Material Safety Data Sheet User's Guide​

8. Fire or explosion hazard

Flash point and method of determination Explosion data – sensitivity to mechanical impact
Lower and upper explosive or flammable limits Explosion data – sensitivity to static discharge
Auto-ignition temperature Means of extinction
Conditions of flammability Special precautions *
Explosion conditions * Hazardous combustion products

*Non-essential information for WHMIS purposes.


 

 

Flash point and method of determination

The flash point is the lowest temperature at which a substance gives off sufficient vapours to form a flammable mixture with the air on contact with a flame or spark. A product’s flash point is determined by either of the two following methods: in a closed cup, meaning inside the container that contains it, or in an open cup, meaning near the surface of the liquid. The lower a liquid’s flash point, the greater the risk of fire.

 

Example

Normal butanol has a flash point in a closed cup of 29°C (Set-a-flash method). It is therefore extremely flammable on a hot summer day when its vapours come in contact with a flame or spark.

 

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20° C

25° C

29° C

 

Lower and upper explosive or flammable limits

These are the minimum and maximum concentrations of a product in the air between which a flammable or explosive mixture can form in the presence of an ignition source. These concentrations are expressed as a percentage of the volume in the air.

 

Example

Ethylene has a lower explosive limit of 2.7% and an upper limit of 36%. Therefore, in the presence of an ignition source, if the concentration of the gas is less than 2.7% or greater than 36%, there is no risk of explosion. But if the concentration of the substance is between these two limits, the mixture could explode. The concentration of the product in the air must be kept under its lower explosive limit, for example by using appropriate ventilation.

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1%

1.5%

2.7%

 

Auto-ignition temperature

This is the lowest temperature at which spontaneous combustion of a product occurs. It begins to burn by itself in the absence of any flame or spark. The closer the auto-ignition temperature is to the ambient temperature, the greater the risk of fire.

 

Example

Turpentine has an auto-ignition temperature of 253°C. Therefore, it will not burst into flame by itself at ambient temperature.

50°C - 200°C - 253°C

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Conditions of flammability

Conditions of flammability indicate whether a product could burst into flame and under what conditions.

 

Example

Toluene is a flammable liquid and will therefore burst into flame if it is near a source of ignition.

 

Note. – When a substance is classified “flammable”, the necessary precautions must be taken to avoid it reaching its auto-ignition temperature or its flash point, depending on the case.

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Explosion conditions

Explosion conditions indicate whether a product is likely or not to explode when it is used.

 

Example

Toluene vapours form an explosive mixture with air.

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Explosion data – sensitivity to mechanical impact

These data indicate whether or not there is a risk of explosion on impact, and if so, specify under what conditions the explosion could occur.

 

Example

Picric acid may explode on impact.

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Explosion data – sensitivity to static discharge

These data indicate whether or not there is a risk of explosion with a static discharge, and if so, under what conditions explosion could occur.

 

Example

When xylene is shaken or when it flows in pipes, it can accumulate a static charge that may cause the vapours to ignite.

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Means of extinction

This subsection contains a list of the extinguishing agents to use to fight a fire when this product is present or when it is the cause of the fire.

 

Example

Toluene: Carbon dioxide, dry chemical, water spray, alcohol foam.

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Special precautions

This subsection describes the special precautions to take to fight a fire when this product is present or when it is the cause of the fire. Also indicated are the specific means for avoiding an explosion or the propagation of the fire.

 

Example

Toluene: Wear a self-contained breathing apparatus. The vapours are heavier than air and can travel a great distance towards a source of ignition and thus cause flashback.

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Hazardous combustion products

This subsection lists the combustion products that are health and safety hazards and that may form when the substance burns.

 

Example

Toluene: Carbon dioxide, carbon monoxide.

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