[Breath alcohol measuring equipment: principles for calibration]

Breath alcohol simulators with aqueous solutions of ethanol (equilibrators) are suitable for simulating the measuring process with a person, while testing different functions of an evidential breath analyser including the temperature measuring device. Therefore they are commonly used for random tests. They are unsuitable for an absolute calibration if the coefficient of solubility of ethanol can not be presumed. Absolute calibrations require the transformation of a known quantity of ethanol within a defined volume into a gaseous state. The concentration of the gas produced in such a way then has to be measured with the analyser to be tested and must be compared with the calculated value. A measuring device with a large volume piston pump was constructed for this purpose. The values of the solubility coefficient coincide with internationally used values.