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Looking for CO, O2, SO2 and NOx. sensors
I'm looking for sensors for continuos gas analysis in a boiler stack...
By W Blandon on 14 June, 2003 - 11:58 am

I'm looking for sensors for continuos gas analysis in a boiler stack.
This sensors should have an standard electrical output (0-10V 4..20mA, etc) in order to be incorporated in a control system.
Any one of you can help me to find a supplier of this kind of sensors with the characteristics mentioned above?

By Anonymous on 17 June, 2003 - 10:42 pm

talk to your ABB agent. They have the Hartmann & Braun range of gas analysers.


By Pugazhendi Ramalingam on 18 June, 2003 - 1:05 pm

Individual instruments are there for analysing the quantum of CO, O2, etc. available in the flue gas going through the stack. Zirconia cell concept by using the reference %O2 available in the atmospheric will tell us the excess O2 flowing through the flue gas. Infra-red rays will be absorbed at particular wavelength by the CO and SO2. Like the fingerprints of human being, the absorption of wave length of IR will vary from one gas to another. This concept will tell us the SO2 and CO quantum available in the flue gas passing through the stack. Chemiluminiscent theory is used in NOx sensors for continuos gas analysis in a boiler stack. M/s. Emerson, M/s. Forbes Marshall are having these instruments which will directly give you 4-20 mA siganl. One more signal you had missed is the particulate emission going along with flue gas. Opacity monitor working on light reflection principle will present us the % of light missed because of the particulate passing through the light path of the stack. If we want the weight of particulate emitted, then the instrument has to be calibrated by comparing the % of opacity and the weight of sample drawn by extraction technique.

With regards,
Pugazhendi R.
pugazhabi @

By K.Senthilkumar SM/C&I/IPP on 19 June, 2003 - 12:29 am

There are lot of suppliers available for this product worlwide.
Some of them are
Environment USA
Amitek USA
HIMA Germany
Thermo environment France.

Please check up in your country for local agencies.


For Canada, I would certainly try this company.

By Randy Hauer on 19 June, 2003 - 1:55 pm

This is Ametek Process instruments responding.

We manufacture UV based analyzers and can measure very low values for SO2 (10 ppm min full scale range)and NOx (0-15 ppm min full scale range)

The UV analyzers are available as cold / dry analyzers for incorporation into a rack mopunteed CEM or as a "hot / wet" analyzer (heated oven)

Either version can be fitted with a O2 analyzer sensor (zirconia or paramag type).

For CO analysis you need an IR type analyzer and we have a IR analyzer that can be ganged with the cold / dry "rack mount" system.

Please refer to our web site ( or call me at 302-456-4430 (direct line).

Thx & regards,

Randy Hauer
Ametek Process Instruments

By Anonymous on 19 June, 2003 - 10:24 pm

You could try CEM Specialties. They not only have the equipment but also can do a complete system.

By Philippe LILLE-PALETTE on 22 June, 2003 - 7:26 pm


I do not know all the manufacturers of this kinf of sensors. But many of my customers do use SIEMENS gaz analyzers. The range includes ULTRAMAT, CALOMAT, FIDAMAT and OXYMAT analyzers. For some of them a big advantage is that you can do your calibration with ambient air. Depending on your working conditions it may be helpful not to have to handle heavy gaz bottles to calibrate your sensor.
Further information on :

Good luck in your research.



Did you get what you need?

my recommendation is please go for zirconium type online o2 analyser ... for sx/nox/co please go with insitu probe type analyser which is having more advantages compare to hot /dilution type extractive analysers .. which is having more maintenance and high power consumption... required AC room... many components which required to maintain spare ... use insitu p[rope type CEM which is the ideal solution..

please also note there are two type insitu analyser cross duct and probe type.. please go with insitue probe type..

please let us know the dia meter of ur stack ?..

we are using FORBES MARSHALL CODEL insitu analyser and which is working fine for last 4 years .. you can contact them for further details..