Model 930 H2S in Sulfur Pit Analyzer



In many sulfur recovery units, produced sulfur is stored in liquid form in sulfur pits. Operators are increasingly aware that sulfur pits present potential danger to plant personnel and overall plant safety. It is therefore critically important to monitor H2S in the vapour space of sulfur pits to ensure that it remains below the Lower Explosive Limit (LEL) (4.3% by volume). Additionally, the presence of rising concentrations of SO2 in the sulfur pit vapour space provides an early indication of smoldering fires. Therefore, on-line, continuous monitoring of SO2 can enable detection of such fires before they get out of control.
The Model 930 H2S Vapour Space Analyzer was developed  for sulfur pit storage applications. The AMETEK-designed Model 930 has been field proven as one of the industry’s most reliable instruments for monitoring H2S and SO2.

The Model 930 uses a proprietary high resolution UV technology in a dual beam, multiple wavelength configuration. Resolution better than 0.02 nm is provided by high intensity, line source lamps. These sources emit at a fixed wavelength, providing great measurement stability, and emit low total power, removing the potential for sample photolysis. The dual beam configuration, combined with the reference measurement, ensures low noise performance, with minimal baseline and span drift.

The Model 930 analyzer samples the vapour space gas using proven ASR Probe technology. The sampling system has a sulfur knock-out at the probe to eliminate entry of excess sulfur vapour or liquid into the system. The sample is transported through an electrically traced sample line.


  • Simultaneous, accurate measurement of both H2S and SO2
  • Output alarms for H2S (LEL) and SO2 (smoldering fire)
  • Common design with Model 900 (air demand) and Model 910 (stack gas)
  • Exceptional baseline stability
  • Improved sample conditioning via ASR Probe