$($iii$)$ The diagram below represents a stirred vessel which is situated indoors and contains methanol $($a volatile, flammable organic solvent$).$ The vessel is opened regularly as part of normal processing operations.

$)$

$($ regularly

In the context of ATEX, re$-$draw the diagram in your answer book and sketch in $($approximately$)$ the relevant hazardous area classifications.

$(3$ marks$)$

$($iv$)$ Outline the key features$/$steps of a LOTO procedure.

$(2$ marks$)$

$($v$)$ Explain why a fire or explosion might not occur even though a sufficiently energetic ignition source comes in contact with a mixture of air and flammable organic solvent vapour on the production floor of a chemical plant.

$(1$ mark$)$