OPSIS Gas Analysis

OPSIS analyzers are continuous monitoring systems for ambient air quality, industrial emissions and processes. These high-tech systems, thanks to their DOAS technology, enable high-precision measurements even under difficult conditions.
  • High precision measurement
  • System suitable for harsh environments
  • Minimal maintenance
  • Single or multi-gas mono or multi-point measurement
  • Durability of equipment
  • Scalable system
  • International approvals (TÜV, MCERTS, ...)


The measurements are based on DOAS (Differential Optical Absorption Spectroscopy) technique.
A xenon lamp projects a light whose spectrum is known through an optical path (open air, chimney or process line).
The gas molecules inside the beam absorb light at wavelengths that are specific to them. A receiver transmits this light to an analyzer via an optical fiber.
The spectrum of the light is extracted there and analyzed to deduce the concentrations of gas sought.
This system can measure many gases such as: CO, CO2, NOX, HCl, SO2, H2O, NH3, HF, CH4, H2S, O2, phenol, formaldehydes, benzene, toluene, mercury ...


The 400 WASTE system is ideal for fast and continuous multi-parameter measurements.
DOAS technology performs measurements without direct contact between the gases and the analyzer, which allows the monitoring of very difficult environmental concentrations, with a lot of dust, aggressive gases or very high temperatures. It thus requires a minimum of maintenance and runs unattended for long periods. This solution is both economical and scalable thanks to the possibility of using a single analyzer for multi-point measurements (up to 8 optical paths) and the addition of post-installation gas.

LASER DIODE gas analysis for process measurements

  • Fast response time
  • Low detection limit
  • No interference

Ambient gas analysis

The 300 WASTE analyzer is ideal for environmental measurements on long measuring paths (up to 1500m).
Within a few minutes several hundred cubic meters of air interact with the light between the transmitter and the receiver.
This light is analyzed and allows the simultaneous measurement of numerous pollutants of backgrounds.
It is thus easy to determine the evolutions of the concentrations of pollutants present in the air, such as sulfur dioxide (SO2), nitrogen dioxide (NO2), ozone or BTX.

The system can also be used for monitoring air quality in working environments and storage areas.
Continuous measurement of toxic gases such as formaldehyde, H2S, NH3 or BTX is an excellent way to ensure compliance with personnel exposure limits and accidental leakage alerts.


Enviman is a tool for environmental management developed by OPSIS environment experts. It makes it possible to model the evolutions of pollution in time and space taking into account meteorological, physico-chemical and topographical phenomena. This comprehensive solution, suitable for both urban and industrial studies, is divided into three main functions:
  • Data management, validation, graphic presentation, statistical analysis, forecasting and preparation of environmental reports
  • Space modeling, dispersion modeling and scenario simulation
  • Integration of meteorological data, dispersion information


OPSIS also offers additional measuring devices such as oxygen, pressure, temperature, flow, dust and other sensors.


The OPSIS Total Mercury Analyzer is based on contactless DOAS technology, using an optical path. The gases pass through a catalyst before being analyzed in the optical path. This solution allows an efficient analysis with a minimum of maintenance.
NO CO H20 H2S Benzene
NO2 CO2 HF O2 Toluene
SO2 HCL N20 BTX Many gases on request!
NH3 HG CH4 Xylene
ISO9001 ISO 14001 ISO 17025  
Temperature Dust Debit
Oxygen Pressure VOC
Cement works Petrochemical industry Production of sulfuric acid
Incineration of waste Production Rock wool Aluminum foundries
Fertilizer Factory Power plant Ambient air quality monitoring station
Airports Petrochemical Sites Tunnels
OPSIS is a Swedish company that develops, manufactures and markets continuous monitoring systems for ambient air quality, industrial and process emissions, including a software suite. Created in 1985 by 2 scientists, this company is present throughout the world by relying on a network of qualified, trained and experienced distributors. Hundreds of systems are already operational on all continents. NEREIDES has been an exclusive distributor of OPSIS in France for more than 20 years.