Abstract: 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.

Abstract: A scuba diver uses air not only for breathing, but also to inflate a buoyancy jacket or vest. A single mechanism controls the flow of air for buoyancy and for breathing. The mechanism is held by a mouthpiece and includes (1) a demand regulator, (2) a breathing chamber between the regulator and the mouthpiece, (3) a pruge or one way exhaust valve connected to the breathing chamber, (4) a buoyancy chamber communicating with an inflation/deflation hose for the jacket or vest, (5) a first manual control valve for sending relatively high pressure air to the buoyancy chamber and (6) a second composite manual control valve that in its initial position opens the buoyancy chamber to the breathing chamber for exhaust of air through the purge valve and consequent deflation of the buoyancy jacket or vest, and that in its final position closes the purge valve for oral inflation or emergency breathing.

Abstract: When the regulator is stored, a removable spacer is interposed between the pressure sensing diaphragm and the regulator case in order to position the resilient closure of the demand valve away from its seat. The resilience of the unconfined closure causes it to assume its normal free configuration. A compression set, which would impair sealing capability, is avoided.

Abstract: A power deflator for a buoyancy vest includes a Venturi tube attached to the vest fitting. A mouthpiece control unit has an actuator movable in a path. Initial movement opens a conduit for slow deflection powered by ambient pressure. Continued movement of the actuator sends pressurized air through the Venturi tube for faster deflation of the vest.

Abstract: A scuba diving oil filled depth gauge has a rigid or semi-rigid case that houses operative depth gauge elements. Outside pressure is communicated to the inside oil through a rolling diaphragm made of thin and highly flexible rubber-like material. The expansion and contraction of the oil due to thermal and other effects produces compensation at the rolling diaphragm without the imposition of stresses whereby a true communication of external to internal pressure is accomplished for accurate reading of the gauge.

Abstract: An independent weight system for underwater breathing equipment, the underwater breathing equipment having an air tank and a flotation device attached to a supportive back pack assembly, the weight system having a clamping means securing a weight assembly to the tank whereby the center of gravity of the underwater breathing equipment and attached weight system is below the center of buoyancy of the underwater breathing equipment and weight assembly.