US Patent 7501283 Fluid dispensing apparatus

A fluid dispensing apparatus includes a mounting assembly having a plurality of mounting apertures and a plurality of fluid dispensing cartridges positioned within the mounting apertures. The mounting apertures and cartridges include matching cross-sectional profiles that lack symmetry. Each fluid dispensing cartridge includes a fluid reservoir, at least one valve, a metering chamber and a piston. The apparatus also includes a magnetic switch assembly controlling the movement of the piston and a means for damping the movement of the piston.