Abstract: Overlapping lenses for use in a light fixture provided to project a beam of light in a first beam shape having a first cross-sectional geometry. A first lens device is supported in the fixture and movable into a position to interrupt the beam of light for selecting beam shape by altering the first projected beam shape from the first cross-sectional geometry to a second cross-sectional geometry different from the first geometry. The first lens device includes at least one lenticular lens element having lenticules oriented in a first direction. A second lens device, separate from the first device, is supported in the fixture and movable into a position to interrupt the beam of light for selecting beam shape by altering the second projected beam shape from the second cross-sectional geometry to a third cross-sectional geometry different from the first and second geometries.

Abstract: In an automated process for deaerating and purifying both the water which is recirculated in a coolant loop through a stack of fuel cells and the make-up water for the coolant loop, a portion of the water from the coolant loop is blown down into a deaerator water reservoir to which make-up water is added by condensing water from the fuel cell stack reactant gas streams into a deaeration column disposed above the reservoir. The blowdown provides some of the heat for deaeration; and the amount of blowdown is controlled as a function of the amount of make-up water added to the coolant loop by sensing the location of a steam/liquid interface within the deaeration column. Water is withdrawn from the reservoir, purified, and then introduced into the coolant loop at a rate sufficient to maintain the desired amount of water circulating in the coolant loop.