately toreduce the danger. Sprinklers prevent the fastdeveloping fires of intense heat, which arecapable of trapping and killing dozens of building occupants.

How do sprinklers work?

Sprinklers are generally located at the ceiling level of a building. The fire sprinkler has a fusible link that meltswhen the heat given off by a fire reaches a certain heat level. When the link melts and the sprinkler opens,water flows out in a spray pattern. The sprinkler system is designed to flow a specific amount of water per square foot based on the type of hazard that it is protecting.

How many sprinklers activate in a fire? Despite what many people think, generally only one or two sprinklers open up and flow water during a fire-allthey do not go off at once are not designed to go off at once!

How much water damage will a sprinkler head cause? Since the amount of water coming out of a sprinkler head is much less than that in a fire hose, the water damage will be considerably less. After a fire is put out by a sprinkler head, there are often comments about"all of the water damage that the sprinkler caused". What people often don't realize is how much fire AND

water damage there would be if the sprinkler head had not activated and controlled the fire!

How effective are sprinklers? According to the NFPA, automatic sprinklers are highly effective elements parts of the total system design for fire protection in buildings. Sprinklers typically reduce your chances of dying by one-half to two-thirds in anykind of property where they are used. The most effective fire loss prevention and reduction measure for bothlife and property is the installation and maintenance of home fire sprinklers. Fire sprinkler systems offer theoptimum level of fire safety because they control the fire immediately in the room of origin, help limit thespread of fire, and often extinguish it before the fire department arrives.

Can sprinklers be damaged? While sprinklers are very rugged devices, they should not be tampered with, misused or vandalized. For example coat hangers or other objects should not be hung from a sprinkler head, for example, because the

hanger may accidentally strike the fusible link element and open the sprinkler head. In another example, if asparkler sprinkler head is covered with clothing, this may reduce the heat getting to the sprinkler and delay itsopening.

My building is fireproof. Why do I need sprinklers? Often, it is not the building that burns in fatal fires, but the contents-furniture, clothing and other furnishings.A sprinkler system will stop the fire in its tracks before it has time to spread very far.



We have smoke detectors in our building. Do we need sprinklers too? Smoke detectors provide an excellent method of detecting a fire early and warning everyone to get out.However, the fire still has to be put out quickly before it can spread and put a lot of other people in danger.That is the job for sprinklers, which can react in seconds. While we have great fire departments with excellentresponse times, it may take a fire department up to ten minutes, or more, until they are able to put water ontothe fire. This information is from the Home Fire Sprinkler Coalition (2/07)

Fire Video Clip

Firesprinkler application and installation guidelines, and overall firesprinkler systemdesign guidelines, are provided by the National Fire Protection Association (NFPA) 13,(NFPA) 13D, and (NFPA) 13R.

Fire sprinklers can be automatic or open orifice. Automatic fire sprinklers operate at a

predetermined temperature, utilizing a fusible element, a portion of which melts, or afrangible glass bulb containing liquid which breaks, allowing the plug in the orifice to be

pushed out of the orifice by the water pressure in the firesprinkler piping, resulting inwater flow from the orifice. The water stream impacts a deflector, which produces a

specific spraypattern designed in support of the goals of the sprinkler type (i.e., controlor suppression). Modern sprinkler heads are designed to direct spray downwards. Spray

nozzles are available to provide spray in various directions and patterns. The majority of automatic fire sprinklers operate individually in a fire. Contrary to motion picture

representation, the entire sprinkler system does not activate, unless the system is aspecial deluge type.

Open orifice sprinklers are only used in water spray systems or deluge sprinklers systems.They are identical to the automatic sprinkler on which they are based,

with the heat sensitive operating element removed.

Automatic fire sprinklers utilizing frangible bulbs follow a standardized color coding

convention indicating their operating temperature. Activation temperatures correspond to

the type of hazard against which the sprinkler system protects. Residential occupancies

are provided with a special type of fast response sprinkler with the unique goal of life

safety.



Effect of Sprinkler Discharge PressureManufacturer¶s data as shown in Figure 23 demonstrates that at moderatepressures thewater distribution pattern becomes more horizontal with increasing pressure (athigh

pressures this trend is reversed and the spray cone becomes narrowed),however thespray patterns show that this effect is not sufficient to cause a neighbouringsprinkler to bedirectly wetted. This is consistent with recognised installation standards whichrequire aminimum spacing between adjacent sprinklers to avoid wetting of adjacentsprinklers andcausing skipping. It is also known that skipping is not normally a significantparameter inthe performance of sprinkler systems with normal (smaller) clearances between

thesprinklers and the stored goods, therefore it is unlikely that the change in spraypatternthat occurs with increasing pressure is responsible for an increase in skipping

behaviour.

This is also consistent with the work carried out by Gavelliet al17 which attributedthetransfer of minute water droplets to the hot gas plume.

The analysis carried out by Croce et al utilised the sprinkler discharge density.Thesprinkler discharge density is defined as the flow rate of the sprinkler divided bythe floor area covered (refer Equation 4). This can be easily revaluated based on nozzlepressurebyutilising Equation 1 and Equation 4 as follows.



Figure 23: Spray distribution patterns for a Tyco Model TY-B upright spraypatternsprinkler with a K factor of 8.0 l/min.kPa1/2 for pressures of 50 kPa (0.5 Bar) and210 kPa(2.1 Bar).

All of the sprinklers were spaced at 3.05m x 2.44m centres giving an area per sprinkler of 7.442m2. For example using Equation 4 the flow rate of the sprinkler for test 6can becalculated as follows:



Sprinkler Spacing

As the skipping phenomenon is caused by water droplets wetting the frangible

element of

neighbouring un-operated sprinklers it is reasonable to assume that the spacingbetween

sprinklers may impact on the ability of droplets to travel from an operated

sprinkler to a

neighbouring sprinkler, with greater spacing reducing the likelihood of skipping.

The experiments carried out by Croce et al16 had the sprinklers spaced at 3.05

m apart in

the north ± south direction and 2.44 m in the east ± west direction giving a

difference in

spacing of 0.49 m between the two directions. The results published by Croce et

al16 for

test 2 and 10, and reproduced below as Figure 35 and Figure 36, show no

difference in

the tendency to skip between the sprinklers orientated in the north ± south

direction versus

the east ± west direction.

Although no bias in skipping rates is apparent based on direction it is apparent

that

skipping occurred predominantly in the second and fourth sprinkler rings and

very rarely in

the third and fifth sprinkler rings as shown in Figure 37. This suggests that water

droplets

are capable of travelling distances of at least 3.0 m from an operated sprinkler

but may not

have the ability to travel a greater distance of up to 6.0 m in sufficient numbers to

cause



skipping. This result suggests that there may be a benefit in using extended

coverage

sprinklers in occupancies with height ceiling clearance to reduce skipping.

The impact of extended coverage sprinklers has not been adequately consideredin the

work by Croce et al16 as these sprinklers have a different deflector design to

allow them to

throw the water over a wider coverage area, and this difference in deflector

design may

result in skipping at greater spacing. Nam et al15 carried out one fire test utilising

extended

coverage sprinklers to explore this issue, however as only one sprinkler activated

in the

test the result must be seen as inconclusive and more testing is required to

determine the

effect of extended sprinkler spacing.

3.2. Water spray model

The formation of water droplets from a sprinkler spray involves many complex processes and presents

difficulties for modeling it numerically. Since the primary aim of this work is not on the droplet formation, we

adopt Nam's [9] approach to represent the water spray. He characterized the water spray by measuring the

water droplet size, spray velocity, flow rate and discharge angle of the water droplets. A Lagrangian

approach can be used to track the water droplet trajectories from the spray nozzle. However, it is impossible

to track the trajectory of every water droplet due to the tremendous number of droplets in the water spray.

Therefore, the concept of droplet group [19] is used to group water droplets with similar characteristics, and

trace the movement of this finite water droplet groups.

In the current work, to understand the effect of water spray on fire suppression, the interactions between fire

plume and water sprays of different spray patterns (i.e. hollow and solid spray cone patterns), water drop

sizes as well as various spray flow rates are investigated. Some other factors, such as water spray mass

flow rate, spray angle and speed, have been studied previously in the experimental work of Kim et al. [ 26]

and Yao et al. [27]. The water spray parameters used in our simulations are listed in Table 2. These

parameters, associated with each study case, reflect the typical scenarios that would be expected from a

sprinkler/water mist system [9, 26 and 28]. The distribution of water flow rate for the solid water spray nozzle

is assumed to be uniform across the outlet cross section of the nozzle. The droplet sizes in the various water

sprays are allowed to vary from 100 to 270 m in diameter. However, for each water spray, we assume that



the water droplets have a uniform size at the discharge point. Since the primary interest of the current work

is to study the interaction between fire plume and water spray, the interaction between the wall/burning

surface and water spray droplet is not considered, as it would add further complications to the problem. This

will be investigated in a future study.

Table 2. The water spray parameters used in the simulations

4.1. Effect of water spray pattern

The simulation results of steady-state combustion of gas fuel in an open quiescent environment are shown

in Figs. 2(A) ±7(A), where the velocity, temperature and water vapor concentration distributions within the fire

plume are illustrated. This is taken to be the base case or the initial state from which the transient events

develop. Fig. 2(A) shows the gas velocity vectors in the base-state fire plume. The fuel gas-methane is

injected from the fuel nozzle located on the floor and burns in the open environment. The combustion heat

raises the gas temperature as shown in Fig. 3(A), and builds up a hot fire plume.

- Never stack items close to fire sprinklers (keep 18" minimum below the sprinkler). When items

are stacked near fire sprinklers, they could block the spraypattern of the sprinkler and not

allow the sprinkler to work as it was intended.

Sprinkler Spacing Under Horizontal Ceilings

Several maximum coverage areas are used for

residential sprinklers in accordance with minimum listed

flows and pressures. The area of coverage must be

equal to or greater than both the length and width of the

hazard area. Residential sprinklers must be located not

more than half the listed spacing nor less than 4´ (102



mm) from walls. Adjacent sprinklers must be located no

farther apart than the listed spacing; the minimum

distance to prevent cold soldering, unless otherwise

specified, is 8 feet (2.44 m).

When selecting an area of coverage, the suggested

practice is to select one that can be adequately

supplied by the available water supply, allowing for the

installation of as few sprinklers as possible while

observing all guidelines pertaining to obstructions and

spacing. After selection of an area of coverage,

sprinklers must be spaced according to the criteria set

forth in the NFPA standards and this document.

Sprinkler Spacing Under Sloped Ceilings

For installation under sloped ceilings, several maximum

coverage areas are also provided, but at different

minimum flows and pressures than those for horizontal

ceilings. The spacing of sprinklers is measured along

the slope when determining the distance off of walls and

between sprinklers. Residential sprinklers may be

located no more than ½ the listed spacing nor less than

4´ (102 mm) from the peak of the sloped ceiling.

Residential sprinklers located at the highest elevation

must not be located more than 3 feet (0.9 m) measured

vertically down from the peak. Refer to Reliable Bulletin

035 for listed coverage areas, flow and pressure



requirements, and positioning criteria for residential

sprinklers installed under sloped ceilings.

Obstruction to Water Distribution

Refer to Figures 1 through 13 for the location of

sprinklers relative to obstructions. The discharge from

residential sprinklers is directed radially outward and

downward from the sprinkler. Sprinklers must be

located such that there will not be any spaces shielded

from distribution by walls, dividing partitions, or other

dwelling construction features. If the sprinkler water

distribution pattern is obstructed, the obstruction is to be

considered the maximum distance of coverage for a

given sprinkler. Additional sprinklers beyond the

obstruction may be necessary unless the obstruction

criteria contained herein can be met. Consult the

appropriate NFPA standard and/or the AHJ for

guidance regarding these situations.

Reliable flat plate concealed sprinklers, the Models RFC

43 and RFC 56, utilize a drop-down style deflector. The

distance the deflector drops below the ceiling is needed

when determining the position of the deflector above the

bottom of an obstruction. These distance are as follows:

Nonadjusted (cover plate flush to cup) - 7

8



_ (22mm)

At full (1

2

_ ) adjustment - 3

8

_ (9.5mm)

Continuous and Noncontinuous Obstructions

A minimum distance is required to be maintained

between sprinklers and continuous obstructions, such

as beams, soffits, and long horizontal light fixtures. See

Figures 1, 2, 4, 5, 6, 7 and/or 13.

Aminimum distance is also required to be maintained

between sprinklers and noncontinuous obstructions,

such as ceiling fans and certain light fixtures. The ceiling

fan motor housing is the primary element that can

obstruct the sprinkler discharge pattern. Testing has

demonstrated that no adverse effects occur as a result

of the ceiling fan¶s blade rotation in either direction.

With regards to location of sprinklers near light

fixtures, there are two considerations; the amount of

heat the light gives off and the light fixture as an

obstruction. The minimum distance of a sprinkler

relative to the light as a heat source is given in Table B. If

the light is also an obstruction, then the obstruction

criteria must be applied, relative to the minimum



distance required from Table B.

For noncontinuous obstructions, apply the ³four times

rule´ as provided in NFPA 13 where it is determined that

the sprinkler can spray to at least two sides of the

obstruction, either over and under or around the

obstruction on both sides. Sprinklers shall be positioned

away from the obstruction aminimum distance of four times the maximum dimension of the obstruction. The

maximum clear distance required shall be 36C

(914mm).



How does a residential firesprinkler head work?

The objective of the residential firesprinkler head is to respond in less than 60 seconds,

keep smoke levels above 5 feet and maintain a breathable atmosphere. This concept can be achieved by proper spacing of the residential firesprinkler heads with regard to

obstructions, a critical consideration and placement within the protected rooms Simplystated the industry and it¶s partners developed a sensing element, now known as Fast

Response and incorporated it in a frame assembled with a deflector which causes water distribution to be in a flatter plane thus reaching higher up on the boundary walls of a

dwelling space. Hence, home fire suppression products are now available which allowfor placement along walls, concealed or exposed in ceilings and for use in freezing

conditions. Home firesprinkler systems should meet the firesprinkler system designcriteria of the local fire officer and the manufacturers guide lines. The resulting products

are now produced in various finishes, mounting configurations and flow capacities.

sprinkler.pdf

12. Determine the design area and design density

The design area is a theoretical space within the building that's designated as the worst

possible place where a fire can break out. Once determined as the highest risk area in the building, this area's risk level is usually applied to the entire building. Once that's done,

determine the amount of water per square meter would be needed to put afire

out in thedesign area. The calculations should be done in liters of water per minute. This will help

you determine the type of sprinkler heads, firesprinkler design, and amount of water pressure you'll need.

3. Determine which firesprinkler installation and design will best meet your needs



You'll need to find a firesprinkler design that can deliver the amount of water per squarefoot required to put out a fire in your design area. Doing this entails complex calculations

that account for the initial water pressure, as well as reductions or elevations to it due tofriction in the pipes, momentum from the speed the water travels, and the difference in

elevation between the water pump and the sprinkler heads. Nowadays, these calculations

are often performed by computer software-although firesprinkler installation professionals are still required to learn to do them by hand as part of their certification.

Waterspray systems are built to control a fire until firefighters arrive on the scene withhigh pressure hoses. The purpose of these is to spray enough water to keep the fire from

spreading to flammable objects, but to reduce the damage from excessive amounts of water. The water is released in droplets to cover a larger area within a home or office.

Read more: The Types of Fire Sprinklers |eHow.comhttp://www.ehow.com/about_5465265_types-fire-

sprinklers.html#ixzz15AewCjWO

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