July 2005

"Smart Paints" Will Help NASA Detect Hydrogen Leaks

Because hydrogen is such a light gas, it can readily leak out from a storage tank, in transport or during use, posing potential safety problems. Monitoring hydrogen storage and usage sites for leakage is thus a crucial step in a safe operation plan.

Nahid Mohajeri
Nahid Mohajeri
(Photo: Nick Waters)

FSEC researchers undertook investigations into hydrogen safety to assist NASA in readily discerning the presence of hydrogen leaks as part of the work currently conducted in the Hydrogen Research at Florida Universities project. Working on this research are Drs. Gary Bokerman, Nahid Mohajeri, Nazim Muradov and Ali T-Raissi.

NASA currently uses point-of-use electronic sensors to detect hydrogen leaks in transfer lines and storage sites, but there are definite drawbacks to using these sensors. Their use is time-consuming and highly laborious because of the large surface area that must be monitored. The sensors may also be impacted by environmental factors such as wind, causing a loss of sensitivity. NASA's need to find more effective ways to detect hydrogen leaks resulted in the work on hydrogen leak detection at FSEC.

The primary objective of the research is to develop "smart" materials that readily reveal, visually, the location of hydrogen leaks from hydrogen pipes, flange joints or ports, etc. The "smart paint" developed by FSEC for NASA-KSC applications is a special powder that can be painted onto the surface to detect the location of minute hydrogen leaks. Unlike natural gas that can be easily detected by its odor, hydrogen is odorless and invisible. Operations at KSC require the use of extremely pure hydrogen, so no additives to the gas are permitted. The FSEC technique provides a visual method to detect and locate possible hydrogen leaks in the field lines when hydrogen is transported for use.

FSEC researchers have identified special metal oxide-based powders that can be synthesized inexpensively and applied like paint or deposited onto tapes that can be adhered to the pipe and flange joints.

Nahid Mohajeri
Smart paints change color if hydrogen leaks.
(Photo: Nick Waters)

One formulation is based on white color titania-supported precious-metal oxide powder that turns a dark color upon contact with hydrogen gas. The color change is very distinct and easily discernable by the naked eye. Another version uses a different formulation that changes color when exposed to hydrogen and then reverts back to its original color when contact with hydrogen ceases (such as when the leak is fixed). One advantage to this reversible hydrogen-detecting powder is that re-application of the material is not needed after a leak has been detected and eliminated. The material will indicate a leak if it recurs.

Scientists and engineers at NASA-KSC have been trained to prepare these formulations and presently are evaluating them for possible fielding at KSC and other NASA facilities. FSEC has a patent pending with the U.S. Patent and Trademark Office for aerospace and other applications of these functional materials ("Smart Paints").

Although the "smart paints" developed at FSEC are especially formulated for the KSC and aerospace applications, there will be many other uses for these materials. They can be used in oil refineries, semiconductor manufacturing plants, ammonia and fertilizer plants and in other industries that produce, transport or use hydrogen. As the Hydrogen Economy emerges, we may well see "smart paints" used at fueling stations, at hydrogen storage sites, and for uses yet to be developed, ensuring the safe handling and storage of both gaseous and liquid hydrogen.