The Influence of Hydrogen on the Indications of the Electrochemical Carbon Monoxide Sensors

This article examines electrochemical carbon monoxide (CO) sensors used as mobile devices by rescue and firefighting units in Poland. The conducted research indicates that the presence of chlorine (Cl 2 ), ammonia (NH 3 ), hydrogen sulfide (H 2 S), hydrogen chloride (HCl), hydrogen cyanide (HCN), nitrogen (IV) oxide (NO 2 ), and sulfur (IV) oxide (SO 2 ) in the atmosphere does not affect the functioning of the electrochemical CO sensor. In the case of this sensor, there was a significant cross effect in relation to hydrogen (H 2 ). It was found that the time and manner of using the sensor affects the behavior in relation to H 2 . Such a relationship was not recorded for CO. Measurements in a mixture of CO and H 2 confirm the effect of hydrogen on the changes taking place inside the sensor. Independently of the ratio of H 2 to CO, readings of CO were flawed. All analyses showed a significant difference between the electrochemical CO sensor readings and the expected values. Only in experiments with a 1:3 mixture of CO and H 2 was the relative error less than 15%. The relative error in the analyzed concentration range for a sensor with an additional compensation electrode ranged from 7% to 38%; for a sensor without this electrode, it ranged from 23% to 55%. It was ascertained that in the cases of measurements for tests carried out at higher concentrations of H 2 in relation to CO, a sensor with an additional electrode is significantly better (more accurate) than a sensor without such an electrode. Differences at the significance level p = 0.01 for measurements made in the CO:H 2 mixture at a ratio of 1:3 were ascertained.