The new S4000TH Hydrogen Sulfide Gas Detector from General Monitors (USA) is designed to protect people, equipment, and plants from the dangers of hydrogen sulfide (H2S), and features the HART® communication protocol for ease of field communications. HART is a field-proven instrumentation communications protocol that provides two-way digital communication without disturbing the integrity of the 4-20 mA analog output. HART permits several variables, parameters, device configuration, and device diagnostics to be transmitted digitally at the same time as the analog signal. Unlike other digital communication methods, HART is backward compatible with the installed base of instrumentation in use today.
Because of the detector’s multiple communication methods, a user can perform gas checks or single point calibrations through a magnetic interface, HART, or Modbus. No special tools or area declassification is required.  The S4000TH also stores the maintenance event with date and time stamp for improved record keeping.
The S4000TH H2S gas detector is suitable for use in SIL 3 systems and approved by CSA and FM. Additionally, the detector is compliant with the ATEX directive and has the CE marking. Gas concentrations are displayed on a three-digit LED enclosed in an explosion-proof housing. The S4000TH is also available with an optional relay configuration that is appropriate for SIL 2 processes.
The S4000TH is equipped with a metal oxide semiconductor (MOS) sensor. MOS sensors are highly selective; unaffected by ammonia, hydrogen, alcohols, and other gases commonly present in plant environments. The detector monitors H2S gas in parts per million (ppm) and provides status indication and alarm outputs.  The MOS sensors are compliant with ISA 92.0.01 Part I – 1998 and available in 0-20 ppm, 0-50 ppm or 0-100 ppm to support a wide range of applications.
