Providing Products and Technology for a Better Environment
Providing Products and Technology for a Better Environment

Readings Archives - LANDTEC North America

Q: Readings – How do temperature extremes affect my readings and instrument? What can I do to work in extreme temperatures?

A: Above 104°F (40°C) or below freezing, 32°F (0°C), your readings may be incorrect, or the instrument may otherwise malfunction. In extreme heat, the GEM-2000 screen goes black. If you are working in sub-freezing temperatures, you can use a hand warmer to keep the instrument warm. You might also keep the instrument inside your coat. In extreme heat, try to keep the instrument out of the direct sun. If its readings become erratic or the screen goes black, bring it into a cooler environment, such as your air-conditioned truck.

Q: Readings – What is a “cross-gas” effect?

A: Some gas sensors are sensitive to more than one type of gas. Methane sensors, for example, measure hydro-carbon bonds, which are present in all hydrocarbons, such as Ethane, Propane, Butane and others. So, if these other gases are present, your GEM will read them as Methane, and therefore report more Methane than is actually present. Because landfills are known to contain large amounts of Methane, and don’t normally contain these other hydrocarbons, this cross-gas contamination is not usually a problem. The Oxygen and Carbon Dioxide sensors in the GEM instruments are relatively free of cross-gas effects. The H2S and CO sensors in the gas pods and the GEM™2000 Plus do show some cross-gas effects. The GEM™2000/GEM™2000 Plus manual has a cross-sensitivity table for these sensors.

Q: Readings – Why is my methane reading so high?

A: You probably have other hydrocarbons in your gas. The methane detector is sensitive to all hydrocarbons, so the presence of ethane, propane, butane and others in your gas stream will cause your methane reading to be too high. LANDTEC sells “Charcoal Absorber Filters (1-00000-5084)”, which will reduce the contamination from non-methane hydrocarbons. For more information, see section on “Cross Gas Effects” of the GEM™2000 Manual