Fire Fighting Equipments Ramki

INDEX The Andhra Petrochemicals limited Introduction Definitions Anatomy of Fire Fire Triangle or Pyramid Class of Fire Emergency Fire Fighting Fire Protection in Petrochemical Industry Fire Drills Fire Risk of Electricity Abbreviations Bibliography

INTRODUCTION The Andhra Petrochemicals Limited is a Joint Venture company of the Andhra Sugars Limited and Andhra Pradesh Industrial Development Corporation to manufacture 36,000 MTPA capacity of Oxo-Alcohols. The low-pressure oxo technology jointly developed by Union Carbide Corporation Davy McKee – Johnson matthey. The company was incorporated in 1988, with the capital investment of 150 crores. The first product was commenced during the year 1993. The annual turnover of the plant is 180 crores.

The plant is situated in 75 acres site at Visakhapatnam. In which 30acres is plant and remaining is green belt. The location of the plant is away from the city and near the sea. Site is 7 km away from the National Highway for the transportation of the products by the road tankers. The site is leased from Visakhapatnam Port Trust with renewal options. The major advantage of site is that it is adjacent to HINDUSTAN PETROLEUM CORPORATION LIMITED, VISAKHA REFINARY .One of the raw material, Propylene is drawn through the direct pipeline and another raw material, Naphtha and other fuels are also brought from HPCL by road tankers. Thus transport cost is minimum The Design of the plant is to minimize hazardous chemicals emission and losses thereby ensuring maximum safety of the plant and negligible environmental impact.

The products of the plant are taken by campaign basis according to the market demand. These are 1. 2-Ethyl Hexanol

30,000 MTPA

2. Normal Butanol

2,314 MTPA

3. Iso Butanol

3,686 MTPA.

OXO – ALCOHOLS PLANT A unique Oxo–Alcohols Plant in the south India, Designed by DAVY McKee Limited, ENGLAND with TATA HONEY WELL TDC 3000

and EXPERION

Distributed control system to have better control of the plant. Adopting the lowpressure technique to produce 2 Ethyl Hexanol, N- Butanol and I-Butanol at the total capacity of 36,000 MTPA by using Naphtha and Propylene as the raw materials. The name Oxo process indicates that conversion of α - Olefins to Aldehydes and/or alcohols containing an additional carbon atom i.e., propylene reacts with synthesis gas to produce Butyraldehyde and consequently into Butanols. Low pressure Oxo Process has been adopted to achieve better-feed stock advantage and maximize the production of Normal Butyraldehyde over Iso Butyraldehyde.

Campaign operation of alcohols plant enables a significant reduction in Capital cost of the hydrogenation and to produce a wide variation in Alcohol product slate according to the market demand. The Oxo – Alcohols Plant consist mainly.  Synthesis Gas Plant  Aldehyde Plant  Alcohols Plant  Offsites  Utilities

Over All Process Description Synthesis gas is produced by the Adiabatic and Tubular Steam Reforming of Naphtha. High purity hydrogen is achieved through pressure swing adsorption process. This synthesis gas is reacted with propylene to give Aldehydes, N – Bal, and I– Bal by low pressure Hydroformylation. The products 2-EH, N-BUOH and I-BUOH are produced on campaign basis. N – Butyraldehyde after Aldolisation and Hydrogenation produces 2-Ethyl Hexanol.

Hydrogenation of individual N – Butyraldehyde and I – Butyraldehyde, produce two other Alcohols N – Butanol and I – Butanol on campaign basis, respectively. Raw materials and products are stored in off sites. Cooling water, DM water, Steam, Instrument air, Nitrogen and Electricity are supplied from Utilities.

 Product Uses 1) 2-ETHYL HEXANOL 2) 2-ETHYL HEXANOL

Product

Dioctyl Phthalate

Use

Plasticiser in PVC production.Main general purpose plasticiser for both Vinyl & rubber applications.

2-Ethyl HexylAcrylate

Adhesives,& as an internal plasticiser for Vinyl Acetate which is used in surface coatings,Paper & Textile applications.

Nitrate Esters

Cetane Improves.

Lube Oil Additives Other Plasticiser

 Dioctyl Adipate, Trioctyl Trimellitate.

2) BUTANOL Product

Use

Butyl Acrylate

Internal plasticiser for vinylacetate.

EGMBE

For watersoluble paints and inks.

Butyl Acetate

Solvents and lacquers.

Butyl Benzyl Phthalate

Plasticiser.

Butyl Amines.

Pesticides.

DEFINITIONS Fire Vehicles: are mobile vehicles meant for transporting equipment /fire fighting agents / fire fighting crew to the site of fire / other emergency. Foam :are an aggregate of air filled bubbles that will float on the surface of a flammable liquid . They are made from aerated solutions of water and a proper proportion of foam concentrate. Foam forms a cohesive floating blanket on the liquid surface that extinguishes the fire by mothering an cooling the fuel. They also prevent re-ignition of combustibles mixtures of vapour and air. Foam Tender: is a mobile fire tender consisting of pump, foam proportioning system, foam monitor, water and foam compound tank which can generate foam for blanketing / fire fighting DCP Tender: is a mobile fire vehicle consisting of Dry Chemical Powder Vessels, Nitrogen gas cylinders. The Dry Chemical Powder can be used with pressure to knockdown the flame / fire. Foam Nurser : is a mobile fire vehicle consisting of pump, foam compound tank which can be used to replenish the foam compound in the foam tenders /Trailer mounted foam tank monitors at emergency site. Emergency Rescue Tender (ERT): is a mobile fire vehicle consisting of emergency rescue equipment which can help to provide immediate assistance for controlling emergencies like fire, oil spillage, accidents etc. Emergency Rescue Tender (ERT) : for handling LPG emergencies is a mobile fire vehicle consisting of pump, compressor for handling LPG emergencies (particularly off-site area) including emergency equipment. Water Tender : is a mobile fire vehicle consisting of pump, water tank which can be used to deliver water with pressure or foam with auxiliary connection for fire fighting. Oil Terminal : That portion of property where combustible/flammable liquids are received by tanker, pipelines, tank wagons, tank trucks and are stored or blended in

bulk for the purpose of distributing such liquids by tankers pipelines, tank wagons, tank trucks, portable tanks or containers constitutes an oil terminal. Wharf: The area at the dock basin where ancillary facilities such as crane, warehouse etc. are provided for serving the ship. Jetty: The actual frontage of the wharf where the tender system is attached for the vessels to berth. Pier : This is the exclusive area where the warfare is constructed in the port.

THE ANATOMY OF FIRE Oxidation or combustion processes of fire are dynamic, continuously reacting process. They are unbalanced and unsatisfied systems containing energy seeking an equilibrium between the molecules of the reactants of the system to a lower less active level of energy. In the course of this procedure they give off heat energy in the form of fire and flame. These processes are initiated by a small input of activation energy (spark) to start the reaction, after which propagation (flame spread) continues as long as there is supply of energy (fuel) and a reactant (oxygen) for consumption of a union to a more satisfied, lower level or energy (ash).

Physics And Chemistry Of Combustion The reactions which occur during combustion and burning are chain reactions which branch off or fragment into very active chemical species called free radicals. The free radicals are very reactive, unstable

combinations of atoms which are only

temporarily present and immediately link up with other atoms to form more stable molecular compounds. Research has shown that extinguishment procedures that utilize actual chemical reactivity for halting the process of the fire, attack these free radical fragments, rendering them incapable of furthering or extending the combustion chain reaction.

Sources of Heat i.

Heat from Mechanical Energy : Friction always produces heat, every moving thing is a possible source of heat energy spinning shafts cause considerable heat in the bearings that support them, to prevent the destruction of the shaft and to reduce the temperatures when the equipment is operating it is lubricated. Oils and greases not only make the shaft to turn smoothly, but also conduct the heat away from the shaft and the bearing rapidly. As such a plant engineer should look on every friction source as a potential fire hazard.

ii.

Heat by compression : Anything that is squeezed or compressed gets warmer. When gas is compressed it heats up, this principle is used in diesel

engine by compressing the air to such an extent as to burn the fuel when injected. iii.

Heat by Electricity : As electricity flows through a conductor, heat is produced. If the cable is large enough to carry the current the heat produced will be harmlessly dissipated, on the other hand if the cable is small and the current is more, it will produce excessive heat and will create a serious fire risk. To prevent such incidence correct size fuse or proper circuit breakers to be installed in the circuit.

iv.

Heat from Chemical Action : A strong acid will produce considerable heat when water is added to it, even time for instance will generate enough heat to ignite combustible materials when water is added to it. Now a days various chemicals are used in industries as a result fire in industries have increased manifold due to carelessness or accidental mixing of chemicals which infact releases excessive heat. A striking example Is glycerine and potassium permanganate when these two chemicals comes in contact first fumes (slow combustion) and soon afterwards burst into flames (rapid combustion) The absorption of oxygen by certain vegetable or animal oils and facts and the absorption of oxygen by certain substances like coal may lead to such an increase in temperature as to bring out spontaneous ignition. However to raise the temperature to a point sufficient to cause spontaneous combustion, it is essential that the heat generated by the various chemical reaction should be in excess of the heat dissipated. It is therefore, recommended that the adequate ventilation should be provided to minimize the potential danger.

Ignition Temperature The temperatures at which combustion can take place fall into three categories, namely, Flash Point, Fire Point and Spontaneous Ignition Temperature. a.

Flash Point : At certain temperature, the vapor given off by a liquid will “Flash” momentarily on the application of a small flame but will not continue to burn. There are several types of apparatus for determining flash point (Abel, Pensky-Martyn)

b.

Fire Point : This may be defined as the lowest temperature at which the heat from the combustion of a burning vapor is capable of producing sufficient vapor to enable the combustion to continue. It will be seen that the difference between flash point and fire point is that the flash point temperature is only the required to produce vapor to enable a momentary flash to take place where as the fire point temperature has to be high enough to produce sufficient vapor to sustain the reaction, so that the substance continues to burn independently of the ignition source.

c.

Spontaneous Ignition Temperature : this is the lowest temperature at which the substance will ignite spontaneously that is the substance will burn without the introduction of flame or other ignition source. This implies that under certain conditions some materials undergo spontaneous combustion. This is sometimes referred to as Ignition Temperature.

Specific Gravity (Relative Density) Vapour Density a. Specific gravity (Relative Density) : The specific gravity (also known as relative density) of a substance is the ratio of the mass of any volume of it to the mass of an equal volume of water. Specific Gravity = Mass of any volume of he substance Mass of an equal volume of water It should be noted that specific gravity has no units, it is simply a number or ratio and it is the same whatever system of units is being used for expressing densities. b. Vapour Density : The density of a gas or vapour is often given in relation to the density of an equal volume of Hydrogen or Air, under the same condition of temperature and pressure. Hydrogen is often used as a basis of vap9our density

because it is the lightest gas, and the vapour density of Air as compared with Hydrogen is 14.4. For carbon dioxide the corresponding figure is 22 and carbon dioxide is, therefore, about 1 ½ times as heavy as air at the same temperature and pressure. For fire service purposes it is much more convenient to compare the density of gases and vapours with that of Air, but in that case the reference gas should be qucted e.g. vapour density of methane is 0.856 (air-1) or the vapour density of methane is a 8 (hydrogen-1). The following are the examples of vapour density as compared with Hydrogen. Hydrogen

1

Lighter than

Methane

8

air

Ammonia

8.5

Air

14.5

Carbon Dioxide

22

Heavier than

Sulphur Dioxide

32

air

Chlorine

35.5

To calculate the vapour density the following formula may be used : Vapour density of a compoun = Molecular weight of a compound 29 In the above formula 29 is the composite molecular weight of air.

FIRE TRIANGLE OR PYRAMID Three conditions have long been regarded as essential components of any fire : 1. Fuel (i.e. the combustible material). 2. Oxygen (from the atmosphere). 3. Heat (essential to start the fire initially, but maintained bye the fire itself once it has started).

These are familiar to fire fighters as the ‘fire triangle’ or pyramid. If any one of these conditions is removed, the fire goes out. Methods of fire fighting thus depend on removing or shutting off the source of fuel, excluding oxygen or removing heat from the fire faster than it is liberated. A fourth condition is now recognised. Flames proceed chemically as branched chain reactions through the intermediary of free radicals which are constantly being formed and consumed. If the free radicals can be removed and prevented from continuing the chain reaction, the flame goes out. Various chemicals used in dry powder and halogenated hydrocarbon extinguishers capture free radicals and put out the fire in this way. Potassium bicarbonate is more effective than sodium bicarbonate and free halogen radicals, especially bromine formed when a brominated hydrocarbon meets a fire, are also effective. Thus the familiar fire triangle becomes a pyramid and now includes the fourth condition.

CLASSES OF FIRE Various classes of fire are recognised in order to rationalise the choice of extinguishing media and devices, and the precautions taken in the protection and fire fighting. A. Solid materials corresponding to the old class A.

B. Flammable liquids corresponding to the old class B.

C. Gases and gas containers.

D. Metal fires.

Class A Fires. Carbonaceous Solids The general method of extinguishing class A fires is by water jets which quench the fire and cool the material to below its ignition temperature. Class A fires are often deep-rooted and well below the surface of the material, so that sufficient water must be applied to penetrate and cool the whole of the burning material to below its ignition temperature.

Class B Fires. Flammable Liquids In dealing with flammable liquids two main hazards must be recognised. 1. If the liquid is lighter than water and dose not mix with it, the use of water may actually spread the fire rather than extinguish it, since the liquid will float on the water and be carried into surrounding areas, cellars and drains. 2. If the liquid has a low flash point, its vapour will form an explosive mixture with air and this may spread and extend a considerable distance from the liquid itself. A source of ignition for instance a spark or lighted match, anywhere in this area will cause a sheet of flame or flash-back which will set fire to liquid and any easily ignitable materials in its path. Flammable liquids in general must be vaporised in order to burn, and it is the vapour not the liquid which burns. Flash point. The flash point of a flammable liquid is the lowest temperature at which enough vapour is given off near the surface of the liquid to produce a flammable mixture with air; that is a mixture which may be ignited by a spark or other source of ignition, and which contains the proper ratio of vapour and air to support combustion. These rations vary widely from liquid to liquid, but it should always be assumed that any flammable solvent above its flash point is in equilibrium with a flammable vapourair mixture. Once a fire has started, its heat rapidly vapourises more liquid until the whole mass is a flame. In general, the lower the flash point of a liquid the more flammable is the material and the more violent the resulting fire.

The fact that a liquid is at a temperature below its flash point does not mean that it is safe. If a material such as kerosene with a flash point of 400C is brought into contact with a source of intense heat – a welding torch, furnace or open fire-a small part of it could be heated above the flash point, give off vapour and burst into flame. The heat thus produced would heat the rest of the kerosene and the fire would spread. A mist of a high flash solvent is also almost as easily ignited as if it were a true mixture of air and vapour. Nearly all flammable vapurs are heavier than air, so that explosive mixtures of air and vapour will spread over the ground or floor when the air is still and flow into depressions in the ground, drains, trenches and cellars. Explosive limits of vapour-air mixture. The vapour of every flammable liquid has a minimum concentration in air below which it does not ignite when in contact with a source of ignition. There is also a maximum concentration of vapour above which flame is not propagated, although this is only found at room temperature if the flash point of the material is low. These limits are known as lower and upper explosive limits and they vary widely for different flammable liquids.

General Precautions For Flammable Liquids Flammable liquids used in industrial buildings should be kept in safety cans which have a fire arrester in the spout and a spring closing cap so that they are always closed when not in use. This obviates two of the main danger; escape of flammable vapours from an open container, with risk of ignition and flash-back and ignition with explosive force of the residual vapour left in apparently empty containers. Building in which flammable liquids are used should have good ventilation and the quantities of liquid in a building should be kept to a minimum. No smoking should be the rule in a building where flammable liquids are used and a careful check should be made regularly to eliminate all other possible sources of ignition. Empty containers of flammable liquids should not be kept in the building but returned to stores for refilling.

Many of the fire involving flammable liquids have occurred where the liquid was present as a paint, lacquer or rubber solution or paste solvent. The vapour from the drying article where the solvent was used or from the open paint or paste tin built up in concentration and spread to a point of ignition until a flash back occurred. Where flammable liquids are used in plants for washing and dipping operations the tanks or containers should be provided with hinged covers which are automatically closed by a fusible link and a spring operated mechanism if the tank or container catches fire. Water should only be used to extinguish a flammable liquid fire in certain limited and clearly defined circumstances. 1. For liquids heavier than water (e.g. carbon disulphide) and at temperatures lower than the boiling point of water. 2. For liquids readily soluble in water provided either that the quantity of diluted material is small enough to be contained or provided that the material can be washed away without causing an unacceptable pollution problem. Alternatively the most suitable3 extinguishing agents are dry powder, foam, carbon dioxide or a suitable vapourising liquid provided they are used in conditions where they do not create a new hazard. If water has to be used to cool other equipment or plant close to a vapourising liquid fire, care must be taken that the water does not flow into the burning liquid and spread the fire. When a fire involving a flammable liquid has been extinguished there is often a danger that fresh vapour will form and mix with air creating an explosive vapour mixture which will re-ignite, often on hot or glowing material left from the earlier fire. While various measures may be taken to prevent this, there are some cases where it is better to let a vapourising liquid fire burn itself out, at the same time concentrating efforts on cooling objects exposed to the fire and preventing it from spreading.

Class C Fires, Gases and Electrical There is always a serious danger whenever a fire from a leaking or fractured gas main or container is extinguished, that the unignited gas continuing to escape will mix with air to form an explosive mixture. This when reignited may result in a serious explosion which causes more destruction and injury than the original fire would have done if left to burn itself out. The only safe way of estinguishing a gas fire is to shut off the supply of gas to the fire. Cooling should, however, be applied to objects heated by the fire, particularly if they are combustible or contain flammable materials; water should be applied through a spray nozzle. Flammable materials, particularly compressed and liquefied gases in cylinders should be removed as quickly as possible from the neighborhood of a fire. If a gas fire is extinguished accidentally by a water spray and the supply of gas cannot be intently shut off, the area should be urgently evacuated. Great care should be taken where electrical appliances and switches are exposed to a gas leak. It may seem logical to switch off any electric motors or other electrical equipment in the neighborhood of such a leak. But unless the switch is flameproof the mere act of switching off a motor may create a sparking in the switch which could ignite an explosive gas-air mixture surrounding the switch. Electrical appliances exposed to such conditions should therefore be switched off remotely from a switch in a safe area and not from a switch exposed to the gas-mixture, unless the switch itself is known to be flameproof. A high proportion of gas fires is caused by leaks from damaged or perished flexible rubber hose used with portable LPG cylinders for cutting and welding, etc. besides taking the precautions, the used of rubber hose and portable cylinders inside buildings should be kept to the absolute minimum. Such equipment should be replaced as far as possible by fixed piping deriving its supply from the gas main or from a bank of cylinders secured in a safe place outside the building.

Most cylinders in the UK which contain flammable gases are not as yet fitted with pressure-relieving devices. Thus if a cylinder is involved in a fire, its internal pressure is likely to rise until it bursts, and its contents escape as a fireball. Unless the cylinder can be positively cooled, all fire fighters should withdraw to a safe distance. If a gas cylinder starts to leak and the leak cannot be immediately stopped, it should be moved at once to the open air where the gas can disperse safely. If a cylinder has been involved in a fire, it should be emptied and tested in a proper cylinder testing station or returned to its makers properly marked for testing.

Class D Fires. Metals The most commonly encountered metal fires are those of magnesium and its alloy, although several powdered metals, notably aluminum, can form explosive dust clouds, whilst sodium and potassium react vigorously and catch fire in contact with water. The fumes from most metal fires are dangerous and some, e.g. those from cadmium, beryllium, and lead are extremely toxic.

EMERGENCY FIRE FIGHTING Once needs to distinguish between large and specialized appliances, used by fire brigade and professional fire fighters for dealing with fires which have got out of control of the local works personnel, and smaller appliances used mainly by works personnel for dealing promptly with fires in their early stages. Incidentally, the old expression ‘fire engine’ is deprecated in BS 4422; part 5, 1976, which recommends the use of the word ‘fire appliance’ to cover all equipment provided for the purpose of detecting, recording or extinguishing a fire. The larger appliances used exclusively by fire brigades which include mobile pumps, mobile turntables, platforms and extension ladders, rescue and demolition equipment are not dealt with in this section since they come under the control of a trained and experienced fire officer. Equipment which is handled by the normal (and also in most cases by the works fire brigade or department) works personnel is dealt with here. It falls broadly into two categories. 1. Fixed appliances and hose reels. 2. Portable appliances.

Fire Extinguishers And Fixed Appliances Fixed extinguishers may be designed for manual or automatic operation. They may also be classed as (1) those for general application and (2) those for use where there is a special risk. Fixed installations using water and high expansion foam are most suitable for general protection while those using other extinguishing agents are intended for special risks such as oil or electrical fires. The choice and positioning of fixed installations should be considered when a works or building is being designed, since it is more expensive to install them once building has been completed.

Hose Reels Hose reels are first-aid fire extinguishing equipment provided for the use of the occupants of a building or works and they may be installed instead of, or in addition to, portable water type extinguishers. When installed they will also be used on small fires by the brigade on arrival. This causes less water damage than the brigade’s larger hoses. A hose reel consists of a length up to 36 m of non-kinking rubber tubing with an internal diameter of 19-25 mm. A valve and nozzle are attached to the free end of the hose which is wound on a metal reel. The reel is usually supported by a wall braket and may be arranged to swing on a pivot. The reel has a hollow rotating shaft to the centre of which water is fed. The hose tubing is connected to an outlet on this rotating shaft. The shaft is permanently connected to a suitable water supply through special pipework. With one type of hose reel, all that is necessary to obtain a jet of water is to grasp the nozzle, pull out the amount of hose needed to reach the fire and open the cock at the nozzle. The action of unwinding the reel or removing the nozzle from a special wall fitting turns on the water supply valve. With another type, a valve on the water inlet to the reel must be opened manually before the hose is run out. A hose reel may be fixed or pivoted. The fixed type has guides fitted so that the hose can be pulled off the reel without kinking or jamming. The pivoted type swings to the direction in which the hose is pulled. Nozzles for hose reels are available with internal diameters of 4.5-6.5 mm. The size chosen depends mainly on the pressure of water available. Nozzles should give a minimum flow of 0.38 liters per second. For a 4.8 mm bore nozzle, this requires a water pressures of 2.5 kg/ cm2 gauge at the nozzle. For a 6.4 mm bore nozzle this requires a water pressure of 0.8 kg/cm2 gauge at the nozzle. The pressure loss caused by friction through 10 m of hose at a flow rate of 0.38 liters/second is 0.15 kg/cm2 for a 19 mm bore hose and 0.035 kg/cm2 for a 25mm hose.

Hose reels may be supplied with fixed covers to protect them from dust. Dirt and light which cause deterioration of the rubber tubing. They should be positioned so that no part of a building is more than 6 m from a nozzle when the hoses are fully extended, making due allowance for obstructions. The flow of water through a hose reel with nozzle can be simply checked by measuring the maximum horizontal throw of the jet by directing it over a flat roof or open floor. A nozzle with a bore of 4.8 mm should give a maximum throw of at least 12 m and a nozzle with a bore of 6.5 mm should give a maximum throw of at least 18 m. Hose reels require regular maintenance and checking at least once a year, in accordance with manufacturers recommendations. Brief instructions for operating a hose reel should be displayed on or close to it. All employees should be trained to use hose reels, including how to pull the hose round obstacles.

Hydrants Hydrants are arrangements of piping outlets to which large diameter hose (64 mm or more) may be connected for use by the fire brigade or fully trained works firemen. Some hydrants inside buildings which are known as dry risers are kept empty until they are needed. These are used in cold climates where water in a wet riser might freeze, and also in very tall buildings where water will not reach the top of the riser until the fire pump is started. Other hydrants, known as wet risers, are kept permanently full of water. If the water pressure in the fire main is not sufficient to deliver it to hydrant outlets at the top of tall buildings must be supplied with water from a pump, usually a mobile one carried by a fire brigade. Wet risers are generally preferred to dry once in situations where they can be used. Hydrants may be fitted with foam inlets to which firemen attach a supply of foaming agent that mixes with water in the hydrant and hose.

Automatic Sprinklers These consist of a system of pipes, spray nozzles and heat operated valves by means of which a fire is automatically detected, the alarm given and water delivered to the fire. Sprinklers are useful for stores and other buildings containing combustible materials which are left unattended. The cost of the installation may be partly or wholly offset by the reduction in the fire insurance premium paid. Similar systems may also be used on the outside of buildings and tank to keep them cool if a fire develops near them and so to prevent the fire from spreading to them.

High Expansion Foam The system consists of one or more foam-making machines fitted with short rigid ducts inside the roofs of single-storey buildings. Multi-storey buildings are protected, with similar but larger ducts which run from roof to ground level. One or more floors may be flooded with a foam of very low density but sufficient stability not to collapse at once when exposed to a fire. The foam may be filled with carbon dioxide instead of air. Its action is to smother and blanket a fire. This is a relatively new system which has been mainly used to protect basements and tunnels to which access may be difficult if a fire develops there. It is finding wider application in warehouses and large buildings. The local fire brigade should be consulted for advice when the installation of such a system is considered.

High Pressure Water Spray (FOG) The water is delivered at high pressure through special nozzles to form fine droplets. A high pressure water spray requires the use of a special booster pump (carried by most brigades) which gives a pressure of about 50 kg/cm2. It rerely forms part of a fixed installation. Its main use is to protect against fires of flammable liquids

and liquefied gases. The use of a very fine and carefully directed water spray removes the main disadvantages of water in dealing with such fires.

Medium Expansion Foam Foam may be produced from a fixed foam solution vessel and carbon dioxide cylinder or from foam making equipment carried by the fire brigade. In either case it may be applied through systems of fixed pipework either to the seat of the fire or to the plant to be protected. Brigades normally carry supplies of normal protein foam only. This is mainly suitable for flammable liquid fires where the liquid is immiscible with water. Liquids such as alcohols which mix with water tend to break down the foam blanket. But for these conditions special compounds are available, which give stable foams, although they are more expensive than protein foam.

Carbon Dioxide And Other Inert Gases These systems must be used with great caution indoors when people are present, due to their asphyxiating action in lowering the oxygen content of the air. In at least one case a man fighting a fire in a basement with carbon dioxide extinguishers which were handed down to him from above collapsed and died as a result of oxygen deficiency in the atmosphere. Gas extinguishing systems consist of a supply of the inert gas under pressure (usually in cylinders), a system of pipework and valves delivering the inert gas to the points of application and an automatic detection and initiating system which opens inert gas valves once the fire has been detected. It also, in many cases, closes doors and ventilation ducts. These systems operate by reducing the oxygen content of the atmosphere and/or by interrupting the chemical reaction in a flame. Most of the gases used are suitable for electrical equipment and plants handling flammable liquids. This system is particularly suitable for protecting valuable equipment which is easily damaged by water and foam, such as computers. For these systems to operate most effectively, the fire fighting equipment should be housed in a gas-tight compartment which is closed to the atmosphere when a fire starts. Carbon

dioxide installations need special care to avoid introducing risks of ignition by static electricity.

Dry Powder Dry powder is a term used for various free-flowing powders which when poured or otherwise discharged over a fire will extinguish it. The compositions of many fire extinguishing powders are not publicised by their makers for obvious reasons. They generally contain three principal ingredients each with a particular function. 1. Sodium or potassium bicarbonae. These liberate carbon dioxide when heated. Bicarbonates are thus a convenient means of applying carbon dioxide. They also react with and neutralise acids and some other reactive compounds and prevent damage from acids released by a fire. Potassium bicarbonate is claimed to be more effective than sodium bicarbonate due to its greater chain terminating effect. 2. Certain finely powdered salts of metals which when present as a dust in the atmosphere strongly absorb radiant heat, thereby cooling and in some cases extinguishing flames. 3. A compound which prevents the powder particulars from adhering to one another and forming lumps, thus preserving the free-flowing properties of the powder. Dry powder installations comprise dry powder container to which a gas cylinder (usually carbon dioxide) is coupled, and a system of piping and outlets which are located above the places where fires are likely to break out. They can be operated automatically or manually by opening valve on the gas cylinder so that the gas drives the powder to the outlets. These installations are suitable for flammable liquids and electrical equipment and for protecting some processes involving solids which are easily damaged by water or foam.

Portable Appliances Portable fire extinguishers may be used to deliver water, dry powder, foam, carbon dioxide or a vapourising liquid to the seat of a fire. Their use should, as far as

possible, be standardised and the minimum number of types necessary should be carried. Hose reels are generally preferable. Supervisors should be abel to identify the different classes of fires and should know which type of portable extinguisher to use. All personnel should know how to recongnise and use the various types of extinguishers present. Practice sessions should be set up to ensure that all personnel act promptly and effectively in dealing with small fires.

Portable Water Discharging Extinguishers Extinguishers which deliver water operate in various ways: a. The water bucket. This is the simplest of all; it must, however, be kept full of clean water and always in the place reserved for it. Some skill is required in directing the contents of a water bucket onto a fire probably more so than closed portable extinguishers with nozzles. b. Gas pressure applied from a cartridge. A small cartridge of liquefied carbon dioxide is held inside the top of the cylindrical extinguisher. The cartridge has a brass cap which is pier4ced by a plunger passing through a gland in the top of the extinguisher. This is actuated by a sharp blow by the hand to the top of the plunger. Gas released in the extinguisher drives the water out through a discharge tube which extends to the bottom of the cylinder and is connected outside the cylinder to a nozzle via a short length of flexible hose. c. Stored gas pressure. The whole extinguisher is pressurised with gas at the time of charging with water. Water is discharged by opening a valve on the discharge tube. d. Gas pressure formed by reaction between an acid and a carbonate within the extinguisher. The extinguisher has an inner container filled with an acid solution (generally aluminum sulphate). The main body or outer container of the extinguisher is filled with a solution of sodium bicarbonate. The contents of the inner cylinder are released into the outer cylinder by inverting the cylinder and releasing a spring operated plunger. When the solutions mix, gas is formed which pressureises the extinguisher. A jet of water issues through a nozzle on the upper part of the extinguisher, so ling as the extinguisher remains inverted.

The flow of water stops when the extinguisher is turned the ritht way up and surplus gas escapes. e. Hand pump inside the cylinder. This is operated by a handle extending through a gland in the top of the cylinder. The applications and limitations of water extinguishers have already been discussed. Water is best used for fires on solid materials which may re-ignite if not adequately cooled. It can readily penetrate to reach a deep seated fire. Portable water extinguishers have capacities from 4 to 10 liters and an effective range of about 10 m. one or two extinguishers depending on their size are normally required for general protection per 220 m2 of floor area. When using a water-filled extinguisher, direct the jet at the base of the flame and keep it moving across the area of fire. A fire moving vertically should be attacked at its lowest point and followed up. Seek out any hot spots after the main fire is extinguished.

Portable Foam Extinguishers Foam extinguishers are of two types, mechanical and chemical. These correspond to water extinguishers in which the pressure is derived from a gas cartridge and from chemical reaction respectively. But the chemical foam extinguisher, unlike the soda-acid type of water extinguisher, is used in the normal upright position. Portable foam extinguishers have a capacity from 4 to 10 liters and a range of about 7 m. 10 liters for foam are normally required to extinguish 1 m2 of burning liquid. When a liquid fire has been extinguished by foam, the foam blanket left over the liquid remains in position thus preventing re-ignition and allowing the liquid to cool. Foam extinguishers should therefore be used for liquid fires where the liquid has been burning for some time and has become hot.

Foam is not effective on flowing liquids, whether the flow is horizontal or vertical. Foam conducts electricity and should not be used on live electrical fires. Most water miscible liquids break up ordinary foams. When a liquid on fire is in a container, direct the jet at the far inside edge of the container, or at an adjoining vertical surface above the level of the burning liquid. This breaks up the jet and allows the foam to build up and flow across the surface of the liquid. When this is not possible, stand well back and direct the jet slightly upward so that the foam falls on to the surface of the liquid. Move the jet gently from side to side to cover the surface of the liquid. Do not direct the jet into the liquid because this will dive the foam beneath the surface and render it ineffective. It may also splash the burning liquid on to surrounding objects.

Portable Dry Powder Extinguishers The use and composition of dry powder have already been discussed under fixed installations. Portable dry powder extinguishers are made with capacities from 2 to 10 kg of powder. In operation and appearance they are like water extinguishers where the pressure is supplied from a gas cartridge. Their range is less than a water extinguisher, usually from 3-6 m. These are the best type of extinguisher for dealing with fires of flammable liquids. They extinguish the flames over the liquid and thus act faster than foam. They can deal with larger areas of burning liquid than other extinguishers of the same size, and they are effective on fires of flowing liquid. Dry powder can be safely used on electric fires. The main limitation of dry powder is that it gives no protetion against reignition after application ceases since it has poor quenching properties. It is less effective than foam on liquid fires where the liquid has become overheated (i.e. through prolonged burning). Two kilograms of dry powder can normally extinguish a liquid fire converting and area of one square meter when properly applied.

Portable Carbon Dioxide Extinguishers Carbon dioxide extinguishers should only be used sparingly in buildings due to the dangers of asphyxiating personnel. A second hazard of carbon dioxide extinguishers is the formation of static electricity in the discharge which can ignite flammable vapours, sometimes with fatal consequences. Carbon dioxide acts more rapidly than foam and is more suitable for dealing with fires which might spread to surrounding materials before a complete foam blanket could be formed over the burning liquid. Carbon dioxide extinguishers are suitable for dealing with small fires of liquids flowing over horizontal and vertical surfaces. They should be used where the main concern is to avoid damage or contamination by dry powder deposit or foam, for example to laboratory equipment or food preparation. The cooling properties of carbon dioxide are limited and it gives no protraction against re-ignition after application ceases. It is less effective that foam for very hot liquids burning in containers. Carbon dioxide extinguishers contain the carbon dioxide and high pressure as a liquid in steel cylinders, with a valve leading via flexible hose to a horn shaped discharge tube. These extinguishers are normally used with the valve uppermost so that carbon dioxide is discharged as a gas. If they are inverted, a mixture resembling snow of carbon dioxide gas and solid carbon dioxide is discharged, provided the extinguisher is full and the ambient temperature is not excessive. Portable carbon dioxide extinguishers have capacities ranging from 1 to 6 kg and a range from 1 to 3 m.

Portable Vapourising Liquid (Halon) Extinguishers Portable vapourising liquid extinguishers are now mainly restricted to the use of two compounds, bromochlorodifluoro methane or BCF, and bromotrifluoro methane or BTM. These may be discharged either by gas cartridge (containing carbon dioxide) or by pressuring the container with nitrogen. They can be fitted with a control valve if

desired, so that can be discharged in short bursts, but once the seal has been broken they should be emptied, recharged and resealed. Their main action is by excluding oxygen from the flames. Since they do not conduct electricity they can be sued on electrical fires. They have less static electricity risk then carbon dioxide, but they present the same asphyxiation hazard. In addition there is some risk of forming toxic decomposition products when their vapours are in contact with very hot metal, although this risk is far less than with older types of vapourising extinguisher which contained carbon tetrachloride, methyl bromide and other compounds which are little used now because of the toxic problem. These extinguishers have a range of up to 6 m and 1 liter of liquid is sufficient to extinguish flames over an area of one square meter of burning liquid. The methods of using dry powder, carbon dioxide and vapourizing liquid extinguishers are essentially the same. On fires involving liquids, either in containers or on the ground, direct the jet or discharge horn towards the near edge of the fire and with a rapid sweeping motion drive the fire towards the far edge until all the flames are extinguished. On fires in falling liquids, direct the jet or horn at the base of the lames and sweep upwards. When dealing with electrical equipment fires, first turn off the current. Then direct the jet or horn straight at the fire. When the equipment is enclosed, direct the jet or horn straight at the fire. When the equipment is enclosed, direct the jet or horn into any opening so that it penetrates the interior. If the extinguisher has a control valve on the discharge, shut it when the fire appears to be extinguished, wait until the atmosphere clears and, if any flame is then visible, open the valve and discharge again.

Recharging Extinguishers All extinguishers should be recharged immediately after use, irrespective of whether they have been completely or only partly discharged. The safety or fire officer should arrange for books to be kept by supervisor to record every use of an extinguisher and when it was recharged.

Colour Identification Of Portable Fire Extinguishers The availability of many type of portable fire extinguishers for different types of fire have led to steps being taken to standardise their body colours for ease of identification. BS DD 48 1976 Draft for development proposes the following body colours for the different types of extinguishing agent : Water

Signal red

Foam

Pale green

Powder (all types)

French blue

Carbon dioxide

Black

Halogenated Hydrocarbon

Emerald Green

Extinguisher Type

Type of Fire Ordinary Combustibles Fires in paper, cloth, wood, rubber, and many plastics require a water type extinguisher labeled A.

Water

OR

Flammable Liquids Fires in oils, gasoline, some paints, lacquers, grease, solvents, and other flammable liquids require an extinguisher labeled B.

CO2 Electrical Equipment Fires in wiring, fuse boxes, energized electrical equipment, computers, and other electrical sources require an extinguisher labeled C.

Dry Chemical

Ordinary Combustibles, Flammable Liquids, or Electrical Equipment Multi-purpose dry chemical is suitable for use on class A, B, and C.

Multi-Purpose Metals D

Combustible metals such as magnesium and sodium require special extinguishers labeled D

Air-pressurized water extinguishers (APW)

Water is one of the most commonly used extinguishing agents for type A fires. You can recognize an APW by its large silver container. They are filled about two-thirds of the way with ordinary water, then pressurized with air. In some cases, detergents are added to the water to produce a foam. They stand about two to three feet tall and weigh approximately 25 pounds when full. APWs extinguish fire by cooling the surface of the fuel to remove the "heat" element of the fire triangle. APWs are designed for Class A (wood, paper, cloth, rubber, and certain plastics) fires only.

Important: Never use water to extinguish flammable liquid fires. Water is extremely ineffective at extinguishing this type of fire and may make matters worse by the spreading the fire. Never use water to extinguish an electrical fire. Water is a good conductor and may lead to electrocution if used to extinguish an electrical fire. Electrical equipment must be unplugged and/or deenergized before using a water extinguisher on an electrical fire.

Carbon dioxide extinguishers

This type of extinguisher is filled with Carbon Dioxide (CO2), a non-flammable gas under extreme pressure. These extinguishers put out fires by displacing oxygen, or taking away the oxygen element of the fire triangle. Because of its high pressure, when you use this extinguisher pieces of dry ice shoot from the horn, which also has a cooling effect on the fire. You can recognize this type of extinguisher by its hard horn and absent pressure gauge. CO2 cylinders are red and range in size from five to 100 pounds or larger. CO2 extinguishers are designed for Class B and C (flammable liquid and electrical) fires only.

Important: CO2 is not recommended for Class A fires because they may continue to smolder and re-ignite after the CO2 dissipates. Never use CO2 extinguishers in a confined space while people are present without proper respiratory protection. Locations: Carbon dioxide extinguishers will frequently be found in industrial vehicles, mechanical rooms, offices, computer labs, and flammable liquid storage areas.

Dry chemical extinguishers

Dry chemical extinguishers put out fires by coating the fuel with a thin layer of fire retardant powder, separating the fuel from the oxygen. The powder also works to interrupt the chemical reaction, which makes these extinguishers extremely effective. Dry chemical extinguishers are usually rated for class B and C fires and may be marked multiple purpose for use in A, B, and C fires. They contain an extinguishing agent and use a compressed, non-flammable gas as a propellant. ABC fire extinguishers are red in color, and range in size from five pounds to 20 pounds. Dry Chemical extinguishers will have a label indicating they may be used on class A, B, and/or C fires.

or

Locations: These extinguishers will be found in a variety of locations including: public hallways, laboratories, mechanical rooms, break rooms, chemical storage areas, offices, commercial vehicles, and other areas with flammable liquids

FIRE PROTECTION IN PETROCHEMICAL INDUASTRY From the above one car well imagine the potential fire risks in a petrochemical industry. The fire protection can be divided into three phases :

i.

i.

By good plant, design and layout

ii.

Fire control – keeping the fires localised

iii.

Fire extinguishment

Plant Design & Layout : A good plant, design and layout, with strict adherence to safe operating procedures, proper built-in fire prevention system, fire-fighting training and adequate emergency plan to meet fire emergencies, is the best way to minimise the possibility of fire damages. Factors to be considered for the plant layout include adequate spacing and proper arrangement of various utilities, process units, storage units and vessels, loading and filling installations. For plant layout, safety rules laid down in the petroleum act should be followed.

ii.

Fire Control : This embodies protection of tanks, pressure vessels, structures, pipelines and equipment that are effected by direct flame impingement or by radiate heat exposure. Cooling prevents the spread of fire from its point of origin to the surrounding areas.

iii.

Fire Extinguishers : After adequate fire control measures fire is extinguished by employing suitable extinguishing media, like water, foam, dry chemical powder, Co2, Halogenated vapourising .

Storage Tanks In a petrochemical complex, storage tanks of various types of storing the raw materials like Naptha, and Zylene as also the other products are required. These materials being highly inflammable adequate fire protection, fire prevention and fire-fighting arrangements are very essential. In case of any fire emergency, there must be arrangement to cool the tanks which is involved and the surroundingones. Arrangements for fighting the fire is also necessary, while planning the fire protection arrangement, it should worked out on the basis of meeting a major fire indicants. Among the extinguishing media water is employed extensively for cooling and foam

generation. The maximum water flow rate is determines by taking into consideration the possibility of following simultaneous operations. i.

Water for foam generation.

ii.

Water for cooling.

i.

Water for foam generation : As per N.F.P.A. Handbook and code and American Institute Standard for petroleum refineries, water for foam generation for fixed foam pourers should be provided not less than 4.03 L/min for each IM2 of the liquid surface area. For hose streams, at least 6.5 Lit/min of water should be provided. In case of liquid hydrocarbon a delivery rate of 300 liters of foam/m2 of burning area is specified for a minimum period of 10 min.

ii.

Water for cooling : In a fire emergency the tanks which are on fire to be cooled as also the adjoining tanks are to be protected from exposure. For these purposes a flow rate of 10.2 L/min to 20.4 L/min per m2 and 8.16 L/min – 10.2 L/min respectively is considered satisfactory.

Water Storage Adequate water storage is one of the most essential requirement of fire-fighting system. The total capacity of water storage as usually based on 4-10 Hrs. duration of firefighting. Provision storage tanks. The fire water storage tanks should be so placed that water can be delivered under gravity in case of failure of all pumps.

Fire Water Supply System Water supply arrangement should be designed for a reliable and adequate supply of water under pressure (7 kg/cm2) for fire-fighting at each strategic point. This is generally measured by laying independent fire water mains of appropriated diameter along plant roads and access codes in block system. The main network is arranged in such a way that each area is surrounded by mains and sub-headers. Block valves, on the ring main, for maintenance purpose are placed at suitable intervals in such a way that they always ensure sufficient water supply for the operation of fire-fighting appliances.

Fixed Installations i.

Fire Hydrant : Hydrants are to be placed at suitable intervals on fire water mains. Normal distance between the hydrants is 45 m to 90 m depending upon layout of area, water requirement. Discharge from each hydrant should be 1125 l/min at a high pressure.

ii.

Hose Reels : For immediate availability of water in process area permanently connected hose-reels are used extensively. These reels should be provided with 40 mm bore hose of 30 m length.

iii.

Monitors (For Water/Foam) : Fixed monitors are preferred for spot use. Because of limited area coverage from these monitors careful consideration has to be given in locating the same to ensure maximum effectiveness. Water stream, water spray/jet could be applied through the monitors by using co9mbination nozzles.

Water Spray System Water spray cooling system are usually provided to minimise fire exposure. Manual / automatic/ remote controlled water spray is practically useful for cooling uninsulated steel structures elevated pipes, vessels, spheres etc.

Water Fog System Water fog systems are intended to reduce fire intensity by mixing of water with fuel vapour or by the contact of fire drops or a very fine mist of water with oil surface. Water fog is effective on viscus oil or high flash point oils, where areas are within the range of fog nozzles. However, except under ideal conditions, it is seldom effective for extinguishment of fires in gasoline or other low flash point products. Pumps handling, hydrocarbon, compressors control valve, main folds, columns, and other vessels under high temperature and pressure are protected with water fog systems. These systems can be either manual or automatic.

Portable Fire Extinguishers Since in a petrochemical industry most of the fire encountered are that of liquid hydrocarbon, or vapours, portable extinguishers such as foam, dry powder, Co2 in adequate numbers are to be provided at strategic points to tackle a fire at its incipient stage.

FIRE DRILLS Introductory The fire exit drills are absolutely essential in all public institutions, hotels, boarding houses, hospitals. Factories and especially in Schools and Colleges. Properly conducted, they not only secure the orderly and rapid evacuation of the building, but teach self-control as well.

Principles and Procedure The danger which may threaten persons of fire breaks out depends on many different factors, consequently it is not possible to construct a model procedure for action in the event of fire which would be suitable in all premises. Having thoroughly understood the fundamental principles, however. The student should experience to difficulty in adopting them to the circumstances of each case. It is therefore, important that before fire drills are planned, the following points must be of prime consideration. The purpose of fire drills. Formulating a fire routine. Instruction and Training. Fire routine details. Frequency of drills.

Purpose of Fire Drills The responsibility for carrying our fire drills rests on the occupier of the premises. A fire drill is intended to ensure, by means of training and rehearsal, that in the event of fire. The people who may be in danger act in a calm and orderly manner. Where necessary, those designated carry out their allotted duties to ensure the safety of all concerned. The means of escape are used in accordance with a predetermined and practiced plan.

Formulating a Fire Routine Before formulating a fire routine, it is essential to visit the premises concerned, when our fundamental points will need to be considered. The points are : The type of buildings. The occupancy. The existing means of escape. Fire defense. a. The type of Buildings : Are the buildings attached or detached? Are the buildings single-storey or multi-storey? Are the buildings of fire-resisting or non-fire-resisting construction? Will the degree of effective fire-resisting compartmentation preclude the necessity of total evacuation? b. The Occupancy : This covers two points : i.

Population characteristics, i.e. the number of occupants, their distribution in the building, their physical condition and the way they can be expected to react in any emergency. The last two characteristics depend on such factors as age, discipline and whether they are asleep or alert.

ii.

The use to which the building is put, i.e. the processes carried on the nature of the contents of the buildings including furnishings, and goods stored or displayed.

c. The existing means of escape : Is the existing means of escape adequate - distance to travel-place of safety lighting etc.? d. Fire Defense : Have satisfactory arrangements been made to cover the following points? Type of fire alarm and arrangements for sounding it. Fire extinguishers - hose reels - fire parties. Arrangements for calling the fire service. General and specific notices. Availability of staff in certain premises, assembly points, roll call.

Training : Repeated practice evacuations will be necessary in many cases to ensure that the “plan of action” is fully understood and can be carried out efficiently when the occasion demands. Varying conditions should be assumed for these practices so that the occupants are familiar with all alternative routes. Labour, turn-over and newly engaged staff will need to be considered. Whilst it is desirable that as few people as possible know of an impending fire drill, great care should be taken to ensure that this can be carried-out without danger of damage from sudden interruption of the process being carried out. The time taken for persons to reach a place of safety will indicate the degree of efficiency attained by the occupants in their fire drill.

Fire Routine Details A fire routine as a general rule should be based on a sequence of events. Details will vary in accordance with the circumstances of each occupancy and the following list will assist in drawing up a relevant routine to cover most premises. i. Alarm Operation

:

Type - single or two - stage - audible or otherwise - total or partial - notification to central point.

ii. Power

:

Stopping

certain

processes

or

machines,

isolating power supplies. iii. Call Fire Brigade

:

Precise instructions - Watchman's/receptionist’s instructions.

iv. Evacuation

:

Two-stage – instructions – closing of doors and windows – search of toilets etc. – responsible persons.

v. Assembly

:

Away from premises – under cover mutual arrangements with near by premises.

vi. Roll Call

:

Registers -= staff lists – responsible person – report to fire brigade officer.

vii. Attacking the Fire

:

Circumstances

will

dictate

fire-fighting

operations should be attempted; the important

thing to remember is that fire-fighting must always be secondary to life safety and that, whilst small fires such as a quantity of spilled inflammable. Liquid in laboratory can be dealt with summarily, for a sizeable fire safe evacuation should be the primary concern.

Frequency of Drills The amount of instruction and frequency of drills will vary according to the degree of risk i.e. the liability to out break of fire and the size, construction and layout of the premises and any legislative requirement.

Preamble Introduction As a result of increased demands for synthetic fibers, detergents, plastics and fertilizers etc., the petroleum and petrochemical industries are assuming greater importance in our country. The processes involved in a petrochemical industry are manifold and depends on the final products manufactured. These industries generally deal with bulk quantities of highly inflammable materials, mostly liquid and gases and employ high temperature and pressure ranges for processing which may ignite them spontaneously. Thus industries are very much susceptible to fire and explosion. Considering the potential risk in a petroleum industry a sound fire protection plan is of paramountrimportance for the every existence and growth. Petroleum industries have essentially table located away from cities and have therefore, to be self-sufficient in fire fighting arrangement.

FIRE RISK OF ELECTRICITY Heating Effect of Current The flow of Current is called the circuit and if there is an excess flow of the current, through any circuit as over the designed load the cable swill become overheated and the insulation’s may catch fire and burn with emission of large volume of smoke. This may also happen if there is an accidental short circuit between the two wires carrying the current between the positive line and the negative terminals or between the phase and the neutral wires (A.C. Circuits). To prevent this type of contingency, current should never be drawn in excess, through multi-plugs or otherwise by having too many fans or lights in the some circuit, than what the circuit is designed for.

Preventive Measures As a preventive measure against fire due to short circuit, some protective device should be incorporated in the circuit, such as by “thermal Fuse” or “Magnetic Circuit Breakers”. In domestic wirings or in the office premises normally, thermal Fuses of the appropriate rating is inserted in a convenient position, near the main, main switch board and in industrial installation, where high voltage motors etc. are in operation, magnetic circuit breakers are to be provided. In the case of thermal fuses, a metal alloy of low melting point (about 3000F) is usually inserted in the distribution system. In the event of an excess current flowing through the circuit, the thermal fuses will melt at a much lower temperature before any fire could take place and it will disconnect the circuit. Whereas in the event of industrial motors, when an excess current flows, magnetic circuit breakers will trip the circuit by the magnetic relay switch render the circuit safe, such as in the single phasing of multi-phase A.C. motor (commonly known as “Single Phasing”).

Assessment of the Hazard It must be borne in mind that the circuit is overheated when there is a drawal of excess current and the heat that is produced is proportional to the quare of the current,

the resistance of the circuit and the time through which the current is twicesits strength, the heat will be produced four times, the resistance of the circuit and the time remaining the same. Now-a-days, cartridges type of fuses to tally enclosed in a glass case or other suitable device is incorporated in the circuit. They are known as H.R.C. type of safety fuses.

Importance of Main Enhance of Electrical Appliances & Circuit Proper maintenance of electrical equipment’s is quite important such as these including transformers, switch gears etc. as are used in industrial installations. They should be properly maintained by a competent electrician. Regular checking of the earthing resistance, insulation resistance, periodical inspection of the transferors and the switch gears oils and measurements of their posed load of the circuit, so as to keep it within the designed limit, should be enforced upon. The insulation resistance of the oil, used for transformers or switch gears (Dielectric strength) should be checked and examined and the same should be changed as required, depending upon the test results. Tests should be carried out once every six months for transformers and switch gears and the condition of motors, specially for their safety devices, insulation and possible “Single Phasing”.

Electrical Installation For Hazardous Location Selecting the proper types of electric installation for hazardous for location characterised by hazardous concentrations of flammable vapours, gases, dusts, or fibers, either continuously or occasionally, requires considerable judgement. Hazard must be correctly evaluated to assure safety of personnel and property, while avoiding unnecessarily expensive installations. Wherever possible, electrical equipment and wiring are best located outside the areas of most severe hazard.

Lights, for example, may be located outside a hazardous room or enclosure and illuminate the inside through transparent panels. Motors can be located outside, with drive shafts extending through the wall or partition, with openings for the shafts tightly sealed. Controllers, switches, cutouts, remoter scan be located in adjoining, less hazardous areas. Such arrangements frequently effect a considerable saving.

Maintenance of Electrical Equipment’s Approximately one out of every five industrial fires is of electric origin. Many of these fires can be prevented and the usual life of electrical equipment increased by proper maintenance. Three kinds of maintenance are recognised : 1. Repairs after a failure of breakdown. 2. Ordinary maintenance, which consists of repairs, adjustments or replacement of parts shown to be necessary by visual inspections at irregular intervals before a breakdown occurs. 3. Preventive maintenance, which consists of regularly scheduled inspections and periodic dismantling of equipment to check every detail likely to cause trouble. A regularly scheduled preventive maintenance program is the most important factor in correcting electrical deficits and preventing electrical breakdown.

Inspections should be made by a competent electricians. He should pay special attention to equipment in hazardous locations.

ABBREVIATIONS

1.

BLEVE

-

Boiling Liquid Expanding Vapor Explosion

2.

VCE

-

Vapor Cloud Explosion

3.

OISD

-

Oil Industry Safety Directorate

4.

ISRS

-

International Safety Rating System

5.

DGFASLI

-

Directorate General Factory Advice Service & Labor Institutes

6.

CIMAH

-

Control of Industrial Major Accident Hazards

7.

NSC

-

National Safety Council

8.

MIC

-

Methyl Iso Cyanate

9.

SCBA

-

Self Contained Breathing Apparatus

10.

TREMCARD -

Transport Emergency Card

11.

PEL

-

Permissible Exposure Limit

12.

STEL

-

Short Term Exposure Limit

13.

TWA

-

Time Weighted Average

14.

TLV

-

Threshold Limit Valve

15.

MSDS

-

Material Safety Data Sheet

16.

COD

-

Chemical Oxygen Demand

17.

BOD

-

Biological Oxygen Demand

18.

APELL

-

Awareness And Preparedness For Emergencies At Local Level

19.

CFC

-

Chloro Fluoro Carbons

20.

UL

-

Underwriters Laboratories

21.

HAZOP

-

Hazard and Operability Studies

22.

BIS

-

Bureau of Indian Standards

23.

ISO

-

International Organization for Standardization

24

WTO

-

World Trade Organization

25.

ISO-9001

-

Quality Management Systems

26.

ISO 14001

-

Environmental Management Systems.

27.

EIP

-

Emergency Information Panel

28.

OHSMS

-

Occupational Health & Safety Management Systems

29.

ACGIH

-

American Conference of Government Industrial Hygienists

30.

CCOE

-

Chief Controller Of Explosives

31.

ELCB

-

Earth Leakage Circuit Breaker

32.

FLP

-

Flame Proof

33.

PLT

-

Pipe Line Transfer

34.

ILO

-

International Labor Organization

35.

TAC

-

Tariff Advisory Committee

36.

NDC

-

Non-Destructive Testing

37.

PPE

-

Personal Protective Equipment

38.

LPA

-

Loss Prevention Association

39.

NEERI

-

National Environmental Engineering Research Institute

40.

MAH

-

Major Accident Hazard

41.

LEL

-

Lower Explosive Limited

42.

UEL

-

Upper Explosive Limit

43.

IDLH

-

Immediately Dangerous to Life and Health

44.

P&ID

-

Process and Instrumentation Diagram

45.

PFD

-

Process Flow Diagram

46.

UNICEF

-

United Nations International Children Emergency Fund

47.

IAEA

-

International Atomic Energy Agency

48.

AGFFF

-

Aqueous Gel Film Forming Foam

49.

AFFF

-

Aqueous Film Forming Foam

50.

SHE

-

Safety, Health And Environment

BIBLIOGRAPHY

•

Safety Magazines

•

Internet

•

Safety Manuals

•

Safety Handbooks