Calibration gas is a reference gas or a mixture of gases which are usually compressed. The composure of calibration gas exists of one initial gas and is enhanced by one or more component(s). Calibration gas is used to calibrate gas analysers or gas detectors.
Calibration gases can be divided into two categories; zero calibration and span calibration. Zero calibration gas is a gas which is free from flammable gases. Zero calibration gases are performed when gas detection or gas analysers get calibrated with none of the analyte gas structures to which the analyser or detector will respond. For example, a zero calibration of an oxygen-, or carbon dioxide analyser can be performed with pure nitrogen. Because nitrogen does not hold either oxygen or carbon dioxide, a zero point can be confirmed this way.
A span gas calibration is a more advanced type of calibration gas by which there is a precisely composed concentration of detectable gas exposed towards the gas detector or gas analyser.