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Zero and Span Gas Guidelines

Zero and Span Gas Guidelines

LI-COR technical support often receives questions about choosing a set of CO2 calibration gases for our analyzers.   While we realize that every customer’s measurement situation may be slightly different, we do have a few suggestions for selecting a set of calibration gases.

We recommend having a zero gas, or the equipment to perform a chemical zero at the very least.  A zero gas is best if the gas is really CO2-free.   It’s not necessary to purchase pure nitrogen or argon…

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How to Routinely Check an Eddy Covariance System to Ensure Normal Operation

How to Routinely Check an Eddy Covariance System to Ensure Normal Operation

Most eddy covariance (EC) systems are deployed in remote areas and exposed to harsh environmental conditions. During years-to-decades of continuous operation, potential issues related to contamination, power, animal damage, lightning, and other natural events such as fog and precipitation can arise. Aging of the hardware and out-of-date software could also become issues. In order to minimize data loss, routinely checking your EC system should be part of your maintenance plan. Considering time consumption and effectiveness, here are our recommendations:

  1. Check…

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Control Over Drought

Control Over Drought

Water is one of the most precious natural resources—and one that we often take for granted. But droughts are common and they’ve proven time and time again that we don’t know enough about the water cycle. That is why the Chinese Ecosystem Research Network (CERN) selected LI-COR eddy covariance systems to measure evapotranspiration across the country. Recently the Water and Waste Digest interviewed Dave Johnson, Senior Product Manager, to learn more about how the Chinese Ecosystem Research Network is using evapotranspiration to…

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Temporary Fix for a Bad IR Source

Temporary Fix for a Bad IR Source

The infrared (IR) source for the LI-8xx series analyzers has an operational life of better than 20,000 hours, or about two years of continuous use. The IR source is essentially an incandescent light bulb, and fails as a result of the filament thinning with use as it burns away. Eventually the filament becomes thin enough that it cracks and breaks, at which point the source no longer works.

The permanent fix for a failed source is to replace it with…

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How to set the clock in the LI-7500A or LI-7200 CO2/H2O gas analyzer to local standard time

How to set the clock in the LI-7500A or LI-7200 CO2/H2O gas analyzer to local standard time

The LI-7500A or LI-7200 with the LI-7550 Analyzer Interface Unit is a network-based instrument.  Multiple users can log data from a single instrument over multiple TCP/IP (Transmission Control Protocol/Internet Protocol) connections. Therefore, the LI-7500A and LI-7200 use Coordinated Universal Time (UTC) for their onboard time-keeping tasks. The default time stamp is UTC time, but the LI-7550 clock can be set to any time you desire.

For Eddy Covariance measurements, local standard time is generally recommended because it does not get…

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