The HML series carbon monoxide transmitters are designed for detecting carbon monoxide in underground parking garages. The sensing element is an environmentally friendly electrochemical cell with a long service life, excellent long-term stability, and high accuracy. Since the sensor is heated, the transmitter also operates reliably at very low temperatures down to -30°C. The HML series features an analog output with a range of 0 ... 100 or 0 ... 300 ppm CO for controlling ventilation systems.