Ocean Engineering Studies Compiled 1991. Volume 11. Pressure-Resistant - Glass Light Enclosures.

摘要

Manned and unmanned diving systems require underwater lights for illumination to illuminate search and work areas. Electric light bulbs can neither tolerate the temperature shock resulting from immersion in cold water nor the pressure exerted by water at operational depth. They must be protected by transparent enclosures capable of withstanding the sudden immersion in cold water and long-term compression by external hydrostatic pressure. Low thermal conductivity of plastics, impedes heat dissipation from the interior of the plastic enclosure to the water. Only enclosures fabricated from borosilicate or pure silica glass with very low temperature expansion coefficient can satisfy operational requirements. The low coefficient of thermal expansion, coupled with high heat transfer capability, allows enclosures from this group of glasses to operate successfully with a very high temperature differential across the wall thickness. These glasses also possess compressive strength exceeding 200,000 psi. This property allows such enclosures to be constructed with very thin walls, thus further improving the heat transfer from the inside of these enclosures to the cold water outside. Testing involved establishing the critical pressure and cyclic fatigue life of glass enclosures due to (1) the effect of enclosure shape, (2) type of bulkhead, (3) the configuration of mating surfaces, and (4) gasket material used. Three types of glass enclosures were investigated: cylindrical domes with conical flanges, pipes with conical flanges, and tubes without flanges.