patent application relates to a demand valve, or regulator, used in underwater breathing apparatus. US4411285 (published 25 October 1983): Demand valve. This American patent relates to a demand valve, or regulator, used in underwater breathing apparatus described in British patent application GB2075848. See also References External links Double-hose regulators - Submarine SEA LION by Submarine Products Ltd. Hexham remembered - Submarine Products Subskimmer Diving equipment manufacturers Defunct manufacturing companies of the United Kingdom Companies based in Northumberland Manufacturing companies established in 1959 Manufacturing companies disestablished in 1990 1959 establishments in England 1990 disestablishments in England Defunct companies of England British companies established in 1959 Hexham British companies disestablished in 1990 Underwater diving in the United Kingdom