Practical use of commercially available compressed (dry gas) alcohol standards

Abstract

ABSTRACT Approved Instruments for Breath Testing in Canada require the use of alcohol standards to ensure that they are in proper working order at the time of testing. Newer generation breath testing instruments allow for the use of Dry Gas (ethanol and nitrogen in compressed gas tanks) as the alcohol standard. Three areas were evaluated: (1) consistency of alcohol readings over time as the gas tank depletes; (2) altitude compensation in the Intox EC/IR II and Datamaster-DMT at two different elevations; and (3) the effect of exposing the dry gas tanks to weather conditions that could be encountered during shipping or storage. The results demonstrated that (1) the concentration of alcohol was found to remain stable as the tank emptied; (2) both instruments correctly compensated for the change in atmospheric pressure due to elevation change; and (3) when dry gas tanks from different manufacturers were subjected to −20°C for 48 hours, some tanks were found to have decreased pressure and an increase in alcohol concentration. Some tanks exposed to freezing temperatures for an extended period may not produce the appropriate reading and as such precautions should be taken when shipping or storing dry gas tanks in cold temperatures.