#156 - Nova Analyzers from the Field – Episode 2

We noticed this portable Nova analyzer on the equipment list of a metallurgical lab at the University of Laval in Quebec, Canada. It looks like this facility within the university is focused on aluminum production research.

The analyzer model is probably Nova 335L. The Model 335 analyzers usually use thermal conductivity technology to measure hydrogen in a binary gas mixture such as H2 in air or H2 in nitrogen. However, the 335L signifies ‘low range’ and refers to trace H2 measurement at ppm levels. The description on the University’s list indicates that the range of this particular unit is 0-2000ppm H2.

Nova’s low range H2 instruments use an electrochemical type sensor instead of a thermal-conductivity detector. A thermal-conductivity based analyzer does not have the sensitivity to measure gases in the ppm range. This is makes sense; we wouldn't expect a few ppm of a constituent gas to significantly change the overall thermal-conductivity of a gas mixture.

We can assume that the typical gas sample at Laval’s aluminum lab contains little or no O2. How do we know this?

From the photo, you will note that this analyzer has two flow meters and an air flow control adjustment on the front panel. One characteristic of many electrochemical sensors is that they require the presence of a small amount of oxygen to function properly. If a gas sample does not have at least a small amount of O2 in it, the signal output of the cell will begin to taper off as the diffusion layer at the sensor inlet is depleted of residual O2. To maintain a good electrochemical response to the target gas, a small amount of O2 needs to be metered in also. The flow control and the second flow meter are used for this purpose.

The Model 335L doesn’t appear to be visible on the Nova website. So if you have a requirement for analysis of ppm H2, contact us with your inquiry. We can help determine if the Nova Model 335L is suitable for your application.

Episode 1 - old portable flue gas with dual CO channel

For information on Nova gas analyzer systems, give Mike or Dave at Nova a call, or send us an e-mail.

1-800-295-3771

sales at nova-gas dot com

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http://www.nova-gas.com/

https://twitter.com/NOVAGAS

http://www.linkedin.com/company/nova-analytical-systems-inc-

http://www.tenovagroup.com/

University of Laval website:

http://www2.ulaval.ca/en/home.html

Industrial Research Chair NSERC/Alcoa on Advanced Modeling of Electrolytic Cells and Energy Efficiency (MACE3)

http://www2.ulaval.ca/en/research/research-groups-and-chairs/research-and-innovation-chairs/industrial-research-chairs.html

Equipment List

http://mace3.fsg.ulaval.ca/en/recherche/equipements/

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