Oxygen bomb calorimeters determine the calorific value of materials by measuring the heat of combustion.
Heats of combustion are determined by a measured substitution procedure in which the heat obtained from the unknown sample is compared with the heat obtained from combustion of a similar amount of benzoic acid or other standardizing material whose calorific value is known.
A calorimeter has two modes of operation.
‘Standardisation’ is the term used for obtaining results with a benzoic acid “standard” for calibrating the instrument.
‘Determination’ is the term used for obtaining calorific values of unknown samples.
Certain material contain chlorine and other halogenated compounds. Under combustion conditions halogens can react with the standard stainless steel bomb and cause serious corrosion. This will be of particular concern if you work in the waste or recycling industry as plastics, solvents and other exotic materials all contain chlorine and halogens.
The way to avoid this is to change the material of construction from standard stainless steel bomb to a chlorine / halogen resistant alloy, Hastalloy C276. This can be offered on all Parr calorimeters.