Development of A New Portable Rescue Tool Using Metal Hydride Alloys

This paper addresses the development of a new rescue tool for saving survivors buried in the debris of a collapsed building caused by a large-scale natural disaster. Because access to the public energy supplies as well as the seriously stricken area are frequently cut off just after the occurrence of a large natural disaster, a new rescue tool powered by metal hydride (MH) is being proposed. The tool achieves a large lifting force solely utilizing thermal energy; in addition, it is effective for confined space entry and rescues without the need for electricity or fuel. The lifting tool that was designed and experimentally produced was comprised a robust telescopic cylinder having 50 mm of lifting stroke and 6500 N of lifting output force per 0.1 MPa of internal pressure, an airtight MH container, and a portable heat source employing calcium oxide. The composition of MH as the pressure source was LaNi4.3Co0.5Mn0.2, which slightly desorbed hydrogen at 40°C and possessed 0.2–0.3 MPa of equilibrium pressure at 80°C. The MH source was enclosed within a solidly constructed airtight container that heated the MH via a heat source in contact with the bottom surface of the container. When the MH was heated using 200 and 300 g of calcium oxide; the MH temperatures in both the cases reached in excess of 70°C after 48 seconds. This reaction created a lifting force of 10000 N in the telescopic cylinder for hydrogen pressures of 0.17 MPa. The 300 g of calcium oxide reaction created MH temperatures in excess of 75°C and allowed for constant hydrogen desorption for over five minutes from the start of heating. It is estimated that the lifting tool utilizing this mechanism, MH compositions, and a higher equilibrium pressure at 75°C will provide a higher output force. In addition, a lifting tool where the initiation of hydrogen desorption occurs at lower temperatures will provide a faster response time for the lifting operation.