Presentation is loading. Please wait.

Presentation is loading. Please wait.

PROPERTIES OF FLAMMABLE MATERIALS. Flammability Flammable Flammable –Capable of being ignited and of burning –Synonymous with combustible.

Similar presentations


Presentation on theme: "PROPERTIES OF FLAMMABLE MATERIALS. Flammability Flammable Flammable –Capable of being ignited and of burning –Synonymous with combustible."— Presentation transcript:

1 PROPERTIES OF FLAMMABLE MATERIALS

2 Flammability Flammable Flammable –Capable of being ignited and of burning –Synonymous with combustible

3 Pour point Lowest temperature for any liquid will remain fluid Lowest temperature for any liquid will remain fluid Important consideration for handling cargo at low temperature conditions Important consideration for handling cargo at low temperature conditions

4 Ignition point / temperature Minimum temperature of a combustible substance is required to initiate the process of burning as follow; Minimum temperature of a combustible substance is required to initiate the process of burning as follow; –Flash point (ignitable mixture and sustain combustion) –Pyrolysis –Fire point –Self ignition temperature –Spontaneous combustion

5 Flash point Is the lowest temperature at which the liquid fuel produces sufficient amount of vapour to gives off to form an ignitable mixture nears its surface or flashes momentarily when a source of ignition is applied, but is not sufficient to sustain combustion Is the lowest temperature at which the liquid fuel produces sufficient amount of vapour to gives off to form an ignitable mixture nears its surface or flashes momentarily when a source of ignition is applied, but is not sufficient to sustain combustion

6 Ignitable mixture Is the mixture of vapour and air that is capable of being ignited by an ignition source, however not sufficient to sustain combustion Is the mixture of vapour and air that is capable of being ignited by an ignition source, however not sufficient to sustain combustion

7 Sustained combustible It takes place at a slightly higher temperature, referred to as the fire point of the liquid It takes place at a slightly higher temperature, referred to as the fire point of the liquid

8

9 Pyrolysis Before solid fuel starts burning, it must be transformed into the vapour state. The pyrolysis, which is generally defined as chemical decomposition by the action of heat Before solid fuel starts burning, it must be transformed into the vapour state. The pyrolysis, which is generally defined as chemical decomposition by the action of heat In this case, the decomposition causes a change from the solid state to the vapour state. If the vapour mixes with sufficient amount of air and is heated to a high enough temperature, combustion will occur In this case, the decomposition causes a change from the solid state to the vapour state. If the vapour mixes with sufficient amount of air and is heated to a high enough temperature, combustion will occur

10 Fire point This may be defined as the lowest temperature at which the heat from the combustion of a burning vapour is capable of producing sufficient vapour to sustain the reaction and to enable combustion to continue This may be defined as the lowest temperature at which the heat from the combustion of a burning vapour is capable of producing sufficient vapour to sustain the reaction and to enable combustion to continue

11 Self ignition temperature The minimum temperature from the exothermic reaction heating up the unburn portion of the fuel and leading to ignition The minimum temperature from the exothermic reaction heating up the unburn portion of the fuel and leading to ignition

12 Some substances reach the ignition temperature rapidly other may take hours or days or even months while other are not, thus in this case pressure is also important factor. Some substances reach the ignition temperature rapidly other may take hours or days or even months while other are not, thus in this case pressure is also important factor.

13 Spontaneous combustion This is a special kind of combustion but by no means uncommon. In spontaneous combustion the three sides of the fire triangle exist, although this may not be immediately apparent This is a special kind of combustion but by no means uncommon. In spontaneous combustion the three sides of the fire triangle exist, although this may not be immediately apparent Heat is generated by chemical reaction within a substance and the process continues to a point of ignition. Usually spontaneous heating begins with slow oxidation which generates heat. Heat is generated by chemical reaction within a substance and the process continues to a point of ignition. Usually spontaneous heating begins with slow oxidation which generates heat. As the heat increases the chemical reaction takes place at a progressively increasing rate until the ignition temperature is reached As the heat increases the chemical reaction takes place at a progressively increasing rate until the ignition temperature is reached

14 Burning temperature

15 Burning rate Speed at which solid or liquid substance burns Speed at which solid or liquid substance burns For solid fuel depend on: For solid fuel depend on: –Configuration (chemical & physical properties) –Surface area exposed to the heat For liquid fuel depend on: For liquid fuel depend on: –Its flash point –Rate of vapour released - temperature

16 Thermal speed

17 Specific volume Volume occupied by one kg of the substance at 15°C and 760mm Hg pressure

18 Therm The therm is equal to 1,000,000 BTU (British thermal unit) The therm is equal to 1,000,000 BTU (British thermal unit) British thermal unit British thermal unit –Quantity of heat reqd to raise 1 pound of water through 1 degree of Fahrenheit

19 Thermal value

20 Flammable range The flammable vapour of a liquid must mix with air in the adequate proportion to make an ignitable mixture. The flammable vapour of a liquid must mix with air in the adequate proportion to make an ignitable mixture. It will be seen that the flammable gas or vapour will only burn in air if the composition lies between certain limits referred as follow; It will be seen that the flammable gas or vapour will only burn in air if the composition lies between certain limits referred as follow; –Lower flammable limit –Upper flammable limit

21 Explosive limit The limits of the explosive range i.e. the range between the minimum and maximum concentrations of hydrocarbon vapour in air which form explosive (flammable) mixtures Usually abbreviated to LEL (Lower Explosive Limit) and UEL (Upper Explosive Limit) Sometimes referred as LFL (Lower Flammable Limit) and UFL (Upper Flammable Limit)

22

23

24 Upper flammable limit The upper flammable limit (UFL) defines as the highest concentration of a hydrocarbon gas in air below which there is sufficient amount of hydrocarbon gas to support combustion. The upper flammable limit (UFL) defines as the highest concentration of a hydrocarbon gas in air below which there is sufficient amount of hydrocarbon gas to support combustion. Above the UFL, the mixture is too rich to initiate burning Above the UFL, the mixture is too rich to initiate burning

25 Lower flammable limit The lower flammable limit (LFL) defines as the lowest concentration of a hydrocarbon gas in air above which there is sufficient amount of hydrocarbon gas to support combustion. The lower flammable limit (LFL) defines as the lowest concentration of a hydrocarbon gas in air above which there is sufficient amount of hydrocarbon gas to support combustion. Below LFL, the mixture is too lean to initiate burning Below LFL, the mixture is too lean to initiate burning

26 Too lean A tank atmosphere made incapable of burning by the deliberate of the hydrocarbon content below the lower flammable limit A tank atmosphere made incapable of burning by the deliberate of the hydrocarbon content below the lower flammable limit

27 Too rich An atmosphere made incapable of burning by deliberately maintaining the hydrocarbon content of the tank over the upper flammable limit An atmosphere made incapable of burning by deliberately maintaining the hydrocarbon content of the tank over the upper flammable limit Also referred as Over Rich Also referred as Over Rich

28 Gas % LFL % UFL Gasoline Gasoline Kerosene Kerosene Propane Propane Hydrogen Hydrogen Methane Methane Ethylene Ethylene Ammonia Ammonia Butane Butane Acetylene Acetylene Benzene Benzene Typical limits of flammability

29 Auto ignition The lowest temperature at which a solid, liquid or gas combusts spontaneously without initiation by spark or flame

30


Download ppt "PROPERTIES OF FLAMMABLE MATERIALS. Flammability Flammable Flammable –Capable of being ignited and of burning –Synonymous with combustible."

Similar presentations


Ads by Google