73275509
Aug 25, 1980
Aug 10, 1982
Communications System Especially Suited for Hazardous Environments and Offshore Drilling Rigs, Comprising a Cabinet Housing an Alarm Network, Telephone Interface and Power Supply, and Speaker Amplifier in Communication with a Plurality of Remote Weatherproof Hand Set Stations and Loudspeakers Even Under Line Fault Conditions
Electrical and Scientific Apparatus