NASA Technical Reports Server NTRS 20150023595: Color Changing Hydrogen SensorsReport as inadecuate



 NASA Technical Reports Server NTRS 20150023595: Color Changing Hydrogen Sensors


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During the Space Shuttle Program, one of the most hazardous operation that occurred was the loading of liquid hydrogen LH2 during fueling operations of the spacecraft. Due to hydrogens low explosive limit, any amount leaked could lead to catastrophic event. Hydrogens chemical properties make it ideal as a rocket fuel; however, the fuel is deemed unsafe for most commercial use because of the inability to easily detect the gas leaking. The increased use of hydrogen over traditional fossil fuels would reduce greenhouse gases and Americas dependency on foreign oil. Therefore a technology that would improve safety at NASA and in the commercial sector while creating a new economic sector would have a huge impact to NASAs mission. The Chemochromic Detector for sensing hydrogen gas leakage is a color-changing detector that is useful in any application where it is important to know not only the presence but also the location of the hydrogen gas leak. This technology utilizes a chemochromicpigment and polymer matrix that can be molded or spun into rigid or pliable shapes useable in variable temperature environments including atmospheres of inert gas, hydrogen gas, or mixtures of gases. A change in color of the detector material indicates where gaseous hydrogen leaks are occurring. The irreversible sensor has a dramatic color change from beige to dark grey and remains dark grey after exposure. A reversible pigment changes from white to blue in the presence of hydrogen and reverts back to white in the presence of oxygen. Both versions of the sensors pigments were comprised of a mixture of a metal oxide substrate and a hydro-chromic compound i.e., the compound that changed color in the presence of hydrogen and immediately notified the operator of the presence of low levels of hydrogen. The detector can be used in a variety of formats including paint, tape, caulking, injection molded parts, textiles and fabrics, composites, and films. This technology brings numerous benefits over the traditional hydrogen sensors: The technology has excellent temperature stability 4K to 373 K, it can be used in cryogenic fluid applications, it is easy to apply and remove; it requires no power to operate; it has a quick response time; the leak points can be detected visually or electronically; it is nonhazardous, thus environmentally friendly; it can be reversible or irreversible; it does not require on-site monitoring; has a long shelf life; the detector is very durable; and the technology is inexpensive to manufacture.



Author: NASA Technical Reports Server (NTRS)

Source: https://archive.org/







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