When using any infrared technology for gas measurement other gases with a similar wavelength can show an increased CH4 value.  For CH4, this can be seen in the presence of VOCs (volatile organic compounds). These gases are long chain hydrocarbons, which like methane are made up of a combination of carbon and hydrogen atoms.  This has a positive cross gas effect, meaning that any influence from VOCs will be in addition to the CH4 composition of the gas mixture.

If VOCs are known to be present, or higher than expected values of CH4 are recorded, the use of an H2S / VOC filter for a second measurement will remove the majority of hydrocarbons other than Methane, providing more accurate results.

Geotech’s portable and fixed biogas monitors give worldwide reliability

Regardless of where in the world they are, from a biogas purification project with chicken manure in China to a waste water monitoring requirement in Europe, Geotech’s customers all have a common need for reliability and accuracy in the analysers measuring the quality of biogas. Geotech now has almost 70 trained distributors working in as…
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Redvale Energy Park pleased with GA3000 PLUS

Application Continuous inline monitoring of incoming landfill gas Customer Redvale Energy Park Requirement The customer needed to monitor continuously for any changes in the gas composition, as they are running gas engines to generate power. The GA3000 PLUS is being used to monitor CH4, CO2 and O2 and ensure the gas composition and levels remain…
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An analyser is only as accurate at the moment of calibration. Following this point infrared benches can drift over time. However alongside ensuring regular servicing, we recommend you perform regular user calibrations and checks. By using span gases similar in composition to your typical CH4 values, the accuracy of the CH4 channel can not only be maintained, but can be improved for your specific application. Always ensure that your analyser is purged with fresh air between readings and at the end of the day’s readings to ensure no residual gas remains in the analyser.

Other gases


Methane is 20 times more of a potent greenhouse gas than CO2. The anaerobic process has been replicated artificially in the form of anaerobic digesters to produce cleaner energy to power houses and even cars. Through monitoring with a Geotech analyser you can optimise your process to ensure you make the most from your plant as well ensuring that your engines aren’t damaged if CH4 drops below optimal levels.

Carbon Dioxide

Carbon dioxide is critical to maintain at a constant level during IVF and cell culture growths. It’s also a bi-product of respiration and in confined spaces these levels can increase. Careful analysis of CO2 within an IVF chamber using a Geotech analyser can ensure that embryos develop correctly. The detection of CO2 in confined spaces e.g. a lorry can be indicative of a stowaway.


Oxygen is required in the combustion process where CH4 is burnt to produce heat and energy but too much can cause damage to the engine. Pinking occurs when too much oxygen is present in the engine during combustion. Continuous analysis with a Geotech analyser allows you to set alarms when thresholds of O2 are passed which in turn can close down the engine saving expensive damage and increased downtime.

Carbon Monoxide

Carbon Monoxide is produced during incomplete combustion, this occurs when there is limited levels of oxygen and increased Carbon Dioxide. Levels of 90ppm or greater can be indicative of underground fires on a landfill site. Geotech offers unique technology to gain accurate results about the health of your landfill site and to ensure the safety as well as value of the cell is retained.

Hydrogen Sulphide

Hydrogen sulphide is particularly harmful when biogas is used in internal combustion engines. Its chemical reactions and those of its combustion product - sulphur dioxide - lead to corrosion and wear on engines. Through careful monitoring of this using a Geotech analyser you can ensure the health of your engine and save costs through engine downtime or increased servicing.


Electrochemical sensors are used industry wide, they are micro fuel cells designed to provide an accurate, stable and low cost measurement technique that can be easily maintained in a portable analyser.


Ammonia is one of the digestion products in anaerobic digestion. If nitrogen-rich feedstocks are used, inhibition by ammonia is often the reason for a process imbalance. Therefore, monitoring NH3 concentrations in the digester helps to estimate if ammonia inhibition is causing the process imbalance.

Nitrous Oxide

Nitrous oxide is widely used in hospitals as a general anesthetic. It’s important that concentrations are accurately measured and also leaks and exposure levels are monitored closely, as long term and repeated exposure can be harmful to human health.