Lined pumps are a type of chemical pump designed for pumping chemically aggressive liquids. A characteristic feature of this type of pump is the presence of a coating of the flow path with chemically resistant plastic or rubber. For the coating (lining), in particular, materials such as PP (polypropylene), PVDF (polyvinylidene fluoride) are used. The lining of the flow path makes it possible to significantly reduce the cost of production of high-capacity pumps, since the main working parts of the pump (working chamber, impeller) are made of relatively cheap cast iron or steel with subsequent application of a chemically resistant coating.