Ametek Process Instruments - THERMOX

Model 931 - Single Gas H2S Analyzer (opt. + H2 and HC)



The Model 931 uses a sophisticated UV-VIS photometer to measure any single UV-absorbing gas species for process monitoring and control. Additional IR and thermal conductivity sensors capable of detecting non-UV absorbing species, such as CO2 and H2 can be incorporated into the design. The 931 is provided as an explosion-proof package making it suitable for most chemical and petrochemical applications.

This analyzer uses AMETEK's proprietary high-resolution UV-VIS technology which is completely free from water or hydrocarbon interference, maximizing measurement accuracy. A very flexible design, the 931 can be optionally equipped with additional sensors to add the capability to monitor CO2 and H2.

The Model 931 analyzer utilizes industrial electronics to provide concentration calculations, data processing, temperature control, calibration and sophisticated self-diagnostics. No matter what your need is, this rugged analyzer is solid proof of AMETEK’s worldwide reputation for durability and reliable performance.

  • Class I, Division 1, or ATEX II 2 G Hazardous Area Rating
  • Direct measurement
  • Provision to return sample to process (with heated acid gas probe option)
  • Minimal sample conditioning
  • Dual-beam, dual-wavelength design
  • Optional detectors available (thermal conductivity-hydrogen and IR-hydrocarbon

  • Methodology: Dual wavelength, high resolution, nondispersive UV/VIS
  • Full Scale Ranges: ppm and % vol are standard, other ranges are available

Standard Range

  • H2S: 0 to 4,000 ppm min. to 0 to 100% max.
  • Other components and ranges are available upon request. Other components may include NH3, COS, CS2 and SO2
  • Accuracy:
    • Standard range (UV): ±1% of full scale
    • Optional (TCD) H2 sensor for TGTU applications: ±2% of full scale
    • Optional (IR) sensor for THC, CO2: application specific, consult factory
  • Repeatability: Better than ±0.5% of full scale
  • Linearity: Better than ±1% of full scale for H2S
  • Zero Drift: Better than ±2% of full scale, with auto zero disabled over 24-hour period
  • Speed of Response: Typically less than 30s to T90 (excluding sample system)
  • Number of Gases: one
  • Zero Gas: Nitrogen or instrument air
  • Maximum Sample Cell Pressure:: 6.9 barg (100 psig)
  • Maximum Sample Gas Temperature:: 165 ºC (329 ºF)
  • Typical Sample Flow: 2.5 L/min (5 SCFH)
  • Sample Transport: Application dependant (options include Heated Acid Gas probe)
  • Outputs:
    • Up to 4 isolated 4-to-20 mA, loop or selfpowered, 30 VDC Max; 4 non-isolated 1 to 5 VDC;
    • 5 independent sets of SPDT, Form C, potential free alarm relay contacts, 2 A at 240 VAC
  • Digital Communication: RS485 Modbus port; RS232 / RS485 service port
  • Utility Requirements:
    • 120 VAC (104 to 132 VAC), 47 to 63 Hz, <3A
    • 240 VAC (207 to 264 VAC), 47 to 63 Hz, <2A
  • Power Consumption: 500 W max. (with heated probe and cell)
  • Ambient Temperature: 0 to 50˚C (32 to 122˚F)
  • Physical Dimensions: 1185 x 780 x 254 mm (46.65 x 30.7 x 9.97 in.)
  • Weight: Approximately 145 kg (320 lbs)

  • CEC Class I, Division 1, Groups C&D; Ex d IIB + H2, T3
  • NEC Class I, Division 1, Groups C&D; AEx d IIB + H2, T3
  • CEC/NEC Class I, Division 2, Groups B, C&D, ExP T3 (unit verification)
  • ATEX II 2 G Ex d IIB T3 Gb (IIB + H2 unit verification pending)
  • Russian Ex Proof Certification; 1ExdIIBT3 X
  • Russian Gosstandart Pattern Approval
  • Complies with all relevant European directives

  • Hydrogenation Reactions (hydrogen sulfide, hydrogen)
  • Feed gas analysis
  • Reaction rate monitoring
  • Impurity detection
  • Quality assurance monitoring

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