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Tuesday, July 5, 2011

#13 - Subsurface Fire Detection in Landfills, and other fire-related gas analyzer applications

Over the years we have run across a few fire-related gas analysis applications. Following are a few that come to mind.

Fire Suppression

People who research fire suppression systems are frequently interested in carbon dioxide (CO2) analysis. They may be using CO2 to blanket an area to stifle a fire. Or they may be burning something in a controlled environment and want to observe the effects.

Different concentrations of gas may stratify in enclosed areas. So in the past we have produced CO2 analyzers with three entirely separate CO2 channels. This allows the users to get a picture of what levels of CO2 are developing at different elevations in the space. For this application, we have typically used our Model 302 Portable CO2 Analyzer and modified it to essentially result in a 3-in-1 analyzer. (This is a link to the standard, un-modified version of Model 302.)

Fire Detection – Coal Mines

“Where there’s smoke, there’s fire.”

Besides being rather hot and bright, fires have other characteristics. The old saying above points out another obvious sign of fire. But sometimes you can’t see or feel the fire and smoke. You have to exploit other means to detect a fire.

I was reading a while back about subsurface coal mine fires. This is a global problem that can render a region unsafe for human habitation. It’s also an environmental problem.

We were pleased to have these cool guys give us a call and express interest in a portable gas analyzer. I think they were/are doing research on gas permeation through coal masses in the context of coal mine fires. The requirement was for portable % oxygen, ppm carbon monoxide, & ppm carbon dioxide analysis. We built a modified version of our Model 375K analyzer for them.|1004|1096

Fire Detection – Landfills

Fires can start under the ground in landfills due to the fuel available in the form of garbage and flammable gases. All that is required is heat/ignition source and oxygen. The biological decomposition process can supply the necessary heat, which may lead to ignition. Ingress of oxgen via leaks in the landfill cover or associated systems will facilitate combustion.

From the USA, California's Department of Resources Recycling and Recovery (CalRecycle) has a decent discussion of landfill fires here:

Because they are way out of sight, subsurface landfill fires are sometimes hard to detect. The only way to detect them is by their ‘tail-pipe’ effects. One of the signature combustion gases is carbon monoxide (CO). By analyzing the landfill gas for low levels of CO, subsurface fires can be detected. The CalRecycle link above also cites some other helpful fire indicators.

Some landfill operators test for CO using a handheld flue gas analyser. The problem with this approach is that it is only a brief on-the-spot check. Landfill gas can also contain aggressive constituents that can interfere with or degrade the sensors in a traditional portable flue gas analyzer.

So we have recently added a CO option to our 910 Series Continuous Landfill Analyzers. It’s not yet on the website, but we can quote you on adding a 0-2.0% CO channel to the analyzer. The analysis is by infrared detector and is not as sensitive to fouling and interference by landfill gas as are many electrochemical flue gas sensors. This new option will give you continuous around-the-clock subsurface fire detection. The CO reading can be tied into an alarm, for prompt warning.

Oxygen ingress will feed a fire. Oxygen analysis is valuable for discovering a leak in the landfill collection system. Most models in the 910 Series have oxygen analysis built in.

We make gas analyzers for oxygen, hydrogen, carbon monoxide, carbon dioxide, methane, and many other atmospheric gases. We provide gas analysers for syngas, landfill gas, purity gas, biogas, and others.

Give Mike or Dave at Nova a call, or send us an e-mail.
sales at nova-gas dot com
websales at nova-gas dot com

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