The VOXI series of fixed transmitters utilize photo-ionization detection (PID) technology to monitor volatile organic compounds (VOCs) at resolutions of 1 ppb with the MP812 and 10 ppb with the MP815. A built-in heater prevents the condensation of moisture in the transmitter under high-humidity conditions. Innovative designs of the ultraviolet (UV) 10.6 eV lamp and electrometer reduce contamination, producing more accurate and stable readings and extending maintenance intervals. Mobile apps and a Bluetooth controller make on-site configuration, testing and trouble-shooting easy and handy. The OLED display is visible from a distance even under strong lighting, while data and alarms are continuously sent to a controller wirelessly or via cables. Outputs include analog 4-20 mA, digital RS485, 3 relays and a Strobe/Horn port. Major applications include VOC emission monitoring around petrochemical plants, manufacturing and processing facilities.