Flexible impeller
A flexible impeller pump is a positive-displacement pump that, by deforming impeller vanes, draws the liquid into the pump housing and moves it to the discharge port with a constant flow rate. The flexibility of the vanes enables a tight seal to the internal housing, making the pump self-priming, while also permitting bi-directional operation. The output from these pumps tends to be smooth or gentle when compared to the operation of a reciprocating pump (for example). In 1938, Arthur M. Briggs filed a patent for this type of pump. Uses. Particularly suitable for transfer of  viscous, delicate, and slurry fluids even with high solid content. Widely used in the oenological field, food processing, chemical industry, cosmetic and marine field. Materials. Pump housing can be made of high grade stainless steel, bronze for marine applications, or other materials. The impeller can be made of: The end face mechanical seal can be made of: