ABSTRACT
Carbon is often used for pump and motor elements other than bearings and seals. Carbon should be considered for sliding elements wherever the fluid that is being pumped is a poor lubricant. The most common examples are air pumps or blowers. Small amounts of oil mist are particularly damaging to carbon vane pumps and air motors. Carbon has interatomic bonding energies so high that grain growth or migration of crystal defects is virtually impossible to obtain. Carbon vanes in air pumps are subjected to repeated high loads as the vanes flop from side to side in the rotor slot and move in and out radially. Scratches along the vane flank, together with chips along the edges of vanes, are difficult to avoid during manufacture. Carbon vane pumps have many advantages for pumping compressible fluids, but their design, manufacture, and use requires painstaking attention to details.
