Question

When a flammable liquid such as gasoline ignites, the substance actually burning is vapor that is generated from the liquid. If the concentration of the vapor in the air about the liquid exceeds a certain level called “lower flammability limit” the vapor will ignite if it is exposed to a spark or another source of ignition. Once ignited the heat released is likely to cause additional vaporization of the liquid and the resulting fire may continue until all the combustible material has been consumed.

Give reasons why it would be unsafe to maintain an open container of methanol in an

environment below the LFL. (i.e., the value calculated in part (b)) if there are ignition

sources nearby. List common ignition sources that may be found in a laboratory.

Answer 1

a) The flash point of Methanol (The flash point of a volatile material is the lowest temperature at which vapours of the material will ignite, when given an ignition source) is 11 degree Celsius. This is well below the room temperature of the lab (considering 23 degree Celsius as room temperature). If the container of Methanol is kept open, then vapors of Methanol would be generated. The LFL for Methanol is 6 percent and UFL is 36 percent. If an ignition source is provided to the Methanol vapors then this will lead to explosion or fire. This will be escalated if there is presence of other combustible materials in the lab.

b) Damaged electrical pugs, damaged non insulated electrical live wire, overloading of electrical sockets, Bunsen burner, sodium metal, smoking, matchsticks are some examples of ignition sources.