NASA Moisture Analyzer Technology Delivers Readings That Are Laser Fast and Accurate

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Advanced natural gas analyzers use “tunable diode laser” technology developed by NASA’s Jet Propulsion Laboratory to quickly and accurately report moisture content in natural gas before it enters the pipeline.

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We were able to put the TDL sensor to valuable commercial use when we formed SpectraSensors as a spin off of JPL

The U.S. Space Program has delivered dozens of breakthroughs in materials, microelectronics, navigation and other technologies that have dramatically advanced science and industry today. One of those breakthroughs, using the “tunable” diode laser for gas detection is now enabling natural gas producers and pipeline operators to get precision moisture analyzer measurements in their product so quickly and easily that it is completely revolutionizing the world of the moisture gas analyzer.

A tunable diode laser (TDL) is a type of semiconductor-based laser that can be tuned to a very specific wavelength (or color) of light. NASA’s Jet Propulsion Laboratory (JPL) developed long wave length (near infrared) tunable lasers and processor controls that enable users to precisely “target” specific molecules and detect small traces of gas. In the space program, this technology was vital to research and operations in the Space Station and Mars Polar Lander programs as well as studies on global warming, emissions, weather and climates throughout our world.

“We were able to put the TDL sensor to valuable commercial use when we formed SpectraSensors as a spin off of JPL,” explains Greg Sanger, Vice President of Engineering at SpectraSensors (San Dimas, CA). “That enabled us to offer a highly accurate moisture analyzer that requires virtually no maintenance. Natural gas producers and pipeline operators love it because it can help them generate more revenue by making sure that wet gas does not get into the line. Also, natural gas contains H2S (hydrogen sulfide), which becomes sulfuric acid when mixed with water, and pipeline operators certainly don’t want that wreaking havoc on their system.”

In addition to accuracy, though, the TDL-based moisture analyzer offered by SpectraSensors can lower maintenance efforts and costs that are common to conventional gas sensors. If such maintenance is overlooked, these sensors eventually produce erratic measurements that can end up costing producers and pipeline operators a bundle.

Conventional surface-based (electrochemical or quartz crystal) sensors start out accurate, but due to direct exposure to corrosive contaminants within natural gas, the probes become coated and clog up, and thereafter provide false or erratic readings. Inaccurate readings result in wet gas, unnecessary dehydration costs and preventable shut-ins -- with single incidents costing tens or even hundreds of thousands of dollars. Studies show the cost of operating and maintaining “conventional” electrochemical sensors carry a cumulative annual expense often exceeding $5,000 per unit, including labor, recalibration and rebuilding, back-up sensor heads as well as unnecessary gas dehydration and tariffs.

Conversely, the TDL-based moisture analyzers help ensure that moisture and other contaminants are under tariff, that exorbitant shut-ins will not occur, and that expensive probe maintenance and replacements are eliminated. Using ultra-precise laser spectroscopy, these analyzers perform measurements in a “sample cell.” Because they are not exposed to corrosive contaminants, these analyzers perform within two per cent accuracy over very long periods, thereby maximizing dependability and minimizing cost of ownership.

The laser-based gas moisture analyzer provides a reliable measurement that will not drift, and can be used in a closed loop to control the blending of dry and wet gas, allowing the producer or pipeline operator to optimized costs by staying within the tariff. Also, with the TDL-based gas analyzers there are no wet-up or dry-down delays. Moisture problems are detected with extremely high accuracy and measurement intervals as frequent as within a second, enabling practically instantaneous response, and thereby eliminating the chance that wet gas will get through between reading times.

For information contact:

Samuel C. Miller, PE; Product Line Manager, SpectraSensors, Inc., 972 N. Amelia Avenue,

San Dimas, CA 91773; Phone: (800) 619-2861; Fax: (909) 542-0402 or visit the web site:


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