Infrared Multi-Gas Analyser


8869 is a rugged process analyser for measuring up to 3 IR-absorbing gases in heavy duty applications in safe area and hazardous area with the best ATEX protection mode (Zone 1 / 21). 

Designed to withstand the most severe process conditions, this resilient analyser have no choppers or other moving parts that may affect the reliability.

Measureable Gas

Acetylene [C2H2]

Carbon Monoxide [CO]

Ethylene Oxide (ETO) [C2H4O]

Nitric Oxide [NO]

Styrene [C8H8]

Vinyl Chloride (VCM) [C2H3Cl]

Ammonia [NH3]

Ethanol [C2H6O] 

Hydrogen Chloride [HCl]

Nitrous Oxide [N2O]

Sulfur Dioxide [SO2]

Water [H2O]

Carbon Dioxide [CO2]

Ethylene [C2H4]

Methane [CH4]

Propane [C3H6]

Toluene [C7H8]

Xylene [C8H10]

Main Features

Extreme Roughness

  • No choppers and other moving parts
  • Wet parts in selected materials for use with gas like pure Ammonia, VCM, HCl and other demanding streams
  • Resistant to the most severe industrial environments


High Performances

  • Designed to measure up to 3 IR-absorbing gases with a unique sensing unit
  • Precision optical filters minimize effects of background gases
  • Single beam source and no gas-filled cells
  • A unique source-emission control system allows up to 20% windows fouling without effect on accuracy.
  • Sensing unit temperature controlled
  • Insensitive to ambient temperature variations


Easy Maintenance

  • The sensing unit can be easily disassembled for field maintenance and cleaning.
  • Modular construction
  • Fast access to the inner PCB just unscrewing the housing cap


European Compliance

  • Low Voltage Directive 2014/35/EU
  • EMC Directive 2014/30/EU
  • Directive ATEX 2014/34/EU (optional)



ATEX certification for Zone 1 / Zone 21 with protection mode:

II 2 G D     Ex db IIC T6 Gb

Ex tb IIIC T85°C Db



ATEX Certificate Number CESI 03 ATEX 130


Accuracy± 1% of span (output signal).
Further improvable with autocalibration.
Repeatability± 0.3% of span (short term).
Reproducibility24 hours: ± 1% of span.
Linearitywith control unit: better than ± 0.5% of full scale
Response TimeInitial: less than 1 sec.; 90% of step-change: 6 sec.
(with max. 1000 cc/min. flow rate)
Drift (without autocalibration)Zero: max. ± 1% of span per week
Span: max ± 1% of span per week
Ambient Temp. Influence± 0.05% O2 per °C
Atm. Pressure Influence± 0.1 ÷ 0.18 % of reading per hPa
Flow Rate Influence< 0.5% of span over flow variation from 250 to 2000 cc/min.
Line Voltage Influencemax. 0.02% of span, for each 1% change of power voltage.
Gas InterferenceDepending of gas. Typically less than 2% of span
Sample RequirementsFlow Rate: 250 ÷ 2000 cc/min.
Pressure: min. 3000 Pa (with filter & flow meter).
Outputnon-normalized output current that functions as input of the selected ADEV control unit
Relative Humidity90% maximum.
Operation Temperature-10 ÷ +50°C (14 to 122 °F).
Temperature controlledat 65°C (or higher depending on the application)
Storage Temperature+70°C (158 °F) max.
Power Requirements24 ÷ 30 Vdc, 45 VA from dedicated power supplier.
Pneumatic Connections¼” or 6 mm OD tubing (compression fittings)
Wiring Connections2 openings for GK 1/2" (cable grip or conduit).


Heat treatments (furnace atmosphere, carburizing, nitriding)

Iron and steel industry

Blast furnaces and combustion processes

Sulphur Production

Biogas & Landfill Gas

Gas production industry (gas purity)

Copper melting furnaces

Water measurement in high concentration and at high temperature

ETO sterilizing processes

In general, selective measurement of any gas with infrared absorption spectrum


Sampling System

The 8869 needs an external sampling system able to deliver an almost clean sample gas to the analyser at the proper temperature, pressure and flow rate.

ADEV has a wide experience in process and can provide the 8863 analyser combined with a sample and condition system designed for the specific application requirements. Contact ADEV for details.

Measuring Principle

The heart of the model 8869 Infrared Analyser is the cell assembly, which consists of:

  • 2 helically-wound Nichrome wires which provide the I.R. source
  • 1 temperature-controlled sample cell in which the sample circulates
  • 1 detector assembly with: one measuring detector with an interference filter focused on the selected IR absorption band for the gas to be analysed; and one reference detector with an interference filter with a band able to compensate ageing effects, dirty built-up on the optical path and background gas variations.

A very particular innovative technique allows a perfect system balance that eliminates drifts and the automatic restore of the sensitivity by controlling the energy that reaches the detector.

 This design can be expanded up to 3 gas variables.