Fire Extinguisher – Buying guide

Fire Extinguisher – Buying guide

A fire extinguisher may not be very effective against a large-scale developed fire, but it is extremely effective in dousing an incipient fire before it goes out of control. This is what makes them so perfect for homes and offices. Now use of fire extinguisher is increasing every day. Thanks to FSAI that many people start understanding the use and value of the extinguisher as it saves from hazardous things like fire. Extinguishers have the advantage of portability that can be very handy in dousing fires that are difficult to reach by other mechanisms.

There are lots of stuff that you need to know before you go for shopping when it comes to this, apart from this there are companies related to fire extinguishers refilling in India, who can help you when your extinguisher require refilling. But before that, you should understand few basic kinds of stuff to avoid any kind complication in future. Here is our handy extinguisher guide:

✅Specialist or wide range: Fire safety equipment involves more than just fire extinguishers and you may want a more comprehensive system. In that case, you should check if the fire safety extinguishers supplier offers other firefighting equipment like fire blankets and fire alarms. You can choose to go with a separate vendors or manufacturers, but a single vendor is more likely to give you competitive pricing apart from saving your time and effort.

✅Which size do you want? Well, the size of your extinguisher does not affect the working as it only means that you have the larger volume in the fire extinguisher. However, it depends on the need and the location/area you want to cover.  A multi-stored building will need an extinguisher on each floor. The area of the floor and partitions within will again decide the number of extinguishers. For instance, a large floor with multiple rooms, offices or homes may need multiple extinguishers, while a small floor may work perfectly well with a single extinguisher. Your car with its limited space will require a small portable extinguisher.

✅Selecting the right type: All extinguishers may look the same, but they are actually quite different. Extinguishers are classified according to the type of fire, which depends on the accelerants present. The accelerant is be the material that is found on the premises and will differ from one location to another. The classification of fire is as follows:

-    Class A: Fires involving organic solids like paper and wood.

-    Class B: Fires involving flammable liquids like petrol and diesel.

-    Class C: Fires involving flammable gases.

-    Class D: Fires involving combustible metals.

-    Class E: Fires involving electrical equipment.

-    Class F: Fires involving cooking oil and fat.

The type of fire will decide the agent that we use to extinguish the fire. Agents used in firefighting are water, wet chemical, foam, dry chemical, dry powder, carbon dioxide, and vaporizing liquid. Type A fire requires a water extinguisher, while a Type D fire requires a dry powder extinguisher. So, a water extinguisher may work in your bedroom, but for your kitchen you may need a wet chemical extinguisher.

✅Location: Decide on the location of the extinguisher before you buy it. There are a few rules here that you must keep in mind:

-    It must be installed above ground.

-    It should be placed in a location where nothing obstructs it path.

-    It should be clearly visible.

-    It should be placed near an exit so that one does not have to walk into the fire to retrieve it.

-    It should not be placed near an inflammable substance.

✅Complexity of the extinguisher: Some fire extinguishers are more difficult to operate Carbon dioxide extinguishers, for instance, must be handled very carefully since the gas expelled is extremely cold. In such cases, it is important to ensure that you have people trained to use such extinguishers.

✅How to use it? Not just buying is a hectic stuff but also knowing how to use the fire extinguisher is another thing that you should consider. However, these modern extinguishers are much easier to use as you just have to follow PASS which stands for Pull, Aim, Squeeze and Sweep. After using it, make sure to refill it again. These are important factors will help you to buy whatever kind of extinguisher you need. Also, do know about the refilling a recharging process. Make sure your extinguisher is properly maintained and ready to use when it is needed. Apart from that, do check the working and the overall extinguisher to make sure it’s safe for use or not.

✅ Mounting Guidelines:
If a fire extinguisher weighs more than 40 lbs, the top must be mounted no higher than 3.5 ft (1.07 m) from the ground.
If it weighs less than 40 lbs, the top can be mounted up to 5 ft (1.53 m) high.
In both cases, the bottom of the extinguisher must be at least 4 inches (102 mm) above the ground.

✅ Coverage Area Considerations:
A single extinguisher should effectively cover an area within a 75 ft (22.7 m) radius, ensuring no unprotected gaps.

✅Rechargeable or Disposable: Rechargeable extinguishers have a metal valve where disposable extinguishers have a plastic valve. While the rechargeable may seem more expensive, it is more economical in the long-term. However, if you need the extinguisher for just a short time span, you may consider disposable extinguisher.

✅Placement of the extinguisher: Fire Extinguisher travel distance as per hazard types are shown in below:

✅Refilling services: A fire extinguisher requires refilling at certain intervals. This will be specified by the manufacturer. In addition, it must be refilled every time gas is expelled. You must keep these expenses in mind when buying an extinguisher. Find a fire extinguishers refilling India agency that offers the best package. For instance, some agencies offer a comprehensive maintenance package that includes repairs as well as refilling services that may be more economical in the long run.

✅Certification: Every extinguisher must comply with the proper ISO certification. This means that it meets all the regulations regarding its working and safety. This is the minimum quality control that you must maintain.

✅Check for service terms: It is important to see what kind of services the supplier is offering. Extinguishers need regular servicing. So, any supplier who also has a servicing facility wins brownie points. See if you can get a favorable deal along with your extinguisher. Many suppliers offer complimentary service for a limited period. This should also be considered in the overall pricing.

So, before you buy an extinguisher, find out the type of fire that is likely to take place, the area and availability of fire extinguishers refilling India.

BASIC FIRE SCIENCE

BASIC FIRE SCIENCE

A.   FIRE TRIANGLE

Four things must be present at the same time in order to produce fire:

 
1.    Enough oxygen (O2) to sustain combustion,
·         Oxygen (O2) is an element from the atmospheric air that supports the combustion process.  It makes up 21% of the total air mixture.
2.    Enough heat to raise the material to its ignition temperature,
·         Heat is a form of energy which may be produced by mechanical or chemical reaction and transmitted via radiation, conduction and/or convection.
3.    Some sort of fuel or combustible material,  
·         Fuels are combustibles that may exist in solid, liquid, molten and/or gaseous states. Examples of fuels are paper products, wood products, molten chemicals, flammable fluids and gases.
4.    The chemical, exothermic reaction known as fire.

Fire occurs when fuel and oxygen come into contact with substantial amount of heat energy. This will cause a chain reaction to take place which will in turn produce sufficient heat energy to propagate the burning in the presence of subsequent fuel and oxygen.

Oxygen(O2), heat, and fuel are frequently referred to as the "fire triangle." Add in the fourth element, the chemical reaction, and we actually have a fire "tetrahedron."

Combustion will continue as long as all these factors are present. Removal of one of the factors will lead to the collapse of the "triangle/ tetrahedron" and combustion stops, and we will not have a fire or the fire will be extinguished.

B.   METHODS OF EXTINGUISHING FIRE

Fire Safety, at its most basic, is based upon the principle of keeping fuel sources and ignition sources separate.

Fire can be extinguished with one or a combination of the following methods:

 
1.    Starvation: Removal of the combustible substances.
 
2.    Smothering: Limiting the amount of oxygen (O2) that supports combustion.
 
3.    Cooling: Reduce the temperature to the point of fire extinction.
 
4.    Breaking (blocking) or interfering with the chemical reaction occurring in the flame.
  

C.   BASIC STAGES OF FIRE DEVELOPMENT

Fir
Fires can be commonly seen to develop in the following stages:
1.    Initial
The fire develops from its point of origin. If the combustion reaction is capable of emitting further heat in the presence of subsequent fuel and oxygen, the reaction will propagate and temperature will continue to rise.
 
2.    Flashover
This is the transition stage between the Initial and the full development stage. The fire spreads rapidly and large merged flames are produced. Flashover will especially occur in a confined space fire.
 
3.    Full
Fire will be fully developed burning at/near its development maximum intensity.
 
4.    Decay
Fire is slowing down due to depletion of Oxygen and/or fuel. Introduction of subsequent Fuel and/or Oxygen will however propagate a second initial development.

D.   CLASSIFICATION OF FIRE

The different types of fire are classified into the following "Classes":
 
1.    Class A : For fires involving the burning of ordinary combustible materials like wood, paper, cloth, furnishing, plastics and rubber.
 
2.    Class B : For fires involving flammable liquids, solvents, oils, paints, thinner and flammable gases.
 
3.    Class C : For fires involving live electrical equipment like electrical mains, transformers and electrical appliances, etc and where extinguishing medium used must be electrically non-conductive. (If the electrical equipment is de-energised, extinguishers for Classes A and B can be used.)
 
4.    Class D : For fires involving combustible metals, eg. Potassium (K), magnesium(Mg), titanium(Ti), sodium(Na), lithium(Li) and zirconium.

 E.   IGNITION AND COMBUSTION

1.    IGNITION
 
i.      Ignition is the process of starting a combustion process through the input of energy.  
 
ii.     If the substance is a liquid, ignition can only occur when
·         There exists a gas/air mixture whose composition lies within the flammable range for that substance. A small ignition source, e.g. a spark or small flame, will then start ignition.
·         Enough vapour is given off the vapour surface so that a vapour/air mixture is formed whose properties lie within the flammable range for that substance. The flash point is the temperature at which the liquid gives off just enough vapour to form this flammable vapour/air mixture. For temperatures above the flash point a small igniting source will start ignition.
 
iii.    If the substance is a solid, ignition will only start when either:
·         The solid is heated so that destructive decomposition starts and flammable vapours are given off. When these vapours form a flammable vapour/air mixture combustion can be started if a small flame is applied. Most organic materials will come under third category. The size of ignition source needed will depend on the physical form and shape of the material. If it is in the form which has a high surface area to mass ratio only a small igniting source is required.
·         The solid is heated in air so that the surface oxidation is initiated of sufficient vigour to be self-sustaining reaction. Carbon and most metals are examples f this type of combustion. A high surface area to mass ratio is needed for ignition and this means that the metal has to be in he form of finely divided powder. An intense source of heat is required in most cases to ignite solids which burn this way.
 
 
2.    COMBUSTION
 
i.      Combustion is a reaction between a substance and oxygen in which heat is given out, i.e. it is an exothermic reaction, and enough heat must be given out either to maintain the temperature of the reactants or to continuously increase their temperatures so setting up a chain reaction.
 
ii.     In some cases the reaction between a substance and oxygen requires heat to be applied to maintain the reaction and the reaction stops when the applied heat is removed, this is not combustion.
 
iii.    All combustible materials burn as vapour phase reactions, i.e. they are reactions between two gases, one of which is usually oxygen. The combustible materials which are usually solid will, because of high temperatures involved, either melt and then vapourise and burn, or decompose by pyrolysis and give off flammable vapours which will then burn. There are exceptions and there can be reactions between oxygen and solid surfaces which are vigorous and exothermic and so can be termed combustion, e.g. carbon and certain metals. Liquids also vapourise before combustion takes place.
 
iv.   The following are the products of a combustion process:
 
Thermal           -           Flame & Heat
 
Non-Thermal   -           Smoke & Gases
 

·         Damage to property is due mainly to thermal effects although smoke and gases can also cause considerable damage. Some of the gases produced during combustion are corrosive, or become corrosive in solution with water.
 
·         Most fire deaths or injuries, however, may be attributed to smoke or gases arising from smoke inhalation and suffocation. Smoke can also cause panic among occupants which is likely to cause further injuries and death. Heat and flamers are primary causes of fewer deaths or injuries than smoke or gases.
 
·         The heat generated in the process of combustion can completely destroy a building. Steel will have lost two-thirds of its strength by the time it has been heated to 600 ° C. This is by no means uncommon temperature in a domestic fire. Concrete is more resistant material; but as reinforced concrete depends on steel for its tensile strength, there needs to be sufficient insulation of the steel to prevent it reaching its critical temperature. Timber, of course, burns but is a very good structural material as burning occurs at a fairly constant rate and so structural timbers can be oversized to provide a known measure of fire resistance. Bricks provide one of the best fire-resistant materials as they have already been kiln-fired at high temperature during manufacture.

CLASSIFICATION OF FIRES

CLASSIFICATION OF FIRES

Fires are classed according to fuel and most effective extinguishing agent.

Class A

Fire involving common combustion material and which can be extinguished by use of water or water solution in form of jet and spray e.g. materials include wood, wood based material, cloth, rubber, and certain plastics.

Class B

Fires involving flammable or combustion liquids, paints, varnishes, greases and similar products, either miscible or immiscible with water.

Extinguishing agents include water spray, foam, carbon dioxide and dry chemicals.

Class C

Fires that involve gases or liquid gases in the form of a liquid spillage or a liquid or gas leak. Gases include methane, butane etc.

Foam or dry chemicals may be used to control class c fires involving shallow liquid spills, water in the form of spray is used to cool the containers.

Class D: 

Fires that involve combustion metals, e.g. sodium, magnesium etc.

Extinguishing agents like water, CO2 and bicarbonates are infective and hazardous if used.

Powered graphite, powered talc, soda ash, limestone and dry sand are normally suitable for extinguishing class d type fires.

Class K:

Class K fires involve combustible cooking media such as oils and grease commonly found in commercial kitchens. The new cooking media formulations used form commercial food preparation require a special wet chemical extinguishing agent that is specially suited for extinguishing and suppressing these extremely hot fires that have the ability to reflash.

Electrical Fires

Electrical fire by itself does not constitute a class since any fire involving or started by electrical equipment will be a fire of class a, b, c or d.

In case of a fire involving electrical equipment, electricity supply to the respective equipment must be cut off and an extinguishing medium appropriate to what is burning must be used.

NOTE: Although ABC and BC Dry Chemical extinguishers can control a fire involving electronic equipment, the National Fire Code (NFPA 75-1999 edition), Section 6-3-2, specifically advises against dry-chemical extinguishers for fires involving computers or other delicate electronic equipment due to the potential damage from residues.

Standard for the Protection of Electronic Computer/Data Processing Equipment

6-3.2 Listed extinguishers with a minimum rating of 2-A shall be provided for use on fires in ordinary combustible materials, such as paper and plastics. Dry chemical extinguishers shall not be permitted."

Class F:

New class specifically dealing with high temperature (  360°C) cooking oils used in large industrial catering kitchens, restaurants and takeaway establishments’ etc. Cooking oil fires, because of their high auto-ignition temperatures, are difficult to extinguish.

Conventional extinguishers are not effective for cooking oil fires, as they do not cool sufficiently or may even cause flash back, thereby putting the operator at risk.  These extinguishers contain a specially formulated wet chemical which, when applied to the burning liquid, cools and emulsifies the oil, extinguishing  the  flame,  sealing  the  surface  and preventing re-ignition.