• Measurement specific to H₂S
    No interference from other components
  • Wide range capability
    Measures between 0-50ppb to 0-600ppm
  • Low volume humidifier
    Response times as low as 10 seconds
  • Electronics temperature compensated
    Improves stability
  • No instrument air / N₂ required
    Lowers running costs
  • Fiber optic link between housings
    Reduces effects caused by ambient temperature swings
  • Up to 4 detection modules per controller
    Minimizes capital investment
  • Multi-streaming capability
    Will control up to 4 streams with one controller

With its wide-ranging ability to measure H₂S from % levels down to
ppb levels, the HG400 range of H₂S process analyzers can be
utilized in many process industries, including:
Natural Gas pipelines Reformer recycle gas
Offshore gas production Fuel gas monitoring
Biogas Sour gas treatment plants

A reel of paper tape impregnated with lead acetate is exposed to
the gaseous process sample in the sample chamber. Hydrogen
sulphide (H₂S) in the process sample reacts with the lead acetate,
after acidification, to form lead sulphide (PbS), a brown compound
that stains the tape. The higher the concentration of H₂S the darker
the stain. A focused LED and single photodetector system
continuously measures the darkening stain and the analyser
reports this as a 4-20mA output of the concentration of H₂S.
Incremental measurements are made on the same spot until saturation occurs when the tape is advanced to a fresh portion of the tape. This avoids the need for frequent zero or span calibrations.

Measurement principleColorimetric (complies with ASTM D4045, D4084, D4323, D4468)
SoftwareC++ Windows XPe based, SIL 2 certified
ElectronicsPC104, Intel Celeron 400MHZ microprocessor, 256Mb SDRAM, 512Mb compact flash for the operating system, application, customized parameters, and calibration curves storage
KeypadAccessible through flameproof box using Touchsense™ technology
Measurement rangeBetween 0-50ppb H₂S to 0-600ppm H₂S
Repeatability± 1.5% full scale
MultiplexingUp to 4 detection modules on one controller
Output1 x 4-20mA per module (Modbus optional)
Alarms1 x measurement alarm, 1 x instrument failure alarm.
Additional optional alarms available
Area classificationATEX approved, Ex d [ia] IIC T4
Ambient temperature limits-20°C to +40°C
Tape lifeUp to 60 days depending on the application.
Weather protectionIP66
Response timeDepends on the application but typically 10secs for 0-10ppm range
Power120 / 240 VAC 50 / 60 Hz
Power rating40 VA
Process sampleMax pressure 1.5 – 4.0 bar,  flow rate 0.15 to 0.3 l/min, 40°C max temp
Process connections⅛” OD inlet, ¼” NPT female vent (to atmospheric vent)
Analyser VentTo Atmospheric, no back pressure or vacuum allowed
Weight30 Kg approx
Dimensions378(w), 975(h), 235(d) mm
Application Range
Process conditions
Wall mounting or free-standing frame Power supply

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