1. INTRODUCTION
Fire – kills and seriously injures people, destroys plant, equipment and property and last but not the least our environment. Rapid industrialization and technological advancement have introduced new materials with characteristics of flammable, toxic or both. Specialised occupancies such as high rise buildings, large warehouses, huge storages of petroleum and other flammable liquids in storage tanks, spheres and bullets have all brought in serious fire and explosion hazards.
The fire protection industry is continuously engaged in manufacturing various types of Fire Protection Equipment, with research, development and innovation. Hence, there exists large number of different types of fire fighting equipment, appropriately made to suit specific requirements. In this article a sincere effort is made to summarize, the salient features of important equipment used in fire protection. The types of equipment are dealt with Portable, Fixed and Mobile.
2. PORTABLE FIRE PROTECTION EQUIPMENT
2.1 Portable Fire Extinguisher :
Portable extinguishers are designed to cope with fire of limited size and are absolutely necessary even though the plant is equipped with automatic sprinklers, fire water system along with fixed monitors/hose reels and fire engines. Though portable extinguishers are regarded as first aid fire-fighting appliances, they are very valuable if used promptly and efficiently in the early stages of fire.
In addition to their portability, the most important features of these hand appliances are the immediate availability for use by one person or at the most by a small crew. Since their capacity is limited, their operational value depends upon the initial charge being sufficient to overcome and confine the fire, eliminating a major fire. Many flammable materials fire, potentially of serious nature, have been put out by diligent use of several hand-operated extinguishers with secondary protection provided by large capacity wheeled extinguishers. If extinguishers are to be relied upon, then they must be of: (a) right type, in sufficient quantity, and easily accessible, (b) properly maintained, and (c) operable by area personnel. When selecting the extinguishers, the materials in the processes involved and the nature of hazard anticipated should be taken into consideration. For this purpose proper understanding of the classification of fires and suitability of portable appliances is necessary which are given in IS 2190 – Code of Practice for Selection, Installation and Maintenance of First-Aid Fire Extinguishers.
The Bureau of Indian Standards, has also published a number of standards on fire extinguishers and some of them are IS 940, IS2171, IS2878, IS4862, IS6234, IS5490, IS5896, IS6234, IS6382, IS7673, and IS10658. Number of fire extinguishers provided will depend upon the fire hazard of the materials. Further relevant rules / standards from appropriate authority have to be ensured, such as State Factories Rules, National Building Code, Local Fire Brigade Norms, and Insurance Association Rules, etc. The general principle is that extinguishers are readily available and in sufficient quantity, so that even one fails, another is available within short distance. Rule 71-B (7) of the Maharashtra Factories Rules, 1963 gives the requirement of extinguishers.
For example, in factories having more than 100 square meters floor area and where fire may occur due to combustible materials other than flammable liquids, electrical equipment and ignitable metals, soda acid or equivalent type of portable extinguishers at the rate of one every 500 square meters of area, spaced not more than 30 meters apart subject to a minimum of one extinguisher. This means a person can pick up an extinguisher by moving 15 meters only. Extinguisher should be mounted in easily accessible places near entrances, walkway platforms on process units. These can be conveniently mounted on handrails, structure members, etc. On open process units, it is worthwhile to protect the extinguishers from weather by metal cover. Similarly wheeled units should be protected with a metal box. Ensure that not to keep extinguishers near sources of heat. It is recommended that extinguishers installed in any one building or single occupancy shall be similar in shape and appearance and shall have the same method of operations as far as possible.
Further wherever possible one suitable type should be provided if there is more than one risk e.g. if there is a hazard due to flammable liquid and also electricity, we can provide dry chemical extinguishers, instead of one Foam type and one CO2. This will eliminate inadvertent use of wrong type of extinguisher. It is important that extinguishers are properly maintained and kept in good operating condition at all times.
For this sufficient refills should be kept in hand and also spare extinguishers. Complete guidance is given in Indian Standard on maintenance, inspection and testing, which should be referred to. Atleast once a week routine maintenance should be carried out – observe external appearance; check nozzle, cap, and plunger. Ensure the seal of the extinguisher is intact. If the seal is broken, then thorough inspection is warranted. Once in three months inspection of the extinguisher should be done – open, inspect charges, plunger, nozzle cap, etc.
Annually thorough inspection – testing and recharging should be done. Once we have selected the right type of extinguishers, installed them throughout the plant and maintained them properly, all personnel who work in a specified area should be able to operate the extinguishers quickly without any hesitation; that means, a systematic training should be arranged for all personnel. Training should be both in theory and demonstration.
Each person should be asked to actually use the extinguishers, preferably in a demonstration fire in the training ground. Correct and safe method of use can be effectively taught and the user will gain confidence and then will not hesitate to use in actual fire. This training can be conducted in groups of about 10. Time, money and effort put on portable extinguisher system is worth it, since we may be able to put out all small fires, which results in the elimination of many potential large fires. We shall examine in detail some of the important type of extinguishers.
2.1.1. Gas Cartridge and Water Extinguishers :
The gas cartridge and water extinguishers uses a mixture of plain water or special anti-freeze solution, which is expelled by pressure from a small cartridge of carbon dioxide gas, released when the cartridge top is punctured. The only extinguishing action is the cooling action of water. The cartridge-water extinguisher has a range of approximately 9 to 12 meters. Capacity of the common size is 9 litres. The extinguisher may be used on class A – fires – ordinary combustibles. (wood, textiles, rubbish). However, do not use these extinguishers on fires of energized electrical equipment. This type of extinguisher is hung on a wall or post with the top not more than 1.5 meters above floor. The user grasps the bottom handle with one hand and the nozzle and upper ring with the other. Upon reaching the fire, he bumps the projecting plunger to puncture the sealed cartridge of carbon dioxide inside the extinguisher. The stream of water is directed at the base of the flame.
Once a year the gas cartridge should be removed from the extinguisher and weighed to check for loss of weight. The cartridge should be replaced if there is loss of weight greater than 14.2 grams. The level of water should be checked at the filling mark. The extinguisher should be refilled with water and the cartridge renewed immediately after use. At the time of the annual inspection, the interior of the cylinder should be examined and the hose blown through to make sure it is clear and free of leaks.
2.1.2. Carbon Dioxide Extinguishers :
The carbon dioxide (CO2) extinguisher contains liquid carbon dioxide under approximately 60 kg/cm2 (850 psi.) which, when released turns into 'snow' which smothers fire by exclusion or displacement of air. The snow also exerts a temporary chilling effect, which aids in prevention of immediate re-ignition. Depending on the size of the extinguisher, its range is 1 to 3 Meters. Capacities of common size are 2.2Kg, 3Kgs, 4.5Kgs, and 6.8Kgs. Wheeled units of 9Kgs, and 22.5Kgs, are also available. The CO2 extinguishers may be used on Class B and C fires (oils, gasoline, solvents and gaseous substances under pressure) and on fires of electrical equipments. To extinguish a fire, the extinguisher is removed from its bracket or stand and carried to the fire. The locking pin or sealing wire is removed or broken. To discharge, the horn is aimed at the base of the fire and the gas is released by opening the hand-wheel valve. To prevent re-flash, the snow should be spread over the burned surface even after the flames are extinguished. On flowing flammable material the snow should be worked back toward the source of fire. The weight of carbon dioxide extinguishers should be checked monthly. If the weight loss is greater than 10 percent of the weight listed on the extinguisher, recharging by companies equipped to do it is necessary. Even though only partially discharged, extinguishers should be recharged immediately after use.
The record cards should then be filled out and the extinguishers replaced. Every time the extinguisher is sent for recharging, the organization doing the recharging shall be asked to certify that the cylinder has been tested to 210 kg/cm2 (2980 psi) pressure before recharging. The snow released by CO? is dry and non-toxic, and will not harm materials of fine machine parts. It does not conduct electricity and presents no clean-up problem. There is some danger of freezing if it is sprayed on the skin at close range. Recharging is not necessary so long as weight is up to 90 per cent of correct weight. The CO?unit is especially suited for use on mobile equipment, on uneven burning surfaces, or in oil drums, paint spray booths and other confined spaces. However, CO? has many disadvantages and some of them are:
Operators must have air to support life and should not enter rooms in which large quantities of carbon dioxide have been used until the rooms have been ventilated.
Operators must approach close to the fire. The snow has limited penetrating power and is not suitable on deep-seated fires in wood, rubbish and the like.
The snow gives no permanent insulating effect (like foam), but reapplication provides protection against re-ignition.
It is not well suited to open fire outdoors because wind currents may dissipate the gas. The unit requires recharging with special equipment.
2.1.3. Dry Chemical Extinguishers :
The dry chemical extinguisher consists of an internally or externally mounted cartridge of carbon dioxide or nitrogen gas which, when the top is punctured or the cartridge valve is opened, expels chemically processed bicarbonate of soda powder in the outer shell through the hose and nozzle. The action of Dry Chemical Extinguisher in putting out the fire is due to the blanketing of powder, which is expelled when carbon dioxide cartridge is punctured; evolution of CO? and the consequent cooling effect when CO? is formed.
For portable extinguishers, the range is 2 to 7.5 Meters, depending upon capacity. Capacities of common sizes are 1kg, 2kgs, 5Kgs, and 10Kgs. Larger wheeled units of 25Kgs, 50Kgs, & 75Kgs are also available. The dry chemical unit may be used on Class B and C fires (oils, gasoline, solvents and gaseous substances under pressure) and on fires of electrical equipment. To extinguish a fire, the extinguisher is carried to the scene of fire. After removing the locking pin, the dry chemical chamber is pressured by puncturing the cartridge or opening the cartridge valve. The discharge is controlled by, squeezing the nozzle handle. The flame is swept ahead by the discharged dust and backed up to its source.
The pressure cartridge of dry chemical extinguishers should be weighed at least once a year. If the loss of weight of the cartridge is greater than 10 per cent, the cartridge should be replaced or recharged by a company equipped to do so. The condition of the powder should also be checked. The powder should be dry and not caked. To recharge the extinguisher, the empty gas cartridge is replaced with a full one, and the outer shell is refilled with the nominal weight of dry chemical. The operator should blow through the hose, to be certain, it is clear. After use, the cartridge is replaced and the cylinder refilled with the powder. All plugs and caps should be screwed tightly to prevent leakage. Record cards should be filled out, and the extinguisher replaced and protected from damage and corrosion.
One fifth of the total number of extinguishers of this type on charge shall be selected for this test every year. The test shall be carried out by, actually operating the extinguisher and watching for satisfactory performances. Pressure test shall be carried out once in three years and are to be tested at pressure of 25Kgf/cm2 (355 psi). The dry chemical powder is a non-conductor of electricity and, being non-toxic and non-corrosive does not harm electrical or mechanical equipment or the operator. However, the fine powder deposit may present a difficult cleaning problem. Recharging can be done quickly without special equipment. Some extinguishers of this type have a limited range and the operator must approach close to the fire. The dust gives no permanent blanketing or insulating effect, and re-ignition is possible. The extinguisher is best suited for installation in outdoor process units.
3. FIXED FIRE PROTECTION EQUIPMENT
3.1 Fire Pumps :
They are required for pressuring hydrant system with firewater. Horizontal centrifugal pump is used for above ground storage water in tanks and vertical centrifugal pump in underground storage tanks.
Centrifugal fire pump has become the standard today. Its compactness, reliability, easy maintenance, hydraulic characteristics and variety of available drives – electric, steam turbines and internal combustion engines – have made centrifugal fire pump, most ideal for this service. Discharge pressure is set by the minimum residual pressure requirement at the extremity of the system plus the system piping friction loss. Normally the residual pressure at the most remote hydrant should be at least 5.6 Kg / cm².This would indicate a pump discharge pressure of about 8.8 Kg / cm² in an adequately sized piping system.
The selection of drive for the pump is important. From the standpoint of low maintenance, ease of start-up and operation, electric drive is preferable. However, at the time of power failure, electric drive pump would not be able to operate. Hence, diesel or gasoline pumps are preferred. It is a standard practice to provide diesel driver pump as a stand by fire pump. In case all the pumps are electrically driven, then it is strongly recommended to provide emergency power supply from captive power generation facilities such as D. G. Sets, etc. Jockey pumps are used to maintain pressure on the fire water systems when not in use.
The capacity of this pump should be sufficient to maintain pressure against leakage. Usually, electric motor is provided with automatic start – up. The pump could be started manually from control room or from fire station and also from the local switch at the pump. There is arrangement also for automatic start of the pump, in case system pressure falls below set pressure. Generally manual shutting of the pump is provided. Fire pump should be procured from reputed manufacturers. This is the most important equipment and hence needs proper selection, inspection, maintenance, and testing regularly.
3.2 Water Spray System :
Water spray system can be of two type viz. (i) Medium Velocity and (ii) High Velocity. Medium Velocity Water Spray System (1.4 bars to 3.5 bars) is very essential and provides protection for cooling in equipment such as storage tanks, spheres, bullets etc. High Velocity Water Spray System (3.5 bars to 5 bars) is generally used for the protection of transformers.
3.3 Water Monitors :
Water is still the best medium for cooling large fires of combustible / flammable materials, particularly in process operating units, storage tanks, oil jetties, loading / unloading gantries, etc. Consider the provision of monitors covering an entire operating unit, fixed on the hydrants. By just starting the fire pump, one person can go around and open number of monitors, raining high flow of water, very fast, in just four to five minutes after noticing a large fire. Hence it makes real sense to provide monitors liberally, wherever, situation warrants their use. Water Monitors, with hand lever operation are available in three different types, designed for Fixed type, (stand post), Portable type, and Trolley Mounted Type.
The well-designed constructions allow high flows and throw ranges, complete horizontal and good vertical traverses. Further, the monitor can be locked indefinitely in desired horizontal and vertical positions, by operating two screw mechanisms. Provision of appropriate materials of construction and operating mechanisms can ensure trouble free operation. Though these monitors are developed for high flow, long range water throw attached with straight nozzles, they can be converted to water fog or foam application, by changing the nozzles quickly, which will be supplied by the manufacturer on request.
3.3.1. Oscillating Water Monitors :
Large fires requiring wide coverage or specific targets, which have to be cooled for a long time, need tremendous effort, associated with high risk for fire fighting personnel as well. Further, limitations are provisions of large numbers of men and equipment, for a long time. To meet this problem, Water Driven Oscillating Monitors have been developed. It is designed to provide an oscillating water or foam stream over a preset area of protection. It provides rapid blanketing for combating fires in aircraft hangers, on helicopter decks and in tank farms and other high risk areas.
The advantages are excellent – water powered and hence can be safely used in hazardous area; wide oscillating arc and good elevation controls; long range horizontal throw; continuous unattended operation and automatic starting at fixed horizontal sweep and vertical elevation.
3.4. Water – Foam Monitors :
Foam is a permanent extinguishing agent and the best medium for containing, controlling and extinguishing large fires of flammable or combustible liquid tank or spill fires. Foam is versatile, in as much as that it can not only put out large fires, but of very great help to prevent vapour transmission for some time and also prevent fires in non burning liquid surface in tanks or spills, by forming a foam blanket. No doubt it is of critical
importance to start the foam attack immediately at the outbreak of fire, preferably in the very first few minutes.
It is invariably possible to put out the fires efficiently, in the incipient stages of fires. Delayed action will help the fire to become big and serious, requiring large scale resources of man power and equipment, to control the fire. Hence it makes good fire protection management sense, to provide Water – Foam Monitors with foam storage, in required locations such as operating units, loading / unloading facilities, storage tanks, effluent treatment plants, oil jetties, airport, etc.
There are different types and capacities of Water – Foam Monitors, suitable for all kinds of fire fighting operations and some of them are:
Water Foam Monitor – Stand Post Type (Fixed Type)
Water Foam Monitor – Trolley Mounted Type
Water Foam Monitor – Trailer Mounted Type (Without Foam Tank)
Water Foam Monitor – Trailer Mounted Type (With Foam Tank)
3.5 Trailer Pump :
Trailer pump is useful for boosting up pressure in a particular location. Lower pressure from the hydrant can be increased for application in higher elevations such as towers, structures, etc. Diesel engine trailer pumps of 1800 Lit/min. capacity are also available.
3.6. Hose Reels :
Hose Reels are usually provided in addition to hydrants in buildings and operating units. Hose, heavy duty rubber, of 2.5cm (1inch) or 3.75cm (1½inch) of about 15 meter length are kept wound on a drum of Hose Reel, connected with a nozzle. The advantage is for fast pulling and raining water on scene of fire quickly.
3.7. Foam Protection for Storage Tanks :
Fire on storage tanks are by and large limited, but when it occurs in a storage tank of flammable or combustible liquids, it becomes very serious hazard and can envelop the entire facility, particularly, when the roof sinks, it is a disaster. Fixed Foam Protection facilities are provided for cone roof as well as floating roof tanks. It is probable that foam chambers could also be blown off. Hence, large capacity long-range monitors and Fire Engine with aerial platform with foam pouring facility have been successfully used in large sunken roof tanks. Large quantity of proper type and quality of foam compound is a basic necessity for such conflagrations.
3.8. Automatic Sprinkler Installation :
Automatic sprinkler protection is a facility designed to discharge water automatically in sufficient density (litres/minute/m2) to control or extinguish a fire in its early stages. It consists of water discharge devices (sprinklers or sprinkler heads), one or more reliable sources of water at the desired pressure, valves to control water flow, piping to distribute and convey water to the sprinklers and auxiliary equipment such as alarms and supervisory devices.
The temperature rise during a fire activates the sprinkler heads, which discharge a spray of water over the protected area. Sprinkler systems apart from controlling and extinguishing fires also give out an alarm and alerts people to take suitable action to tackle the fire. Automatic sprinkler protection has been widely used in a variety of locations. Examples of indoor usage are in factories, warehouses, office building, ships hold, etc.
Every sprinkler installation is tailor – made to suit various factors such as features of building construction, dimensions of the compartment, fire load of the occupancy, the possible type of fire, etc. Designing a sprinkler installation, therefore, calls for a through understanding of these factors. An installation which has not been properly designed cannot be expected to function in the desired manner. Extensive guidelines for installation, care and maintenance for automatic sprinkler systems are given in the codes of the National Fire Protection Association (NFPA) of U.S.A.
3.9. Detection Systems :
There are various devices used for detection of fires. Some of the common devices used for detection of fires are given below:
Smoke detectors using ionization / photo-electric devices
Heat detectors using fixed temperature / rate of temperature rise devices.
Flame detectors using infrared / ultra violet, spark devices.
LHS cables using digital / analogue devices.
Gas detectors
Manual call points
Along with detection systems, which will give alarm in local panel as well as control room panel, can also be utilised in conjunction with Automatic Sprinklers, Dry Chemical Powder System, Carbon Dioxide System, etc. These systems will have to be carefully designed with expertise for proper operation and effectiveness, keeping in clear view the occupancies involved.
4. MOBILE FIRE PROTECTION EQUIPMENT
4.1 Foam Tender :
Foam tender is provided in refineries, oil storages, chemical plants, etc. Foam tender will be taken to the
location of tanks and foam pumped through foam lines from roadside. Foam tender consist of various components and a typical tender can consist of: (i) Foam tender is fabricated on diesel chassis. (ii) Fire pump has a capacity of 3200 LPM at 8 Kg / cm2. (iii) Water tank has a capacity of 3000 Litres. (iv) Foam tank ha capacity of 3000 Litres. (v) Monitor is fitted on top of the tank. (vi) Control panel with compound gauge, pressure gauge, engine throttle control, pump to foam proportional, foam tank to foam select or valve, auxiliary foam connection, cooling valve, drain valve, pump to monitor, throttle and pump to hose reel.
4.2. Fire Tender :
Fire tender is similar to Foam Tender but it does not have foam – producing facilities. While Foam tender is provided in refineries, oil storage, terminals, fertilizer plants, chemical plants, etc. Fire tender is usually provided by Municipal / State Fire Brigades and industries, which do not have large storage of flammable / combustible liquids.
4.3. DCP Cum Foam Tender :
DCP Cum Foam Tender is capable of operating of water, water foam and dry chemical powder separately. The components include – Water Pump, Water Tank, Foam Tank, Foam Proportioning Procedure, Foam Monitor, DCP Vessels, Gas Expelling System, Hose Reel and DCP Monitor.
4.4. Emergency Rescue Tender :
The Emergency Rescue Tender (ERT) including all accessories should be designed and manufactured as per relevant Indian Standards wherever applicable and should be as per sound engineering practice. Following are components that are usually provided, but others can be included as per customer's requirement.
Diesel Generator, Battery Operated Amplifier System, Extension Ladder, Pneumatic Lifting Equipment, Leak Sealing Pads, Leak control Kits, Low Temperature Protective Suit, Fire Entry Suit, Fire Proximity Suit, Hydraulic spreader and cutter, Portable Gas Detectors, Self Contained Breathing Apparatus (SCBA), LPG Transfer Equipment, Traffic Control Equipment, etc.
5. CONCLUSION
Portable fire extinguishers have an important role to play in the fire protection programme of any industry. However, they have their limitations. They are not designed to fight a large or spreading fire. Even against small fires, they are useful only under certain conditions. Water has greater cooling properties than any of the other extinguishing agents and can be used to reach a deep seated fire. So water should be used on burning solids.
However, it is infective in many fire scenarios, especially on oil fires. CO2 is most suitable for dealing with small contained fires and small fires involving escaping liquids on horizontal and vertical surfaces. Foam is the only proven method of controlling and extinguishing fires in storage tanks, tank farms, effluent water treatment facility, etc. Dry powder is the most suitable type of extinguisher for dealing with fires in flammable liquids. It is also a non conductor of electricity and can be safely used on fires where there is a risk of electrical shock.
In spite of all technical advances, water is the cheapest, most efficient and environmentally friendly fire extinguishing medium. No amount of appliances or equipment would be of much use, if sufficient quantities of water, under required pressure were not available for fire fighting. An automatic sprinkler installation will, in a large majority of circumstances control and extinguish a fire with less than 1000 litres of water and may, therefore be the most economic way of limiting the loss in a fire, particularly in areas of limited water supplies.
The best way to fight fire is to prevent it. Each industry and occupancy must provide itself with proper type and adequate number of fire fighting equipment to combat, control and extinguish fire and explosion efficiently, in their industries and occupancies. While procuring fire equipment, ensure proper quality, approved by recognised authority such as Bureau of Indian Standards (BIS).
The successful use of any type of fire equipment depends upon three elements being in place at the same time i.e. Equipment, Maintenance and Training. It should be kept in mind that the correct equipment and proper maintenance without effective training on how to use the equipment is inadequate. Similarly the effective equipment in the hands of trained personnel will not be effective if the equipment has not been maintained and fails or performs poorly in a fire. Trained personal using well maintained equipment will not be successful if the equipment was not the proper type for the hazard.
