Product Description Replacement Infrared Carbon Dioxide/Hydrocarbon LEL sensor for the Ventis® Pro. The CO2/HC sensor is a single sensor that can detect both CO2 and the LEL of a variety of different hydrocarbons. The CO2/HC sensor has a CO2 measuring range of 0-5% by volume with a .01% by volume resolution, and the HC LEL sensor has a 0-100% LEL measuring range with a .01% LEL resolution. The standard calibration gas for a CO2 sensor is 2.5% vol CO2, and the standard calibration gas for the HC LEL sensor is 25% LEL Propane. A list of different correlation factors for the HC LEL sensor can be found in the Ventis Pro manual. This 4 series sensor is only available for the Ventis Pro 5 and must be installed in location 2. (This sensor will not fit or work with Ventis MX4 Series Gas Monitors)Has your CO2/HC sensor failed or has a measuring range that's all over the place? It might be time to replace it. Repair your Industrial Scientific Ventis Pro Multi-Gas monitor by purchasing a new genuine Industrial Scientific (CO2/HC) Carbon dioxide / Hydrocarbon Infrared Sensor.Need some DIY help changing a sensor or just some friendly technical help with repairing your instrument? Call customer service at 1-800-949-7233.