Abstract: An electrically-powered, diver-borne air compressor is used with a draw-type snorkel to supply air from above the surface to a swimmer. The use of a non-positive displacement compressor--e.g. a blower--allows a shallowly submerged swimmer to breathe through the apparatus when the motor is turned off, which provides extended battery life. The compressor is selected to provide an adequate volume of air to a diver submerged at the depth limit set by the length of the flexible air conduit leading from the surface to his/her mouthpiece. In the simplest embodiment of the invention, the excess air supplied to a less deeply submerged diver is vented through an exhaust valve. In other embodiments, which offer improved operational efficiency at the cost of greater complexity, this otherwise excess air is stored in a tank. When the tank becomes full the compressor is turned off (either manually or automatically) until the stored air is exhausted.

Abstract: Apparatus is provided for six-phase distribution of high voltage electrical power. The invention provides new six phase distribution wiring, using coaxial conductors, that is configured to reduce fringing electric and magnetic fields when used either as part of an overhead distribution system, or when buried underground.

Abstract: An acoustic sensor and associated electronic circuitry are used to determine when a catastrophic leak (as e.g. may be caused by a sprinkler nozzle being broken off a pipe) occurs in a sprinkling system. When a catastrophic leak is detected, an alarm signal is generated and a shutoff valve may be actuated in order to prevent loss of fluid and possible damage that can occur due to localized high flow of the fluid that is being sprayed. The acoustic sensor responds to a frequency range of acoustic signals that encompasses the generally low frequency signals generated by the relatively unconstrained flow of fluid through a pipe, as well as the higher frequency signals generated by flow of fluid through one or more nozzles. Electronic signal processing means are employed to form a ratio of the acoustic power in two different frequency regions and to generate an alarm signal when flow generates an excess of low frequency acoustic power.