A small solder plug is melted to release a pressurized gas.
The figure depicts the main parts of a prototype miniature, lightweight, one-time- opening valve. Like some other miniature one-time-opening valves reported in previous issues of NASA Tech Briefs, this valve is opened by melting a material that blocks the flow path. This valve is designed to remain closed at some temperature between room temperature and cryogenic temperature until the time of opening.
In a test, the plugged tube was pressurized to 1,000 psi (6.9 MPa) with helium and leak-tested. It was then cooled to a temperature of 77 K (about –196 °C) and again leak-tested at the same pressure. Finally, at a lower pressure, the plugged end of the tube was heated to about 200 °C (the melting temperature of the solder is 183°C), causing the solder plug to be ejected (see figure). It has been estimated that in a subsequent version of the valve, the plug could be melted by electrical heating, using a nichrome wire having a mass of only 10 g.
This work was done by Jack Jones, Juinn Jenq Wu, and Robert Leland of Caltech for NASA’s Jet Propulsion Laboratory.
This Brief includes a Technical Support Package (TSP).
Miniature, Lightweight, One-Time- Opening Valve (reference NPO-42236) is currently available for download from the TSP library.
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