Abstract: An intrinsically safe supply for supplying back-up power during a power-out event incorporates one or more rechargeable fuel cells. The power supply is provided with switching circuitry operable to provide an output back-up current from the fuel cells upon a power-out event. The fuel cells are housed within a sealed metal housing immersed within an electricity insulating potting material chosen to arrest spark formation and/or electrically insulate any created sparks. The fuel cells comprise sealed lithium iron based fuel cells for supplying back-up electrical current. A charging circuit electrically connects the fuel cells with an external power source for providing a charging current during normal power-on conditions.

Abstract: A mechanical seal assembly for creating a sealing relationship between a housing and a shaft which is rotatable relative thereto. The seal assembly includes first and second coaxially aligned and axially adjacent seal rings disposed in an encircling relationship to the shaft and having axially adjacent and opposed flat seal faces for creating an annular sealing region therebetween. The seal assembly further includes a self-contained grease supply device for supplying a continuous flow of grease to a seal chamber at a substantially steady or uniform flow rate and a grease discharge device for pressurizing the grease and permitting a flow of excess grease therethrough. The pressurized grease is positioned adjacent the seal rings to provide a self-regulating supply of grease which is drawn into the sealing region during upset conditions of the seal.