As a rule, volatile fuels are measured very seldom because they are very consistent. However, if the fuel absorbs water, then frequent analysis is called for.
Volatile fuel such as alcohol must be prevented from evaporating during the handling process that is from weighing to ignition of the sample.
The process requires a sticky cello tape to cover the crucible and stick to the rim (crucible cover discs). The cello tape is measured beforehand and the calorific value (CV) is established once.
Then the crucible is tared, the cello tape is glued to the rim and the overhanging parts are cut off with a sharp knife. Then the crucible and tape is weighed, and the taped mass is established. This mass is entered into the calorimeter as "Spike Mass" and the CV of the tape is entered in "Spike CV". The crucible and tape are tared again and the volatile substance is injected with a syringe into the crucible by piercing the tape.
The crucible is put into the combustion vessel and a normal calorimeter is started with filling the vessel with oxygen, stabilizing the vessel, igniting the sample, and determining the heat release. The Calorific value is automatically calculated and displayed, and printed if so desired.