Device and process for measuring breath alcohol

A process for measuring breath alcohol, the process comprising the steps of:

• receiving in a flow chamber, exhaled breathing gas flow of a person being tested;
• providing a flow diaphragm arranged in said flow chamber;
• measuring a differential pressure occurring over said flow diaphragm after a breathing gas sample is released by the person to be tested;
• determining values for a volume of the breathing gas flow based on measured differential pressure;
• comparing said values for said volume of the breathing gas flow with stored reference values;
• sampling the exhaled breathing gas flow and measuring alcohol concentration when said differential pressure is nonzero and integration over a preset time of the values for the volume of the breathing gas flow reaches a preset, stored minimum breathing gas volume.

A device for measuring gas, the device comprising:

• a flow chamber receivable of a flow of the gas;
• a flow chamber restriction arranged in said flow chamber and dividing the gas into upstream and downstream gas, said flow chamber restriction causing a pressure drop in the flow of the gas;
• a gas sensor in communication with said flow chamber;
• a sample system in communication with said flow chamber through said gas sensor and for pulling gas from said flow chamber into said gas sensor;
• a throttling element arranged between said gas sensor and said sample system;
• a differential pressure sensor connected upstream and downstream of said flow restriction and measuring a pressure difference between the upstream gas and the downstream gas, said differential pressure sensor measuring one of the upstream and downstream gas through said gas sensor;
• a control unit receiving pressure and gas signals from said pressure sensor and said gas sensor, said control unit controlling said sample system.