EM-5 Flue Gas Analyzer


EM-5 flue gas analyzer is a self-developed gas analysis product for domestic and overseas environmental and industrial on-line monitoring online analysis. The analyzer is based on DOAS and chemometric algorithms PLS), able to measure SO2, NO, NO2, O2, NH3, CO, CO2, Cl2, O3, H2S, HCl, CH3I, etc.. With high accuracy and reliability, low operating costs, fast  response time, wide measurement range and application fields, it has achieved even surpassed similar products home and abroad.It can be widely used in environmental online monitoring, industrial process control, safety monitoring, etc.

Technical Principle

EM-5 flue gas analyzer (standard form) uses the long optical path UV DOAS technology. Its optical technology platform consists of light source, gas chamber, optical and spectroscopic (including diaphragm, holographic grating, linear array detector) and other optical components. As shown in figure.

Ultraviolet light is sent by the photosource through the optical window into gas chamber (optical path 0.25 meters) , and absorbed by the sample gas flow through the gas chamber. The light carrying sample absorption information gathers through lens coupled into the fiber and then transmits through the optical fiber into the spectrometer. After light splitting and photovoltaic conversion, absorption spectrum is obtained and analyzed to calculate the concentration of the related components in gas.

Product Features

High measurement accuracy

  • Ultraviolet has no moisture absorption, undisturbed by moisture and dust
  • No cross interference between the gas being measured (see table 1)
  • NO and NO2 can be measured at the same time, dispense  with converter
  • Low detection limit

​High reliability

  • DOAS + PLS technology, small amount of zero drift and span drift
  • Modular design
  • No optical moving parts and no vibration influence
  • Strong gas cell, low cost
  • Spectrum automatic adjustment technology, long free maintenance cycle
  • Light source adopts the pulse source, the service life is 10 years


Measuring TechniqueDOAS(SO2、NOx),Electrochemistry(O2)
Measuring Range0-300-3000ppm(SO2、NOx),0-25%(O2)
Linearity Error≤±1%F.S.
Zero Drifting≤±2%F.S./7d
Measuring Range Drift≤±2%F.S./ 7d
Response Time< 25s( T90 )
Warm-up TimeNone
Relay Output14
Binary Input6
Analog Output4×4 -20mA
Analog Input2×4 -20mA
Digital CommunicationRS232/ RS485 /GPRS
Enclosure RatingIP65
Ambient Temperature-10ºC~40ºC
Ambient Humidity0% Rh~95%Rh


  • Low detection limit and temperature-drift
  • Getting NOx by directly measuring NO and NO without NO →NO2 converter
  • No interference of particulate matter, moisture and other factors
  • No optical moving parts, high reliability, no interference to the measurement by field


Wide application scope
  • Titanium white production process.
  • Sulfur recovery process.
  • Natural gas purification process.
  • Methyl iodide analysis for the coal chemical industry.
  • Online air monitoring.
  • Coal-fired power plants.
  • Cement plant.
  • Industrial furnaces.
  • The desulfurization process monitoring.
  • Denitration process monitoring
  • Incinerators.


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