Fire Protection Design

Fire Protection Design 1. Classification of Fire

2. Classification of Sprinkler system 3. Types of Sprinkler Heads

4. Sprinkler spacing

5. Standpipe and Hose system 6. Fire Extinguisher

7. Foam Suppression system

2. Classification of Sprinkler System

a)

Wet Pipe System

– a system employing automatic sprinklers attached to a piping system containing water and connected to a water supply so that water discharges immediately from sprinklers opened by fire.

b)

Dry Pipe System

– should be installed only when heat is not adequate to prevent freezing of water in all section of the system.

c)

Preaction System

- is used where an alarm in advance of sprinkler operation is desired and where it is particularly important to prevent accidental discharge of water.

d)

Deluge System

– has open head sprinklers and is used where it is desirable to deliver water through all sprinklers simultaneously as to wet down the entire area protected such as in airport hangar and similar special hazard needing for immediate application of large quantity of water.

3. Types of Sprinkler Heads which are commonly used

a) According to orientation;

Pendent Sprinklers – sprinklers that are installed in such a way that the water stream is directed downward against the deflector.

Upright Sprinklers – sprinklers that are installed in such a way that the water stream is directed upward against the deflector.

Sidewall Sprinklers – sprinklers having special deflectors that are designed to discharge most of the water away from the nearby wall in a pattern resembling one quarter of a sphere with a small portion of the discharge directed at the wall behind the sprinkler

b) According to design and performance characteristics;

Early Suppression Fast Response (ESFR) - a type of fast response sprinkler providing fire suppression to high challenge fire hazard such as dangerous goods/chemical fire.

Large Drop Sprinklers - a type of sprinkler that is capable of providing fire control to specific high challenge fire hazard such as fire in warehouses.

Extended Coverage Sprinklers – a type of spray sprinkler that complies with the extended protection areas defined in NFPA 13.

Open Head Sprinklers – sprinklers that do not have actuator or heat responsive element and are used in dry suppression system such as deluge.

WHERE SPRINKLERS ARE NEEDED

1. In noncombustible buildings wherever contents are combustible, including areas where flammable liquids are stored or used.

2. Throughout all buildings of combustible construction or those having appreciable amounts of combustible components.

3. As the basic protection at hazardous processes such as those involving flammable liquids, even though protected with fixed extinguishing systems.

4. In concealed spaces of combustible construction such as floors, roofs, and low attics, except where

the ceiling is attached directly to the underside of the supporting beams of a combustible roof or floor and fire- stopping is provided.

5. In vacant spaces under the first story of buildings with combustible floors and under the combustible floors of exterior docks, platforms and piers.

6. Under roofs over outside loading platforms or docks, and under other exterior canopies except where construction is noncombustible and the area under the canopy is not used for storage. 7. In enclosed equipment such as ovens, dryers, dust collectors, large ducts, spray booths, paper machine hoods, paper machine economizers, parts of textile preparatory machines, and similar enclosures

where combustible materials are processed or combustible wastes or deposits may accumulate. 8. In small enclosed structures such a penthouses, stairways, passageways, small offices, stock rooms, closets, or similar enclosures of combustible construction or containing combustible material.

9. In elevator towers, including in and under penthouses and in elevator machine rooms.

10. Under cutting tables regardless of width, and under ducts and storage shelves, including slatted

decks, that are over 4 ft. (1.2 m) wide, where there are combustibles beneath. Sprinklers are needed under ducts of less width if distribution from ceiling sprinklers is obstructed, as may be the

case with ESFR or large-drop sprinklers.

11. At exposed steelwork supporting process equipment such as large tanks, stills, pipelines, or equipment containing flammable chemicals or liquids so constructed or located that the steel would

not be well protected by the usual installation of building sprinklers.

12. Where combustible storage or construction is introduced in areas where buildings and contents

are otherwise noncombustible. 13. Telephone equipment rooms.

4. Sprinkler spacing

a) Maximum area of sprinkler protection based on occupancy

Light Hazard

1 sprinkler per 18.60m2 or 20.9m2 if hydraulically calculated

3m X 4m Grid 4m X 4m Grid Ordinary Hazard 1 sprinkler per 12.10 m2 3m X 4m Grid

Extra Hazard

1 sprinkler per 8.4m2 or 9.3m2 if hydraulically calculated

2.8m X 2.8m Grid

a) Sprinkler distance against a dry wall

Minimum is 0.10m

b) Sprinkler distance against soffit

Minimum is 0.025m

b) Standpipe and Hose system

a) Type

Automatic Dry – shall be a dry standpipe system normally filled with pressurized air. A device such as a dry pipe valve is used to admit water to the system piping automatically upon opening a hose valve.

Automatic Wet – shall be a wet standpipe that has a water supply that is capable of supplying the system demand automatically.

Semi automatic Dry – shall be a dry standpipe system that uses a device such as a deluge valve, to admit water into the system piping upon activation of a fire detection device. Manual Dry – shall be a dry standpipe system. This system does not have a permanent water supply attached to the system.

Manual Wet – shall be a wet standpipe system connected to a small water supply for the purpose of maintaining water supply to the system but is not capable of supplying the whole system demand to the standpipe system

b) Classes

Class I Standpipe system – shall provide a 65mm hose connection (either landing valves or fire hose cabinets marked as FHC 1) to supply water for the use of firemen and those trained in handling heavy fire streams.

Fire Hose Cabinet Class I (FHC I)

Class II Standpipe system – shall provide 40mm hose station or fire hose cabinets marked as FHC2 to supply water to be used primarily by the building occupants or by the fire

department during initial response. A minimum 25mm hose station shall be permitted to be used in light hazard occupancies.

Class III Standpipe system – shall provide 40mm hose station to supply water for use by the building occupants and 65mm hose connection to supply larger volume of water for use by the fire department and those trained to handle heavy fire streams

Fire Hose Cabinet III (FHC III)

c) Commonly used symbols

6) Fire Extinguisher

Fire extinguisher shall be selected for class or classes of fire or hazard to be protected

Class A Fire/Hazard

a) Water type shall not be placed in areas where temperature is outside the range of 4 deg. C to 49 deg. C. It contains water based agent such as aqueous film forming foam (AFFF), Film forming fluoroprotein foam (FFFP), anti freeze and loaded stream.

b) Dry chemical or ABC type contains a specially fluidized and siliconized mono ammonium phosphate chemical. It chemically insulates Class A fires by melting at approx. 176 deg., coating the surface to which it is applied.

c) Wet chemical type are specially designed to tackle Class K fires but they also have Class A rating. Wet chemical includes, but are not limited to, aqueous solutions of potassium acetate, potassium carbonate or combination of the materials

Class B fire/Hazard

a) Aqueous Film Forming Foam (AFFF) are water based and frequently contained hydrocarbon based surfactant such as sodium alkyl sulfate and fluoros surfactant such as fluorotelomers and penfluoro octanoic acid. They have the ability to spread over the surface of hydrocarbon based liquid such as crude oil, diesel fuel etc.

b) Film Forming Fluoroprotein Foam (FFFP) are class A and B rated. FFFP is alcohol resistant and is effective on a wide variety of Class B materials such as alcohol, solvents and hydrocarbons. Applying FFFP to non ignited Class B liquid spills will seal the surface minimizing the chance serious fire.

c) Carbon Dioxide extinguisher are used for Class B and C fires. CO2 extinguisher are highly pressurized

d) Dry chemical contains a specially fluidized and siliconized mono ammonium phosphate chemical. It chemically insulates Class B fires by melting at approx. 176 deg., coating the surface to which it is applied.

Class C Fire/Hazard

a) Hexa Fluoropropane (FE-36 or HFC 236) is stored as liquid gas that allows the user to accurately deliver suppressant to the source of fire. Once it is released the chemical reverts to a gaseous form that extinguishes fires using a combination of chemical reactions and oxygen deprivation.

b) Dry chemical or ABC type contains a specially fluidized and siliconized mono ammonium phosphate chemical. It chemically insulates Class C fires by melting at approx. 176 deg., coating the surface to which it is applied.

Class D Fires/Hazard

a) Sodium Chloride dry powder extinguisher can be used against Class D fires to

form a crust that prevents oxygen from reaching the blaze and dissipating heat

away from burning metal

b) Sodium Carbonate based extinguisher are used where stainless steel piping and

equipment could be damaged by other type of extinguisher.This type is

recommended wherever stress corrosion of stainless steel is kept to an absolute

minimum

c) Graphite based extinguisher contains dry graphite that smothers very hot burning

metal like lithium

Class K Fire/hazard

a) Class K extinguisher, creates a foam blanket by saponifying hot cooking oils,

cooling both appliance and hot cooking oils and offering improved visibility

during fire fighting

7) Foam Suppression system

Foam systems are the best fire extinguishing application for the protection of;  Petroleum Refineries

 Petrochemical Plants  Chemical Industries

 Flammable liquid and dangerous goods storage

Three (3) basic components are necessary. Foam concentrate, water and air. When these 3 components are correctly and continuously mixed a homogeneous foam blanket is

obtained that when delivered on a burning substance, it extinguishes the fire by separation of the flame source from the oxygen.

8) Clean Agent Fire Suppression system

Clean agent extinguishes a fire by a combination of chemical and physical

mechanism without affecting the available oxygen. This allows the personnel to

see and breathe, permitting them to safely leave the fire area. It is effective for

use on class A surface fire, class B flammable liquid fire and class C electrical

fires. The system can be stand alone which means that it has its own detection

devices which upon detection and confirmation gives signal to the clean agent

control panel to activate the system or it can be activated through the signal

sent by the fire alarm control panel.

Broadly speaking, there are two methods for applying an extinguishing agent:

total flooding and local application.

Systems working on a total flooding principle apply an extinguishing agent to a

three dimensional enclosed space in order to achieve a concentration of the

agent (volume percent of the agent in air) adequate to extinguish the fire. These

types of systems may be operated automatically by detection and related

controls or manually by the operation of a system actuator.

Systems working on a local application principle apply an extinguishing agent

directly onto a fire (usually a two dimensional area), or into the three

dimensional region immediately surrounding the substance or object on fire.

The main difference in local application from total flooding design is the

absence of physical barriers enclosing the fire space.

In the context of automatic extinguishing systems, local application normally

does not refer to the use of manually operated wheeled or portable fire

extinguishers, although the nature of the agent delivery is similar

a) Commonly used clean agent system (all the system are similar in its

application except for the gas design concentration)

Inergen

b) Commonly used drawing symbols

c) Commonly used devices in Clean Agent Fire Suppression

Discharge nozzle

Control panel