[Principal investigator Dr. Luke] Roberson explained that, from time to time, during the Space Shuttle Program tracking down the precise location of a hydrogen leak was a difficult challenge. Liquid hydrogen is a lightweight and extremely powerful rocket propellant used extensively by NASA. Its characteristics also make it highly flammable and explosive, requiring close attention to avoid leaks…NASA enlisted the assistance of University of Central Florida in developing a pigment that would change color when exposed to hydrogen. Chemochromic materials respond to the exposure to different chemicals with a change in color due to a chemical reaction within the substance.
“After two years of research, the team at UCF came up with a pigment that could be added to a silicon caulk,” Roberson said. “While it worked well, the caulk eventually dried out. We were then successful in adding the pigment to an air-tight Teflon tape.”
The end result was the development of the innovative “Color Changing Materials for Hydrogen Detection…One of the first applications took place as the space shuttle Endeavour was being prepared for the STS-118 mission in the summer of 2007.
“There was a hydrogen leak on the OMBUU and Launch Pad 39A,” said Roberson. “It proved to be elusive and we thought the tape could help.” The OMBUU was the Orbiter Midbody Umbilical Unit, a horizontal access arm for servicing the mid-fuselage portion of the space shuttle at the launch pad. It was used for loading liquid hydrogen and liquid oxygen into the spacecraft’s fuel cells.
“Sensors were successful in identifying that there was a leak,” Roberson said. “The tape helped pinpoint the exact location.”The tape works by changing color from beige to high-contrast black in less than three minutes when concentrations as low as 0.1 percent are detected. This is well before reaching the explosive combustion threshold of about four percent. The pigment is completely passive requiring no power and is highly resistive to environmental factors including ultraviolet exposure, salt spray and humidity.
The article points out the potential uses for the chemical manufacturing and oil and gas industries. Nice to see more spinoffs from the Shuttle program.