SO2/CO2/NOx Monitoring

Process control of an SO2 scrubber on a ship is a challenge due to wet and corrosive gases. In such environment, extractive gas sampling systems require high levels of maintenance in order to operate correctly. OPSIS monitoring system solves this by using an optical, non-contact, cross-duct technique.

A light beam is sent across the duct or stack to be measured, and the captured light is sent through an optical fibre cable to an analyser. The analyser measures SO2, CO2 and NOx concentrations using UV and IR absorption, approved reference methods.

The sulfur content in the bunker oil is measured based on the SO2/CO2 ratio in ppm/Vol.%, where the ratio has to stay below 4.3, which is equivalent to 0.1% sulfur content in the bunker oil.

One analyser can be connected to several measurement paths using an optical multiplexer, making a cost effective solution for up to 12 monitoring points.

Besides SO2 and CO2 monitoring, OPSIS provides instruments for NOx monitoring. The OPSIS system M800 is certified for all three gases.


  • Measure SO2 and CO2 using UV and IR reference methods
  • No sampling required, non contact system
  • Operates with a minimum of maintenance
  • One system for all scrubbers on a ship
  • DNV certified for ship installations
  • Serviced by highly skilled service network

    System Overview
    UV and FTIR DOAS for monitoring in marine applications

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