At times, combustion is accompanied with the production of sound as well. The sound produced may be a hissing sound, crackling sound or an explosion. Combustion is a process in which a substance is on fire. Types Combustible and Non-combustible substances The substances which get ignited catch fire when brought near a flame are combustible substances.
Examples A piece of paper, fabric, wood, kerosene, petrol, fuel gas are some of the combustible substances. The substances which do not catch fire on bringing a flame near them or on placing them on fire are non-combustible substances.
Water and sand are the most common non-combustible substances. They are used to put out fires. Such type of combustion is called Explosive Combustion. It catches flame instantaneously. Such type of combustion is called Spontaneous combustion. Such type of combustion is called Rapid combustion. Such type is called slow combustion. Combustible material Presence of combustible material is necessary for combustion. Fire can easily be made with petrol, spirit, kerosene, wax, wood, coal, paper and straw.
All these are combustible materials OR fuels. Air Oxygen Light a spirit lamp. It has a flame. Place a lid over the flame. The flame goes off.
The lid cuts off the supply of oxygen to the flame and the flame goes off. Thus, oxygen is necessary for combustion. Oxygen supports combustion.
Ignition Temperature The temperature at which a substance catches fire is called its ignition temperature. Attainment of ignition temperature at which the fuel vapourises on its surface is necessary for starting combustion. A fuel catches fire immediately if it is in the form of vapour gas. Cooking gas catches fire immediately.
Spirit and petrol vapourise at room temperature, hence they catch fire immediately. Similarly, camphor gets ignited fast. Cloth and paper get ignited at room temperature. When a piece of cloth or paper is soaked in kerosene and is put on fire, the paper catches fire immediately. Same is true of vegetable oils. The wick in the vegetable oil lamp takes time to get heated and only then it catches flame. The flame on the tip of the wick vapourises the oil below, which keeps the flame going.
In case of fire accident, fire-fighters rush to the accident site with a tanker full of water, a pumping device and other fire-fighting equipments like fire extinguishers, axe, rope and ladders. This helps in two ways : a Lowering the temperature of the burning materials, and b Putting off flames by cutting off the supply of oxygen to the flames.
In addition to water, cutting off the supply of oxygen to the flames is also performed by either putting sand or soil over the burning material or with a spray jet of carbon dioxide gas from a fire extinguisher. Fire extinguishers are of two types : One, which is filled with carbon dioxide gas under high pressure. Two, which is filled with acid in a glass bottle and sodium bicarbonate solution. To use, glass bottle containing acid is broken by striking the nozzle to the ground.
Acid comes out and reacts with sodium bicarbonate to release carbon dioxide gas. It is obligatory for offices, institutions and multistorey buildings to install fire extinguishers at places from where they are readily available.
If a person is on fire, it is better to wrap him with a blanket or a carpet to put out the flame from his burning clothes and also to cut off the supply of oxygen to his burning body. Spraying water on his burns may cause blisters on his body. Water is heavier than oil. It sinks under the layers of oil and the oil comes up floating on water. Thus it continues to be on fire. Combustion without fuel is not possible.
Fuel is the substance which on burning produces heat and light. Kinds of Fuels We make use of different kinds of fuels in our day to day life.
In the kitchen we use cooking gas. Some people use kerosene in stoves or coal or even wood in hearths. Petrol and diesel are used in vehicles. We may group these fuels on the basis of their physical state at room temperature as solid, liquid or gaseous fuels. Vegetables oils, tallow animal fat in liquid form, alcohol spirit and liquefied hydrogen being used in rockets are liquid fuels.
Natural gas is methane which is given out from putrefying organic matter, biogas and also being collected and supplied from sewage plants. Fuel Composition of Fuels All fuels are carbon rich compounds. Carbon is the base fuel. In addition, fuels specially obtained from petroleum are rich in hydrogen. Petroleum fuels are hydrocarbons. Containing petrol spills allows you to reuse the fuel and protects the environment from becoming polluted.
Petrol and other flammable liquids are incompatible with a number of other dangerous substances. To avoid violent chemical reactions, flammable liquids must be segregated from incompatible substances by certain distances determined by the dangerous goods segregation chart. As large quantities of flammable liquids have the potential to cause severe fires, they must be separated from public and protected places by certain distances to avoid harm to people in the event of a fire.
A petrol fire will be triggered by an ignition source and therefore all petrol storage facilities must be isolated from ignition sources. A public place is any place other than private property, open to the public, which the public has a right to use and which includes a public road.
Parking areas for commercial buildings are not considered to be public places. A protected place is a factory, workshop, office, store, warehouse, shop, or building where persons are employed, that is outside the property boundary of the installation.
To warn workers and visitors of the potential risks associated with the flammable liquids that are stored on a premises, clear dangerous goods signage must be displayed on all flammable liquids storage facilities. Also to ensure the least amount of risk to those using flammable liquids, AS outlines certain operational requirements for those handling flammable liquids.
To enhance the safety of those that have to store and handle flammable liquids, AS outlines different requirements for indoor storage and outdoor storage. Flammable liquids can be safely stored indoors using a flammable storage cabinet. For outdoor storage, flammable liquids can be stored safely using a chemical storage container that has been manufactured in full conformance to AS An example of a chemical storage container that has been manufactured in full conformance to AS is shown below:.
More advanced and safer methods can be used to store, handle and dispense flammable liquids by utilising outdoor dispensing stations. Outdoor petrol dispensing stations can be manufactured to meet specific storage and dispensing requirements of those that use flammable liquids on a regular basis. As petrol is classified as a flammable liquid , it is very important that you store and handle the substances in a way that reduces the risks that they may have upon the people, property and environment of your organisation.
This can be done by adhering to the requirements outlined in AS If you would like more information on how to reduce the risks associated with flammable liquids, download our FREE eBook by clicking on the image below. He helps organisations reduce risk and improve efficiencies in the storage and management of dangerous goods and hazardous chemicals. Segregate the 9 different classes of dangerous goods in a way which will reduce risk to people, property, and the environment.
Learn more. Are you storing flammable chemicals? The heat produced was measured to be , kJ. Calculate the calorific value of the fuel. Can the process of rusting be called combustion? Abida and Ramesh were doing an experiment in which water was to be heated in a beaker.
Abida kept the beaker near the wick in the yellow part of the candle flame. Ramesh kept the beaker in the outermost part of the flame. Whose water will get heated in a shorter time? Exercise: 1 Mark Questions. An important liquid fuel, used in home is ……….. What are the main constituent of biogas and kitchen gas L. What is biogas? Fuel must be heated to its ……….. When fuels bum what do they produce? Define combustion.
What name is given to the substances which can bum easily? Give two examples of the combustible substances. What name is given to the substances which do not bum? Classify the following as combustible and non-combustible substances- Paper, iron nails, cloth, glass. How is heat and light produced in the sun? When does a substance start burning? Give two examples of inflammable substances. When does a fire brigade arrive? How does the fire brigade put off fire? When water is poured on a fire, which condition of combustion is not fulfilled?
What is meant by rapid combustion? What name is given to combustion which takes place on its own? When crackers are ignited, what type of combustion takes place? What is a flame? Which substances bum with a flame? What is meant by global warming? What is acid rain? How is acid rain harmful? What is the full form of LPG?
Why is a smelling agent added to LPG? Why is respiration referred to as slow combustion? Give one reason why LPG is a better fuel than kerosene? Why does yellow phosphorus catch fire on its own? A person sleeping in a closed room with burning coal, feels suffocated after sometime.
Exercise: 2 Mark Questions. What is a fuel? Name two liquid fuels. Is the food a fuel for our body? Distinguish between combustible and non-combustible substances. Can you bum paper when a burning matchstick is brought near it? What is forest fire? Why do different substances catch fire at different temperatures? Kerosene oil catches fire faster than wood.
Why is water poured to extinguish burning wood? Can you put off a fire due to electric short circuit by using water? Supposing the kerosene oil catches fire. How will you put it off?
How is fire extinguished at airports and petrol pumps? What is meant by spontaneous combustion? Give one example of a substance which shows spontaneous combustion. Does magnesium bum with a flame?
Camphor bums with a flame, but charcoal glows. Hydrogen has the highest calorific value, but it is not used as a fuel. Why petrol cannot be used as a fuel in stoves at homes?
Amit and Sunil were doing an experiment in which water was to be heated in a beaker. Amit kept the beaker near the wick in the yellow part of the candle flame.
Sunil kept the beaker in the outermost part of the flame. Exercise: 3 Mark Questions. Name the type of nuclear reaction taking place in the atmosphere of Sun. Define ignition temperature. Why water should not be used to put out fire caused by burning of petrol. Give two examples each of solid fuel, liquid fuel and gaseous fuel. Write any four characteristics of an ideal fuel. What is C. Mention its one use.
Explain the different zones of a flame with the help of a neat and well labelled diagram. Which is the hottest zone and the coolest zone of a flame?
Why does the middle zone of the candle flame glow with yellow colour? Why do we use paper or kerosene oil to start fire in wood or coal?
Explain how water extinguishes the fire. How does the foam type fire extinguisher work? You are given three substances A, B and C. How will you find out which of them as a combustible material? When the clothes of a person catches fire, we cover him with a blanket.
Red buckets containing sand are kept in offices and cinema halls. What is the function of a wick in the candle?
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