Technical Report Documentation Page

Special Testing for Possible Carry Over Effects Using the Intoximeters, Inc. Alco-Sencor IV at 10 degrees Celcius

CONDE, Edward

Volpe National Transportation Systems Center
Kendall Square (55 Broadway)
Cambridge, MA 02142

National Highway Traffic Safety Administration
400 7th Street, S.W.
Washington, DC 20590

Dr. James F. Frank was the project monitor for this project.

Laboratory testing showed that when simulator samples at 0.170 grams of ethanol per 210 liters were repeatedly tested with an Intoximeters, Inc. Alco-Sensor IV at 10 degrees C. ambient temperature, some ethanol and water eventually condensed onto the cool airway surfaces of the instrument. When the instrument was operated in screener mode without any heating element and without proper protocols, some of this alcoholic condensate carried over to subsequent screening tests. However, no carry over was seen when the Alco-Sensor IV was operated in the evidential mode, or when the optional CEM heating accessory was used, or when proper test protocols were used.

The results show that the possibility for the occurrence of carry over in breath testing must be addressed when operating at low ambient temperatures, particularly when using unheated breath testers. The results also show that the potential for carry over can be eliminated easily by using procedural controls, such as performing an air blank before the test, or by testing two separate breath samples and/or by using a warm air flushing of the breath tester airway.

A table listing all breath testers on both the NHTSA Conforming Products List (CPL) for Screening Devices, as well as the Evidential Breath Tester CPL indicates whether specific devices have a built-in heater, or a flushing pump, and whether the instructions accompanying them address the possibility of alcohol carry over during low temperature operations.

Alcohol, breath alcohol testing, Alco-Sensor IV, carry over effects, Driving under the Influence (DUI)

Copy available from National Technical Information Service, Springfield, Virginia 22160. Also see www.nhtsa.dot.gov for a copy.

 Unclassified

 Unclassifed

 5