The Rosemount 935 is an open-path combustible gas detector designed for continuous monitoring of hydrocarbon gases in harsh environments where dust, fog, rain, snow, or vibration can cause obstruction. It utilizes infrared technology with a detection range of up to 660 ft (200 m), depending on configuration. Heated optics eliminate condensation and icing, ensuring reliable operation in extreme weather.Sensitivity ranges from 0–5 LEL.m for methane/propane to 0–8 LEL.m for ethylene, with a built-in data logger recording up to 256 events.

The detector offers user-programmable communication via HART or RS-485 Modbus protocols, with built-in event recorder and data logger (256 events). It has a response time of ≤3 seconds and is not influenced by solar radiation, hydrocarbon flames, or other IR sources. The 316L stainless steel housing is rated for hazardous areas, and the device carries worldwide approvals including ATEX, IECEx, FM/FMC, INMETRO, TR CU, and SIL 2 (TÜV). It is suitable for offshore platforms, petrochemical plants, gas terminals, and pipelines.