H2S OMA-300 Measuring Hydrogen Sulfide in Natural Gas

The composition of pipeline natural gas varies widely by source but typically reflects a mixture of simple hydrocarbon gases with a few other components including water vapor, carbon dioxide, helium, nitrogen, and sometimes hydrogen sulfide (H2S). Hydrogen sulfide can be especially problematic because it is both toxic and corrosive, representing one of the largest threats to pipeline integrity when stress corrosion cracking occurs. Hydrogen sulfide detection is an integral element of natural gas analysis from the wellhead to burner in North America and throughout the world.

The OMA-300 is a highly field-proven solution for fast response H2S measurements in several natural gas applications. Due to high accuracy and dynamic range, the OMA is the analyzer of choice both for high-level and ow-level H2S ranges. The OMA provides fast response measurement with less downtime than alternatives for more effective control in a natural gas process. When compared against other photometers, the OMA provides more accurate measurement of a wider concentration range due to the dispersive “full-spectrum” acquisition at high resolution.


  • Dispersive UV-Vis absorbance spectrophotometer
  • 1,024-photodiode array
  • Rugged flow cell
  • 316 SS NEMA 4X Enclosure


  • Cell located independent from power
  • Continuously measures H2S concentration in natural gas
  • Accurate measurement of 0-10 ppm, 0-100%, or any range in between
  • Direct analysis of hot, wet, high-pressure sample
  • Solid state device with no moving parts
  • Low maintenance


Measurement Principle Dispersive UV-Vis/SW-NIR absorbance spectrophotometry
Detector nova IITM Spectrophotometer
Data sheet: http://aai.solutions/documents/AA_DS201A_novaII.pdf
Spectral Range 200-800 nm (UV-Vis model) or 400-1100 nm (SW-NIR model)
Light Source Standard: pulsed xenon lamp with average 5 year lifespan (dependent on application)
Fiber Optic Cables Standard: 600 μm core 1.8 meter fiber optic cables (qty = 2)
Data sheet: http://aai.solutions/documents/AA_DS206A_FiberOptics.pdf
Sample Medium Gas or Liquid
Sample Introduction Standard: stainless steel 316L flow cell with application-dependent path length
Options in data sheet: http://aai.solutions/documents/AA_DS207X_FlowCell_All.pdf
Photometric Accuracy ±0.004 AU at 220 nm
Response Time 1-5 seconds
Sensitivity ±0.1 % full scale
Sample Temperature Standard: -20 to 70 °C (-4 to 158 °F)
Sample Pressure (max) Using standard flow cell: 206 bar (3000 psi)
Analyzer Environment Indoor/Outdoor (no shelter required)
Ambient Temperature Standard: 0 to 35 °C (32 to 95 °F)
Optional: -20 to 55 °C (-4 to 131 °F)
To avoid radiational heating, use of a sunshade is recommended for systems installed in direct sunlight.
Electrical Requirements 85 to 264 VAC 47 to 63 Hz
Power Consumption 45 watts
Outputs 1x galvanically isolated 4-20mA analog output per measured analyte
2x digital outputs for fault and SCS control
Optional: Modbus TCP/IP; RS-232; RS-485; Fieldbus; Profibus; HART; more
I/O Electronics Voltage/Current Interface Module (i.e. I/O Board)
Data sheet: http://aai.solutions/documents/AA_DS205A_VCIM.pdf
Accuracy Custom measurement ranges available; example ranges below. Accuracy specifications represent headspace gas sample analysis validated with span gas.
H2S 0-10 ppm: ±1 ppm
0-100 ppm: ±1% full scale or 1 ppm (whichever is larger)
0-10,000 ppm: ±1% full scale