| 摘要 |
<p>A first stage scuba regulator operates to supply breathable air at a pressure of say, about 125 psi above ambient to a second stage demand regulator. The first stage regulator includes a piston subjected on one side to ambient pressure, and on the other to downstream air pressure, and so arranged as to open when the ambient pressure overpowers downstream pressure by a preset amount determined by a bias spring and to close when downstream pressure rises to the present amount. Instead of directly conducting outside water to the first side of the piston, an inert barrier fluid of high molecular weight is used that fills the piston chamber. Low temperature silicone grease is the preferred material. The barrier fluid is retained by a porous closure that offers very limited restriction to the flow of water, but significantly greater resistance to the flow of the barrier fluid. The mechanism is protected from malfunction due to icing and is isolated from sand, silt, coral and other particulate matter having deleterious effects upon rubber seals and other parts of the mechanism.</p> |
